Note: Descriptions are shown in the official language in which they were submitted.
An Implantable Bodily Fluid Drainage Valve with Magnetic Field Resistance
Engagement Confirmation
BACKGROUND 0 F THE INVENTION
Field of the Invention
[0001] The present invention relates to a system and method for an implantable
drainage
valve for drainage of a bodily fluid (e.g., cerebrospinal fluid). In
particular, the present
inventive system and method is directed to verifying whether a mechanical
feature in the
valve for resisting changes to performance setting when exposed to magnetic
fields is
properly engaged. For example, magnetic fields generated while undergoing
Magnetic
Resonance Imaging (MR1) or other foreign magnetic fields generated by common
household
magnets (e.g., refrigerator magnets or electronic notebook covers.
Description of Related Art
[0002] Hydrocephalus is the accumulation of cerebrospinal fluid in the brain,
resulting from
increased production, or more commonly, pathway obstruction or decreased
absorption of the
fluid. Cerebrospinal fluid (CSF) shunts have been used for decades for the
treatment of
hydrocephalus. A CSF shunt involves establishing an accessory pathway for the
movement of
CSF to bypass an obstruction of the natural pathways.
[0003] The shunt is positioned to enable the CSF to be drained from the
cerebral ventricles or
sub-arachnoid spaces into another absorption site (e.g., the right atrium of
the heart or the
peritoneal cavity) through a system of small catheters. A regulatory device,
such as a valve,
may be inserted into the pathway of the catheters. In general, the valve keeps
the CSF
flowing away from the brain and moderates the pressure or flow rate. The
drainage system
using catheters and valves enables the excess CSF within the brain to be
evacuated and,
thereby, the pressure within the cranium to be reduced.
[0004] Some implantable valves are fixed pressure valves (i.e., monopressure
valves) while
others have adjustable or programmable settings. Programmable or adjustable
implantable
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valves are desirable in that the valve pressure setting may be varied non-
invasively via an
external control device over the course of treatment without requiring
explantation. One such
conventional adjustable or programmable implantable valve using magnets is the
CODMAN HAKIM Programmable Valve (CHPV), as disclosed in US Patent No.
4,595,390, which is assigned to DePuy Orthopedics, a J&J company related to
that of the
present assignee. Another programmable implantable drainage valve is the
CODMAN
CERTAS or CERTAS Plus Programmable Valve, as disclosed in US Patent No.
8,322,365, also assigned to DePuy Orthopedics, a J&J company related to that
of the present
assignee.
in its entirety. Medtronic also has a programmable implantable shunt valve
Strata
controlled using magnets. The pressure setting in these aforementioned
conventional
programmable implantable valves may be non-invasively adjusted post
implantation in the
body using a rotating construct or rotor with at least one magnet.
[0005] Magnetic resonance imaging (MRI) is a medical procedure for examining
internally
one or more parts, organs or other sites of the body exposed to powerful
magnetic fields
(typically at approximately 3.0 Tesla magnetic exposure levels). However, due
to the
presence of the magnets in the programmable implantable drainage valve such
systems are at
high risk of malfunction or improper operation (e.g., unintentional changes in
performance
settings) when exposed to powerful magnetic fields, for example, during MRI
procedures.
Similar malfunction in operation of the valve may occur upon exposure to other
magnets as
well.
[0006] To avoid such risk, some conventional programmable implantable valves
have been
modified to include a locking, engagement or magnetic field resistance
mechanism which,
when functioning or operating properly, ensures that unintentional changes in
the
performance settings will not occur when the device is exposed to rogue or
foreign magnets.
However, if not properly locked or engaged the magnetic field resistance
mechanism may not
accomplish its intended functionality leaving the programmable implantable
valve susceptible
to possible change in parameter settings without advanced warning of such
risk. Due to the
possibility, albeit a relatively small probability, of non-engagement of the
magnetic field
mechanism (i.e., not properly seated or locked), the implantable bodily fluid
drainage valve
2
Date Recue/Date Received 2023-08-18
may not always be resistant to undesired changes in valve setting when exposed
to foreign
magnets.
[0007] It is therefore desirable to develop a system and method that confirms
whether the
magnetic field resistance mechanism is properly locked or engaged, and thus
accomplishing
its intended functionality of the valve resisting change in programmed valve
settings when
exposed to rouge or foreign magnets.
Summary of the Invention
[0008] An aspect of the present invention is directed to a system and method
that confirms
whether the magnetic field resistance mechanism is properly locked or engaged,
and thus
accomplishing its intended functionality of the valve resisting change in
programmed valve
settings when exposed to rouge or foreign magnets.
[0009] Another aspect of the present invention relates to a method for
verifying whether a
magnetic field resistance mechanism is properly engaged in an implantable
programmable
bodily fluid drainage system comprising an implantable bodily fluid drainage
valve having an
adjustable valve unit including a rotating construct and a pair of primary
magnetic elements
for programming the adjustable valve unit to a desired valve setting. Using a
toolset, a
determination is made whether the magnetic field resistance mechanism is
properly engaged.
An alert is generated whether the magnetic field resistance mechanism is at
least one of
properly engaged or not properly engaged. In accordance with the present
invention, the
determination of whether the magnetic field resistance mechanism is properly
engaged is
based on: (i) a measured angular position of a detected one of the pair of
primary magnetic
elements relative to a direction of flow of fluid through the implantable
bodily fluid drainage
valve; and/or (ii) a measured distance separation between respective centers
of the pair of
primary magnetic elements.
[0010] In one particular aspect of the present invention, the implantable
bodily fluid drainage
valve includes a fixed reference magnet aligned with a marking on the
implantable bodily
fluid drainage valve denoting a direction of fluid flow therethrough and a
center point midway
between the pair of primary magnetic elements. The housing of the rotating
construct
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comprises an upper casing having a plurality of downward projecting teeth in
which the pair
of primary magnetic elements are respectively located and a lower casing
including a plurality
of corresponding setting pockets for receiving the downward projecting teeth.
Each of the
setting pockets is bound on at least one side by a lock stop projecting
upwardly from the
lower casing towards the upper casing. In this particular aspect of the
invention, the
determination of whether the magnetic field resistance mechanism is properly
engaged is
based on the measured angular position of a detected one of the pair of
primary magnetic
elements relative to a direction of flow of fluid through the implantable
bodily fluid drainage
valve. Such determination includes the step of detecting using a sensor array
in the toolset a
magnetic field pattern produced by each of: (i) the fixed reference magnet;
and (ii) the pair of
primary magnetic elements. The center point midway between the detected pair
of primary
magnetic elements is then located. A direction of flow line is defined as a
reference line
intersecting with: (i) the arrow indicia denoting direction of flow of fluid
through the
implantable bodily fluid drainage valve; (ii) the located center point midway
between the
detected pair of primary magnetic elements; and (iii) the detected fixed
reference magnet.
Thereafter, a rotating construct vector is defined connecting centers of the
detected pair of
primary magnetic elements. A rotating construct angle is measured starting
from the defined
direction of flow line traveling in a counter-clockwise or clockwise direction
until intersecting
the rotating construct vector. Finally, the measured rotating construct angle
is compared to a
predetermined mechanical angular spacing for each of the setting pockets as
stored in a
memory device. If the measured rotating construct angle matches the
predetermined
mechanical angular spacing for any of the setting pockets then the magnetic
field resistance
mechanism is deemed properly engaged. Otherwise, if the measured rotating
construct angle
does not match the predetermined mechanical angular spacing for any of the
setting pockets
then the magnetic field resistance mechanism is deemed not to be properly
engaged. That is,
the magnetic field resistance mechanism is engaged when the plurality of
downward
projecting teeth are properly seated in the corresponding setting pockets,
whereas the
magnetic field resistance mechanism is not properly engaged when any of the
plurality of
downward projecting teeth are resting on one of the lock stops. The
aforementioned
determining step may be performed following programming of a valve setting of
the
implantable bodily fluid drainage valve and/or prior to a magnetic resonance
imaging
procedure.
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[0011] In still another particular aspect of the present invention the
implantable bodily fluid
drainage valve includes a rotating construct rotatably mounted in a housing
about an axis with
a substantially cylindrical central part fixedly mounted on the axis. The
rotating construct
includes lateral branches on either side of the axis for moving parts each
housing a respective
one of the pair of primary magnetic elements with opposing faces of opposite
polarity. A
mating lead in element extends respectively from each of the moving parts. The
moving parts
are displacable linearly inside the rotating construct in a substantially
radial direction thereof
to actuate the mating lead in element in a circular succession of pockets
defined radially
inward along an outer perimeter of the substantially cylindrical central part.
In this
configuration, the mechanical resistance mechanism is engaged when the mating
lead in
element is seated in one of the pockets, whereas the magnetic field resistance
mechanism is
not engaged when the mating lead in element is resting along the outer
perimeter of the
substantially cylindrical central part between the pockets adjacent to one
another. Moreover,
in this configuration, the determination of whether the magnetic field
resistance mechanism is
properly engaged is based on the measured angular position of a detected one
of the pair of
primary magnetic elements relative to a direction of flow of fluid through the
implantable
bodily fluid drainage valve, as described above. Alternatively, in this
configuration the
determination of whether the magnetic field resistance mechanism is properly
engaged may
be based on the measured distance separation between respective centers of the
pair of
primary magnetic elements. This is accomplished by detecting a center of each
of the pair
primary magnetic elements. Then a distance separation between the detected
center of each
of the pair of primary magnets is calculated. The calculated distance
separation is compared
to a predetermined locking value. If the calculated distance separation is
equal to the
predetermined locking value, then the magnetic field resistance mechanism is
deemed
properly engaged. Otherwise, if the calculated distance separation is greater
than the
predetermined locking value, then the magnetic field resistance mechanism is
deemed not to
be properly engaged.
Brief Description of the Drawing
[0012] The foregoing and other features of the present invention will be more
readily
apparent from the following detailed description and drawings of illustrative
of the invention
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wherein like reference numbers refer to similar elements throughout the
several views and in
which:
[0013] Figure 1 is a schematic perspective exploded view of a programmable
valve device
having an adjustable valve unit;
[0014] Figure 2 is an exploded perspective view of the adjustable valve unit
of Figure 1;
[0015] Figure 3 is a top view of the adjustable valve unit of Figure 2;
[0016] Figure 4 is a side cross-sectional view of the adjustable valve unit of
Figure 3 along
lines 4-4;
[0017] Figure 4A is a side view of a single rotor tooth in engagement with a
single lock stop;
[0018] Figure 5 is a cross-sectional view of the adjustable valve unit of
Figure 3 along lines
5-5;
[0019] Figure 6 is a partial cross-sectional view of the adjustable valve unit
of Figure 4
approximately along lines 6-6 at a first pressure setting;
[0020] Figure 6A is a deeper cross-sectional view of the adjustable valve unit
of Figure 4
approximately along lines 6A-6A at a first pressure setting;
[0021] Figures 6B-6H are partial cross-sectional view of the adjustable valve
unit of Figure 4
at different, successive pressure settings;
[0022] Figure 61 is a partial cross-sectional view of the adjustable valve
unit of Figure 4 at an
exemplary first pressure setting illustrating the arrow marking on the
programmable valve
device denoting a direction of fluid flow therethrough and a fixed reference
magnet;
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[0023] Figure 6J is a top view of the programmable valve device of Figure I
wherein the
adjustable valve unit is at the same first pressure setting illustrated in
Figure 61 and also
showing the direction of flow arrow marking and positioning of the fixed
reference magnet;
[0024] Figure 7 is a deeper cross-sectional view of the adjustable valve unit
of Figure 4
approximately along lines 7-7;
[0025] Figure 8 is a cross-sectional view of the adjustable valve unit of
Figure 7 showing the
transition to a different pressure setting;
[0026] Figure 9 is a perspective view of the spring arm unit with optional
torsion spring;
[0027] Figure 9A is a top plan view of the element of Figure 9;
[0028] Figure 10 is a side cross-sectional view of the adjustable valve unit
of Figure 8 along
lines 10-10 showing axial lifting of the rotatable construct;
[0029] Figure 11 is a shallower partial top cross-sectional view of the
adjustable valve unit of
Figure 61-1 showing the "virtual off' position in an unconstrained condition;
[0030] Figure 12 is a side view along lines 12-12 of Figure 11;
[0031] Figure 13 is a side cross-sectional view along lines 13-13 of Figure
11;
.. [0032] Figure 13A is a partial cross-sectional view along lines 13A-13A of
Figure 13;
[0033] Figure 14 is a perspective view of a tool set including an integrated
locator/indicator
tool, an adjustment tool and a screwdriver;
[0034] Figure 14A is a top perspective view of the integrated
locator/indicator tool and
adjustment tool of Figure 14, prior to the adjustment tool being inserted into
the integrated
locator/indicator tool;
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[0035] Figure 14B is a top perspective view of the integrated
locator/indicator tool and
adjustment tool of Figure 14, with the adjustment tool inserted into a
complementary cavity in
the integrated locator/indicator tool;
[0036] Figure 15 is an exploded perspective view of the integrated
locator/indicator tool of
Figure 14;
[0037] Figure 16 is an exploded perspective view of the adjustment tool of
Figure 14;
[0038] Figure 16A is a perspective view of the placement of the half round
magnets on either
side of the magnet shield comprising part of the magnet assembly of Figure 16;
[0039] Figure 16B is a perspective view of the assembled magnet assembly of
Figure 16;
[0040] Figure I 6C is a top view of the assembled bottom and middle housing
sections of the
adjustment tool of Figure 16 showing the internal vertical ribs;
[0041] Figure 16D is a perspective view of the assembled adjustment tool of
Figure 14
without the outer housing section to illustrate the magnet assembly;
[0042] Figure 17A is a perspective view of an alternative configuration of the
lower casing of
the adjustable valve unit;
[0043] Figure 17B is a perspective view of the alternative configuration of
the lower casing
of Figure 17A with the rotating construct nested therein;
[0044] Figure 18A is an alternative configuration of a prior art programmable
valve; and
[0045] Figure 18B is a prior art setting device for use with the programmable
valve of Figure
18A.
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Detailed Description of the Invention
[0046] Figure 1 illustrates a prior art programmable shunt valve device 10
having a shunt
housing 12, preferably formed of a translucent material such as silicone, with
proximal
connector 14 and distal connector 16. A ventricular catheter or other proximal
catheter is
connectable to connector 14 to bring fluid into shunt housing 12. Fluid passes
into sampling
or pumping chamber 18 and then through a valve mechanism in inlet 102 into
adjustable
valve unit 100, which is shown and described in more detail below in relation
to Figures 2-
13A. Valve unit 100, Figure 1, includes a casing 103 formed as upper casing
104 and lower
casing 106 which are joined by sonic welding in this construction. A needle
guard 20,
preferably formed of a rigid polymeric material, and lower casing 106 are
secured within
housing 12 by a backing plate 22, preferably formed of silicone reinforced
with a polymeric
mesh, which is bonded to housing 12 by a medical grade epoxy. A fixed
reference magnet
800, as described in detail further below, is preferably seated in a bump or
projection 801 on
the needle guard 20.
[00471 When fluid pressure at inlet 102 exceeds a selected pressure setting
within valve unit
100, fluid is admitted past a valve mechanism and then flows through valve
unit outlet 110
into passage 30 of housing 12. Ultimately, fluid exits from housing 12 through
distal
connector 16 into a peritoneal catheter or other distal catheter.
[0048] Valve unit 100, Figure 2, includes a rotor 120, spring arm unit 130,
valve mechanism
140, and a rotor retention spring 150. Rotor 120, also referred to as a
rotating construct, is
formed of a lower cam structure 122 having a plurality of radially flat cam
surfaces, as shown
and described in more detail below, and an upper, magnet housing 124 carrying
magnetic
elements 123 and 125, N and S pole magnets, respectively. Housing 124 also
defines a finger
127 which engages a stop in upper casing 104 when rotor 120 is moved to an
unconstrained
condition as described below. Rotor 120 rotates about axle 126 which defines a
substantially
fixed axis of rotation Rat a first location in casing 103.
[0049] Preferably, rotor 120 is also capable of moving along the axis of
rotation, in a
translational motion, to an unconstrained condition when an adjuster tool is
applied to it, as
described in more detail below. Retention spring 150 biases rotor 120 to a
downward,
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normally constrained condition. Preferably, spring 150 is a coil spring having
sufficient bias
to resist the effect of gravity, regardless of the position of the valve unit,
and to resist
magnetic or ferrous objects, such as magnets in an indicator tool described in
more detail
below. However, spring 150 is insufficient to resist the effects of an
adjustment tool, also
described below. Lower cam section 122 has a sufficient height to ensure that
cam follower
132 remains in contact with a cam surface in both the constrained and
unconstrained
conditions.
[0050] Spring arm unit 130 includes cam follower 132, a resilient spring
element 134, and
upper and lower axles 136 and 138 at a second location in casing 103. Axle 138
turns about a
bearing 139 formed of a low-friction, hard material such as synthetic ruby. It
is desirable for
casing 103, rotor 120 and spring arm unit 130 to be formed of
polyethersulfone, while all
spring components are formed of medical grade non-ferromagnetic stainless
steel.
[0051] Valve mechanism 140 includes seat 142 and movable valve member 144.
Preferably,
seat 142 and valve member 144, such as a ball, are formed of the same non-
ferromagnetic
material such as synthetic ruby. In other constructions, the movable valve
member may be a
disc, a cone, or other type of plug. A spherical ball is currently preferred
because that shape
enables tight, precise tolerances, assembly and control relative to the valve
seat. Also, the
position of the seat within a port can be adjusted during assembly of the
valve unit to alter the
actual performance value achieved at each setting, using a force versus
displacement
relationship. First, a mandrel checks the position of the ball, and the seat
is inserted to an
estimated desirable location within the port. Ball displacement is tested at
one or more
settings to confirm that desired performance will be achieved.
[0052] Valve unit 100 is shown assembled in Figures 3-5 and positioned at a
second pressure
setting, as described in more detail below. Rotor housing 124 carries
downwardly projecting
teeth 160 and 162 with cooperate with four lock stops projecting upwardly from
lower casing
106 in this construction. Lock stop 172 is shown in partial cross-section in
Figure 4 and lock
stops 170 and 176 are visible in Figure 5. Preferably, the lower surfaces of
rotor teeth 160
and 162 are rounded and the upper surfaces of casing lock stops 170, 172, 174
and 176 each
have a plurality of facets to create a chisel-like, lead-in topography which
encourages the
CA 3019544 2018-10-02
rotor teeth to return to a constrained position, as illustrated in the side
view in Figure 4A.
However, the vertical surfaces of teeth 160, 162 and of stops 170-176 abut
when engaged and
do not "lead out", that is, relative translational movement is discouraged,
once again
illustrated in Figure 4A. Pure vertical lift must be provided by an adjustment
tool, as
.. described in more detail below, to overcome the tooth-to-stop abutment and
change the
performance setting.
[0053] A limiter 180, Figure 4, restricts travel of spring 134 away from seat
142 so that ball
144 does not become misaligned or dislodged relative to seat 142. A gasket 182
of epoxy is
shown in Figures 4 & 5 as an optional, redundant seal between upper casing 104
and lower
casing 106 in this construction.
[0054] The operation of valve unit 100 is illustrated in Figures 6-8 in
relation to valve unit
100, with identical reference numerals identifying identical components and
features. Not all
.. such components and features are labelled in each drawing for the sake of
visual clarity.
Figures 6 & 6A show different levels of top partial cross-sectional views for
valve unit 100 at
a first pressure setting. Cam follower 132 slidably contacts only a first cam
surface 191,
which has an arc length bounded by points 190 and 192, because rotor housing
tooth 162 is
captured between casing lock stops 170 and 172 in the normal, constrained
condition. First
cam surface 191 has a first, preferably shortest radial distance 210 relative
to the axis of
rotation of rotor 120. By comparison, outermost cam surface 205 has a greatest
radial
distance 218. An optional torsion spring 220 is shown in greater detail in
Figure 9.
[0055] When rotor 120 is translated upwardly by magnets using an adjustment
tool rotor
tooth 162 is lifted so that subsequent clockwise or counter-clockwise rotation
of the
adjustment tool rotates tooth 162 up and over casing lock stop 172. After the
adjustment tool
is removed and when the second pressure setting has been selected as shown in
Figure 6B,
rotor 120 is biased downwardly by spring 150, Figures 2, 4 & 5.
.. [0056] Rotor tooth 160 is illustrated as not being in contact with any stop
in Figures 4 & 6B,
for example, because in the constrained condition rotor tooth 162 is now
captured between a
pair of lock stops 172 and 174, Figure 6B, which is sufficient to prevent
rotation of rotor 120
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relative to the cam follower 132 beyond points 192 and 194 on the cam
structure of rotor 120.
Points 192 and 194 represent a second arc length for second cam surface 193.
Surface 193 is
at a second radial distance 212 which is greater than distance 210 and is less
than distance
218, Figures 6A & 6H. The arc length of second cam surface 193, Figure 6B, can
be the same
or different than the arc length of first cam surface 191 but, preferably, is
substantially the
same length.
[0057] The outward radial motion of cam follower 132 as it slidably travels
from first cam
surface 191, Figure 6A, to second cam surface 193, Figure 6B, increases the
biasing force by
.. valve spring 134 on ball 144 as increased torque is applied by cam follower
132 to the
remainder of spring arm unit 130. Improved precision in pressure control is
achieved by
having a stiff cam follower 132 in contact with the selected cam surface and a
flexible
element, spring 134, in contact with the valve ball 144. The enhanced result
is opening of the
ball 144 from the valve seat 142 by requiring only the resilient spring
element 134 to bend,
which provides a constant spring force to the ball 144. The opening pressure,
and overall
valve performance, is not reliant on axial pivoting of the spring arm unit
130.
[0058] A third opening pressure setting is shown in Figure 6C with rotor tooth
162 positioned
between casing stops 174 and 176 such that cam follower 132 experiences only
third cam
.. surface 195 between points 194 and 196 at a third radial distance 214. To
achieve a fourth
pressure setting, Figure 6D, both rotor teeth 160 and 162 are utilized
relative to casing stops
170 and 176, respectively. Cam follower 132 is restricted thereby to fourth
cam surface 197
between points 196 and 198.
[0059] Fifth through seventh pressure settings are illustrated in Figures 6E-
6G as rotor tooth
160 is successively captured between casing lock stop pairs 170-172, 172-174,
and 174-176,
respectively. Cam follower 132 is restricted thereby to fifth cam surface 199
between points
198 and 200, Figure 6E, sixth cam surface 201 between points 200 and 202,
Figure 6F, and
seventh cam surface 203 between points 202 and 204, Figure 6G.
[0060] Preferred opening pressure settings currently range from approximately
30 mm to 210
mm water (294 Pa to 2,059 Pa) in seven increments of 30 mm (294 Pa), with a
final, "virtual
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off' setting described in more detail below. Preferably, each valve unit is
calibrated and
tested at the time of manufacture at one or more flow rates. Actual opening
pressure for each
setting tends to vary according to flow rate, typically measured in
milliliters per hour. Also,
when tested with a 120 cm long distal catheter having an inner diameter of 1
mm, the average
opening pressure typically will increase by 9 mm water or more at flow rates
of .5 ml/h or
more.
[0061] The final setting, Figure 61-1, of approximately at least 400 mm water
(3,920 Pa)
minimizes flow as a "virtual off' setting, that is, as substantially closed.
This final setting is
achieved by exposing cam follower 132 to outermost cam surface 205, defined by
points 204
and 206, having greatest radial distance 218. This greatest cam setting forces
stiffener
element 133 of spring arm unit 130 against valve spring 134 to shorten its
active, effective
length and thereby dramatically increase the biasing force applied against
ball 144. The final
opening pressure is increased by more than fifty percent over the prior
setting. In other
constructions, a stiffener element is forced against a valve spring during two
or more final
cam settings at desired pressure increments.
[0062] Spring arm unit 130 is shown in greater detail in Figures 9 and 9A with
cam follower
132, stiffener element 133, and valve spring 134. Cam follower 132 terminates
in a triangular
head 233 with rounded or chamfered edges, one of which serves as a bearing
surface 235. In a
preferred construction, spring element 134 is formed from stainless steel
having a thickness of
0.020 inches and terminates in an enlarged pad 230 for contacting the valve
ball or other
movable valve member. In one construction, spring element 134 is attached to
the remainder
of spring arm unit 130 by a post 232 and rivet 234 which are secured by
ultrasonic welding.
Torsion spring 220 has a first leg 221 which is retained in recess 236 of
projection 238.
Second spring leg 223 rests against an inner surface of the casing.
[0063] Use of torsion spring 220 is optional, and is possible because only
spring element 134
contacts the movable valve member. As a result, additional spring force from
torsion spring
220 can be utilized to force bearing surface 235 of cam follower 132 against a
cam surface of
the rotor. This biasing force provided by torsion spring 220 augments
rotational position of
the spring arm reflective of the intended cam displacement without otherwise
impacting the
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force applied to the ball or other movable valve member. This provides for a
more accurate
and repeatable opening pressure and a more manufacturable and robust design as
it reduces
the need to maintain minimal friction such as when the valve spring element
solely provides
the force needed to maintain the cam follower on the cam surface.
[0064] The position of the components and features within valve unit 100 at
the first pressure
setting shown in Figure 6A is illustrated at a deeper partial cross-sectional
view in Figure 7.
Opening 222 into the lower cam portion of rotor 120 inhibits negative pressure
from
developing under rotor 120, that is, opening 222 ensures pressure equalization
as
cerebrospinal fluid passes through valve unit 100.
[0065] The transition from the first pressure setting to the second pressure
setting is
illustrated in Figures 8 & 10 as rotor 120 is translated upwardly by magnetic
attraction with
an adjustment tool so that rotor tooth 162 is able to clear casing lock stop
172. Cam follower
132 is shown in Figure 8. 8 at point 192 passing from first cam surface 191 to
second cam
surface 193. Lower cam section 122 has a sufficient height relative to cam
follower bearing
surface 235 to ensure that cam follower 132 remains in contact with a cam
surface of cam
portion 122 in both the constrained and unconstrained conditions. Rotor
retention spring 150,
Figure 10, has been compressed, its biasing force being overcome by magnetic
attraction
between rotor 120 and the adjustment tool while it is positioned over valve
unit 100. Also
illustrated in Figure 10 are upper and lower synthetic ruby bearings 242 and
139 for upper and
lower axles 136 and 138, respectively, of spring arm unit 130. Synthetic ruby
bearing 240
rotatably supports rotor axle 126.
[0066] The position of the components and features within valve unit 100 at
the final, "virtual
off' or substantially closed setting shown in Figure 6H is depicted at a
shallower cross-
sectional view in Figure 11 in an unconstrained condition. Further clockwise
rotation of rotor
120 is prevented by rotation stop or limiter 250 which projects downwardly
from upper casing
104 to contact finger 127. Rotation stop 250 contacts the opposite surface of
finger 127 when
rotor 120 is turned fully counter-clockwise in an unconstrained condition. The
actual position
of rotation stop 250 may be shifted to the right of the position shown in
Figure 11 so that cam
follower 132 is able to track nearly the entire portion of cam surface 205.
Preferably, one side
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of stop 250 prevents rotor movement from the lowest setting directly to the
highest setting,
and also prevents the cam follower from touching the cam projection for the
highest setting
when the rotor is at its lowest setting. The other side of stop 250 prevents
movement from the
highest setting directly to the lowest setting. A side, partial cross-
sectional view of rotation
stop 250 blocking rotor housing 124, as well as spring 150 compressed between
rotor 120 and
upper casing 104, is shown in Figure 12 for this unconstrained condition.
[0067] Further detailed views of selected features and components of rotor 120
in one
construction are illustrated in Figures 13 & 13A. In particular, the housing
portion 124 is
shown as integral with cam portion 122. Pocket cavity 260, Figure 13, contains
magnet 123
and tantalum reference ball 129 which is readily visible during imaging of the
valve unit 100
after implantation in a patient to confirm the actual pressure setting. Pocket
cavity 262 holds
magnet 125. A partial end view of housing portion 124 through magnet 125,
pocket 262 and
rotor tooth 160 is provided in Figure 13A.
[0068] It is therefore the particular design of the abutting rotor-tooth-to-
lock-stop vertical
surfaces requiring purely vertical lift by an adjustment tool to overcome the
rotor-tooth-to-
lock-stop abutment in order to change the pressure setting that provides the
resistance to
change of valve settings in the presence of a foreign magnet. The rotor-tooth-
to-lock-stop
abutment mechanically prevents rotational movement from a given performance
setting as the
vertical surfaces provide no lead in to facilitate travel up and over the
casing stops. Axial
movement is restricted due to the orientation of the rotating construct
magnets inducing a
combined attraction and repulsion when interacting with a strong north or
south magnet.
Furthermore, the interference between the axle and the bushing surface of the
rotating
construct mechanically limit tilt associated with attraction/repulsion to an
external magnetic
field.
[0069] However, it is only when the downward projecting teeth 160, 162 of the
rotor housing
124 are properly locked, engaged or seated in corresponding setting pockets
171, 171', 171",
171' defined by at least one of the lock stops 170, 172, 174, 176 projecting
upwardly from
the lower casing 106 that the programmable implantable bodily fluid drainage
valve is
resistant to magnetic fields from foreign magnets. The device has been tested
to be 100%
CA 3019544 2018-10-02
resistant to change of valve settings at least for magnetic fields up to
approximately 3T so
long as the magnetic field resistance mechanism is properly engaged. Figures
6A-614 depict
proper engagement of the magnetic field resistance mechanism for each of the 8
valve
settings. During programming or adjustment of the valve it is mechanically
possible for the
downward projecting teeth 160, 162 when vertically lowered to undesirably rest
on top of one
of the lock stops 170, 172, 174, 176. Figure 8 illustrates just such an
example with tooth 162
resting on top of lock stop 172. When one of the teeth 160, 162 is resting on
top of a lock
stop 170,172, 174, 176 (i.e., not properly seated or engaged in the respective
setting pockets
defined between adjacent lock stops) the programmable implantable bodily fluid
drainage
13 valve is at risk of possible unwanted change to the valve setting if
exposed to a magnet.
Heretofore, conventional programming valves are not able to verify whether the
magnetic
field mechanism is properly locked or engaged, that is whether teeth 160, 162
are properly
seated in the setting pockets 171, 171', 171", 171". It is therefore uncertain
whether the
valve would be resistant to possible change in setting when exposed to
magnetic fields. To be
.. certain, following exposure to a foreign magnet (e.g., after undergoing an
MRI procedure),
the programmed valve setting must once again be verified by medical personnel
using the
indicator tool from the associated toolset. Despite the relative small
probability of the teeth
not being properly seated, the possibility of a change in valve setting upon
exposure of the
valve to a foreign magnet is still particularly problematic since the
implantable programmable
bodily fluid drainage valve cannot be guaranteed as being resistant to
magnetic fields within a
predetermined range (up to approximately 3T).
[0070] The present inventive improved implantable valve drainage system
eliminates this
uncertainty by verifying, following programming of a valve setting or in
advance of exposure
to a foreign magnet, whether the downward projecting teeth 160, 162 are
properly seated in
the respective seating pockets 171, 171', 171", 171". In essence, verifying
whether the
magnetic field resistance mechanism is properly locked or engaged to ensure
that the valve
setting does not change if the valve is exposed to a foreign magnet.
[0071] As discussed above, the programmable valve 10 includes a fixed
reference magnet
800, in addition to the primary magnetic elements 123, 125 disposed in the
housing 124 of the
rotor 120 of the adjustable valve unit, as illustrated in Figure 61. Referring
to Figure 6J, by
16
CA 3019544 2018-10-02
way of illustrated example, the fixed reference magnet 800 is located in the
valve between the
proximal connector 14 and the sampling/pumping chamber 18 within the direction
of flow of
the valve. However, the location of the fixed reference magnet 800 in the
valve may be
altered, as desired. In addition, instead of being disposed in the implantable
valve itself, the
fixed reference magnet 800 could be on a card that is placed externally
overtop the
valve/patient tissue to aid an electronic tool. Preferably, fixed reference
magnet 800 has a
different magnetic strength (nominal 2.7x10^-9 Weber Meter) from the primary
magnetic
elements (nominal 3.2x10^-9 Weber Meter) 123, 125 and a different nominal
distance between
magnets (i.e., distance between reference magnet 800 and primary magnet 123
compared to
distance between primary magnets 123 and 125) for proper identification by the
sensor array.
Nominal distance between primary magnetic elements 123, 125 is approximately
5.48mm
measured from bottom inner corner to bottom inner corner. Fixed reference
magnet 800
nominal distance is approximately 17.5mm from the rotating construct axle to
leading edge of
reference magnet 800. Fixed reference magnet 800 is aligned with an arrow
indicia or
marking "A" on the programmable valve 10 itself denoting the direction of flow
of fluid
therethrough and a center point "C" midway between the magnetic elements 123,
125. A line
passing through these three points (referred to as a direction of flow line)
is the basis for
determining the orientation of the programmable shunt valve 10 using an
integrated
locator/indicator tool 1405 from the exemplary tool set 1400 in a case, as
illustrated in Figure
14. It is noted that the locator and indicator tools described herein and
illustrated in the
accompanying drawings have been integrated into a single device for simplicity
of operation,
but could be two distinct devices. It is, however, contemplated and within the
intended scope
of the present invention for some, none, or all of the tools of the toolset to
be integrated. Also
included in the toolset is an adjustment tool 1415, a screwdriver 1410 and
spare batteries
1408.
[0072] A top perspective view of the integrated locator/indicator tool 1405
and adjustment
tool 1415 of Figure 14, prior to the adjustment tool 1415 being inserted into
a cavity 1420 of
the integrated locator/indicator tool 1405, is shown in Figure 14A. While
Figure 1413 shows
the adjustment tool 1415 following insertion into the cavity 1420.
17
CA 3019544 2018-10-02
[0073] Figure 15 is an exploded perspective view of the integrated
locator/indicator tool 1405
of Figure 14 which includes a housing. In the illustrated example, the housing
comprises a
bottom housing section 1505, a middle housing section 1510 and a top housing
section 1515,
each separate from one another. A cylindrical shaped section 1530 of the
middle housing
section 1510 defines a passageway or channel 1535 extending longitudinally
therethrough.
Top housing 1515 has a chimney 1525 complementary in size and shape to be
received within
the passageway or channel 1535 of the cylindrical shaped section 1530 of the
middle housing
section 1510. Chimney 1525 is closed at one end and open at an opposite end.
The open end
of the chimney 1525 receiving therein the adjustment tool 1415, as described
in detail below.
An exterior surface of the bottom housing 1505 has a recess 1520 defined
therein that is
complementary in shape and size to the outer contour of the programmable
implantable bodily
fluid drainage valve. In use, the integrated location/indication tool 1405 is
positioned with the
exterior surface of the bottom housing 1505 against the skin of the patient
and the implantable
bodily fluid drainage valve seated within the recess 1520. A top covering or
layer 1540 may
be mounted to the top of the assembled housing. Such covering or layer 1540
has a
complementary size and shape opening 1542 to that of the chimney 1525.
Disposed about the
perimeter of the opening 1542 are a series of markings or indicia representing
the different
valve settings in predetermined increments (e.g., 1, 2, 3õ5, 6, 7, 8). A
second opening 1550
in the top covering or layer 1540 permits viewing therethrough of a display
1555, such as a
Liquid Crystal Display (LCD). The integrated locator/indicator tool 1405 is
powered by one
or more batteries and turned ON/OFF by a button 1560. The batteries are housed
within a
battery enclosure assembly 1565 that includes a tray with conventional
electronic contact
terminals between which the batteries are inserted. Access to the battery
enclosure assembly
1565 for insertion/removal of the batteries therefrom is via a removeable
battery door
assembly 1575. A two-dimensional array of 3-axis magneto-resistive sensors
1570 printed on
a circuit board independently detects the magnetic field pattern produced by
each of the
magnetic elements 123, 125 disposed in the housing 124 of the rotor 120 and
the fixed
reference magnet 800. It is within the intended scope of the present invention
to substitute
other types of sensor arrays capable of detecting magnetic fields, such as
Hall sensors, for the
39 3-axis magneto-resistive sensors 1570. Another printed circuit board 1573
includes a
processor/controller, memory device and other electronic circuitry.
18
CA 3019544 2018-10-02
[0074] Figure 16 is an exploded perspective view of the adjustment tool 1415
of Figure 14.
In the illustrated example, housing 1600 comprises an outer housing section
1610 and a top
housing section 1615, each separate from one another. A magnet assembly 1620
is disposed
in the outer housing section 1610. In particular, the magnet assembly 1620 in
Figure 16A is a
Halbach array comprising two half round magnets 1630, 1635 connected by a yoke
1650 and
separated by a shield magnet 1640 that redirects the magnetic field allowing
deeper
penetration. The strength of the half round magnets 1630, 1635 selected for
use in the
adjustment tool 1415 depends on one or more factors, such as distance from the
valve and the
design of the sensor array. In the magnet assembly 1620, the two half round
magnets 1630,
.. 1635 are rotated until their flat side lays flush against the shield magnet
1640, as depicted in
Figures 16, 16A, 16B & 16D. The orientation of the magnets 1640, 1630, 1635
should
preferably with the magnet north side of the shield magnet 1640 in contact
with the half round
magnet 1630, 1635 with a magnetic north pointed toward the bottom of the outer
housing
section 1610. One of the two half round magnets 1630, 1635 faces the tantalum
reference ball
129 (Figure 13). The shield magnet 1640 is partially repelled by the half
round magnets 130,
1635 and thus is held down by a yoke 1650 mounted on top of the shield magnet
1640 that,
when assembled, is also in contact with the two half round magnets 1630, 1635.
It is these
components of the magnet assembly 1620 that when assembled together are
inserted into the
outer housing section 1610 so that the two half round magnets 1630, 1635 are
received in
respective recesses defined in an interior surface of the outer housing
section 1610 with the
half round magnet facing the tantalum ball 129 facing towards the to 8 stop'.
As is visible
in the top view in Figure 16C, the outer housing section 1610 includes a
plurality of vertical
ribs 1655 with which the half round magnets 1630, 1635 connect. A cylindrical
shaped
spacer 1625 is positioned above the yoke 1650 (Figure 16D). The top housing
section 1615
with a marking indicator is secured to the outer housing section 1610 forming
the assembled
adjustment tool 1415.
[0075] The magnetic field pattern produced by each of the magnetic elements
123, 125
disposed in the housing 124 of the rotor 120 and the fixed reference magnet
800 is detected by
the two-dimensional array of 3-axis magneto-resistive sensors 1570 of the
integrated
locator/indicator tool 1405. Once these three magnets are detected, the center
point "C"
midway between the two detected magnetic elements 123, 125 is located (Figure
6J). A
19
CA 3019544 2018-10-02
direction of flow line "DOF" (i.e., reference line) is identified as passing
through the detected
fixed reference magnet 800, the arrow indicia or marking "A" denoting the
direction of flow
on the implantable valve, and the center point "C" midway between the two
detected
magnetic elements 123, 125. A rotating vector "RV" is defined connecting the
two detected
magnetic elements 123, 125. Thereafter, a rotating construct angle a is
measured between the
direction of flow line "DOF" and the rotating vector "RV". Specifically, the
rotating
construct angle a is measured starting from the direction of flow line "DOF"
(as a staring
reference line) traveling in a counter-clockwise direction until intersecting
with the rotating
vector "RV".
[0076] Once the rotating construct angle a has been ascertained based on the
detected three
magnets in the adjustable valve unit the value is compared to stored
predetermined
mechanical angular spacing values for each of the setting pockets for that
particular
implantable valve, as described in further detail below. If a match exists
between the
measured rotating construct angle a and the predetermined mechanical angular
spacing of any
of the setting pockets, then the magnetic field resistance mechanism is deemed
properly
locked or engaged. Otherwise, if the measure rotating construct angle a does
not match the
predetermined mechanical angular spacing of any of the setting pockets, then
the magnetic
resistance mechanism is found not to be properly locked or engaged. A visual
indictor (e.g.
text and/or icon) may be generated on display 1555 of the integrated
locator/indicator tool
1405 confirming when the magnetic field resistance mechanism is properly
engaged and/or
found not to be properly engaged. In addition to such visual display
indicator, a tactile
indicator may be provided. If the magnetic field resistance mechanism is not
properly
engaged, instructions and steps to be taken to reprogram the valve setting
using the
adjustment tool 1415 and thereafter once again confirm whether or not the
magnetic field
resistance mechanism is properly engaged may be provided on display 1550 of
the integrated
locator/indicator tool 1405.
[0077] Preferably, each time a valve setting is programmed using the
adjustment tool 1415
the integrated locator/indicator tool 1405 in accordance with the present
invention is
thereafter used to confirm whether the magnetic field resistance mechanism is
properly locked
or engaged. Alternatively, the present inventive integrated locator/adjustor
tool 1405 may be
CA 3019544 2018-10-02
employed to verify proper engagement of the magnetic field resistance
mechanism prior to
intentional exposure to a foreign magnet, e.g., before an (MR1) procedure.
[0078] As previously mentioned, based on the particular design of the valve, a
predetermined
mechanical angular spacing relative to the direction of flow of the shunt
valve as (identified
by the arrow marking "A") is associated with each of the setting pockets 171,
171', 171",
171". Each setting pocket 171, 171', 171", 171' is bound on at least one side
by a lock stop.
Depending on the valve configuration, in some designs such as the Strata
programmable
valve, each setting pocket is bounded on either side by adjacent lock stops.
That is, each lock
stop has a clockwise leading edge and a counter-clockwise leading edge.
Therefore, each
setting pocket is bounded on one side by a counter-clockwise leading edge of a
first lock stop
and on the other side by a clockwise leading edge of a second lock stop
adjacent to the first
lock stop. Whether the setting pocket is bound by one or two lock stops, in
either case, the
mechanical angular spacing or width in degrees of each of the setting pockets
for a particular
programmable valve may be dynamically adjusted based on skin depth since it
has been found
that the fixed reference magnet may influence identification of the setting
pockets that vary
slightly as you get farther away from the valve. Distance between rotating
construct magnets
may be used to determine depth. Thus, the mechanical angular spacing or width
is controlled
by the design of the valve. The sensor array does not identify the pockets,
but the magnetics
are not as simple as just measuring the fields. Characterization has shown
that the magnetic
fields change based on distance away from the sensor array of the integrated
locator/indicator
tool. Therefore, the actual boundaries of the setting pockets change based on
the distance
from sensor array. This has been confirmed by testing of multiple valves at
extremes on
setting pocket location and distance from locator/indicator tool. An algorithm
determines
distance and calculates where the boundary should be based on pre-measured
valves. The
predetermined mechanical angular spacing for each setting pocket is
represented by two
mechanical angular boundary values defining either side of the setting pocket.
A first
mechanical angular boundary value representing the mechanical angle of the
leading edge of
each lock stop traveling in a counter-clockwise direction starting from the
direction of flow as
a reference, while the second mechanical angular boundary measurement
represents the
mechanical angle when the constant angular width of the setting pocket is
added to the first
mechanical angular boundary measurement in a clockwise direction. It is the
first and second
21
CA 3019544 2018-10-02
mechanical angular boundary values that represent the predetermined mechanical
angular
spacing for that particular setting pocket. The first and second mechanical
angular boundary
values for each setting pocket of a particular programmable valve are
ascertained in advance
and stored in memory, for example, in the locator/indicator tool.
[0079] Figures 6A-6H are exemplary illustration of 8 different pressure
settings and their
associated setting pockets for the CODMAN CERTAS Plus Programmable Valve. In
which
some of the setting pockets are bound by adjacent lock stops (e.g., 170-172;
172-174; 174-
176), while others are only bound by a single lock stop (e.g., 176). The
mechanical angular
spacing for each setting pocket for the CODMAN CERTAS Plus Programmable Valve
configuration is provided below in Table I.
[0080] TABLE 1:
Pressure Settings Setting Pocket (defined by Mechanical Angular
one or more lock stops) Spacing Clockwise from
direction of flow "A"
st & 5th Between lock stops 170, 172 -29 to -53
2'd & 61h Between lock stops 172, 174 -3 to 20
3rd & 7t1i Between lock stops 174, 176 37' to 65'
4th & 81h Between lock stops 176, 170 82 to 109
[0081] Referring to Figures 17A & 17B, the lower casing 1700 and rotating
construct 1705 of
the Strata Programmable Valve has a different configuration than that of the
CODMAN
CERTAS Plus Programmable Valve. Specifically, the five setting pockets 1710,
1712,
1714, 1716, 1718 are arranged in the lower casing 1700 in a 360-degree
circular
configuration, each setting pocket interposed between adjacent lock stops
1720, 1722, 1724,
1726, 1728. That is, each of the five setting pockets 1710, 1712, 1714, 1716,
1718 is defined
on the one side by a clockwise leading edge of a first lock stop and on the
other side by a
counter-clockwise leading edge of a second lock stop adjacent to the first
lock stop.
Therefore, each of the five setting pockets has a constant angular width or
mechanical angular
spacing.
22
CA 3019544 2018-10-02
[0082] The present inventive safety feature is also applicable to other
configurations wherein
the magnetic field resistance mechanism, when properly engaged or locked, has
one or more
structural components seated within corresponding cavities/pockets/recess.
Rather than one
-- or more downward projecting teeth being received in respective setting
pockets defined by
one or more lock stops (as described above), one alternative design is set
forth in US Patent
No. 5,643,194 as illustrated in Figures 18A & 1813 in which cylindrical shaped
mating lead in
elements or components are received within respective complementary shaped
cavities,
notches, openings or pockets.
[0083] The plan view in Figure 18A depicts a valve body 1, without its upper
cover, and a
casing 3. Cavities 4, represented in broken line in Figures 18A & 18B, are
formed at the
periphery of a substantially cylindrical central part 2a. The valve body 1
includes a
cylindrical and flat internal chamber 5 formed between the lower wall 3b, a
lateral wall 3a of
the casing 3 and upper cover 2. An inlet pipe 6 and a drain pipe 7 are formed
in the lateral
wall 3a of the casing 3, the inner ends of the said pipes 6 and 7 being
arranged diametrically
in the chamber 5. The inlet pipe 6 and the drain pipe 7 are connected
respectively to a
catheter for supplying fluid and to another catheter for draining fluid away.
[0084] A rotating construct or rotor 8 comprising an I-I-shaped bar is
rotatably mounted in the
chamber 5 about central axis 9. Sum) elements 21 projecting from a lower wall
3b of the
casing 3 are provided to limit the rotational displacement of the rotor 8. The
rotor 8 includes
lateral branches 8a which serve as guide means, on either side of the central
axis 9, for
moving parts 10 and 11 each housing a micro-magnet 12 and 13, respectively
with opposing
-- faces of the micro-magnets 12, 13 being of opposite polarity (N and S).
Moving parts 10 and
1 I are displaced linearly inside the rotor 8 in a substantially radial
direction thereof to actuate
the locking mechanism. In particular, the locking mechanism comprises a
circular succession
of open mating pockets, notches or cavities 4 defined radially inward along an
outer perimeter
of the substantially cylindrical central part 2a for receiving complementary
shaped mating
-- lead in elements 10a and Ila (for example, cylindrical lugs) projecting
respectively from the
moving parts 10 and 11. Between adjacent open notches or cavities 4 are
portions of the
substantially cylindrical central part 21 hereinafter referred to as dividing
posts.
23
Date Recue/Date Received 2023-08-18
[0085] The valve body 1 includes a non-return valve consisting of a ball 14
and of a cone-
shaped seat 15 arranged at the inner end of the inlet pipe 6. A semi-circular
leaf spring 16 is
fixed to one lateral branch 8a of the rotor 8, parallel to the lateral wall 3a
of the chamber 5 and
compresses the ball 14 into its seat 15 to regulate, and if appropriate block,
the passage of
fluid into the chamber 5 via the inlet pipe 6. As in the valve design in
Figure 1, the alternative
valve design in Figure 18A may also include a fixed reference magnet 800.
[0086] Figure 18B represents a prior art external setting device 17 arranged
on the valve
body 1 of Figure 18A. The external setting device 17 includes two magnets 18
and 19, for
example made of samarium-cobalt, the opposing faces of which are of opposite
polarities to
(N and S) and of greater magnetic mass than the moving micro-magnets 12 and 13
associated
with the valve body I. The magnets 18 and 19 are mounted on a common annular
support 20,
for example made of soft iron, diametrically opposed and spaced apart by a
distance
substantially equal to or greater than the distance separating the outer poles
of the two moving
micro-magnets 12 and 13 when the lugs 10a and 1 1 a are engaged in the notches
or cavities 4.
[0087] The operation of the external setting device 17 in Figure 18B will now
be described.
Figure 18A represents the valve body 1 in its locked position, that is, with
the cylindrical lugs
10a, Ila both engaged in respective notches or cavities 4 and locked in place
therein as a
result of magnetic attraction brought about by the opposite polarities of the
micro-magnets 12,
13.
[0088] Figure 1813 represents the valve body 1 in its unlocked position,
wherein the
cylindrical lugs 10a, Ila are both disengaged from the notches or cavities 4.
In order to
unlock the valve (disengage or unseat the cylindrical lugs 10a, 1 1 a from the
respective
notches or cavities 4), the external setting device 17 illustrated in Figure
18B is aligned
vertically with the valve body 1 so that the magnets 18, 19, the opposing
faces of which have
opposite polarities (N and S), are positioned symmetrically with respect to
the central axis 9
of the chamber 5 and on either side of the micro-magnets 12, 13. Of course,
the strength of
the magnets 18, 19 has to be greater than that of the micro-magnets 12, 13 to
overcome the
24
CA 3019544 2018-10-02
attraction force which exists between the micro-magnets 12, 13.
[0089] Bearing in mind the difference in magnetic mass which exists between
the magnets
18, 19 of the external setting device 17 and the micro-magnets 12, 13 of the
valve, the simple
fact of bringing the N and S poles of the setting device close to the opposite
S and N poles of
the micro-magnets, subjects the two outer poles of the micro-magnets 12, 13 to
a peripheral
attraction which is greater than the central mutual attraction between the two
inner poles.
This results in the two micro-magnets 12, 13 together with their moving parts
10, 11
separating symmetrically and simultaneously towards the periphery of the
chamber 5, which
unlocks or disengages the rotor 8 and renders it free to rotate. With the
rotor 8 thus unlocked
or disengaged, it is possible to alter its position and consequently to alter
the operating
pressure and throughput of the valve, by pivoting the setting device 17 about
the central axis
of the chamber of the valve, which simultaneously drives the rotor along. In
order to lock the
rotor 8 in a new desired position, the setting device 17 is withdrawn, moving
it away
vertically with respect to the plane of the valve. Since the two micro-magnets
12, 13 are no
longer subjected to external peripheral attraction with the magnets 18, 19,
the micro-magnets
12, 13 approach each other once again under the effect of their mutual
attraction, thus seating
(i.e., locking) the lugs 10a, Ila into the respective notches or cavities 4.
[0090] This type of valve with moving micro-magnets provides magnetic field
resistance
against a change in valve setting in the presence of a strong external foreign
magnetic or
electromagnetic field, because the two moving micro-magnets 12, 13 cannot
simultaneously
disengage from their cavity in the presence of a unidirectional magnetic
field. Insofar as the
two moving micro-magnets 12 and 13 are arranged on either side of the central
axis of the
valve, when one of the micro-magnets is attracted towards the periphery of the
chamber, the
other is repelled into a locking cavity. An external setting device like the
one illustrated in
Figure 1813 is required to unlock or disengage the valve, that is to say in
order to separate the
micro-magnets 12, 13 symmetrically.
[0091] However, the valve shown in Figures 18A & 18B and described above is
not
susceptible to change in valve setting when exposed to foreign magnets only if
the cylindrical
lugs 10a, lla are properly seated, engaged or locked in the respective notches
or cavities 4.
CA 3019544 2018-10-02
Similar to the discussion above with respect to the CODMAN CERTASS Plus
Programmable
Valve once again there is the possibility that when unlocked the lugs 10a, lla
will come to
rest against a region of the outer perimeter of the substantially cylindrical
central part 2a
herein after referred to as a dividing post (region along the outer perimeter
of the substantially
.. cylindrical central part 2a between adjacent notches or cavities 4) rather
than properly seated
or engaged in a respective notch or cavity 4.
[0092] In accordance with the present invention, there are two different ways
to determine
whether the valve in Figure 18B is properly locked in place (i.e., whether
cylindrical lugs 10a,
.. Ila are properly engaged or seated in a respective notch or cavity 4). If
the valve in Figure
18B includes a fixed reference magnet 800, one method by which proper
engagement may be
verified is based on the detected angular position of the micro-magnet 12
(following the
methodology described in detail above using the integrated locator/indicator
tool 1405). Once
the angular position of the micro-magnet 12 has been determined it is compared
to the
predetermined angular spacing of the respective notches or cavities 4. If the
detected angular
position of the micro-magnet 12 matches the predetermined angular spacing of
one of the
respective notches or cavities 4 then the valve is deemed to be properly
locked (i.e., the lugs
10a, 11 a are properly engaged or seated in respective notches or cavities 4).
Otherwise, if the
detected angular position of the micro-magnet 12 does not match the
predetermined angular
spacing of any of the respective notches or cavities 4 then the valve is not
properly locked
(i.e., the lugs 10a, I la are resting on the dividing posts). In such latter
case, the user is
instructed to adjust the valve using the external setting device 17 once again
and thereafter
confirm whether the valve is properly engaged, seated or locked.
[0093] An alternative method for confirming whether the valve of Figure 18B is
locked or
properly engaged is based on the measured distance between the center of the
two micro-
magnets 12, 13. As discussed in detail above, with the external setting device
17 withdrawn
from the valve, the micro-magnets 12, 13 attract one another holding them in
place. If the
micro-magnets 12, 13 are properly seated, engaged or locked in respective
notches or cavities
.. 4, then the distance separation between the center of the micro-magnets 12,
13 will be a
predetermined proper locking value. Otherwise, if the micro-magnets 12, 13 are
instead
resting along the outer perimeter of the substantially cylindrical central
part 2a between two
26
CA 3019544 2018-10-02
adjacent notches or cavities 4 (i.e., on a dividing post) then the centers of
the respective
micro-magnets 12, 13 will a greater distance separation from one another then
the
predetermined locking value. Thus, this alternative method may also use the
same integrated
locator/indicator tool 1405 to detect the centers of the respective micro-
magnets 12,13 on the
rotating construct and measure the distance therebetween, a comparison is
thereafter made
with the predetermined locking value. Of course, the algorithm for the
integrated
locator/indictor tool 1405 would have to be modified accordingly for this
alternative method.
If the measured distance is equal to the predetermined locking value
indicating proper locking
then the valve is deemed to be properly engaged or locked (i.e., the lugs 10a,
11 a, are properly
seated in the respective notches or cavities 4), whereas if the measured
distance is greater than
the predetermined locking value the valve is deemed to be improperly engaged
or not locked
(i.e., the lugs 10a, 11 a are resting on dividing posts). As with the other
embodiments, the user
is instructed to reprogram the valve to the desired setting and once again
confirm that the
valve is properly locked or engaged.
[0094] The present inventive improved toolset employing a sensor array for use
with a
programmable valve provides the additional safety feature of verifying whether
the magnetic
field resistance functionality of the valve is properly engaged. This
additional safety feature
may be invoked every time the valve is programmed to a new setting or prior to
exposure to a
foreign magnet, for example, before an MRI procedure. The inventive toolset
with this
additional safety feature is suitable for use with any type of programmable
valve which when
locked in place has a structural component seated or engaged in a
corresponding notch,
recess, cavity, pocket or other complementary shaped region.
[0095] Thus, while there have been shown, described, and pointed out
fundamental novel
features of the invention as applied to a preferred embodiment thereof, it
will be understood
that various omissions, substitutions, and changes in the form and details of
the devices
illustrated, and in their operation, may be made by those skilled in the art
without departing
from the spirit and scope of the invention. For example, it is expressly
intended that all
combinations of those elements and/or steps that perform substantially the
same function, in
substantially the same way, to achieve the same results be within the scope of
the invention.
Substitutions of elements from one described embodiment to another are also
fully intended
27
CA 3019544 2018-10-02
and contemplated. It is also to be understood that the drawings are not
necessarily drawn to
scale, but that they are merely conceptual in nature. It is the intention,
therefore, to be limited
only as indicated by the scope of the claims appended hereto.
28
Date Recue/Date Received 2023-08-18
