Note: Descriptions are shown in the official language in which they were submitted.
CA 02701809 2010-04-07
1
European Patent Application
AIS GmbH Aachen Innovative Solutions
Catheter Device
The invention relates to a catheter device which is a miniaturised pump.
Implantable blood pumps are used increasingly in the treatment of patients
with serous
heart conditions. Such blood pumps have so far been provided mainly for long-
term use.
However, blood pumps are also being developed which are designed for short-
term
support for the heart and may be inserted by minimally invasive means. Here
the medical
objectives are stress-relief for and recovery of the heart, or to provide
bridging until a
possible heart transplant. The range of application of such pumps depends on
the one
hand on the simplicity of inserting them into the body, and on the other hand
on the
feasible technical properties, in particular the reliable operating life of
the available pump
systems which may be obtained. Ideally it should be possible to insert such a
blood pump
for short-term treatment by percutaneous-intravascular means without any
surgical
intervention.
In eardiogenic shock, the ejection performance of the left ventricle is
considerably
reduced. The reduced coronary supply can lead to irreversible heart failure.
Through the
use of a temporary left-ventricular support system, the pump function of the
left ventricle
should be partly or largely taken over and the coronary supply improved. In
heart
operations such a system may be used for both left and right ventricles and
may replace a
heart-lung machine.
A percutaneous-intravascular system which has to date been of clinical
importance is the
intra-aortal balloon pump (IABP). The intra-aortal balloon pump or intra-
aortal counter-
pulsation is a mechanical system, also used to support the pumping performance
of the
heart in patients with cardiogenic shock. This involves a catheter with a
cylindrical
CA 02701809 2010-04-07
2
plastic balloon being pushed ahead via the groin into the thoracic aorta
(aorta thoracalis),
so that the balloon lies below the outlet of the left clavicular artery
(arteria subclavia
sinistra). There the balloon is blown is inflated rhythmically by an external
pump with
every heart action in diastole with 30-40 cm3 helium and deflated in systole.
In this way
the balloon pump improves the blood supply to the heart muscle and also that
of all other
organs. The obtainable haemodynamic improvement is however very limited since,
on
account of the construction principle of the JAB P. no active blood delivery
takes place.
Through counter-pulsation only the aorta is closed below the left ventricle in
the rhythm
of the heartbeat, so that the blood still discharged by the heart is pressed
back and
redistributed, also in the coronaries. There is no increase in blood flow.
A known transfemoral implantable micro axial pump, "HemopumpTM" of the company
Medtronic Inc., USA, represents after experimental and preliminary clinical
testing a
promising concept for effecting adequate relief of systemic heart strain. The
intake nozzle
of the pump is placed in the left ventricle retrogressively via the aortic
valve. The pump
rotor is located at the end of a cannula in the upper aorta descendens and is
driven by an
external motor. The disadvantage of the system is that the transfemoral
implantation, due
to the large diameter of the rotor, is possible only through an operation
involving a
femoral arteriotomy and if necessary by a graft coupling.
WO 99/44651 discloses an axial pump which may be introduced via the blood
vessel
system of a patient. The axial pump has a flexible, compressible tube which
forms the
pump housing. In the tube is a radially compressible rotor. The drive shaft of
the rotor
runs through a catheter. Together with the tube and the rotor, the catheter
may be drawn
into a cover hose. The radial compressibility of the components makes it
possible to
realise a small puncture diameter suitable for percutaneous implantation by
the Seldinger
technique. Through the unfolding in the heart vessel system, a relatively
large pump
diameter of 10 to 14 mm may be provided. This reduces the rotor speed and
therefore the
mechanical stress on the components.
CA 02701809 2010-04-07
3
Described in US 4,753,221 is a catheter with an integrated blood pump which
has folding
blades. The blood pump is an axial pump provided with a balloon at its end.
The balloon
can be pumped up to unfold the pump jacket and to close the flow path leading
past the
pump, so fixing the pump in the blood vessel. In a further embodiment it is
provided that
a cup-shaped end of the catheter is arranged in a tubular guide catheter which
is then
withdrawn so as to unfold the cup-shaped end.
DE 10 059 714 Cl discloses an intravascular pump. The pump has a drive section
and a
pump section which are so small in diameter that they can be pushed through a
blood
vessel. A flexible cannula adjoins the pump section. To reduce flow
resistance, the
cannula may be expanded to a diameter which exceeds that of the drive section
and pump
section respectively. So that the pump may be introduced into the body by the
Seldinger
technique involving punctures in the blood vessel, the cannula is constricted,
in which
state it has a smaller diameter. In the blood vessel it is expanded so as to
offer less flow
resistance to the blood to be pumped.
Described in JP 4126158 and EP 0 445 782 Al respectively is an artificial
heart for
implantation in the body. The artificial heart has a pump section and a drive
section for
driving the pump section. The pump section is relatively small and serves to
accommodate an axial flow pump in the form of a screw pump. Different types of
screw
pump are provided.
Described in EP 0 364 293 A2 is a catheter with integral blood pump. A
flexible edge
extends over a tubular section of the catheter and contacts the wall of the
aorta, ensuring
by this means that all the blood within the aorta flows through the pump. In
addition the
flexible, expandable edge provides clearance between the pump and the aortic
valve.
The present invention is based on the problem of providing a blood pump to
support the
heart, and which may be inserted through the femoral artery by percutaneous-
intravascular means without the need for surgical intervention.
CA 02701809 2015-07-24
4
Thus, there is provided a catheter device comprising a drive shaft connected
to a motor, and a rotor
mounted on the drive shaft at the distal end section. The rotor has a frame
structure which is formed
by a screw-like boundary frame and rotor struts extending radially inwards
from the boundary
frame. The rotor struts are fastened to the drive shaft by their ends opposite
the boundary frame.
Between the boundary frame and the drive shaft extends an elastic covering.
The frame structure is
made of an elastic material such that, after forced compression, the rotor
unfolds automatically.
Due to the frame structure of the rotor with its boundary frame and rotor
struts, the rotor is very
stable but still capable of folding and of being compressed to a diameter
virtually as small as may be
desired. Due to the fact that, in principle, the rotor may be virtually as
long as desired in the axial
and radial directions, it may be optimised for maximum pump performance,
depending on the space
available. It is therefore possible to optimise pump performance for each
application.
The rotor is so compressible that it may be introduced into the body, using a
puncture needle,
through a puncture with a diameter of approximately 9 french (approx. 3 mm).
The automatic
unfolding of the rotor makes possible a rotor diameter which is many times
greater than the diameter
of the rotor in the compressed state. By this means a high pump performance is
obtained.
Through the scaffolding-like structure of the boundary frame and rotor struts,
the rotor has great
strength, enabling it to operate at high speeds without becoming unbalanced. A
prototype of this
catheter device was operated over several hours to pump a fluid at a speed of
around 32,000 rpm.
The rotor has a diameter of around 18 french (ca. 6 mm) and was designed so as
to obtain a pressure
difference of approximately 120 mmHg. This is an exceptional performance for
such a miniaturised
pump. A distinct advance in reliability and operating life was also achieved
by this catheter device.
5
The frame structure of the pivot axis is preferably made from a memory
material such as
nitinol. During compression, the rotor may be brought to a temperature at
which the
memory material becomes soft. A rotor made of nitinol is compressed for
example at a
temperature of around 0 C. On heating, the memory material again becomes rigid
and
unfolds. As a rule it is not possible to compress the rotor again without
damage unless it
is first cooled down.
The elastic covering between boundary frame and drive shaft is preferably made
of a
polymer coating, e.g. PU, PE, PP, silicone or parylene.
Expediently the rotor is surrounded by a tubular pump section of a pump
housing. The
pump housing is formed by a mesh, the openings of which are closed by an
elastic
covering, at least in the area of the pump section. Such a pump housing may be
made
with a small clearance gap from the rotor, resulting in optimal flow
conditions and the
chance for further optimisation of pump performance.
The mesh of the pump housing is preferably made of a memory material which can
be
compressed together with the rotor.
The pump housing protects the rotor from external influences.
In another aspect, there is provided a catheter device comprising a drive
shaft connected
to a motor, the drive shaft having a proximal end section and a distal end
section; a rotor
mounted on the drive shaft at the distal end section, wherein the rotor is
made of an
elastic material such that, after forced compression, the rotor unfolds
automatically; and
an expandable or compressible pump housing which encompasses the rotor,
wherein the
pump housing comprises a distal connection section, a conical intake section,
a pump
section, a conical outlet section and a proximal connection section, and
wherein the pump
housing is formed by a mesh comprising apertures, wherein the apertures are
closed by
an elastic covering, at least in the area of the pump section.
CA 2701809 2018-03-15
5a
In another aspect, there is provided a catheter device comprising a drive
shaft; a rotor
connected to the drive shaft; and a pump head comprising an expandable and
compressible pump housing with a tubular mesh structure having apertures,
wherein the
pump housing comprises a plurality of sections arranged between a distal end
of the
housing and a proximal end of the housing, the plurality of sections
comprising an intake
section and a pump section, the pump section including the rotor, and wherein
a transition
section is formed in the mesh structure between the pump section and the
intake section,
and wherein at least some of the apertures of the mesh structure in the
transition section
are larger than the apertures of the mesh structure in the pump section.
In another aspect, there is provided a catheter device comprising a rotor; a
drive shaft
connected to the rotor; and a pump head comprising an expandable and
compressible
pump housing having a proximal end and a distal end, the pump housing
comprising a
tubular mesh structure having a plurality of apertures, wherein the expandable
pump
housing comprises an intake section and a pump section arranged between a
proximal
end and a distal end of the pump housing, and the intake section widens
conically
towards the proximal end; wherein the rotor is mounted in the pump section and
the
apertures in the pump section are smaller than the apertures in the intake
section.
In another aspect, there is provided a catheter device comprising a drive
shaft; a rotor,
connected to the drive shaft; a pump head comprising an expandable and
collapsible
pump housing; a body cap, wherein the body cap has a proximal end and a distal
end, the
body cap comprising an atraumatic ball at the distal end; and a body element
that forms a
connection between the body cap and the pump housing.
In another aspect, there is provided a catheter device comprising a drive
shaft having a
proximal end and a distal end, the proximal end coupled to a motor; a
compressible and
expandable helical rotor mounted to the distal end of the drive shaft, the
rotor comprising
a rotor blade configured to self-expand from a compressed state to a self-
expanded state,
wherein the rotor has a length, and wherein the rotor blade has a pitch that
varies along
the length of the rotor.
CA 2701809 2018-03-15
=
5b
The invention is described in detail below, by way of example, with the aid of
the
drawings which show schematically in:
Fig. 1 a perspective view of a catheter device according to the
invention
Fig. 2 an exploded drawing of a catheter device according to the
invention
Fig. 3 a body cap of the catheter device shown cut away at the side
CA 2701809 2018-03-15
CA 02701809 2010-04-07
6
Fig. 4 a distal catheter body element of the catheter device in a cut-away
side
view
Fig. 5 a connection bush of the catheter device in a cut-away side view
Fig. 6 a pump of the catheter device with support in a cut-away side view
Fig. 7a a section along the line A-A through the distal connection bush of
the
catheter device
Fig. 7b a section along the line B-B through the proximal connection bush
of the
catheter device
Fig. 8 a mesh structure of a pump housing of the catheter device
Fig. 9 a detail of the mesh structure of the pump housing of the catheter
device
Fig. 10 a drive shaft with guide spiral and shaft protector of the catheter
device
Fig. 11a a frame structure of a rotor of a pump of the catheter device
Fig. 11b a further frame structure of the rotor of the pump of the catheter
device
Fig. 12 the rotor according to the invention of the pump of the catheter
device in a
perspective view
Fig. 13 an outlet hose of the catheter device in a perspective view
Fig. 14 a clutch according to the invention with clutch housing and motor
of the
catheter device in a perspective view
CA 02701809 2010-04-07
7
Fig. 15 the clutch according to the invention with the clutch housing of
the
catheter device in a perspective view
Fig. 16 the clutch housing of the catheter device in a perspective view
Fig. 17 a square rod of the clutch of the catheter device in a side view
Fig. 18 a clutch element of the clutch of the catheter device in a side
view
Fig. 19 a terminating disc of the clutch of the catheter device in a side
view
Fig. 20 a ball head bearing ball of the clutch of the catheter device in a
side view
Fig. 21 a centering pin of the clutch of the catheter device in a side view
Fig. 22 a motor mounting of the catheter device in a side view
Fig. 23 a top view of the clutch element with the square rod contained
within it
Fig. 24 the catheter device positioned in the body, and
Fig. 25 alternative embodiments of the catheter device in schematic form.
Figure 1 shows a catheter device 1. The catheter device 1 according to the
invention
represents a pump. The catheter device 1 has a pump head 3 at a distal end 2.
The pump head 3 has a rotor 3.2, for pumping a medium in the flow direction 5,
which is
connected to a drive shaft 4. The flow direction 5 is from the distal end 2 to
a proximal
end 6. Located at the proximal end 6 away from the pump head 3 is a motor 7.
The drive
shaft 4 is encompassed by a catheter body 8 and connected non-positively by
means of a
clutch 9 to the motor 7.
CA 02701809 2010-04-07
8
First of all the pump head 3 will be explained in more detail below. The pump
head 3
comprises a body cap 10 at the distal end, the rotor 3.2 mounted on the drive
shaft 4, a
pump housing 3.1 and an outlet hose 18.
The body cap 10 is formed by a ball 10.1 with an attached cylindrical section
10.2. The
body cap 10 is made for example of stainless steel (Fig. 2, Fig. 3). The body
cap 10 could
be made of polyethylene PE, polypropylene PP, polyether etherketone PEEK,
polyvinyl
chloride PVC, Teflon PTFE, acrylic glass, epoxy resin, polyurethane PU, carbon
fibre,
coated materials, composite materials, PEBAX, or a polyether block amide. In
principle
all haemo-compatible materials are suitable, since there is only minimal
mechanical
loading on this component.
The diameter of the ball 10.1 is roughly 3.2 mm. The cylindrical section 10.2
is around
5.5 mm long and has a diameter of approximately 2.2 mm. The overall length of
the body
cap is roughly 7.0 mm.
At its distal end, in the area of connection to the ball 10.1, the cylindrical
section 10.2 has
a through bore 10.3 running at right-angles to the flow direction 5. The
cylindrical section
10.2 also has an axial bore 10.4 which extends from the proximal end of the
cylindrical
section 10.2 to the ball 10.1, thereby forming a communicating passage from
the through
bore 10.3 to the proximal end of the body cap 10. A step 10.5 is formed in the
area of the
axial bore 10.4, so that the latter is widened towards the proximal end.
The through bore 10.3 on the one hand avoids the creation of a blind hole in
the body
cap, while on the other hand permitting the attachment of a thread, which is
helpful in
compressing the pump head 3.
Instead of the ball 10.1 of the body cap 10, a pigtail, a spiral, a meandering
wire with a
spherical tip, or an atraumatic fibre bundle may also be provided. The body
cap is
preferred owing to its small size.
CA 02701809 2010-04-07
9
The tip of the body cap 10 is an atraumatic ball to protect the heart muscle
(endocardium). Via the body cap 10, the pump head 3 may be supported on the
wall of
the heart.
A tubular or hose-like distal catheter body element 8.1 is introduced from the
proximal
end into the body cap 10 up to the step. The distal catheter body element 8.1
is fixed in
the axial bore 10.4 with an accurate fit (Fig. 4). The distal catheter body
element 8.1 is
made of polyurethane or another suitable material, in particular an elastic,
plastic material
(e.g. PE, PVC, Teflon, elastomer). The distal end of the distal catheter body
element 8.1
is connected to the body cap 10. The connection may be in the form of a bonded
joint
using for example cyanacrylate adhesive, or may involve a welded, clamped or
shrink-on
connection. These connection means are suitable in principle for connecting a
catheter
body element to another, in particular a rigid one. In the description below,
therefore, this
will not be explained for each individual connection point.
The distal catheter body element 8.1 forms a straight but very flexible
connection
between the body cap 10 and the pump housing 3.1. The straight connection
creates a
coaxial alignment of all the parts within it (drive shaft, shaft protector,
housing,
connection bush).
In combination with the body cap 10, the distal catheter body element 8.1
serves as a
positioning aid when the pump head 3 is inserted into a vessel or the heart.
In the present embodiment the catheter body element 8.1 has a length of
approximately
25 mm, an outside diameter of around 1.9 mm and an inside diameter of around
1.3 mm.
Provided at the proximal end of the distal catheter body element 8.1 is a
distal tubular
connection bush 12.1 (Fig. 5, Fig. 6). The distal connection bush 12.1 has a
greater
diameter in the distal area than in the proximal area. In the distal area of
the connection
bush 12.1, the proximal end of the distal catheter body element 8.1 is held
with a good fit
CA 02701809 2010-04-07
and fixed in place. Accommodated in the proximal area of the distal connection
bush 12.1
is a distal connection section 3.1.1 of the pump housing 3.1. The distal
connection section
3.1.1 of the pump housing 3.1 is connected to the distal connection bush 12.1
and the
proximal end of the distal catheter body element 8.1 (Fig. 7a, Fig. 7b).
The distal connection bush 12.1 has a length of around 5 mm and an outside
diameter of
approximately 2.2 mm. In the distal area, the diameter is roughly 2 mm and in
the
proximal area it is around 1.5 mm. The shorter the connection bush, the less
the
reinforcement which it provides.
The distal and a similarly designed proximal connection bush 12.1, 12.2 are
made for
example of stainless steel, copper, brass, titanium or another suitable metal,
of
polyethylene (PE), polypropylene (PP), Teflon (PTFE), PEBAX, a polyether block
amide
or another suitable material.
The expandable or compressible pump housing 3.1 is a tubular mesh structure
3.1.6 of
nitinol or another suitable memory alloy or another memory material, e.g.
plastic, ferrous
alloy, copper alloy. The pump housing 3.1 is divided into five sections from
the distal to
the proximal end (Fig. 8).The first distal section is a tubular distal
connection section
3.1.1. A second section is an intake section 3.1.2 widening conically in the
flow direction
5. Next to the intake section 3.1.2 is a pump section 3.1.3. The tubular pump
section 3.1.3
holds the rotor 3.2. In the expanded state, the inside diameter of the pump
section 3.1.3 is
around 6.15 mm. An outlet section 3.1.4 narrows conically in the flow
direction 5 and
forms the connection between the pump section 3.1.3 and a proximal connection
section
3.1.5. The proximal connection section 3.1.5 is, like the distal connection
section 3.1.1,
tubular with a smaller diameter than the pump section 3.1.3. The pump housing
3.1 may
be so compressed that it does not exceed a maximum diameter of less than 3 mm
over its
whole length.
Between the mesh struts, the mesh structure 3.1.6 of the pump housing 3.1 has
apertures
3.1.7 (Fig. 8, Fig. 9). The apertures are in the form of polygons 3.1.7, which
in the
CA 02701809 2010-04-07
11
present embodiment are rhombuses. In the pump section 3.1.3, small rhombuses
3.1.7.1
are provided. In the transition zones from the pump section 3.1.3 to the
intake section
3.1.2 and the outlet section 3.1.4 of the tubular mesh structure 3.1.6, the
small rhombuses
3.1.7.1 are combined step by step to form increasingly larger rhombuses.
Adjacent to a
small rhombus is a larger rhombus with twice the edge length. This doubling of
edge
length is repeated until the apertures reach the desired size. Provided in the
intake section
3.1.2 and in the outlet section 3.1.4 are large rhombuses 3.1.7.2 which have
roughly four
times the edge length of the small rhombuses 3.1.7.1. In the transition zones
from the
intake section 3.1.2 and the outlet section 3.1.4 to the distal and proximal
connection
sections 3.1.1, 3.1.5 of the tubular mesh structure 3.1.6, the large rhombuses
3.1.7.2 are
turned into smaller rhombuses. In the distal and proximal connection sections,
medium-
sized rhombuses 3.1.7.3 are provided which have approximately double the edge
length
of the small rhombuses 3.1.7.1 (Fig. 9). The layout of the apertures 3.1.7 and
the number
of increases in size may be as desired. In the transition from smaller to
larger rhombuses
the width of the mesh struts is increased. In this way the strength of the
mesh struts is
kept roughly the same, and even increased towards the larger rhombuses.
The mesh structure 3.1.6 of the pump housing 3.1 is covered in the pump
section 3.1.3 by
a PU covering 3.1.8, which provides a liquid-proof seal of the mesh apertures.
This covering and the sealing of the mesh structure 3.1.6 may also be provided
by a PU
hose fitted on to the outer or inner surface.
Other coverings than PU may also be used, e.g. PE, PP, silicone or parylene,
so long as
the mechanical and geometrical requirements are met.
Through the selection of individual apertures 3.1.7.1, in particular the
medium- and
larger-sized apertures 3.1.7.3, 3.1.7.2, which are not coated, the performance
parameters
including blood damage from the pump, may be controlled in a targeted manner.
CA 02701809 2010-04-07
12
The polygonal structure and the special finish of the PU covering result in
the pump
housing 3.1 having an approximately round cross-section. In combination with
the round
rotor 3.2, this leads to very small gaps between the rotor 3.2 and pump
housing 3.1. This
leads to comparatively low blood damage, low leakage rates and high
efficiency. The
mesh structure 3.1.6 provides very good radial and axial stability together
with very good
axial compression and expansion properties. The special structure makes
possible very
easy adaptation of length and diameter to performance requirements.
The proximal connection section 3.1.5 of the pump housing 3.1 is held in and
connected
to the proximal connection bush 12.2. In the proximal connection bush 12.2, as
in the
distal connection bush 12.1, a hose-like proximal catheter body piece 8.2 is
located and
connected to it (Fig. 7a, Fig. 7b). The same types of connection as already
described
above may be provided.
Arranged axially within the distal and the proximal catheter body element 8.1,
8.2 are a
distal shaft protector 13.1 and a proximal shaft protector 13.2 (Fig. 6). The
distal and
proximal shaft protectors 13.1, 13.2 are in the form of hose made of PU or one
of the
other materials already referred to above.
The distal shaft protector 13.1 extends in the flow direction 5 from shortly
before the
distal connection bush 12.1 to the distal end of the pump section 3.1.3 of the
pump
housing 3.1, i.e. as far as the rotor 3.2. The proximal shaft protector 13.2
extends from
the proximal end of the rotor 3.2 until shortly after the proximal end of the
distal
connection bush 12.1.
In the two areas in which they lie within the distal and the proximal
connection bushes
12.1, 12.2 and the distal and proximal catheter body elements 8.1, 8.2
respectively, the
distal and proximal shaft protectors 13.1, 13.2 are joined to these former
components.
Together with the components mounted within them (shaft protector, pump
housing,
catheter body), the two connection bushes 12.1, 12.2 form a bearing section
for the drive
CA 02701809 2010-04-07
13
shaft 4. The connection bushes 12.1, 12.2 ensure the axial centricity of the
drive shaft 4 in
particular in the pump housing 3.1.
The drive shaft 4 is mount axially within the distal and proximal shaft
protectors 13.1,
13.2 and the pump housing 3.1 respectively. In the flow direction 5 the drive
shaft 4 has
three sections: a distal section of the drive shaft 4.1 in the area of the
body cap 10; a
pump section of the drive shaft 4.2 on which the rotor 3.2 is non-rotatably
mounted; and a
proximal section of the drive shaft 4.3 extending from the pump section 3.1.3
to the
clutch 9. The rotor 3.2 is adhesive-bonded to the drive shaft. Other non-
positive types of
connection such as welding or clamping may however also be provided.
To guard against blood damage due to the rotation movement of the drive shaft
4 and
adhesion of blood constituents to the drive shaft 4, the proximal shaft
protector 13.2 (Fig.
2, Fig. 6) separates the proximal section 4.3 of the drive shaft 4 physically
from the pump
medium. This prevents the build-up of shear forces. There is no direct
interaction
between the drive shaft 4 and the blood due to the very small gap, and only
minimal
transport of blood through this gap is possible. The distal and proximal shaft
protectors
13.1, 13.2 centre and support the drive shaft 4 in operation and during the
compression
and expansion process.
The drive shaft 4 is preferably formed by several, in particular six, wires
(not shown)
wound to left or right around a core. The outside diameter of the drive shaft
4 is roughly
0.48 mm. The drive shaft 4 may however also have a different number of cores
and wires
and a smaller or larger diameter. The diameter of the drive shaft may lie in
the range
between 0.3 mm and 1 mm, and is preferably around 0.4 mm to 0.6 mm. The
smaller the
diameter of the drive shaft, the greater the possible speed, since the smaller
the diameter
the greater is the speed at which the periphery of the drive shaft moves
relative to its
environment. A high peripheral speed is problematic when the drive shaft comes
into
contact with the environment. The catheter device is designed for speeds of
more than
20,000 rpm and up to 40,000 rpm. The diameter of the drive shaft 4 is
therefore made as
small as possible, but thick enough to give it adequate strength.
CA 02701809 2010-04-07
14
Against the direction of winding of the drive shaft 4 - in the present
embodiment it is
wound to the left ¨ is a guide spiral 14 with opposite winding (here wound to
the right)
fitted axially around the distal and proximal sections of the drive shaft 4.1,
4.3. Its
purpose is to minimise friction of the drive shaft 4, to avoid wall contact of
the drive shaft
4 with the proximal catheter body element 8.2, and to prevent kinking of the
drive shaft 4
as a result of bending. Through the guide spiral 14, the drive shaft 4 is
guided and fixed
or stabilised (Fig. 10). The guide spiral 14 may be made of stainless steel
and glued to the
shaft protector 13.1, 13.2. The guide spiral may also be provided in the form
of a spring.
The direction of winding of the guide spiral 14 may also be the same as the
direction of
winding of the drive shaft 4.
The drive shaft 4 extends from the distal end of the distal shaft protector
13.1 in the flow
direction 5 behind the distal connection bush 12.1 to the clutch 9.
In combination with the guide spiral 14, the proximal catheter body element
8.2 provides
a connection, constant in length and torsion, between the pump head 3 and the
clutch 9.
Provided at the proximal end of the distal shaft protector 13.1 is a bearing
washer 15 (Fig.
6). The bearing washer 15 is provided with a through bore 15.1. The diameter
of the
through bore 15.1 corresponds roughly to the outside diameter of the drive
shaft 4. The
bearing washer 15 is fitted on to the drive shaft 4 in such a way that it
holds the proximal
end of the distal shaft protector 13.1, bounding it in the flow direction 5.
The bearing washer 15 is made for example of stainless steel, Teflon or a
ceramic or
other suitable material. The bearing washer 15 is bonded to the stationary
shaft protector
using cyanacrylate adhesive and is therefore able to absorb axial forces
against the flow
direction 5 (for means of connection see above).
In the pump section 4.2 of the drive shaft 4, the spiral-shaped, expandable
rotor 3.2 is
mounted non-rotatably on the drive shaft 4. Provided as rotor 3.2 in the
present
CA 02701809 2010-04-07
embodiment is a two-blade, comb-shaped frame structure 3.2.1 of nitinol or
another
memory material, e.g. plastic (see above), which is coated or encompassed with
fluid-
tightness by a PU skin (Fig. 11a). I.e. the covering in the form of the PU
skin is stretched
between the comb-like frame structure. Because of the structure of the rotor
3.2 as a
coated frame structure 3.2.1 of nitinol, it is possible to expand or compress
the rotor 3.2.
The PU skin has high elasticity so that it is not damaged during compression.
The frame structure 3.2.1 has a continuous screw-like or spiral-shaped outer
boundary
frame 3.2.2 with several rotor struts 3.2.3 connected to the boundary frame
3.2.2 and
running radially inwards (Fig. 12). Rings 3.2.4 are formed at the free ends of
the rotor
struts 3.2.3. The drive shaft 4 extends through the rings 3.2.4 of the rotor
struts 3.2.3.
Provided between every two adjacent rings 3.2.4 there is a spacer sleeve 16.
The distal
end of the rotor 3.2 abuts the bearing washer 15 with a distal-end spacer
sleeve 16. The
end spacer sleeves 16 may also be in the form of a special bearing spacer
sleeve 16. In
this way two of the frame structures 3.2.1 form a two-blade rotor 3.2.
The rotor 3.2 may also be made in one piece (Fig. 11b) or have several frame
structures
(Fig. 11a). Each frame structure forms a rotor blade. Figs. llb and 12 show a
frame
structure 3.2.1 for a rotor 3.2 which forms two rotor blades. If required, it
is also possible
for several rotor blades and therefore several frame structures 3.2.1 to be
fitted to a rotor
3.2. The frame structure may also take any other suitable form.
The distance between two adjacent rings 3.2.4 is less than the corresponding
section of
the spiral-shaped boundary frame 3.2.2. The greater the difference between the
distance
between two rings 3.2.4 and the corresponding section of the spiral-shaped
boundary
frame 3.2.2, the greater the pitch of the rotor. The pitch of the rotor 3.2
may thus be set
by the length of the spacer sleeves 16, and may be varied within a rotor 3.2.
The pitch of the rotor 3.2 is determined by the length and number of spacer
sleeves 16
relative to the dimensioning of the continuous spiral-shaped outer boundary
frame 3.2.2
CA 02701809 2010-04-07
16
between two rotor struts 3.2.3. The length of the spacer sleeves 16 may be
standard for all
positions, but may also be varied symmetrically or asymmetrically for each
position. The
complete freedom for configuration makes possible very flexible design of the
rotor 3.2,
in turn permitting different pump properties for the rotor 3.2.
The rotor 3.2 has high dimensional stability combined with flexible scope for
configuration with minimum use of material (e.g. thin frame structure).
Maximum
stiffness and stability are obtained. Nevertheless the combination of the
frame structure
and the covering, which further supports the properties of the frame structure
through
stabilisation, allows very strong compression. This leads to very good
compressibility
and expandability of the rotor. Owing to the good surface formation of the PU
skin on the
mesh structure, very good matching of the housing structure to the rotor
structure is
possible.
In the compressed state, the rotor 3.2 has approximately the inside diameter
of the
compressed pump housing 3.1. The outside diameter of the compressed pump
housing is
roughly between 2mm and 4 mm and preferably around 3.3 nun.
In the expanded state, the spiral-shaped outer boundary frame 3.2.2 of the
rotor 3.2 is a
very short distance away from the inner surface of the pump housing 3.1. The
distance
between the outer boundary frame 3.2.2 and the inner surface of the pump
housing 3.1 is
roughly between 0.01mm and 0.5 mm. The smaller the distance between the frame
structure 3.2.1 and the inner surface of the pump housing 3.1, the greater the
pump
performance of the rotor 3.2.
At the distal-end spacer sleeve 16 of the rotor there is contact with the
bearing washer 15
fixed to the distal shaft protector 13.1 and the distal-end spacer sleeve 16,
both of which
are fitted on to the drive shaft 4. Since the rotor 3.2 is set into a rotary
motion by the drive
shaft 4, the distal spacer sleeve 16 of the rotor 3.2 contacts the bearing
washer 15 in the
manner of a sliding bearing. In this way a distal rotor bearing 17 is formed
(Fig. 6). The
drive shaft 4 is held almost free from play by the through bore of the bearing
washer 15.
CA 02701809 2010-04-07
17
Only small free spaces (not shown) remain, however, due to the design of the
drive shaft
4.
During positioning, on account of the flow of the pump medium, the rotor 3.2
is loaded
with an axial force against the flow direction 5. This force is diverted via
the distal-end
spacer sleeve 16 on to the bearing washer 15.
To lubricate the distal rotor bearing, blood or serum is sucked in via the
through bore
10.3 of the body cap 10, the open spaces between the distal shaft protector
13.1 and the
drive shaft 4, and the open space between the drive shaft and the bearing
washer 15. The
suction effect occurs due to the rotary movement of the drive shaft 4 and the
rotor 3.2.
At the proximal-end spacer sleeve 16 of the rotor 3.2, the drive shaft 4 is
similarly held
by a proximal connection bush 12.2.
Located at roughly the proximal end of the pump section 3.1.3 of the pump
housing is a
tubular elastic outlet hose 18 (Fig. 1, Fig. 13). The outlet hose 18 is made
of PU and has a
length of approximately 70 mm, a diameter of around 10 mm and a wall thickness
of
roughly 0.01 mm to 0.1 mm and preferably around 0.03 mm. The two ends of the
outlet
hose 18 are tapered, with a cylindrical section being provided at the proximal
conical end
of the outlet hose.
The distal tapering end of the outlet hose 18 makes a tight seal with the PU
covering of
the pump section 3.1.3 of the pump housing 3.1. The cylindrical proximal
section is
connected securely to the proximal catheter body element 8.2. Both are joined
together
with a fluid-tight seal by means of dissolved PU.
Located at the proximal end of the outlet hose 18 are several radially
consecutive outlets
18.1. The outlets 18.1 may be oval in the flow direction 5. It is however also
possible to
make the outlets circular, half-moon-shaped or with any other geometry in
order to
generate different outflows. The outlets 18.1 agitate the blood passing out
into the aortic
CA 02701809 2010-04-07
18
bulb. This prevents a laminar flow with a resultant water jet pumping effect
on the
coronary arteries.
The outlet hose 18 takes the pump volume of the pump from the left ventricle
via the
aortic valve into the aorta. Here the outlet hose 18 acts like a non-return
valve. If there is
a positive pressure difference between the outlet hose 18 and the aorta, then
the outlet
hose 18 is open to a greater or a lesser extent depending on the flow volume
generated by
the pump. With a nil or negative pressure difference, the outlet hose 18
closes just like
the aortic valve due to its high flexibility, and lies closely against the
proximal catheter
body element 8.2. This flexibility leads to good sealing during through flow,
against the
vela of the aortic valve. Because of this, there is only minimal backflow from
the aorta
into the left ventricle.
Located at the proximal end of the catheter body element 8.2 are the clutch 9
and the
motor 7. The distance between the pump head 3 and the clutch 9 and the length
of the
proximal catheter body element 8.2 respectively may vary according to the
patient and
are approximately 90 to 150 cm.
The method of expanding the rotor 3.2 is described below.
Fitted over the catheter device 1 is a tubular cover hose 29, so designed as
to encompass
the compressed pump head 3 together with the proximal catheter body element
8.2. The
cover hose 29 holds the pump head 3 in its compressed state.
After the pump head 3 has been correctly positioned, the cover hose 29 is
withdrawn
from the fixed catheter device 1 until the pump head 3 is free. Due to the
spring force of
the elastic material, the pump housing 3.1 and the rotor 3.2 unfold radially
outwards. In
other words, the mesh structure 3.1.6 of the pump housing 3.1 and the frame
structure
3.2.1 of the rotor 3.2 expand until they have reached their preset diameter.
Temperature
effects of the memory material may also be utilised to assist in the expansion
process.
CA 02701809 2010-04-07
19
To remove the catheter device 1, the cover hose 29 is pushed forward up to the
body cap
10, causing the rotor 3.2 and the pump housing 3.1 to be compressed and drawn
into the
cover hose, after which the latter is extracted through the puncture point.
The clutch 9 and the motor 7 are explained below.
The clutch 9 is a magnetic clutch (Fig. 14, Fig. 15). The clutch 9 has a
clutch housing 19
with a distal magnet unit 23.1. The clutch housing 19 is connected to the
proximal
catheter body element 8.2, which forms a continuous hollow space. The clutch
housing
19 separates the proximal catheter body element 8.2 hermetically from a motor
assembly
30. The motor assembly 30 has a proximal magnet unit 23.2. The proximal magnet
unit
23.2 is connected non-positively to the motor 7. The distal magnet unit 23.1
is connected
to the drive shaft 4 via a clutch element 22.
The distal magnet unit 23.1 and the proximal magnet unit 23.2 are coupled non-
rotatably
to one another through magnetic forces. A non-positive connection with non-
contact
rotational force transfer is ensured by the two magnet units 23.1, 23.2.
From the distal to the proximal end, the clutch housing 19 has a distal
cylindrical section
19.1, a conically expanding section 19.2, a second cylindrical section 19.3
and a proximal
cylindrical section 19.4. The clutch housing is made e.g. of
polymethylacrylate (PMMA)
or another material which can be injection-moulded or machined.
Formed in the distal cylindrical section 19.1 is a through bore, positioned
centrally in the
axial direction. The through bore extends through the whole of the clutch
housing 19.
From the distal end of the distal cylindrical section 19.1, the through bore
narrows in
three stages from a first catheter body mounting section 19.5 to a second
guide spiral
mounting section 19.6 and to a third drive shaft passage section 19.7.
CA 02701809 2010-04-07
The bore diameter of the catheter body mounting section 19.5 is around 1.9 mm,
that of
the guide spiral mounting section 19.6 approximately 1.28 mm and that of the
third bore
section roughly 1.0 mm.
The proximal end of the proximal catheter body is located in and securely
connected to
the catheter body mounting section 19.5 of the clutch housing 19. The guide
spiral 14 is
mounted in the guide spiral mounting section 19.6.
The drive shaft 4 extends through the through bore of the drive shaft passage
section 19.7
of the distal cylindrical section 19.1 and of the conically widening section
19.1, 19.2. The
drive shaft passage section 19.7 widens in the conically widening section 19.2
into a
fourth bore section 19.8.
At the start of the second cylindrical section 19.3, the fourth bore section
merges into a
hollow-cylindrical bearing section 19.9. Located in the distal end section of
the bearing
section 19.9 is an outer ring magnet 20.1. The outer ring magnet 20.1 is fixed
in the bore
of the bearing section 19.9 by a press fit, and may also or alternatively be
fixed by
adhesive bonding.
The bearing section 19.9 has a diameter of approximately 10 mm.
At the start of the proximal cylindrical section 19.4 of the clutch housing
19, the bore of
the bearing section 19.9 merges into a larger sixth distal clutch section
19.10. Formed in
the distal clutch section 19.10 is a radially aligned rinsing bore 19.15.
Connected to the rinsing bore is a pump (not shown) for the introduction of a
medium
(e.g. NaC1, glucose solution, Ringer's solution, plasma expander, etc.).
The bore of the distal clutch section 19.10 merges into a larger proximal
clutch section
19.11. Formed in the shoulder 19.12 between the distal and proximal clutch
sections
19.10, 19.11 are radially symmetrical 8 x M 1.6 tapped holes 19.13. At the
proximal end
CA 02701809 2010-04-07
21
of the proximal section 19.4, three L-shaped recesses 19.14 are distributed
around the
periphery.
The distal clutch section 19.10 has a diameter of approximately 22 mm. The
rinsing bore
19.15 has a diameter of around 6.5 mm and the proximal clutch section 19.11
has a
diameter of around 30 mm.
The proximal end of the drive shaft 4 is connected non-rotatably and secure
against
tension and compression (non-positively) to a square rod 21 (Fig. 17). In the
axial
direction the square rod 21 has a recess 21.1 to accommodate the proximal end
of the
drive shaft 4. The drive shaft 4 is fixed in the recess. The square rod 21 is
made e.g. of
brass, which has good lubrication properties. Other suitable materials are all
those which
may be extruded or machined, such as e.g. PE, PP, PTFE, gold, silver,
titanium, diamond,
etc.
The square rod 21 has a length of around 19.4 mm and a cross-section of
approximately
2.88 mm x 2.88 mm.
The square rod 21 transmits the rotary motion of the motor to the drive shaft.
The square
rod 21 may have any desired geometrical form which permits a statically
determined
force application.
The square rod 21 is held by an axial recess 22.1 within a rotation-symmetric
clutch
element 22, with the ability to slide axially (Fig. 23). By this means it is
able to
compensate for differences in length in the axial direction (Fig. 18). The
recess 22.1 is
formed by a larger central bore and four smaller bores arranged along the
periphery of the
central bore. The bores may be made by drilling, erosion, ultrasonic drilling,
laser drilling
or water-jet drilling.
The arrangement of the bores provides four double stop edges running axially.
The recess
22.1 is provided within a cylindrical section 22.2 of the clutch element 22
and extends
CA 02701809 2010-04-07
22
from the distal end of the clutch element 22 until shortly before a disc-
shaped proximal
section 22.3 of the clutch element 22.
The cylindrical section 22.2 has an outside diameter of around 8 mm and the
disc-shaped
proximal section 22.3 has an outside diameter of approximately 18 mm.
The recess 22.1 is made in such a way that the square rod 21 is held fixed
radially and in
the peripheral direction, and able to slide axially. The radial fixing of the
square rod 21 is
effected through the contact of all four longitudinal edges of the square rod
21 with one
each of the four double stop edges of the recess 22.1. Axial movement of the
square rod
21 in the recess 22.1 results in only minimal friction at the corresponding
lines of contact.
It is also possible to provide more or less stop edges. Instead of a square
rod it is possible
to provide e.g. a triangular or five-sided rod or a profiled rod with any
desired cross-
sectional surface remaining constant in the longitudinal direction of the rod.
The recess
22.1 should be matched in shape to the cross-sectional surface of the profiled
rod.
At the distal end and at the periphery of the cylindrical section 22.2 of the
clutch element
22, a shoulder 22.4 is formed. Mounted on this shoulder 22.4 is a second inner
ring
magnet 20.2. The shoulder 22.4 accommodates the inner ring magnet 20.2 in such
a way
that its outer surface lies flush with the cylindrical surface of the
cylindrical section 22.2.
This forms, in combination with the outer ring magnet 20.1 similarly
encompassing it in
the bearing section 19.9 of the clutch housing 19, a magnet ring bearing 20.3.
In the magnet ring bearing 20.3, the two ring magnets 20.1, 20.2 are so
arranged that e.g.
the north pole of the outer ring magnet is oriented towards the distal end and
the south
pole towards the proximal end. The north and south poles of the inner ring
magnets are
correspondingly opposite one another. Similarly, the north and south poles of
the two
ring magnets could also be reversed. The magnet ring bearing 20.3 centres the
drive shaft
4 axially and radially. The radial centering is effected through the radial
attraction forces
in the radial direction. The axial centering is effected by means of magnetic
restoring
CA 02701809 2010-04-07
23
forces generated by a slight offset of the inner ring magnet 20.2, which pull
the inner ring
magnet 20.2 into a position coinciding axially with the position of the outer
ring magnet
20.1. With a greater offset, however, repelling forces occur between the two
magnet rings
20.1 and 20.2, causing them to be pressed apart.
In the magnet ring bearing 20.3 the ring magnets 20.1, 20.2 are not in
contact, i.e. no
lubrication is required. In addition, the magnet ring bearing acts as a
vibration damper.
Formed in the disc-shaped section 22.3 of the magnetic clutch element 22 at
the proximal
end of the clutch element is a magnet mounting 22.5. The magnet mounting 22.5
is a
centric circular recess.
The centric circular recess 22.5 has a diameter of approximately 16.5 mm and a
depth of
around 3 mm.
The magnet mounting 22.5 accommodates the annular distal magnet unit 23.1
comprised
of four segments. The annular distal magnet unit is glued into the magnet
mounting 22.5.
Formed centrally in the proximal end face of the clutch element 22 is a ball
head bearing
mount 22.6. The ball head bearing mount 22.6 is a roughly hemispherical recess
22.6.
The hemispherical recess 22.6 has a diameter of approximately 0.5 to 1.3 mm.
The square rod 21 and the cylindrical section clutch element 22 respectively
are held by
the fourth bore section 19.8 and the bearing section 19.9 of the clutch
housing 19. The
disc-shaped section 22.3 of the clutch element 22 is held by the distal clutch
section
19.10 of the clutch housing 19.
The clutch housing 19 is separated hermetically from the motor assembly by a
terminating disc 24 (Fig. 19). The clutch housing 19 has a gas- and fluid-
tight seal apart
CA 02701809 2010-04-07
24
from the rinsing bore 19.15 in the clutch element 22 and the open spaces
between the
drive shaft passage section 19.7 and the drive shaft 4.
The terminating disc 24 is mounted on the shoulder 19.12 of the clutch housing
19 and is
fixed by means of eight screws, suitably held by bores 24.1 arranged with
radial
symmetry in the terminating disc 24, and screwed into the tapped holes 19.13
of the
clutch housing 19. This connection is fluid- and gas-tight. The terminating
disc 24 is
made for example of polymethylacrylate (PMMA) or another non-metallic material
(e.g.
PEEK, PEBAX, Teflon, PP, PE, all non-magnetic materials which can be injection-
moulded, extruded or machined).
On the distal side, the terminating disc 24 has a central thicker section
24.2. Formed in
the centre of the terminating disc 24 is a through bore 24.3 and a centric
hemispherical
recess 24.4. Fixed in the through bore 24.3 is a cylindrical centering pin
24.5 (Fig. 21).
Mounted on the centering pin 24.5 is a ball head 24.6 which is held in the
hemispherical
recess (Fig. 15, Fig. 20).
The distal magnet unit 23.1 is biased by a force towards the proximal. These
opposing
forces produce a resultant force which presses the clutch element 22 against
the ball head
24.6. This resultant force is set so that the ball head 24.6 is supported
securely, while at
the same time wear in the ball head bearing is kept to a minimum.
In combination with the distally located ball head bearing mount 22.7 of the
clutch
element 22, the ball head 24.6 forms a ball head bearing 25. The ball head
bearing 25 is a
sliding bearing. Other sliding bearings, such as e.g. a conical head bearing
or a cylinder
head bearing are also possible, with a cone or a cylinder provided as bearing
body instead
of the ball. The mounting is suitably matched to the shape of the bearing
body.
In conjunction with the magnet ring bearing 20.3, the ball head bearing 25
provides axial
centering and guidance, within the clutch housing 19, of the clutch element 22
and the
drive shaft 4 mounted within it.
CA 02701809 2010-04-07
The axial centering of the magnet ring bearing 20.3 is effected by providing
that the inner
ring magnet 20.2 is mounted axially not exactly in the centre of the outer
ring magnet
20.1, but slightly offset to the proximal side. By this means, the inner ring
magnet 20.2 is
biased towards the distal side. The ball head 24.6 may be made of ruby,
aluminium oxide
or a rigid plastic.
To prevent blood and serum from being sucked in through the open spaces
between the
drive shaft 4 and the proximal rotor bearing 17.2, due to the rotary movement
of the drive
shaft 4, and the blood coagulating ancUor adhering to the drive shaft 4, a
rinsing medium
is introduced through the rinsing bore in the clutch housing to generate a
counter-pressure
to the sucked-in or pressed-in blood flow. By this means the ball head bearing
is
lubricated. Suitable rinsing agents are e.g.:
= 3-20% glucose solution
= 5-40% dextrane solution with a molar weight of 5,000 to 65,000, in
particular 10%
dextrane solution, molar weight 40,000 in 0.9% NaCl
= Ringer's solution: an electrolyte mixture solution with K, Na, Mg
= other physiological electrolyte solutions.
The motor assembly comprises the proximal magnet unit 23.2, a proximal magnet
mounting 26, a coupling flange 27, a motor mounting 7.1, with a cooling fan
mounted
thereon and the motor 7 (Fig. 14, Fig. 22).
On the proximal side of the terminating disc 24, at a distance of roughly 0.5
to 8 mm and
preferably around 1 to 2 mm, there is a proximal magnet unit 23.2 mounted
axially flush
with the distal magnet unit 23.1. Like the distal magnet unit 23.1, the
proximal annular
magnet unit 23.2 has four segments.
The magnet mounting 26 is disc-shaped and has a centric circular recess 26.1
on its distal
side. Bonded into the recess 26.1 by means of two-component epoxy resin or
CA 02701809 2010-04-07
26
cyanacrylate adhesives are, as in the distal magnet unit 23.1 (see above),
four magnet
segments.
The four segments of the distal and proximal magnet units 23.1, 23.2 may be in
the form
of bent bar magnets, each with different poles at their end sections. The four
segments
may also be in the form of short axially aligned bar magnets, arranged in a
ring. It is also
possible to provide more than four segments. In the original position the two
magnets are
arranged so that in each case one north and one south pole of the bar magnets
of the two
magnet units 23.1, 23.2 overlap and attract one another.
The four segments are arranged four times with their north and south poles
alternating on
impact, so that the segments attract one magnetic unit. The distal and
proximal magnet
units 23.1, 23.2 are arranged relative to one another so that in each case
complementary
poles lie opposite one another. By this means the two magnet units attract one
another
and a torque is transmitted, since the magnetic forces wish to maintain this
complementary pole configuration.
The centric circular recess 26.1 has a diameter of around 16.5 mm and a depth
of around
3 mm.
The magnet mounting 26 is connected to a motor shaft 7.2 of the motor 7. The
magnet
mounting 26 is mounted rotatably within a suitably formed recess of the
coupling flange
27 of the motor mounting. Provided along the outer periphery of the annular
web of the
recess are three dowel pins 27.1, evenly spaced.
The clutch housing 19 is connected to the dowel pins 27.1 of the coupling
flange 27 of
the motor assembly via the L-shaped recesses 19.14 of the clutch housing 19.
The coupling flange 27 is fastened to a distal end face 7.1.1 of the motor
mounting, while
maintaining axial symmetry. The motor mounting 7.1 is a rectangular body with
cooling
fins 7.1.3 provided on its side faces 7.1.2.
CA 02701809 2010-04-07
27
In the axial direction, the motor mounting 7.1 has a centrally located bore
7.1.4, through
which the motor shaft 7.2 is guided. Also provided is an axially flush recess
7.1.5 in
which the motor 7 is fitted.
The motor 7 is for example a standard electric motor from the company
Faulhaber with
an output of 38 W at 30,000 rpm, or any other suitable motor.
A cooling fan is provided on one side face 7.1.2 of the motor mounting 7.1.
Provided over the pump head 3 and a distal section of the proximal catheter
body element
is a cover hose 29. The cover hose 29 has an inside diameter which, in the
area of the
pump head 3, corresponds to the outside diameter of the unexpanded pump
housing. The
outside diameter of the cover hose is approximately 3 mm.
The method of coupling with the magnetic clutch 9 is now described below.
The two magnet units 23.1, 23.2 are separated physically from one another by
the
terminating disc 24 in the clutch housing 19. A non-positive connection is
created by the
magnetic attraction forces between the two magnet units 23.1, 23.2. Here the
respectively
opposite poles of the two magnet units 23.1, 23.2 are opposite one another, so
that they
attract one another and a torque-resistant non-positive connection is formed.
Also by this means the ball head bearing mount 22.7 of the clutch element 22
is pressed
on to the ball head 24.6 of the terminating disc 24 to form the ball head
bearing 25. The
ball head bearing centres the axial course of the drive shaft 4.
Through the arrangement of the two ring magnets 20.1, 20.2 of the magnet ring
bearing
20.3, the inner ring magnet 20.1 is guided radially in the outer ring magnet
20.2 with
constant clearance. In this way the magnet ring bearing 20.3, in combination
with the ball
CA 02701809 2010-04-07
28
head bearing 25, centres and guides the rotation-symmetric motion of the
clutch element
22 and the drive shaft 4 respectively, in order to prevent any impact or
imbalance.
Via the non-positive connection between the magnet units 23.1, 23.2, the
rotary motion
transmitted by the motor 7 via the motor shaft 7.2 to the proximal magnet unit
23.2 is
transferred to the distal magnet unit 23.1.
The motor shaft 7.2 rotates at a speed of around 20,000 rpm to 40,000 rpm and
preferably
around 32,000 rpm to 35,000 rpm, which is transmitted to the drive shaft 4. At
32,000
rpm the rotor 3.2 has a pump performance of approximately 2 Umin to 2.5 1/min
at a
differential pressure of 60 mm Hg.
In the event of jamming of the rotor 3.2, the non-positive connection between
motor 7
and drive shaft 4 must be broken, to prevent "winding-up" of the drive shaft 4
while the
rotor is stationary. "Winding-up" of the drive shaft 4 could lead to a change
in position of
the pump head 3, resulting in damage to the heart and/or the aorta and veins.
As soon as the rotor 3.2 jams, the drive shaft 4 twists and shortens, and the
resistance at
the distal magnet unit 23.1 increases. The magnetic fields between the
proximal and the
distal magnet units 23.2, 23.1 do not overlap completely in operation, since
the distal
magnet unit 23.1 always trails the proximal magnet unit 23.2 a little. If now
the torque
required at the distal magnet unit 23.1 increases, the north and south poles
of the magnet
units 23.1, 23.2 no longer overlap but instead abut one another. By this, the
distal magnet
unit 23.1 is pressed away from the proximal magnet unit 23.2 in the distal
direction. The
magnetic connection between the two magnet units 23.1, 23.2 is broken and the
drive
shaft 4 comes immediately to a stand.
Due to the displacement of the clutch element 22 in the distal direction, the
inner ring
magnet 20.2 of the clutch element 22 is similarly shifted in the distal
direction and the
north and south poles of the two ring magnets 20.1, 20.2 of the magnet ring
bearing 20.3
CA 02701809 2010-04-07
29
no longer overlap but instead abut one another. By this means, the clutch 9 is
held in the
decoupled state, resulting in a lasting decoupling of motor 7 and drive shaft
4.
The amount of transferable torque is limited by the magnet ring bearing 20.3
and the
magnetic connection of the two magnet units 23.1, 23.2. As soon as the set
torque is
exceeded, the two magnet units 23.1, 23.2 separate. Owing to the rapid rotary
motion, the
distal magnet unit 23.1 can no longer follow the proximal magnet unit 23.2,
since the
magnetic binding forces are no longer adequate. Because of this, the north and
south
poles no longer overlap and the magnet units 23.1, 23.2 repel one another. The
connection of the magnet units 23.1, 23.2 is broken and the maximum
transferable torque
is limited. The magnet units 23.1, 23.2 are held in the decoupled state by the
magnet ring
bearing 20.3 through the mutual repulsion of the ring magnets 20.1, 20.2.
This state may be changed again by the application of an outer magnetic field.
By means
of a magnet guided past the clutch housing 19 from distal to proximal, the two
magnet
units 23.1, 23.2 may be brought back into their coupled original position.
According to the invention the clutch housing 19 and the motor assembly 30 are
physically separated from one another. Because of this it is possible to
lubricate the drive
shaft 4 through the pump located at the rinsing bore 19.15, at around 5-10
ml/h, despite
the high speed, thereby minimising friction. It may also be provided for an
infusion to be
made via the rinsing bore 19.15, which similarly lubricates the drive shaft 4.
The small diameter of the drive shaft is advantageous at high speeds of around
32,000
rpm. With greater diameters the peripheral speed would be too high and the
friction could
lead to damage to the drive shaft 4 and the adjacent components.
On account of the physical separation by the terminating disc 24 it is
possible to lubricate
and/or seal the drive shaft 4. No known bearing through which a shaft is
guided would
remain leak-proof and allow trouble-free running with this size and at such
speeds.
CA 02701809 2010-04-07
The arrangement of the ball head bearing 25 (sliding bearing), the magnet ring
bearing
20.3 (non-contact, damping and centering) and the axial sliding bearing
between the drive
shaft 4 and the clutch housing 19 creates three stabilisation points. This
enables the drive
shaft 4 to transmit a torque even if there is an axial change in length
(lengthening and
shortening). A change in length occurs, for example, when the pump head 3 is
compressed. Here the rotor 3.2 is pressed together, folded around the drive
shaft and
clamped in place in the housing. The pump housing 3.1 extends to the proximal
side. The
drive shaft 4 is able to move sufficiently for it not to be torn away from the
rotor 3.2. The
ability of the drive shaft 4 to slide makes it possible to compensate for
change in length
of the PU catheter body due to take-up of liquid, variations in temperature,
and bending
of the proximal catheter body element 8.2, which affect the length
relationships between
drive shaft 4 and proximal catheter body element 8.2. This mechanism is
possible
because of the ability of the square rod 21 to slide within the axial recess
22.1.
The pump head 3 is located in the left-hand heart chamber in such a way that
the outlet
hose 18 is arranged roughly centrally in the transition from the aorta to the
heart, i.e. in
the area of the heart valve. The catheter device 1 is preferably designed so
that a certain
pump pressure in the range of around 100 mm Hg to 150 mmHg may be obtained
from it.
If the heart is in the systole, then the catheter device pumps blood when the
pressure built
up by the heart is less than the pump pressure. A sick heart is thus relieved
of stress.
During the diastole, the pressure difference is opposite. If the pressure
difference is
greater than the pump pressure, then the catheter device can not pump blood.
In this case
the outlet hose is pressed together by the heart valve, so that it is closed.
If however the
pressure difference is less than the pump pressure, then some blood will be
pumped
against the pressure difference.
Fig. 24 shows the catheter device 1 positioned to give left-side support to
the heart. The
pump head 3 is located completely in the left heart chamber. The outlet hose
extends
through the heart valve.
CA 02701809 2010-04-07
31
To insert the catheter device, firstly a cover hose 29 is guided by a guide
wire into the left
heart chamber (Seldinger technique). The guide wire is then removed from the
cover
hose. The catheter device 1 is inserted through the cover hose with compressed
and
cooled pump housing 3.1 and rotor 3.2 until the catheter device 1 with the
pump head 3
has reached the left heart chamber. Unfolding takes place through the pulling
back of the
cover hose 29 on to the fixed catheter body 8, until the tip of the cover hose
29 has
released the pump head 3.
To remove the system, the cover hose 29 is pushed forward up to the body cap
10,
causing the rotor 3.2 and pump housing 3.1 to be drawn into the cover hose 29
in the
compressed state, after which the cover hose is extracted through the puncture
point.
In a further embodiment of the present invention, provision is made for a pump
medium
to be pumped from proximal to distal, i.e. against the original flow direction
5 (Fig. 25
II). To support the rotor 3.2 in the axial direction and to absorb the bearing
forces, the
bearing washer 15 is provided on the proximal side of the rotor 3.2. The flow
direction to
the distal side may be obtained either by reversing the direction of rotation
from that of
the embodiment above, or by inverting the pitch of the rotor 3.2. The outlet
hose 18 is
located at the distal end of the pump section of the clutch housing 19 and
extends beyond
the pump head in the distal direction. To reinforce the outlet hose 18 it may
have a mesh
structure of a memory material e.g. similar to that of the pump housing. The
body cap 10
extends beyond the distal end of the outlet hose.
In operation, the pump medium flows into the pump housing through the pump
housing
outlets now serving as inlets, and passes into the outlet hose 18 through the
pump housing
inlet now serving as the outlet. The pump medium passes out of the catheter
device 1
through the distal end of the outlet hose.
The embodiment just described may be provided for example for use in the right
ventricle.
CA 02701809 2010-04-07
32
In a further embodiment, the catheter device according to the invention may
also be
designed so that pumping from distal to proximal and from proximal to distal
is possible
(Fig. 25 III).
In this embodiment, bearing washers 15 are provided at the distal and proximal
ends of
the rotor 3.2. The outlet hose 18 is located at the distal end of the pump
section 3.1.3 of
the pump housing 3.1 and extends in the distal direction. For reinforcement,
the outlet
hose 18 has a mesh structure, e.g. similar to that of the pump housing. The
mesh structure
is covered by a PU skin. The diameter of the outlet hose 18 corresponds
roughly to that of
the expanded pump housing.
In operation a pump medium may enter or exit through the outlets of the pump
housing.
The pump medium then passes for example via the outlets of the pump housing
and the
inlets of the pump housing into the outlet hose, and exits at the distal end
of the outlet
hose. With the direction of pumping reversed, the flow through the catheter
device is
correspondingly reversed. This means that the pump medium enters the outlet
hose at the
distal end of the outlet hose, and arrives at the outlets of the pump housing
via the inlets
of the pump housing. Consequently, a flow to distal or proximal is possible
through the
pressure- and suction-stabilised outlet hose 18.
The embodiment just described may be used for example for drainage or filling
of hollow
organs or spaces.
The reversed direction of flow may be obtained on the one hand by reversing
the
direction of rotation of the rotor and on the other hand by inverting the
pitch of the rotor.
The invention is described above with the aid of an embodiment in which the
magnet
units each have four bent bar magnets, each placed next to one another with
opposite
poles. Within the scope of the invention however the magnet units may also be
so
designed that the north and south poles of the magnet units are oriented in
the axial
CA 02701809 2010-04-07
33
direction, wherein the poles are provided on the axial surfaces facing the
distal or
proximal end. The magnets are arranged in a ring as in the previous
embodiments.
Through such an alignment of the north and south poles of the magnets, the two
magnet
units attract with greater magnetic forces. By this means it is possible to
transmit a higher
torque via the clutch.
A clutch of this kind may be used for example to drive a milling head instead
of a rotor.
Using such a micro-miller, e.g. kidney stone or bones may be milled with
minimal
invasion.
The number of magnets may in principle be varied as desired.
The radial compressibility of the components makes it possible to realise a
very small
puncture diameter, suitable for percutaneous implantation by the Seldinger
technique, on
account of the very small diameter of the catheter device, amounting to
approximately 3
mm. Due however to the expansion of the rotor up to a diameter of around 15
mm, it is
still possible to obtain very high pump performance.
Known from the prior art are expandable catheter pumps (e.g. US 4 753 221)
which have
a propeller with several rigid pump blades. These are mounted pivotably. Since
the
blades are rigid, they can not be made as wide as desired since, in the folded
state, they
would require a catheter which was too thick. Pump performance is therefore
limited.
The rotor according to WO 99/44651 has an elastic band for connecting a
nitinol filament
to a rotation axis. Because of this elastic connection, the filament is not
perfectly centred.
During pumping, this can lead to vibrations which make higher speeds or rates
of
pumping impossible.
Because of the frame structure of the rotor with boundary frame and rotor
struts in
accordance with the catheter device 1, the rotor is more stable, capable of
folding and of
CA 02701809 2010-04-07
34
expansion to virtually any diameter required. Due to the fact that the rotor
may be
virtually as long as desired in the axial direction, the radial extent of the
rotor may be
chosen freely. This makes it possible to obtain virtually any level of pump
performance,
in particular very high performance, and it is possible to adapt pump
performance
specifically for each application.
The pitch of the rotor may also be varied as desired. The rotor may be
designed with one
or several rotor blades, with the rotor blades accordingly having a quarter, a
half a whole
or as many twists around the drive shaft as desired. This means that the rotor
may be
varied as desired in its size, shape and pitch, and may therefore be used for
the most
diverse applications.
CA 02701809 2010-04-07
List of reference numbers
1 catheter device
2 distal end
3 pump head
3.1 pump housing
3.1.1 distal connection section
3.1.2 intake section
3.1.3 pump section
3.1.4 outlet section
3.1.5 proximal connection section
3.1.6 mesh structure
3.1.7 apertures
3.1.7.1 small rhombus
3.1.7.2 large rhombus
3.1.7.3 medium-sized rhombus
3.1.8 PU covering of the pump housing
3.2 rotor
3.2.1 frame structure
3.2.2 boundary frame
3.2.3 rotor struts
3.2.4 rings
4 drive shaft
4.1 distal section of the drive shaft
4.2 pump section of the drive shaft
4.3 proximal section of the drive shaft
5 flow direction
6 proximal end
7 motor
7.1 motor mounting
7.1.1 end face
7.1.2 side face
7.1.3 cooling fins
7.1.4 bore
7.1.5 recess
7.2 motor shaft
8 catheter body
8.1 distal catheter body element
8.2 proximal catheter body element
9 clutch
10 body cap
10.1 ball
10.2 cylindrical section
CA 02701809 2010-04-07
36
10.3 through bore
10.4 axial bore
10.5 step
12.1 distal connection bush
12.2 proximal connection bush
13.1 distal shaft protector
13.2 proximal shaft protector
14 guide spiral
15 bearing washer
15.1 through bore
16 spacer sleeves
17 distal rotor bearing
18 outlet hose
18.1 outlet
19 clutch housing
19.1 distal cylindrical section
19.2 conically widening section
19.3 second cylindrical section
19.4 proximal cylindrical section
19.5 catheter body mounting section
19.6 guide spiral mounting section
19.7 drive shaft passage section
19.8 fourth bore section
19.9 bearing section
19.10 distal clutch section
19.11 proximal clutch section
19.12 shoulder
19.13 tapped hole
19.14 L-shaped recess
19.15 rinsing bore
20.1 outer ring magnet
20.2 inner ring magnet
20.3 magnet ring bearing
21 square rod
21.1 recess
22 clutch element
22.1 recess
22.2 cylindrical section
22.3 disc-shaped section
22.4 shoulder
22.5 magnet mounting
22.6 ball head bearing mount
23.1 distal magnet unit
23.2 proximal magnet unit
24 terminating disc
24.1 bores
CA 02701809 2010-04-07
37
24.2 thicker sections
24.3 through bore
24.4 hemispherical recess
24.5 centering pin
24.6 ball head
25 ball head bearing
26 magnet mounting
26.1 recess
27 coupling flange
27.1 dowel pins
28
29 cover hose
30 motor assembly
