Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A DEVICE AND METHOD FOR TEMPORARY OR PERMANENT SUSPENSION
OF AN IMPLANTABLE SCAFFOLDING CONTAINING AN ORIFICE FOR
PLACEMENT OF A PROSTHETIC OR BIO-PROSTHETIC VALVE
FIELD OF THE INVENTION
The present invention relates to medical devices and procedures, in particular
related
to the fixation within the heart or blood vessel of a device which enables
replacement of a
heart valve, and more particularly, to a novel device for use in a novel
procedure for
performing a catheter-based heart valve replacement.
BACKGROUND OF THE INVENTION
The four valves of the human heart consist of either two or three pliable
leaflets
attached circumferentially to a fibrous skeletal annulus. Normally, heart
valves function to
open in one portion of the cardiac cycle, either systole or diastole,
(depending on the valve),
causing minimal resistance to forward blood flow, but close by hinging from
the annulus
during the other part of the cardiac cycle, with the leaflets (either two or
three) coming into
central contact with each other, such that retrograde flow is inhibited.
Heart valve regurgitation, or leakage occurs when the leaflets of the valve
fail to
come fully into contact. This can be congenital, or the result of a disease
process.
Regardless of the cause, the leakage interferes with heart function, since it
allows the
unintended flow of blood back through the valve. Depending on the degree of
leakage, the
backward flow can become a self-destructive influence on not only function,
but also cardiac
geometry. Alternatively, abnormal cardiac geometry can cause the leakage, and
the two
processes are "cooperative" in causing acceleration of abnormal cardiac
function.
The result of a valve having significant regurgitation is that a pathological
state
develops in which blood may be simultaneously pumped both forward through the
outflow
valve of a chamber and backward through the inflow valve, decreasing forward
cardiac
output. Depending on the severity of the leakage, the capability and
efficiency of the heart to
pump adequate blood flow can be compromised. In the case of the two trio-
ventricular
valves, (the mitral and tricuspid), the process can be caused by myocardial
infarction
damaging papillary muscles located in the left (or right) ventricle, torn or
abnormally
elongated chordae tendineae, or in any valve through damaged valve structures
by infection,
degenerative processes, or stretching of the annulus such that leaflets no
longer come into
contact by virtue of the increased cross-sectional area. Stretching of the
ventricle and
increased distance between the papillary muscles can also cause leakage of the
atrio-
ventricular (NV) valves.
At present, for the most part, regurgitant valves can be either surgically
repaired or
replaced, both currently requiring open-heart surgery, use of cardio-pulmonary
bypass and
stoppage of the heart. Because of the magnitude of the procedure, risk of
death, stroke, and
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bleeding, respiratory, renal, and other complications is significant enough
that many patients
are not candidates for treatment. The heart or aorta must be cut open, and
even when
performed by very experienced surgeons, repairs can fail early, or, if
initially successful, are
not always durable over time.
In the case of the mitral valve, replacement with a prosthetic or bio-
prosthetic valve is
associated with a higher operative mortality than repair of the native valve,
but does not
result in recurrent regurgitation experienced after a repair. The higher
mortality is thought to
be the result of loss of the function of the papillary muscles of the left
ventricle, which are
attached to the mitral valve leaflets by cords known as chordae tendineae,
which contribute
to tethering of the leaflets and systolic shortening of the left ventricle.
However, with
preservation of these sub-valvular structures, the outcomes equalize, or may
be better in
severe cases with replacement and sub-valvular structure preservation. (See
Ann Thorac
Surg 2 81: 1153¨ 61.)
Even though the prognosis of surgically untreated mitral regurgitation is
poor, (see N
Engl J Med 2 352:875-83), only 33% of patients with significant regurgitation
are referred,
due to age, co-morbidities, or physician preference (see European Journal of
Cardio-thoracic
Surgery 34 (2) 935-936).
In the face of a severe, life threatening pathological process with no
treatment offered
to a majority of patients due to the magnitude of the risks of currently
available therapy, a
simpler, less invasive approach to treatment, such as a percutaneous device
that can
effectively eliminate regurgitation, yet preserve annulo-ventricular in atrio-
ventricular
connectivity and function, is severely needed.
For this reason, there is widespread development currently underway for
placement
of valves into the aortic (see Circulation Dec 2002 p. 3006-3008), and
Pulmonary, (see J.
Am. Coll. Card., vol. 39, May 15,2002, p. 1664-1669), positions. There are
currently a
variety of technologies for aortic replacement, but all generally have an
expandable support
structure for attached pliable leaflets, delivered either through the apex of
the ventricle or
retrograde through the aorta from the femoral artery (The Journal of Thoracic
and
Cardiovascular Surgery; October 2008, p 817-819).
Because of the asymmetry of the annuli, as well as the lack of rigidity, the
same
principals cannot be applied to the mitral and tricuspid valves, or in the
aortic valve in the
absence of calcification, as in most cases of aortic insufficiency. In the
mitral position,
several approaches have been pursued. Additionally, in the case of the mitral
valve, radial
expansion of a prosthetic replacement could impinge on the aortic valve, with
which it shares
a portion of its annulus along the anterior mitral leaflet.
Primarily, remodeling or alteration (to support or decrease the size) of the
mitral
annulus by various means has been a focus of intense interest. Some of the
most tested of
these are those that rely on the perceived anatomic proximity between the
posterior annulus
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and the coronary sinus (see Webb, et al). Although initially promising, the
coronary sinus
has been shown in virtually all cases to course on the atrial side of the
mitral annular plane,
and averages 7 to 11 mm from the annulus, and the distances are variable.
Moreover, the
distances increase in subjects with mitre! regurgitation. (See Choure, et al,
J Am. Coll. Card.;
Vol. 48, No. 10, 2.) The approach has been largely abandoned.
Another approach is the central apposition of the anterior and posterior
leaflets at the
midpoint, mimicking the so-called "Alfieri stitch". The benefit comes from
creation of central
coaptation. Devices to create this reconfiguration have been tested and
commercialized, but
do not control regurgitation to the degree achieved in replacement.
In general, current heart valve replacement procedures generally require
invasive
surgery. This, of course, is a long, difficult and complex process and
requires that the patient
endure significant, invasive surgery. While various alternatives have been
proposed to
minimize this trauma, there is still a need in the art to further reduce such
potential injury.
SUMMARY OF THE INVENTION
Recently a number of prosthetic valve-replacement devices have been developed
that can be delivered through a trans-catheter approach, and that expand into
the natural
annulus of a native valve. Since the mechanism of fixation of these valves is
generally radial
expansion, either actively or passively, a rigid annulus, (such as with
calcification or a
previously placed surgical valve or ring), is required, or the replacement
valve would distort,
or even rupture the heart. In many cases of valve pathology, the disease
process does not
include a rigid annulus or fibrous skeleton of the heart. Consequently, the
benefit of these
advances is limited to specific pathological states.
Proof of the concept has been published in the medical literature in a very
similar
way. Inelastic rings were surgically implanted adjacent to the native mitral
valve of sheep.
One week later, percutaneous valves were successfully expanded into the rings
in all five
animals. (See Journal of the American College od Cardiology, Vol. 58, No. 24,
2011.) The
current invention enables the implantation of the ring, or neo-annulus,
through a catheter.
U.S. Patent Application Publication No. 2010/0262232 and International Patent
Application No. PCT/US2010/001077 describe an implantable scaffold that
contains a neo-
annulus into which a prosthetic or bio-prosthetic valve could be implanted.
The present
invention seeks to provide a means through which that scaffold, which is
rigid, can be
inserted such that the radially expanding, trans-catheter valve concept can be
extended to
valves with pathology not currently amenable to this approach.
In a surgical method for improving cardiac function in accordance with the
present
invention, an implantable scaffold or valve support device is inserted inside
a patient's heart
(or blood vessel) and attached in a region adjacent to a natural or native
valve. In the heart,
the scaffold or valve support may be anchored to the heart wall and/or to the
native valve
itself. The scaffold or valve support device defines an orifice which receives
a prosthetic or
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bio-prosthetic valve after disposition of the scaffold or support device in
the heart and either
before or after anchoring of the scaffold or support to the heart.
A catheter is placed into the appropriate location, and the scaffold assembly
is
delivered out the tip of the catheter. The scaffold is positioned in part by
steering the delivery
catheter and in part by manipulating tethers or wires that are removably
attached to the
scaffold. The wires may be flexible, steerable, or relatively stiff, and may
be pre-formed or
made of a component with a memory. In one embodiment of the invention, through
use of
specific fixation methods and devices disclosed herein, the scaffold is then
fixed at its margin
or body to a heart or blood vessel wall adjacent to a native valve. In
sequence, the scaffold
is delivered, positioned, and then fixed to the heart or blood vessel wall.
With the scaffold or
heart valve support system in place, a prosthetic valve can be installed in an
annulus or
aperture of the scaffold. In an alternative approach described herein, after
the scaffold is
ejected from the distal end of the delivery catheter into a heart chamber and
expanded from
a collapsed insertion configuration to an expanded deployment configuration, a
prosthetic
valve is seated in an orifice of the scaffold and the combined assembly is
attached, through
use of specific fixation methods and devices disclosed herein, to the leaflets
or the
subvalvular apparatus of the native valve.
In the case of AV valves, the scaffold or valve support device is at least
indirectly
secured to chordae tendineae, and therefore, the papillary muscles of the
heart. Such a
device can distribute forces to the prosthetic valve similar to those typical
of the normal,
native valve. Thus, the attached or entrained chordae tendineae serve to
retain the scaffold
and prosthetic valve in position in opposition to systolic blood pressure. The
current
invention involves in part a method and an associated device for capturing the
natural valve
and concomitantly and indirectly the subvalvular apparatus and incorporating
those
structures into the scaffold or heart valve support system, or to the
prosthetic valve.
Where the native valve is captured and coupled to a combined
scaffold/replacement
valve assembly, the scaffold and the replacement valve mounted thereto are
attached to the
leaflets of a native valve so that the scaffold and the replacement valve are
in fluid-sealing
engagement with the leaflets. Closure devices may be provided to close
commissure gaps,
if necessary.
During the implantation procedure, the valve-supporting scaffold may be
attached to
the heart chamber or vessel wall via at least one but more preferably a
plurality of flexible or
rigid tensile suspension element(s) or alternatively the scaffold may be held
in place by
tethers or other supporting elements extending from a delivery or deployment
catheter. In
either instance, the scaffold or neo-annulus, or the assembly of the combined
replacement
valve and scaffold or neo-annulus, are attached to the native valve, such that
all forces
normally borne by the native valve, and to which the replacement valve is now
subjected,
are transmitted to the native valve, and its subvalvular apparatus, in the
case of atrio-
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ventricular valves.
A scaffold or neo-annulus in accordance with the present invention, if
employed in a
setting wherein attachment of the valve directly into the annulus of a native
heart valve is not
ideal, possible, or otherwise feasible, enables valve placement wherein it
otherwise could
not occur, yet maintains the normal transmission of forces from the
replacement valve to the
native valve. The present invention provides devices and mechanisms for
fixation of the
suspension elements to the heart or vessel wall, as well as devices and
mechanisms for
incorporation of the sub-valvular apparatus, in the case of atrio-ventricular
valves, (or to the
native valve in the case of ventricular outflow valves), to the implanted
scaffold or neo-
annulus.
Fixation of Neo-annulus Suspension Elements to Heart or Blood Vessel Wall
Deployment of a replacement valve through a trans-catheter approach requires
first
that there is a stable, inelastic valve support scaffold with an orifice into
which the
replacement valve can be inserted. Stability can be achieved through fixation
of such a
valve support scaffold to the heart or blood vessel wall. In this embodiment,
the process
requires first that the scaffold or valve support device be suspended or
supported. This
scaffold-like element defines, in one embodiment, of an orifice into which the
valve will
ultimately be deployed, which is suspended by one or a plurality of structural
elements of the
device, which fixes it to a heart or blood vessel wall.
Therefore, the neo-annulus scaffold may be actively suspended from the heart
or
blood vessel wall through the use of one or more suspension elements, each an
elongate
flexible tensile element. The suspension element(s) may be actively or
automatically affixed
to the heart or blood vessel wall. In the case of active attachment, the
suspension
element(s) may each be provided with a deployment tether that extends through
the
deployment catheter to a site of proposed fixation on the suspension element
to the heart or
blood vessel wall (for example, the end of suspension component remote from
its
attachment the neo-annulus). With the neo-annulus supported in its desired
location, the
end of the suspension element is advanced to the proposed site of fixation on
the heart or
blood vessel wall, and a helical or alternatively-shaped, screw-type fixation
or similar
component or a pronged staple or other fixation element is used to secure the
suspension
element to the heart or blood vessel wall.
Once the appropriate locus for fixation of the suspension component(s) on the
heart
or blood vessel wall has been reached, the tethers used to deliver fixation
device(s) to the
suspension element(s) may be used both to create fixation and to
manipulate/position the
suspension element(s). By advancement of the fixation device(s) over the
tether(s), a
means is provided whereby manipulation of fixation elements and placement of
the elements
in a specific location in the heart or blood vessel wall. Fixation of the
suspension element(s),
once achieved, provides support for the neo-annulus, because of its connection
to the heart
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or blood vessel wall by (an) intervening member(s), which is (are) the
suspension
element(s).
The attachment, or fixation, of a suspension element to the heart or blood
vessel wall
may be made by a separate component, such as a staple, clip or device of other
appropriate
design delivered by a separate component, or may be an integral part of the
suspension
element itself, such as a burr, barb, hook, or other appropriate fixation
element. In general,
the suspension elements are likely to be sigmoid or somewhat linear
structures, extending
radially from the orifice-defining neo-annulus scaffold to the point of
attachment to the heart
or blood vessel wall.
The suspension element or elements are generally part of the construction of,
or
attached to, the scaffold or neo-annulus as a whole, and are attached or
otherwise fixed to
the scaffold, extending to the heart or blood vessel wall, wherein the
suspension element(s)
are attached. However, the suspension elements may be separate structures and
be
delivered and attached to the neo-annulus in-situ. The suspension elements may
be of any
length, so that the neo-annulus may be somewhat distant, very near, of even
essentially in
contact with the wall adjacent to the valve or annulus.
In one embodiment, the orifice-defining neo-annulus scaffold preferably takes
the
form of a ring. The ring made be made of nitinol or other shape-memory
material with a
temperature induced memory or other means by which the scaffold assumes a
substantially
rigid, or at least inelastic configuration of pre-determined shape after
ejection from the
delivery or deployment catheter. Alternatively, it may be passively expanded
and be made
of another appropriate material, such as a weave, fabric, or monofilament
material. The
scaffold is optionally provided with the above-described linear suspension
components,
which are extendible outwardly to attach to the heart or blood vessel wall
near the native
valve for which replacement is intended. The suspension elements may be of any
length or
shape, and may appear like spider legs, or as ring-topped, flattened tripod
(in in instance
wherein three such elements are used). They are constructed preferably of a
spring-like
material and are curved to allow for fixation to a heart or blood vessel wall
of variable
contour, as well as for excursion of the neo-annulus toward or away from the
valve as
necessary, but may be in any appropriate configuration.
The suspension components or "legs" are, in an especially preferred
embodiment,
permanently attached/constructed to the valve-support ring, but are of a
material and design
that allows them to assume a folded or collapsed configuration within the
delivery catheter.
The suspension elements may be actively extended by deployment tethers
operated from
outside the subject or automatically extended, in the case of a spring-like
material, when
released. Also, the suspension elements may either be actively guided toward,
or designed
in a way as to extend automatically to, the heart or blood vessel wall,
wherein fixation of the
ends of the suspension elements to the heart or blood vessel wall will ensue.
Alternatively
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they may be actively deployed, as by balloon expansion or other method.
In the passive-fixation iteration of the device, each of the one or more
suspension
elements has a barb, hook or other appropriate fixation element at its free
end. Apposition
of the hook, barb, or other appropriate fixation element to the heart or blood
vessel wall
results in attachment of the respective suspension element to the heart or
blood vessel wall.
This automatic attachment may be by an expansion or piercing or other passive
fixation
element. The suspension elements are each configured to passively connected to
the heart
or blood vessel wall. In the most preferred iteration, the hook, barb, burr,
or other
appropriate component is manipulated by a tether or other similar component of
the
suspension capable of the manipulation/engagement, but amenable to subsequent
removal.
This could occur through release of a self-expansile suspension element that
engages and
attaches to the heart or blood vessel wall as it expands, as in the case of an
expanding
metal or other memory-like material that expands when released and pierces the
heart or
blood vessel wall.
With the neo-annulus located adjacent to the native valve, allowing free flow
through
its center, and fixation to the heart or blood vessel wall adjacent to the
native heart valve, the
valve replacement process requires deployment of the valve, and simultaneous
or
subsequent capture of the native valve and fixation to the neo-
annulus/replacement valve
complex. In both iterations, the valve-capture tension elements are
incorporated into the
neo-annulus so as to transmit forces generated by cardiac function to the neo-
annulus, and
the tethers run over or near the tension elements to allow a "push-pull" on
the neo-annulus
relative to the native valve.
The orifice, which is more or less central to the device, is generally
circular or
becomes generally circular, and is defined by an inelastic scaffold or neo-
annulus into which
a replacement valve can be deployed, the scaffold or neo-annulus being
deliverable through
a delivery catheter placed at an appropriate position in a heart chamber or
blood vessel
through a percutaneous, trans-vascular approach.
Therefore, the valve-supporting scaffold is flexible and capable of being
collapsed,
folded, twisted, or otherwise compressed that it can assume a low profile for
delivery but
becomes a generally round or otherwise appropriate configuration after
delivery. The
scaffold or neo-annulus may be reconfigured passively or automatically, for
example, by
being made of a temperature-sensitive or non-temperature sensitive shape
memory material
that reconstitutes when liberated from a compressed or folded state.
Alternatively,
reformation into an appropriately round shape may be active, such as by
placement of a
central expansile element, such as an inflatable balloon, that actively
creates a round orifice
or central neo-annulus before deployment of a replacement valve.
In one embodiment, the orifice-defining neo-annulus scaffold preferably takes
the
form of a ring. The ring made be made of nitinol with a temperature induced
memory by
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which the scaffold, having been delivered in a flexible configuration, assumes
a substantially
rigid configuration of pre-determined shape after ejection from the delivery
or deployment
catheter. The scaffold is optionally provided with the above-described linear
suspension
components, which are extendible radially, or generally in an outward
direction, to attach to
the heart or blood vessel wall near the native valve for which replacement is
intended. The
suspension elements appear like spider legs, or as ring-topped, flattened
tripod (in in
instance wherein three such elements are used), or other appropriate
configuration. They
are constructed preferably of a spring-like material and are curved to allow
for fixation to a
heart or blood vessel wall of variable contour, and allow for excursion of the
neo-annulus
toward or away from the valve as necessary.
Since most replacement valves are deployed by radial expansion, the orifice or
neo-
annulus is preferably flexible for at least a given time after ejection from
the delivery
catheter, so as to allow manipulation and reconfiguration after delivery, but
also relatively
inelastic so that a radially expanded valve does not distort it. The valve-
supporting scaffold
or neo-annulus may therefore be constructed of a braided or monofilament metal
or other
appropriate synthetic or naturally occurring material with the appropriate
physical
characteristics.
The scaffold or heart valve support device is thus delivered through a
catheter in a
collapsed configuration, and so is compressible or otherwise reconfigurable to
fit into the
lumen of a delivery catheter. After delivery through the tip of a delivery
catheter, the scaffold
device is be suspended and fixed in a position adjacent to a heart valve for
which
replacement is considered, and into which a valve can subsequently be placed.
Suspension element(s), as well as the neo-annulus, may be covered or coated
with a
substance to enhance tissue ingrowth, prevent clot or blood adhesion, may be
drug eluting,
have heparin or other substance bonding, or or otherwise be constructed of a
material that
enhances tissue ingrowth, prevent clot or blood adhesion, or other properties
deemed to be
advantageous.
After suspension by the elements, attachment to the native valve leaflets and
replacement valve deployment follow essentially as disclosed hereafter.
Stabilization of Neo-annulus Through Temporary Support Through Delivery
Catheter
Prior to Capture of Native Vale/Subvalvular Apparatus, Without Fixation to
Heart or
Blood Vessel Wall
Deployment of a replacement valve through a trans-catheter approach requires
first
that there is a stable, rigid or inelastic neo-annulus, or orifice, into which
the replacement
valve can be inserted. Stability can be achieved through temporary support of
the neo-
annul us or orifice without permanent fixation to the heart or blood vessel
wall.
In this approach, the valve-receiving scaffold is suspended through or by the
delivery
system while the valve is deployed and the native valve leaflets are
incorporated into the
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neo-annulus or replacement valve. Thereafter, since fixation of the neo-
annulus and
replacement valve deployed therein to the native heart valve or subvalvular
apparatus is
completely supportive of the implanted devices, the connection to and support
from the
delivery system may be interrupted and the replacement-valve/neo-annulus left
in situ, with
forces on the replacement valve being transferred to the native valve (and the
subvalvular
apparatus, in the case of A/V valves), wherein they are borne in the normal or
natural
physiological state.
In this embodiment, the neo-annulus may be suspended by a single tether or a
plurality of tethers (preferably three or four) that allow both support and
positional
maneuvering of the neo-annulus. The tethers are removable when the need for
support no
longer exists. Thus the neo-annulus is deployed via the delivery system
connected to the
tethers, and after either actively or passively expanding, is positioned and
supported over
the orifice of the targeted native valve. Most preferably, the tethers are
placed over or near
tensile coupling elements having free or distal ends adapted to entrain,
capture, and grasp
native valve leaflets. The tethers are slidable relative to the
tension/tensile coupling
elements and engage the neo-annulus or scaffold so as to enable the operator
to push the
scaffold in a distal direction while holding or pulling on the tensile
coupling elements, thereby
approximating the scaffold (typically with replacement valve mounted thereto)
and the
leaflets of the native valve.
Regardless of the support/suspension strategy (suspension elements or
temporary
support through the delivery system), the suspended neo-annulus is supported
at least in
part by the positioning tethers that pass over the tensile coupling elements.
The tensile
coupling elements pass through or otherwise are incorporated into the
substance of the neo-
annulus. On the distal ends of the tension elements are devices for capturing
and entraining
the native valve leaflets, to retract the native valve leaflets and bring them
into contact or
near contact with the neo-annulus.
The devices for valve leaflet capture are hooks (e.g., grappling hooks),
barbs, clips,
burrs, or other appropriate entrainment components that allow
adherence/fixation of the
tension elements to the valve leaflets while still allowing their normal or
near normal
excursion. Thus, until engaged, valve leaflets have continued "normal" (or
with no or
minimal additional impediment), or near normal function until such time as
they are captured
and tethered/incorporated into the neo-annulus/replacement valve complex by
simultaneous
"forward" or distally (in the direction of forward blood flow) directed force
on the tethers and
retracting force on the tension elements within or near the tethers.
The hooks, barbs, clips, burrs, or other appropriate components may penetrate,
impinge, entrap, clip over, or in any other appropriate way engage the leaflet
so as to allow
tension to be placed permanently thereon by traction elements to which the
hooks, barbs,
burrs, or other appropriate components are attached. Since the tension
elements are
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incorporated into an aspect of the neo-annulus or central orifice, the valve
leaflets may be
pulled into contact with the neo-annulus or central orifice.
To create the excursion of the neo-annulus with its orifice toward the native
valve
leaflets in a preferred embodiment, the tension members are retracted or
pulled in a
proximal direction from the proximal end (i.e., outside of the body) as the
tethers, generally
tubular members surrounding portions of the tension members, are advanced in a
distal
direction from the proximal end of the delivery catheter. The opposing forces
cause the
valve-supporting neo-annulus or scaffold with its valve-receiving orifice to
move toward the
native valve. In general, since this excursion may also disrupt native
valvular function, it is
contemplated that the replacement valve will have been deployed into the
central orifice of
the neo-annulus or scaffold before the final approximation excursion is
generated.
It is possible for the neo-annulus to be delivered through a catheter passed
directly
through the heart wall. In the case of the AN valves, entry may be made
through a ventricle
and the neo-annulus suspended proximal to the valve on the atrial side. In
that approach,
the support of the valve or sub-valvular structures is achieved from the
ventricular side,
reversing the above-discussed neo-annulus seating and supporting procedure.
More
specifically, in order to approximate a valve support member or scaffold and
the leaflets of a
native valve to one another in a trans-ventricle procedure, the scaffold or
valve support
member may be pulled in the proximal direction (towards to operating surgeon)
while the
valve leaflets are held or pushed in the distal direction. In another event,
appropriate forces
are exerted in order to mover the scaffold or valve support member on the one
hand and the
valve leaflets on the other hand towards one another and into force-
transmitting and
effective fluid-sealing contact.
To permanently position the replacement-valve/scaffold complex in a fluid-
sealing
engagement with the valve leaflets, the tension or tensile coupling elements
preferably have
a "lock" such as a one-way incremental movement device in the nature of a
ratchet. The
ratchet may take the form of cooperating tooth formations and a tapered
passageway or
spring loaded latch, a cam, a compression device or other appropriate
component that
prevents the valve-supporting neo-annulus or scaffold member from moving away
from the
native valve, once having moved toward it. The lock may be built into the neo-
annulus or
scaffold, or be a separate component, advanced over the tension element toward
the neo-
annulus or central orifice.
Once the neo-annulus/replacement valve complex has become fixed to the native
valve, creating a seal, the neo-annulus is supported by the native valve
leaflets. The neo-
annulus or scaffold may be additionally supported by tensile suspension
elements attached
to the cardio-vascular wall, particularly in the event that such suspension
elements are used
to hold the neo-annulus or scaffold in place during the implantation
procedure.
After the securing of the neo-annulus or scaffold to the native valve
leaflets,
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positioning tethers can be removed, as well as proximal portions of the
tensile coupling
elements, The distal end portions of the tensile coupling elements remain in
place holding
the neo-annulus to the native valve leaflets in tension, the final position of
the neo-annulus or
scaffold being secured through the "lock" mechanism.
It is possible that after restriction/capture of the valve leaflets, the neo-
annulus/captured valve contact will not completely eliminate leakage around
the valve. In
one embodiment of an implantation system in accordance with the invention, an
inflatable or
otherwise expandable component such as an annular bladder can be enlarged
around the
neo-annulus to further inhibit paravalvular leak and enhance the seal between
the native
valve and the scaffold/replacement valve. This sealing component may initially
take the form
of a collapsed inner-tube-like component that is attached to the neo-annulus
or that is
separately delivered and positioned in situ. The inflatable sealing component
is provided
with an inflation tube through which air, saline solution, another fluid, or
other appropriate
substance, such as polymers, is infused, expanding the sealing component to
eliminate
potential or actual peri-valvular leak. After expansion of the sealing
component, the inflation
tube is removed /plugged, or otherwise eliminated from permanent connection
with the
inflatable sealing component. Also, a fluid, such as saline, may be initially
infused, but later
be exchanged for another, potentially permanent material, such as a polymer or
orher
material of appropriate properties.
In addition to acting as a means of resolving perivalvular leakage, the
circumferential
or partially circumferential inflatable component may be used simply as a
means to make the
apposition of native valve and neo-annulus less erosive, less distorting to
the heart, more
likely to fit a rigid neo-annulus/replacement valve complex into a generally
soft, beating heart
without long-term tissue change, or other potentially desirable
characteristics. In essence,
the inflatable component may impart the characteristics of a "sewing ring"
such as is found
on most valves constructed for open surgical implantation.
The inflatable sealing component may be delivered as a separate element, or be
a
part of the construct of the central orifice or neo-annulus. It may be
constructed of an
elastic material or one of fixed volume and/or shape, regardless of the
pressure of its internal
contents. It may be filled with fluid long-term, or have a permanent polymer
that can be
infused primarily, or as a replacement for an initial fluid or gas infusate.
It may be covered or
coated with a substance to enhance tissue ingrowth, prevent clot or blood
adhesion, may be
drug eluting, heparin or other substance bonding, or otherwise be constructed
of a material
that enhances tissue ingrowth, prevent clot or blood adhesion
Alternatively, an implantable clip, barb, staple or other approximation device
of
appropriate design may be placed at the site of a gap between native valve
leaflets for
bringing the leaflets into apposition around the scaffold or valve support
device to obliterate
a site of perivalvular leakage. One such device for perforating two nearby
tissue strictures
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has a multi-pronged or multiply legged "V", "U", "Y" structure or other
similarly shaped
component, such that after perforation of the generally two, or paired, barbs
on the clip into
the tissue structures, advancing the clip in one direction (in the examples
described, upward)
the perforation sites are brought into apposition.
Such a clip-like approximation device is constructed of a metallic or other
appropriate
material, may have memory, and are placed and manipulated through the delivery
system or
other means. It is affixed in place, as with bending the arms outward,
automatically
springing when released, fixation with a separate element, or other
appropriate means.
Alternatively, a spring-like device, suture-like device, staple-like device,
or other means of
apposing native valve leaflets at gaps may be used.
The leaflet approximation device may be introduced prior to introduction of
the
remainder of the implantable devices, creating a smaller orifice in the native
valve, and
enabling a potentially more complete circumferentially solid line of contact
between the neo-
annulus/replacement valve complex. Therefore the capture of the native valve,
introduction
of the scaffold, deployment of the replacement valve may follow apposition of
the
commissures, in order to diminish the size of the native vale orifice.
In general, in the implantation embodiment wherein the neo-annulus is only
temporarily supported by the delivery system while permanent fixation to the
native valve is
achieved (or if suspended by either elongate elements, as disclosed above, or
by a
membranous component disclosed previously, and after suspension has been
accomplished), the placement of the scaffold and replacement valve may consist
of a
procedure summarized as follows:
= A delivery system is inserted through the vascular system or heart wall
to an
appropriate site in a heart chamber or blood vessel near a valve to be
replaced.
= A device consisting of the tensile coupling elements for valve capture,
the
neo-annulus, suspension elements, if appropriate, support tethers, and other
components, as required, is advanced out of the delivery system.
= The valve leaflets are engaged by the tensile coupling elements
incorporated
into or attached to the neo-annulus. In some iterations, where a heart wall is
used for introduction, these tensile elements may be compressive.
= The neo-annulus is suspended to the heart or blood vessel wall if
appropriate,
or alternatively, supported only by tethers emanating from the delivery
system.
= The replacement valve is deployed into the neo-annulus.
= The native valve is retracted by the tensile coupling elements with
entrainment or capture components on their ends, such that the retracted
leaflets form a "gasket"-like element toward or around the perimeter of the
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replacement valve/neo-annulus complex, eliminating leak and retracting the
native valve out of the inflow or outflow tract to or from the native valve.
Separate or incorporated locking devices integrated with the tension elements
cause a "one-way" tightening of the tension elements, so that the leaflets are
retracted into the neo-annulus/replacement valve complex.
= The inflatable element, if used, is inflated to eliminate peri-valvular
leakage.
The initial inflation substance can then be replaced if appropriate, and
imaging confirms elimination of peri-valvular leak. Alternatively, a hook,
barb,
clip, or other device of appropriate design is placed into adjacent native
valve
leaflets at the site of a gap, such that valve leaflets are apposed.
= Tethers, tubes, extensions of tension elements are finally removed,
leaving
only the replacement valve, neo-annulus, and inflatable component or gap-
closure device, if used. Any other appendages associated with delivery,
deployment, stabilization, fixation, valve capture, inflation, etc. are
removed.
= As an alternative, the commissures may be apposed prior to the
implementation of the above sequence.
Capture of the native valve
With certain valves in the heart, specifically the atrio-ventricular valves,
the sub-
valvular structures are important for chamber function. It has been
recommended, therefore,
when replacement is performed rather than repair, that these structures be
incorporated into
the annulus of the new valve. (See M. A. Borger, et al Ann Thoracic Surg 2006;
81:1153-
1161.) The current invention provides a device and method for incorporation of
these
structures into the scaffolding, thereby preserving ventriculo-annular
contribution to systolic
function.
Accordingly, the current invention also contemplates a device and means for
attachment of the native valve, or sub-valvular structures (in the case of the
mitral or
tricuspid valves) to either the neo-annulus or another part of the implanted
scaffold. In the
principal embodiment, attachment elements consist of single or multiple hooks,
single or
multiple barbs, or other appropriate means of grasping the valve leaflet(s) or
chordae
tendineae, and attaching them either directly or with an intervening element
to some portion
of the scaffold, such that, in the case of the atrio-ventricular (AN) valves,
systolic ventricular
forces on a valve implanted into the neo-annulus will be transmitted to the
papillary muscles
and cords rather than to the fixation points of the scaffold margin alone,
thus preserving
systolic AN valvular/papillary function.
In a particularly preferred embodiment, the valve leaflets are "snagged" by
one or
more hooks or barbs. As discussed above, a device with multiple hooks is
incorporated,
through tensile or compressive coupling members, into the neo-annulus, and is
delivered
through the native valve orifice during the entrainment process by bringing
the neo-annulus
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toward the leaflets or subvalvular structures. The hooked device may be
advanced through
a catheter and across the native valve orifice prior to emergence through the
delivery system
of the neo-annulus and suspension elements, if used, or advanced from the
ventricle, in the
case where a transmural (across a heart wall) approach is used. In other
words, the valve
capture elements may be first out of the delivery system, followed by the neo-
annulus,
followed by the suspension elements, if used, or the last, depending on the
direction of
deployment and delivery. In this way, minimal delivery system size may be
possible. Other
sequences of delivery are possible.
The hooks, barbs, clips, or other appropriate components attached to the
tensile
coupling elements may precede the delivery of the remainder of the scaffold
out of the
delivery catheter. The hooks, barbs, clips, or other appropriate components
may have one or
more separate delivery components, which enable the capture of the leaflets.
The hooks,
barbs, clips, or other appropriate components are removably or temporarily
attached to the
delivery or deployment device, which may advance the hooks or barbs out of the
catheter
and into the valve orifice as noted above. In a preferred approach, the hooks
may "snap"
into a delivery element, or may be freely advanced through a native valve, and
are passed
from a delivery catheter through the valve orifice, between leaflets. The
delivery element
may have the capability of manipulating the location on the native valve
wherein the hooks,
barbs, clips, or other appropriate components are engaged to the native valve.
Alternatively, the delivery catheter may cross the native valve, deliver the
hooks,
barbs, burrs, or other valve capture elements, then retract back across the
native valve
before releasing the neo-annulus and other components.
The deployment elements may then orient the hooks or barbs, and subsequently
release them once the leaflets were engaged by the hooks or barbs. The tensile
coupling
elements on the hooks may be used to further manipulate the hooks or barbs,
such as
twisting or applying tension to increase or maintain purchase of the hook or
barb on the
leaflet.
In a preferred embodiment, tension or tensile members attached to the hooks or
barbs used to capture the valve leaflets may be permanently attached to or
through a
retention element of the scaffold or neo-annulus, generally at outer edge, so
as to facilitate
the apposition of the native valve around the edge of the neo-
annulus/replacement valve
complex. Alternatively, the elements may be secondarily attached to the neo-
annulus or
scaffold.
Because the coaptation surface of some valves is linear, while the replacement
or
prosthetic valve to be placed is round, it may be desirable to have the hooks
or barbs
dispersed or spread around the perimeter of the neo-annulus/replacement valve
complex. In
the most preferred embodiment, the tension/tensile members are preferably
distributed at
intervals around the neo-annulus. Alternatively, they may be spread separately
after exiting
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from their connection to the central orifice on neo-annulus.
Therefore, there may be a feature of the deployment element that fans out or
separates the hooks or barbs as they leave the delivery catheter. Such a
device element
may consist of a released spring, elastic material, pre-shaped memory
substances, active
opening, or other appropriate means of dispersing or separating the hooks or
barbs over a
length of valve leaflet before attachment of the valve-grasping element to the
scaffold or
valve support system.
In order to assist in the delivery of the valve-capture elements, which are
hooks,
barbs, or other appropriate elements designed to engage the native valve
leaflets, the
hooks, barbs, or other appropriate elements may be collapsed or otherwise
constrained into
a lower profile configuration. This enhances delivery and minimizes native-
valve functional
disruption prior to fixation to the native valve, replacement valve
deployment, and native
valve capture. As such, the hooks, clips, barbs, or other appropriate elements
may be
actively configured into a low profile, as when bound by a fabric or other
constraint element,
which is removed or otherwise released prior to engagement with the valve
leaflets.
Alternatively, the hooks, barbs, or other appropriate elements may be formed
of a self-
expanding material, such that the intended profile/configuration may be taken
on after
delivery.
Tethers, tension elements, infusion ports, or other appendages, if fixed to
the
implantable devices, may be severed or otherwise separated from the
implantable devices
through the use of an end-cutting device, which can be individually passed
over or near the
appendage. Alternatively, an attenuated area may be constructed into the
appendage such
that a natural breakage site can create a severance by twisting, pulling or
otherwise
manipulating the appendage. Other means of separating tethers, tension
elements, infusion
ports, or other appendages, if fixed to the implantable devices, as
appropriate, may be
employed, either through the characteristics of the ancillary elements or
appendages, or
through introduction of a separate component to create the separation, as
appropriate.
The present invention allows attachment of the central orifice or neo-annulus
to the
heart or blood vessel wall by a continuous suspension element (previously
disclosed, see
U.S. Patent Application Publication No. 2010/0262232 and International Patent
Application
No. PCT/US2010/001077), by discontinuous suspension components, with or
without a
specific margin. Alternatively, the central orifice or neo-annulus may be
supported only by
the delivery system until fixation of the orifice ore neo-annulus to the
native valve can be
achieved.
In the current disclosure, the scaffold can be secured to the heart or vessel
wall, such
that a valve may be delivered through a limited intrusion by utilizing a
catheter to deliver and
assemble the heart valve components in-situ. This disclosure describes a
scaffold which
may be attached to the heart or blood vessel wall in a limited way, or else
simply stabilized
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while the valve is inserted, deployed, and subsequently affixed to the native
valve, rendering
the initial attachment of the scaffold, or neo-annulus of lesser or only
temporary importance
to the ultimate fixation of the replacement valve.
Because the replacement valve must be deployed into approximately the same
location as the native valve, it is necessary to alter the position of the
native valve. In the
current invention, a mechanism for pulling the native valve leaflets toward
the periphery of
the neo-annulus and away from the valve center is also provided
Because this fixation of the generally round scaffold, or neo-annulus to the
native
valve would require that the two be more-or-less sealed circumferentially, it
is possible that
native valve leaflets may require plication or otherwise reconfiguration, such
that peri-
valvular leakage does not occur. A device and method for achieving this
reconfiguration is
disclosed herein.
Attachment of scaffold to heart wall via fasteners slid along respective
tethers
The present invention provides devices and mechanisms for fixation of a margin
of a
scaffold or vavle support device to the heart or vessel wall, as well as
devices and
mechanisms for incorporation of the sub-valvular apparatus, in the case of
atrio-ventricular
valves, to the implanted scaffold or neo-annulus..
In the principal embodiment of the present invention, the scaffold has a
series of
tethers or support elements attached to its outer edge or margin at intervals
around its
circumference. In this iteration, there are preferably primary and secondary
tethers. The
margin of the scaffold or valve support is attached to the heart or vessel
wall at the points on
the margin where the primary tethers are attached. Because three points
determine a plane,
in most cases there are three primary tethers (but could be more or fewer).
Secondary
tethers may be used to position additional fixation points of the scaffold
margin after the
scaffold margin is attached to the implantation site at the primary points. In
some cases it
may not be necessary for the secondary tethers to have the ability to
manipulate the margin
of the scaffold.
The scaffold, which is generally delivered through the lumen of a catheter, is
advanced out the tip of said delivery catheter and manipulated in into the
desired position
through the process of advancing or retracting the primary tethers. The
delivery catheter is
advanced through the blood vessels or cardiac chamber of the patient and
positioned in the
appropriate site for scaffold delivery and subsequent fixation. In general,
the scaffold is
crimped or otherwise packed in the catheter lumen, then pushed or otherwise
extruded from
said catheter. The scaffold may expand automatically from the collapsed
insertion
configuration to the opened implantation configuration.
In a preferred embodiment, the tip of the delivery catheter is steerable in at
least one
direction, such that the position of the scaffold can be directed to the
proper location, not
unlike a movie projector aims a film image at a screen. The steering element
may be a
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property of the delivery catheter on by placing a movable element into the
catheter lumen
after the scaffold has been advanced. The scaffold can be moved toward the
appropriate
location by advancing or otherwise manipulating the tethers. The orientation
of the scaffold
is controlled by differentially advancing the tethers, particularly the
primary tethers.
Steerability may not be needed in instances where a heart wall is the site of
introduction of
the delivery system.
Once the appropriate locus of the scaffold margin has been reached, the
tethers
serve not only as holders to maintain position of the scaffold position, but
also as support for
passage and placement of margin fixation devices. In this embodiment, the
sites and
number of fixation points are determinable by the number and spacing of the
primary and
secondary tethers around the scaffold margin.
Once fixation is deemed to be satisfactory, and fasteners have been advanced
or
otherwise placed, the tethers are detached from the scaffold margin, leaving
the scaffold,
attached at intervals around its circumference, to the heart or blood vessel
wall. By
advancement of the fixation devices over the tethers, a means is provided
whereby
manipulation of fixation elements and placement of those elements at specific
points around
the circumference of the scaffold from a remote location and through a
catheter is possible.
Fixation of the outer scaffold margin to the heart, once achieved, provides
support for the
neo-annulus, because of its connection to the margin by an intervening member
such as a
membrane.
In a principal iteration, fixation elements slide over the primary and
secondary
tethers, advanced by sheaths slidably positioned around and over the tethers.
The fixation
elements, in one form, consist of individual screw-like devices, each of which
is located on a
respective one of the tethers. The devices in this case each comprise a double
helix
attached to a cap that may take the form or a circular disk. The cap has a
hole and is passed
over the tether (the tether traversing the hole), such that the screw-like
fixation device can be
advanced over the respective tether to the margin of the scaffold and into the
heart or vessel
wall.
The double helix can be either twisted or simply pressed into the wall.
Typically,
pushing the associated sheath in the distal direction over the respective
tether and against
the cap of the screw-like fastener or fixation device first causes the distal
tips of the helix
wires to insert into the tissue and then induces turning of the helix about
its longitudinal axis.
The helices may have one or more barbs or other elements to inhibit their
unintended
dislocation. Such a barb or other element may be activated after acceptable
deployment
has been achieved. Once the fixation element is embedded in the heart or blood
vessel
wall, the tether can be detached (for instance, by a twisting action or a
simple withdrawal),
leaving the fixation element holding the scaffold margin to the wall. In this
instance, the cap
can straddle the margin with one or both of the helical elements perforating
the membranous
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element.
Alternatively, the fixation elements or fasteners may take the form of a
double,
pronged or pincer-like staple or other appropriate design, pre-formed or super-
elastic
element that, when applied to the margin over the tether, fixates the margin
to the heart or
vessel wall. There may be an element of the device in this instance to hold
the margin
element with or without perforating the membranous element of the scaffold.
In any fastener or staple design, there may an element in the cap of the
fastener or
staple that prohibits the dislodgement of that fastener. For example, the cap
of a helical
fixation element may have a pin, which when advanced, enters the heart or
blood vessel wall
and prohibits unintentional untwisting and removal. Similarly, staples or
pronged fasteners
may have a spring-loaded barb or hook, which advances into the heart or blood
vessel wall
with no resistance but prohibits withdrawal of the staple.
The tethers may be disconnected from the scaffold after fixation either by
unscrewing, twisting to fracture, or other means of separation from the margin
of the
scaffold. Alternatively, a tool can be introduced into the target heart or
blood vessel that is
manipulated to induce the separation.
With certain valves in the heart (specifically the atrio-ventricular valves),
the sub-
valvular structures are important for chamber function. It has been
recommended, therefore,
when replacement is performed rather than repair, that these structures be
incorporated into
the annulus of the new valve. (See M. A. Borger, et al Ann Thoracic Surg 2
81:1153-1161.)
The present invention provides a device and method for incorporation of these
structures
into the scaffolding, thereby preserving ventriculo-annular contribution to
systolic function.
Accordingly, another feature of the present invention relates to a device and
means
for attachment of the native valve, or sub-valvular structures (in the case of
the mitral or
tricuspid valves) to either the neo-annulus or another part of the implanted
scaffold. In the
principal embodiment, these consist of one or more hooks, clips, barbs, or
other appropriate
means of grasping the valve leaflet(s) or cordae tendineae and attaching them
either directly
or with an intervening element to some portion of the scaffold, such that, in
the case of the
atrio-ventricular (NV) valves, systolic ventricular forces on a valve
implanted into the neo-
annulus will be transmitted to the papillary muscles and cords rather than to
the fixation
points of the scaffold margin alone, thus preserving systolic A/V
valvular/papillary function.
In a preferred embodiment, the incorporation of the valve or sub-valvular
elements is
accomplished after the scaffold or valve-support device has been fixed to the
heart or blood
vessel wall. A separate tool is then introduced into the chamber or blood
vessel whereby the
valve leaflets are "snagged" by one or more hooks or barbs. In a most
preferred
embodiment, a device with multiple hooks is advanced through a catheter and
across the
valve orifice when it opened, as in forward flow, and retracted when the valve
closes,
piercing or otherwise capturing the leaflets, such that they (the leaflets)
can be pulled into
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the scaffold as desired. In such an embodiment, the hooks or barbs separate so
that the
individual leaflets are not tethered to each other when the cycle requires the
valve to open,
thereby avoiding an obstruction.
The hooks or barbs, which actually capture or entrain the leaflets, may be
reversibly
or temporarily attached to a delivery or deployment device, which advances the
hooks or
barbs out of a catheter and through the valve orifice as noted above. In one
iteration, the
hooks attach or snap into a deployment element, which is passed from a
delivery catheter
through the valve orifice, between the leaflets. The delivery or deployment
device then
orients the hooks or barbs, and either actively or passively releases them
once the hooks or
barbs engage the leaflets. Tethers (tensile elements) may be attached to the
hooks or barbs
for use in further manipulating the hooks or barbs, such as by twisting or
applying tension to
increase or maintain purchase of the hooks or barbs into the leaflets or
subvalvular structure.
Because the coaptation surface of some valves is linear or planer, while the
replacement or prosthetic valve to be placed is round, it may be desirable to
have the hooks
or barbs dispersed or spread around the perimeter of the replacement valve.
Therefore,
there may be a feature of the deployment element that "fans out" or separates
the hooks or
barbs as they leave the delivery catheter. Such a device element could consist
of a released
spring, elastic material, pre-shaped memory substances, active opening, or
other
appropriate means of dispersing or separating the hooks or barbs over a length
of valve
leaflet before attachment of the valve-grasping elements to the scaffold or
valve support
system.
The present invention contemplates snagging the valve leaflets and rolling
them up
into the new valve annulus or into the scaffold or valve support system. The
natural valve
leaflets are generally disabled by being marginalized, around the edge of the
new valve or
neo-annular element of the scaffold or heart valve support system. This
procedure is akin
to gathering a curtain at the edge of a window and wrapping it tight to the
new frame. In the
case of the AN valves, the cordae tendenae, which are still attached to the
papillary muscles
or ventricular wall, transmit their forces to the margin of the new valve or
the scaffold. The
force generated by ventricular systole keeps the prosthetic valve and scaffold
from
being dislodged into the atrium.
Another issue is that the anterior leaflet of the mitrel valve, if
malpositioned,
can obstruct the LV outflow tract causing subvalvular aortic stenosis. This is
called "SAM",
or systolic anterior motion, and can be the consequence of mitral repair done
imperfectly.
With a pure in-valve replacement of the mitral, the anterior leaflet may be
displaced into the
sub-aortic position, which would potentially create SAM and could be
deleterious to cardiac
function.
The present invention contemplates a leaflet capture device with hooks, barbs,
or
other appropriate components that grasp and entrain the valve leaflet edges
and curl the
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leaflets against the replacement valve annulus or scaffold margin, thereby
retracting and
disabling the leaflets around the margin of the replacement valve or into the
scaffold. This
procedure has the additional benefit of sealing the edge or margin of the
scaffold against
leakage. The bunched up leaflets serve as a "gasket" against leakage of blood
back into the
atrium, thereby making discontinuous attachment to the heart or blood vessel
wall of the
scaffold margin to the atrial wall feasible from a standpoint of valvular or
pen-
valvular regurgitation.
In the case of the aortic or pulmonary valves, the scaffold or heart valve
support
system would be fixed either on the ventricular or arterial side of the valve
with fixation
thereto. In the case of the aortic valve, if placed in the aorta, the scaffold
or valve support
system is perhaps best placed in a sub-coronary ostial position so as not to
obstruct
coronary flow. In this application of the invention, the hooks, barbs or other
appropriate
components for grasping the valves are modified to grasp or entrap the
leaflets from the
convex side of the leaflet, thereby ensnagging or otherwise achieving leaflet
fixation on or
through the ventricular surface or coaptation surface/margin of the valve.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic longitudinal cross-sectional view of a delivery
catheter
containing an implantable device in accordance with the present invention, in
a collapsed,
low profile configuration to facilitate minimally invasive access.
Figure 2 is a schematic side elevational view of a tubular tether surrounding
a
proximal portion of an elongate tension member or tensile coupling element
provided at a
free or distal end with an entrainment element in the form of a grappling
hook.
Figure 3 is a schematic side elevational view of the delivery catheter of
Figure 1 as
advanced through a vascular system of a subject to a native heart valve.
Figure 4 is a schematic side elevational view similar to Figure 3, showing a
multiplicity of hook-like entrainment or capture elements on tensile coupling
members as
shown in Figure 2, advanced inside the native valve of Figure 3 into a heart
chamber or
blood vessel.
Figure 5 is a schematic side elevational view similar to Figures 3 and 4,
showing the
delivery catheter retracted back across the native heart valve with the hooks
and tension
members remaining in place.
Figure 6 is a schematic perspective or side elevational view similar to
Figures 3-5,
showing partial extrusion or ejection of a neo-annulus scaffold or valve
support member from
the delivery catheter, while hooks and tension elements remain in place
adjacent to the
native valve leaflets.
Figure 7 is a schematic perspective view similar to Figures 3-6, showing the
scaffold
expanded in a heart chamber or blood vessel, ready for manipulation or
positioning by a
series of tethers like the tether of Figure 2.
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Figure 8 is a schematic perspective view similar to Figures 3-7 showing
initial
purchase or entrainment of the native heart valve leaflets by the hooks of the
tensile
coupling elements, which condition of initial entrainment still allows normal
or near normal
valve function.
Figure 9 is a schematic perspective view similar to Figures 3-8, showing a
prosthetic
or bio-prosthetic replacement valve deployed into an orifice of the scaffold
or valve support
member.
Figure 10 is a schematic perspective view similar to Figures 3-9, showing a
neo-
annulus/replacement valve complex advanced towards the orifice of the native
valve by
exertion of a retractive or proximally directed force on the tensile coupling
elements and a
simultaneous exertion of a pushing or distally directed force on the tubular
tethers.
Figure 11 is a schematic perspective view similar to Figure 10, showing
further
advancement of the neo-annulus/replacement valve complex towards the orifice
of the
native valve.
Figure 12 is a schematic perspective view similar to Figures 3-11, showing a
seating
of the neo-annulus/replacement valve complex into the orifice of the native
valve and full
retraction of the tension or coupling members.
Figure 13 is a schematic perspective view similar to Figure 12, showing the
neo-
annulus/replacement valve complex seated the orifice of the native valve after
removal of the
tethers and severing of the tensile coupling elements.
Figure 14 is a schematic perspective or side elevational view, showing a step
of an
alternative valve implantation procedure, wherein a ring-shaped neo-annulus
scaffold or
valve support member is provided with a plurality of elongate flexible
suspension elements
that are fixed to the heart or blood vessel wall via respective removably
attached deployment
tethers that deliver staples or clips.
Figure 15 is a schematic perspective view similar to Figure 14, showing the
neo-
annulus scaffold supported by the deployed elongate suspension elements of
Figure 14, and
with the deployment tethers of Figure 14 removed, ready for valve capture and
replacement
valve deployment, followed by advancement of the complex into the native valve
orifice.
Figure 16 is a partial schematic perspective view similar to Figure 14,
showing a
detail of an alternative, auto-fixation, method of attachment of a suspension
line to a heart or
vessel wall.
Figure 17 is a schematic plan view of a native mitral valve, showing valve
commissures.
Figure 18 is a schematic plan view similar to Figure 17, showing a ring-shaped
neo-
annulus scaffold in place over the native mitral valve. Hooks for valve
leaflet capture and the
associated tensile coupling elements are visible through the orifice of the
neo-annulus
scaffold while the positioning tethers of Figure 2 extend between the delivery
catheter and
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the neo-annulus, the lumen of the catheter being shown in cross-section.
Figure 19 is a schematic plan view similar to Figures 17 and 18, depicting the
neo-
annulus scaffold in position abutting the valve leaflets and with a prosthetic
or bio-prosthetic
replacement valve deployed, further depicting commissures leaving gaps in the
seal around
the neo-annulus, resulting in a perivalvular leak.
Figure 20 is a partial schematic perspective view of the neo-annulus scaffold
and
replacement valve of Figure 19 in position abutting the native-valve leaflets,
illustrating a gap
at a commissure, and also schematically illustrating locks on the tensile
coupling elements
holding them in place relative to the neo-annulus.
Figure 21 is a series of three side elevational views of a tissue
approximation clip or
anchor in three configurations relative to apposed valve leaflets, initially
inserted through a
commissure gap, then retracted causing apposition of the leaflets and a
filling of the gap,
and finally with prongs bent for permanent placement.
Figure 22 is a partial schematic perspective view similar to Figure 20,
showing the
anchor-shaped clip of Figure 21 deployed for leaflet-edge approximation.
Figures 23A and 23B are a pair of partial schematic cross-sectional views of
an
annulus or ring-shaped valve support member, a tether and a tensile coupling
element,
Figure 23A showing a collapsed bladder-like component, along with an inflation-
port, Figure
23B showing the bladder-like component after inflation.
Figure 24 is a schematic partial side elevational view of a neo-annulus
scaffold in
apposition with a captured valve leaflet with the inflatable component of
Figures 23A and
23B in an expanded configuration sealing a line of contact and with infusion
tube and port
still attached.
Figure 25 is a partial schematic perspective view similar to Figure 22,
showing a
bladder-like sealing component disposed around a periphery of the neo-annulus
scaffold in a
deflated insertion configuration.
Figure 26 is a partial schematic perspective view similar to Figure 25,
showing the
bladder-like sealing component in an expanded sealing configuration, covering
or closing a
gap between valve leaflets.
Figure 27 is a schematic side elevational view of ratchet-type locking
components
provided on the neo-annulus scaffold and the distal end of a tensile coupling
element to
allow only one-way excursion of the tensile coupling element and its appended
valve-capture
or entrainment element (not shown), the tether being pushed in the distal
direction and the
tensile coupling element being pulled in the proximal direction to clamp the
neo-annulus
scaffold and attached replacement valve to the valve leaflets.
Figures 28A and 28B are a schematic perspective view and a schematic
longitudinal
cross-sectional view, respectively, showing another embodiment of a ratchet
mechanism.
Figure 29 is a schematic perspective view of a neo-annulus scaffold with
collapsed
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perimetral closure bladder, tensile coupling elements with distal hooks
entrained to the ends
or edges of native valve leaflets, and tubular tethers extending from the
distal end of a
delivery catheter and holding the scaffold in position for installation.
Figure 30 is a schematic perspective view similar to Figure 29, showing a
replacement valve mounted to the neo-annulus scaffold.
Figure 31 is a schematic plan view of the neo-annulus scaffold of Figures 29
and 30
in place above the native mitral valve with native valve capture and the
"sewing ring" or
closure bladder inflated, but with the replacement valve omitted.
Figure 32 is a schematic side elevational view of a helical fastener with a
truncated
sleeve, which is slidably disposed over a scaffold-positioning tether, in
accordance with the
present invention.
Figure 33 is a schematic perspective or isometric view of a helical fastener
similar to
that of Figure 32 sliding over a tether. Figure 33 also depicts a portion of a
pusher sleeve or
tube.
Figure 34 is a schematic partial cross-sectional view of the helical fastener
of Figure
32 juxtaposed to a heart wall and a margin of a valve-support scaffold.
Figure 35 is a schematic partial cross-sectional view similar to Figure 34,
showing the
helical fastener advanced into the heart wall, with the fastener straddling
the margin of the
scaffold.
Figure 36 is a schematic partial cross-sectional view similar to Figure 35,
showing the
fastener partially embedded in the heart wall with the pusher sleeve or tube
withdrawn, but
the tether still attached to the scaffold margin.
Figure 37 is a schematic partial cross-sectional view similar to Figure 35,
showing the
fastener partially embedded in the heart wall and holding the scaffold in
place, but with the
tether removed, this view representing the ultimate state of scaffold
fixation.
Figure 38 a schematic perspective or isometric view of a valve-support
scaffold in an
expanded configuration and a plurality of positioning tethers.
Figure 39 is a view similar to Figure 38, showing a pusher sleeve or tube
advanced
over a tether and in contact with a helical fastener at the margin of the
valve-support
scaffold, for deployment of the fastener into a heart or blood vessel wall.
Figure 40 is a schematic side elevational view of an alternative, two-pronged
staple
for fastening a margin of a valve-support scaffold to a heart or blood vessel
wall.
Figure 41 is a schematic cross-sectional view of the staple of Figure 40 with
the
prongs partially inserted into a heart or blood vessel wall over a margin or
rim element of a
valve-support scaffold or frame.
Figure 42 is a schematic cross-sectional view similar to Figure 41, showing
the prons
or legs of the staple in an angled-apart or expanded configuration to create
fixation.
Figure 43 is a schematic cross-sectional view of a second alternative staple
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configuration wherein the tips turn in to create fixation.
Figure 44 is a schematic cross-sectional view similar to Figure 43, shows a
prong of
the staple provided with a removal-prevention barb.
Figure 45 is a schematic perspective or isometric view of a valve retrieval
system, for
Figure 46 is a schematic perspective or isometric view similar to Figure 45,
showing
the valve in an opened state.
Figure 47 is a schematic perspective or isometric view similar to Figures 45
and 46,
Figure 48 is a schematic perspective or isometric view similar to Figure 47,
showing
the valve closed around the valve retrieval system.
Figure 49 is a schematic perspective or isometric view similar to Figure 48,
showing
the retrieval system engaging the valve, with the delivery system retracted.
15 Figure 50 is a schematic perspective or isometric view similar to Figure
49, showing
a pair of leaflet-capture tethers or the retrieval system shifted apart to
engage and curl or
otherwise engage and/or retract the leaflets
Figure 51 is a schematic perspective or isometric view similar to Figure 50,
showing
the retrieval system delivery apparatus removed.
20 Figure 52 is a view similar to Figure 51, showing the tethers of the
retrieval system
drawn through a valve-receiving neo-annulus or aperture of a valve-support
scaffold as a
prosthetic valve is deployed into the neo-annulus of the scaffold.
Figure 53 is a view similar to Figure 52, showing the tethers of the valve
retrieval
system completely engaged with the valve leaflets and fixing the leaflets to
the valve-support
Figure 54 is a view similar to Figure 52, showing the native valve leaflets
fully
retracted and attached to the scaffold and the prosthetic heart valve and with
locking
apparatuses connected on the tethers of the heart valve retrieval system to
reinforce fixation
of those tethers to the scaffold and the deployed prosthetic valve.
30 Figure 55 is a schematic perspective or isometric view of the helical
fixation device or
fastener of Figure 32, showing a pin disposed in a cap of the helical fixation
device, which,
when advanced into the heart or blood vessel wall, prohibits untwisting of the
helical
fastener.
Figure 56 is a view similar to Figure 55, showing the pin in a deployed or
advanced
35 position.
Figure 57 is a schematic perspective view of an expanded valve-support
scaffold
extended via positioning tethers out of a delivery catheter, showing the
catheter in a pair of
configurations illustrating steerability of the catheter tip.
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Figure 58 is a schematic perspective or isometric view of a portion of a
leaflet
entrainment device in accordance with the present invention.
Figure 59 is a schematic perspective or isometric view of a portion of a
modified
leaflet entrainment device in accordance with the present invention.
Figure 60 is a schematic perspective or isometric view of a valve retrieval
system
inserted in a retrograde direction through an opened aortic valve.
Figure 61 is a schematic perspective or isometric view similar to Figure 60,
showing
the aortic valve closed around the valve retrieval system.
Figure 62 is a schematic perspective or isometric view similar to Figures 60
and 61,
showing the retrieval system engaging the valve.
Figure 63 is a schematic perspective or isometric view similar to Figures 60-
62,
showing a pair of leaflet-capture tethers or the retrieval system shifted
apart and engaging
and curling the leaflets.
Figure 64 is a schematic perspective or isometric view similar to Figures 60-
63,
showing the retrieval system delivery apparatus removed the tethers of the
retrieval system
drawn through a valve-receiving neo-annulus or aperture of a valve-support
scaffold, and a
prosthetic valve deployed into the neo-annulus of the scaffold.
DEFINITIONS
The word "tether is used herein to denote an elongate member that extends from
outside a patient to an implantable device inside the patient, especially but
not necessarily
within the vascular system. A tether is used to remotely manipulate and
position the
implantable device within the patient and may also be used to implement
attachment of the
implantable device to organic tissues of the patient. It is contemplated that
a tether is
normally detachable from the implantable device once implantation has been
secured. A
tether may be a wire made of a metallic or metal alloy material and is capable
of transmitting
compressive, tensile and torsional forces as required.
The terms "scaffold" and "neo-annulus" are used interchangeably herein to
denote an
implantable device or structure that serves as a framework for receiving a
prosthetic valve
and anchoring the valve to the patient at the site of a malfunctioning native
valve. A scaffold
or neo-annulus is preferably delivered to the operative site via a catheter.
Consequently, the
scaffold or neo-annulus must be flexible or collapsible for insertion into the
patient. Once the
scaffold or neo-annulus is ejected from the catheter into the patient, the
scaffold or neo-
annulus expans to a predetermined use configuration suitable for receiving,
seating and
attaching to a prosthetic or bio-prosthetic valve. A scaffold or neo-annulus
as decribed
herein defines an orifice, preferably circular, for receiving a prosthetic or
bio-prosthetic valve.
The term "prosthetic" as applied to a valve herein includes bio-prosthetic
valves.
The term "force-transmitting and fluid-sealing contact" as used herein with
reference
to the implantation of a scaffold or neo-annulus in juxtaposition with or
apposition to native
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valve leaflets means in part that the scaffold or neo-annulus is attached at
least indirectly to
the native valve leaflets so as to enable the transmission of operative
natural valve forces at
least in part over the native valve to the scaffold or neo-annulus and the
prosthetic valve
attached thereto. The term "force-transmitting and fluid-sealing contact" also
means that the
implanted scaffold or neo-annulus is effectively sealed relative to the
natural valve so that
blood flow occurs essentially solely through the prosthetic valve upon
completion of the
implantation procedure. Sealing may occur wholly or in part because of direct
contact
between the scaffold or neo-annulus and the native valve leaflets or between
the scaffold or
neo-annulus and the cadio-vascular wall about the native valve. A seal may be
effectuated
wholly or in part because of the use of an ancillary sealing element or
elements such as
staples, clips or sutures or one or more inflatable bladders that close off
potential fluid flow
channels about the scaffold or neo-annulus.
The term "cadio-vascular wall" is used herein to denote the inner surface of a
heart
chamber or a blood vessel into which a prosthetic valve and its associated
scaffold or neo-
annulus is implanted.
The terms "tensile coupling element" and "tension member" and variations
thereof
are used herein to denote an elongate member such as a wire which may be
pushed or
pulled and thus supports both compressive and tensile forces, as well as
torsional forces
and which in part remains in a patient connecting a scaffold or neo-annulus to
a patient
under tension.
The terms "distal" and "distally directed" are used herein to denote a
direction
extending from an operator such as a surgeon, who is outside a patient,
towards the patient
and more particularly towards a valvular structure inside a patient.
Concomitantly, the terms
"proximal" and "proximally directed" denote a direction extending towards an
operator such
as a surgeon from a patient and more particularly from a valvular structure
inside a patient.
DETAILED DESCRIPTION
The present invention provides devices and associated methodology for
attaching a
valve-supporting scaffold or frame member to a subject, particularly to
natural valve leaflets
of a native heart or vessel valve of the subject. Such a valve-supporting
scaffold and
methods related thereto are disclosed in U.S. Patent Application Publication
No.
2010/0262232, the disclosure of which is hereby incorporated by reference.
As illustrated in Figure 1, a delivery system for an implantable valve support
device
610 comprises a delivery catheter 612, which contains the implantable device
in a collapsed
low profile configuration to facilitate minimally invasive access. Figure 1
shows a plurality of
valve-leaflet entrainment or capture elements 614 in the form of hooks, e.g.,
grappling
hooks, or barbs. As illustrated in Figure 2, each leaflet entrainment element
614 is carried at
the free or distal end of an elongate flexible tensile coupling element 616.
Each tensile
coupling element 616 extends through a respective tubular positioning tether
618 that is
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removably attached at its distal end to a locking element 620 in turn
connected to a neo-
annulus or scaffold 622 that receives and supports a prosthetic or bio-
prosthetic valve.
Positioning tether 618 surrounds a proximal portion 624 of tensile or tensile
coupling
member 616. As discussed in detail hereinafter, in a prosthetic-valve
implantation
procedure, neo-annulus or scaffold 622 is moved towards a native valve by
exerting a
distally directed force 626 on tubular positioning tether 618 while exerting a
proximally
directed force 628 on tensile coupling element 616.
Figure 3 shows delivery catheter 612 as advanced through a vascular system of
a
subject to a native heart valve HV having a pair of valve leaflets VL1 and
VL2. A distal tip
630 of catheter 612 is located in or proximate to an orifice VO between valve
leaflets VL1
and VL2. At that juncture of a valve implantation procedure, hook-like
entrainment or
capture elements 614 and distal end portions of tensile coupling elements 16
are ejected
from the distal tip 630 of delivery catheter 612, as depicted in Figure 4.
Then, as shown in
Figure 5, delivery catheter 612 is retracted back across the native heart
valve HV with the
hooks 614 and tension members 616 remaining in place.
Figure 6 shows a subsequent step of a valve implantation procedure, in
particular a
partial extrusion or ejection of neo-annulus or scaffold 622 from delivery
catheter 612.
Hooks 614 and tensile coupling elements 616 remain in place adjacent to the
native valve
leaflets VL1 and VL2. Figure 7 shows neo-annulus or scaffold 622 fully ejected
from
catheter 612 and expanded in the heart chamber or blood vessel. Multiple
positioning
tethers 618 extend to respective locks 620 (Figure 2) and support the expanded
neo-annulus
or scaffold 622 during the implantation procedure. Tensile coupling elements
616 extend
from respective positioning tethers 618 at the periphery of neo-annulus or
scaffold 622.
Leaflet-entrainment hooks 614 dangle loosely within or beyond the native valve
orifice VO.
As shown in Figure 7, the expanded neo-annulus or scaffold 622 takes the form
of a
ring which defines a valve-receiving circular orifice 623. Neo-annulus
scaffold 622 is
preferably flexible for at least a given time after ejection from delivery
catheter 612 so as to
allow manipulation and reconfiguration after delivery, but also relatively
inelastic so that a
radially expanded valve 634 (Figures 9 et seq.) does not distort it. Scaffold
622 may be
constructed of a braided or monofilament metal or other appropriate synthetic
or naturally
occurring material with the appropriate physical characteristics.
Alternatively, scaffold 622
made be made of nitinol optionally with a temperature-induced memory by which
the scaffold
assumes a substantially fixed ring shape after ejection from the delivery or
deployment
catheter 612.
After the ejection of neo-annulus or scaffold 622, tensile coupling elements
616 are
manipulated from outside the patient to bring hooks 614 into engagement with
the edges
(not separately designated) of valve leaflets VL1 and VL2, as depicted in
Figure 8. This
initial entrainment allows normal or near normal valve function. Subsequently,
as shown in
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Figure 9, prosthetic or bio-prosthetic valve 634 is seated in neo-annulus
orifice 623 (see
Figure 7) and attached to scaffold 622 to form a neo-annulus/replacement valve
complex
636.
Figure 10 depicts scaffold 622 with the mounted valve 634 moved closer to
native
valve HV. This change in position of neo-annulus/replacement valve complex 636
is
effectuated by pushing positioning tethers 618 in a distal direction, as
indicated by force
arrow 626 in Figure 2, while simultaneously pulling tensile coupling elements
616 in a
proximal direction, as indicated by force arrow 628 in Figure 2.
Figure 11 is a schematic perspective view similar to Figure 10, showing
further
advancement of neo-annulus/replacement valve complex 636 towards the orifice
VO of the
native valve HV. After a final advancement of neo-annulus/replacement valve
complex 636,
depicted in Figure 12, the neo-annulus/replacement valve complex is seated
into the orifice
VO of the native valve NV and tensile coupling elements are fully retracted to
curl the lips or
edges of valve leaflets VL1 and VL2.
Subsequently, as depicted in Figure 13, positioning tethers 618 are removed or
detached from the implanted neo-annulus/replacement valve complex 636 and
tensile
coupling elements 616 are severed at locks 620 (Figure 2). In the completed
implantation,
neo-annulus/replacement valve complex 636 is held by tensile coupling elements
616 and
entrainment hooks 614 in a fluid sealing engagement with valve leaflets VL1
and VL2. This
mode of implantation ensures that the valve securing forces exerted by the
chordae
tendineae.
Figures 14-16 depict steps in a modified implantation procedure wherein neo-
annulus
or scaffold 622 is provided at spaced intervals around its circumference with
a plurality of
flexible elongate tensile suspension elements 638 that are attachable at their
free ends 640
to a wall CVW of the heart or a blood vessel (collectively, "cardio-vascular
wall").
Suspension members 638 are manipulated via respective deployment tethers 642
that
extend from delivery catheter 612 or a separate deployment catheter (not
illustrated) and
detachably attach to the suspension members at free ends 640 thereof.
Typically, free ends
640 of suspension members 638 are coupled to wall CVW after the ejection of
scaffold 622
from catheter 612 but before the moving of neo-annulus/replacement valve
complex 636 into
engagement with valve leaflets VL1 and VL2, and preferably before the seating
of prosthetic
valve 634 in orifice 623 of neo-annulus or scaffold 622.
Scaffold 622 is optionally provided with suspension elements 638, which are
extendible radially to attach to the heart or blood vessel wall CVW near the
native valve HV
for which replacement is intended. Suspension elements 638 appear like spider
legs, or as
ring-topped, flattened tripod (in an instance wherein three such elements are
used).
Suspension elements 638 may be constructed of a spring-like material and are
curved to
allow for fixation to heart or blood vessel wall CVW of variable contour and
also allow for
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excursion of the neo-annulus scaffold 622 toward the valve HV as necessary.
Figure 15 shows neo-annulus scaffold 622 supported by the deployed elongate
suspension elements 638 of Figure 14, and with deployment tethers 642 removed.
Scaffold
622 is ready for capture of valve leaflets VL1 and VL2 by entrainment hooks
614 and for
deployment of prosthetic valve 634 (not shown), followed by advancement of the
complex
636 into the native valve orifice VO.
Figure 16 depicts a detail of an alternative, auto-fixation, method of
attachment of a
suspension line 638 to cardio-vascular wall CVW. Suspension line 638 is
provided at a free
end with a barb 644 that anchors the suspension line to the cardiovascular
wall CVW.
Deployment tether 642 is removably coupled to suspension line 638 to permit
the forceful
insertion of barb 644 into the tissues of wall CVW and the subsequent
detachment of tether
642 from suspension line 638.
Figure 17 is a schematic plan view of native mitral valve HV, showing valve
commissure gaps VC1 and VC2 between valve leaflets VL1 and VL2. Figure 18
illustrates
ring-shaped neo-annulus scaffold 622 in place over the native mitral valve HV.
Hooks 614
for capture of valve leaflets VL1 and VL2 and the associated tensile coupling
elements 616
are visible through the orifice 623 of neo-annulus scaffold 622 while the
positioning tethers
618 of Figure 2 extend from delivery catheter 612 to the neo-annulus scaffold,
the lumen 646
of the catheter being visible in cross-section. As shown in Figures 19 and 20,
with neo-
annulus scaffold 622 in position abutting the valve leaflets VL1 and VL2 and
prosthetic or
bio-prosthetic replacement valve 634 deployed, commissure gaps VC1 and VC2 are
open at
the periphery of the neo-annulus, resulting in a perivalvular leak. Two
approaches for
closing gaps VC1 and VC2 are discussed below.
Figure 20 also schematically illustrates locks 620 cooperating with the
tensile
coupling elements 616 to hold them in place relative to neo-annulus or
scaffold 622.
Figure 21 is a series of three side elevational views of a tissue
approximation clip or
anchor 650 in three configurations relative to apposed valve leaflets VL1 and
VL2. Clip or
anchor 650 is initially inserted in a distal direction 652 through a
commissure gap VC1 or
VC2 (only VC2 shown). Then clip or anchor 650 us retracted in a proximal
direction 654,
causing apposition of the leaflets and a closing of the gap. Finally prongs
656 of clip or
anchor 650 are bent downwardly at 658 for permanent placement.
Figure 22 is a partial schematic perspective view similar to Figure 20,
showing
anchor-shaped clip 650 deployed for leaflet-edge approximation. Typically, one
or more
clips or anchors 650 are deployed after the locking of neo-annulus/replacement
valve
complex 636 to the valve leaflets VL1 and VL2. However, one or more clips or
anchors 650
may alternatively deployed prior to the engagement or locking of the neo-
annulus/replacement valve complex 636 to the valve leaflets.
In an alternative method for closing commisure gaps VC1 and VC2 (see Figure
31),
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neo-annulus or scaffold 622 is provided along an other periphery with a
collapsed bladder-
like component 660, as depicted in Figure 23A. An inflation tube or port
member 662
extends to collapsed bladder 660 for feeding thereto a fluid such as carbon
dioxide, saline
solution, a liquid polymer, a polymerizable monomer composition, etc., thereby
expanding
the collapsed bladder or balloon 660 to an enlarged configuration 664 shown in
Figure 23B.
The expanded bladder configuration 664 is also depicted in Figures 24 and 26,
while Figure
25 shows the collapsed insertion configuration of balloon or bladder 660. As
depicted in
Figure 26, expanded bladder configuration 664 covers and closes cornmisure
gaps VC1 and
VC2. Typically, as illustrated in Figures 25 and 26, the bladder 660, 664 is
an annular
member extending circumferentially about the outer periphery of neo-annulus or
scaffold
622.
Figure 27 is a schematic side elevational view of ratchet-type locking
components
620 and 666 provided on the neo-annulus scaffold 622 and distal ends of
tensile coupling
elements 616 to allow only one-way excursion of the tensile coupling elements
and the
appended valve-capture or entrainment elements 614 (see other figures).
Locking
component 666 is a series of tapered teeth 668 each having, for example, a
frusto-conical
form (Figure 2). In that case, locking component 620 is a block provided
internally with one
or more tapered passageway sections 670 that are geometrically congruent with
teeth 668.
Tensile element 616 may be pulled in the proximal direction 628 while
positioning tether 618
is pushed in the distal direction 626, which moves locking component 620, and
accordingly
scaffold 622 and neo-annulus/replacement valve complex 636, in the distal
direction relative
to tensile coupling element 616. However, the shapes of teeth 666 and
passageway
sections 670 prevent an opposite relative motion of tensile coupling element
616 and neo-
annulus/replacement valve complex 636. Ratchet-type locking components 620 and
666
thus enable a clamping of the neo-annulus scaffold 622 and attached
replacement valve 634
to the valve leaflets VL1 and VL2.
Figures 28A and 28B show another embodiment of a ratchet mechanism wherein
lock 620 is provided internally with a pivotably mounted latch or détente 672
having a sharp
end 674 pointed in a proximal direction, towards tether 618. Latch or détente
672 permits
motion of tensile coupling element 616 in the proximal direction 28, that is,
towards tether
618 but prevents the opposite motion.
Figure 29 depicts neo-annulus scaffold 622 with collapsed perimetral closure
bladder
660, tensile coupling elements 616 with distal hooks 614 entrained to the ends
or edges of
native valve leaflets VL1 and VL2, and tubular tethers 618 extending from the
distal end of a
delivery catheter 612 and holding the scaffold in position for installation.
Figure 30 is a schematic perspective view similar to Figure 29, showing
replacement
valve 634 mounted to the neo-annulus scaffold 622.
Figure 31 shows neo-annulus scaffold 622 in place above the native mitral
valve HV
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with native valve leaflets VL1 and VL2 captured and the "sewing ring" or
closure bladder 660
in its inflated configuration 664 but with the replacement valve 634 omitted
for clarity.
Suspension elements 638, as well as the neo-annulus or scaffold 622, may be
covered or coated with a substance to enhance tissue ingrowth, prevent clot or
blood
adhesion, may be drug eluting, heparin or other substance bonding, or or
otherwise be
constructed of a material that enhances tissue ingrowth, prevent clot or blood
adhesion.
The implantation device and associated method described above are designed in
such a way as to enhance delivery by construction of the scaffold so that
valve-capture
elements 614, suspension elements 638, if used, peri-valvular inflatable or
gap-closure
devices 650 and 660, if used, are incorporated into the neo-annulus 622 such
that serial
emergence from the delivery system 612 simplifies placement of the entire
system.
Combining valve deployment with capture of the native valve leaflets VL1 and
VL2 may
create a minimal risk of valvular stenosis or insufficiency. Further, the
design of the device
transfers all cardiac forces onto the native valve HV. In the case of AV
valves, the scaffold
or valve support device 622 is at least indirectly secured to chordae
tendineae, and
therefore, the papillary muscles of the heart. Therefore such a device can
distribute forces
to the prosthetic valve 634 similar to those typical of the normal, native
valve.
Figures 32 et seq. below describe alternative methods and devices for
implanting a
prosthetic or bio-prosthetic valve in a heart chamber or blood vessel.
Fastener or fixation
devices 400, 428, and 436 described hereinafter are useful for attaching
suspension
elements 438 to cardio-vascular wall CVW.
As illustrated in Figure 32, a fastener or fixation device 400 for coupling a
valve-
supporting scaffold 402 (Figures 38 and 39) comprises a pair of helical prongs
or legs 404
each attached at one end to a cap or head 406 in the form of a disk. As
illustrated in Figure
34, disk 406 is provided with a hole 408, which is traversed by a scaffold-
positioning tether
410 (Figures 33, 34, 35) so that the fastener or fixation device 400 is
slidable along the
tether. During a deployment operation, a pusher member 412 in the form of an
elongate
sleeve or tube (only a distal end portion thereof shown in the figures)
engages cap or head
406 to press fastener 400 to a distal end of tether 410 and into organic
tissues, specifically a
heart chamber or vessel wall 414. Once distal tips 416 of prongs or legs 404
enter the heart
chamber or vessel wall 414, further distal motion of pusher member 412 induces
fastener to
turn about its longitudinal axis 418 (Figure 32), twisting the fastener deeper
into the organic
tissues. Prongs or legs 404 straddle an outer margin or outer rim element 420
(Figures 34-
37) of scaffold 402, with one of the prongs or legs passing through a membrane
422 that
extends between margin 420 and an inner rim element or neo-annulus 424 of the
scaffold.
Prong tips 416 enter the heart or vessel wall on the opposing sides of margin
420, and the
prongs or legs 404 cooperate with the organic tissue in a camming motion to
induce rotation
of the fastener 400.
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Insertion of fastener 400 is complete when cap or head 406 comes into contact
with
margin 420, as shown in Figure 35. Pusher member 412 is then withdrawn
(compare Figure
36 with Figure 35). Tether 410 is also detached from scaffold 402 and
withdrawn (Figure
37). Pusher member 412 may be extracted from the heart or vessel and from the
patient
prior to the detachment and extraction of tether 410. Alternatively, tether
410 may be
detached first (e.g., by a twisting of the tether), with a subsequent
simultaneous extraction of
the tether and pusher member 412.
Figure 38 shows scaffold 402 after it has been ejected from a delivery
catheter 426
and opened from a collapsed insertion configuration (not shown) to the
illustrated expanded
deployment configuration. A plurality of tethers 410, detachably linked at
their distal ends to
margin 420 of scaffold 402 at spaced locations theralong, includes three
primary tethers
410a and optionally several secondary tethers 410b. Primary tethers 410a are
manipulated
to position margin 420 and concomitantly scaffold 402 into a desired position
and orientation
inside a target heart chamber or vessel. Fasteners 400 are initially deployed
along the
primary tethers 410a (see Figure 39) to connect margin 420 to heart chamber or
vessel wall
414 at three respective locations. Further fasteners 400 may be subsequently
deployed
along the secondary tethers 410b.
As depicted in Figures 40-42, an alternative fastener or margin fixation
device 428 is
a staple having two prongs or legs 430 each attached at one end to a cap or
head 432 in the
form of a perforated disk slidably traversed by tether 410. Prongs or legs 430
each exhibit a
shallow S-shape with an outwardly turned tip 434, the two prongs being mirror
images of one
another. Tips 434 cause prongs or legs 430 to splay outwardly during an
insertion
operation, as shown in Figure 42. This divergence or opening of the staple
prongs 430
serves to anchor fasteners 428 in a heart chamber or vessel wall 414.
As illustrated in Figures 43 and 44, another alternative fastener or margin
fixation
device 436 is a staple having two prongs or legs 438 each attached at one end
to a cap or
head 440 again in the form of a perforated disk slidably traversed by tether
410. Prongs or
legs 438 each have a slightly arcuate proximal portion 442 attached to cap or
head 440 and
an inwardly dog-legged distal end 444. Distal ends 444 cause prongs or legs
438 to crimp
inwardly during an insertion operation. As shown in Figure 44, one or both
prongs 438 may
carry a rearwardly oriented barb or hook 446 for providing enhanced resistance
to removal
of the fastener 436 from the heart or vessel wall 414.
Figure 45 depicts a valve retrieval system 448 comprising an introducer
catheter 450
and a plurality of tethers 452 deployed via the catheter and provided at their
free ends with
capture hooks or barbs 454 for entraining leaflets 456 of a natural atrial
valve 458 and
indirectly capturing the cords (not shown). Valve retrieval system 448 further
includes a
tether guide member 460, which maintains tethers 452 in a suitably arranged or
distributed
array. To that end, tether guide member may be provided with angularly spaced
grooves or
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passageways for guiding the respective tethers 452. Valve retrieval system 448
is inserted
into the patient after the installation of valve-supporting scaffold 402 and
prior to the seating
of a prosthetic valve 462 (Figures 52-54) in neo-annulus 424.
Upon an opening of the natural valve 458 as depicted in Figure 46, valve
retrieval
system 448 is moved in a distal direction and inserted trough the open valve,
as depicted in
Figure 47. The natural valve then closes over valve retrieval system 448 as
shown in Figure
48. At that juncture, valve retrieval system 448 is slightly retracted so that
the hooks or
barbs 454 are juxtaposed to the valve leaflets 456 as indicated in Figure 49.
Tethers 452
and tether guide member 460 are then manipulated to insert hooks or barbs 454
into valve
leaflets 456. As indicated in Figure 50, the distal ends of tethers 452
including hooks or
barbs 454 shift laterally or outwardly to capture and entrain leaflets 456.
This movement of
tethers 452 is implemented via tether guide member 460. To that end, the
grooves or
channels in tether guide member 460 that guide tethers 452 may be formed with
camming
surfaces such as humps that move the tethers laterally outwardly upon a
longitudinal shifting
of the guide member 460 relative to the tethers.
After the ensnaring or snagging of leaflets 456 by hooks or barbs 454,
catheter 450
and tether guide member 460 are withdrawn, as shown in Figure 51. Then, as
depicted in
Figure 52, prosthetic valve 462 is inserted inside a ring of tethers 452 so
that the leaflet-
entraining tethers are clamped between neo-annulus 424 of scaffold 402 and the
prosthetic
valve. Tethers 452 are further retracted at that juncture to curl leaflets 456
and constrain
them about the margin 420 of scaffold 402, as illustrated in Figure 53. Then
tethers 452 are
severed (Figure 53) and locks 464 are attached to the severed tether ends
(Figure 54).
As illustrated in Figures 55 and 56, fastener 400 may be provided with a pin
466
movably coupled to cap 406 for enabling a locking of the fastener to heart
chaber or vessel
wall 414. Upon completed insertion of prongs 404 into heart chamber or vessel
wall 414, pin
466 is moved from a retracted neutral position (Figure 55) to an advanced
locking losition
(Figure 56). In its advanced position, pin 466 prevents fastener 400 from
rotating or
untwisting from its inserted position clamping margin 420 to the heart or
vessel wall.
Figure 57 shows how delivery catheter 426 has a steerable distal end 468 which
may
assume any of a plurality of orientations 468a, 468b, etc. relative to a main
body 470 of the
catheter, thereby facilitating a placement of scaffold 402.
Figure 58 depicts a distal end portion of a leaflet entrainment device 472
having four
hooks or barbs 474 that are actively or passively released when engaged with a
valve leaflet
or cord.
Figure 59 depicts a leaflet entrainment device 476 with two subassemblies 478
and
480 including respective tubular delivery members 482 and 484 and pairs of
hooks or barbs,
486 and 488. Tubular delivery members 482 and 484 are spring biased to
separate as
illustrated after emergence from a delivery catheter 490.
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Figures 60-64 depict a series of steps similar to those described hereinabove
with
reference to Figures 45-54, applied in a retrograde procedure to capture
leaflets 500 of an
aortic valve 502 and attach the captured leaflets to an implanted scaffold 504
and a
prosthetic valve 506 (Figure 64) which is seated in a neo-annulus 508 of the
scaffold. The
procedure of Figures 60-64 is particularly pertinent in solving a problem
called "aortic
insufficiency" where there is no calcium, so, like as in the case of the
mitral valve, an
expanding, radial-force valve cannot be used. This disease is a common
occurrence as a
result of LVAD (left ventricular assist device) placement.
As shown in Figure 60, a valve retrieval system 510 which is similar if not
identical to
system 448, comprises the same components, namely, introducer catheter 450 and
tethers
452 with capture hooks or barbs 454 at the free ends thereof. Hooks or barbs
454 are
effective in the procedure of Figures 60-64 to entrain leaflets 500 of aortic
valve 502. Again,
tether guide member 460 maintains tethers 452 in a suitably arranged or
distributed array.
Valve retrieval system 448 is inserted into the aorta after the installation
of valve-supporting
scaffold 502 and prior to the seating of prosthetic valve 506 in neo-annulus
508.
Upon an opening of the aortic valve 502 as depicted in Figure 60, valve
retrieval
system 448 is moved retrograde in the aorta (not separately labeled) and
inserted through
the open valve, as depicted. The aortic valve 502 then closes over valve
retrieval system
448 as shown in Figure 61. At that juncture, valve retrieval system 448 is
slightly retracted
so that the hooks or barbs 454 are juxtaposed to the valve leaflets 500 as
indicated in Figure
62. Tethers 452 and tether guide member 460 are then manipulated to insert
hooks or
barbs 454 into valve leaflets 500. As indicated in Figure 63, the distal ends
of tethers 452
including hooks or barbs 454 shift laterally or outwardly to capture and
entrain leaflets 500.
This movement of tethers 452 is implemented via tether guide member 460, as
described
above with references tro Figures 45-54.
After the ensnaring or snagging of aortic leaflets 500 by hooks or barbs 454,
catheter
450 and tether guide member 460 are withdrawn, prosthetic valve 506 is
inserted inside a
ring of tethers 452 so that the leaflet-entraining tethers are clamped between
neo-annulus
508 of scaffold 502 and the prosthetic valve. Tethers 452 are further
retracted at that
juncture to curl leaflets 456 and constrain them about the margin 512 of
scaffold 502, as
illustrated in Figure 64. Then tethers 452 are severed. Locks 464 may be
attached to the
severed tether ends, as discussed hereinabove with reference to Figure 54.
In another approach constituting a variation of the procedure described in
U.S.
Patent Application Publication No. 2010/0262232 and International Patent
Application No.
PCT/US2010/001077, a scaffold or valve support device with a central orifice
defining
annulus and a preferably flexible margin or perimeter element is attached to
the atrial wall.
One then waits a few (3-6) weeks for tissue growth to bind the scaffold or
valve support
device to the atrial wall. At that juncture a prosthetic or bioprosthetic
valve is seated in the
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orifice.
Accordingly, fastening elements are provided herein or in U.S. Patent
Application
Publication No. 2010/0262232 and International Patent Application No.
PCT/US2010/001077 for attaching said scaffold or valve support device either
(1) to heart or
blood vessel tissue adjacent to a native heart valve, (2) at least indirectly
to leaflets of a
native valve of a patient, or (3) to both adjacent tissue and directly or
indirectly to heart valve
tissue. Preferably, the attachment is such that the scaffold or valve support
device
potentially is in effective force-transmitting and effective perivalvular
fluid-sealing contact
with the target native valve and substantially fixedly attached to the
patient.
Although the invention has been described in terms of particular embodiments
and
applications, one of ordinary skill in the art, in light of this teaching, can
generate additional
embodiments and modifications without departing from the spirit of or
exceeding the scope
of the claimed invention. For instance, instead of being attached directly to
the valve leaflets
VL1 and VL2, neo-annulus/replacement valve complex 36 of suitable dimensions
may be
attached in whole or in part to the cardio-vascular wall CVW about native
valve HV.
Accordingly, it is to be understood that the drawings and descriptions herein
are proffered by
way of example to facilitate comprehension of the invention and should not be
construed to
limit the scope thereof.
