U.S. patent application number 10/351736 was filed with the patent office on 2003-09-25 for atrial appendage blood filtration systems.
Invention is credited to Bridgeman, John, Peterson, Dean, Sutton, Gregg S., Welch, Jeffrey, Youngberg, Bruce R..
Application Number | 20030181942 10/351736 |
Document ID | / |
Family ID | 27671077 |
Filed Date | 2003-09-25 |
United States Patent
Application |
20030181942 |
Kind Code |
A1 |
Sutton, Gregg S. ; et
al. |
September 25, 2003 |
Atrial appendage blood filtration systems
Abstract
Instrumentation for percutaneous delivery of blood filtration
devices to atrial appendages includes a curved access sheath and a
delivery tube. The curved access sheath is coursed through the
patient's vasculature to gain transseptal access to a left atrial
appendage. A compressed filter device attached to a tether wire is
loaded in the delivery tube. The loaded delivery tube is advanced
through the pre-positioned access sheath to place the device in a
deployment position. The access sheath and the delivery tube can be
mechanically locked and moved together to place the device in a
suitable deployment position. The device is deployed by expelling
it from the delivery tube either by retracting the delivery tube
over the tether wire, or by moving the tether wire forward through
the delivery tube. The expelled device, which is not constrained by
the delivery tube walls, self expands to its useful size in the
subject atrial appendage. A filter membrane in the deployed extends
across the appendage ostium to filter blood flow through the
ostium. The filter membrane is configured to present a flat surface
to atrial blood flow past the ostium.
Inventors: |
Sutton, Gregg S.; (Maple
Grove, MN) ; Welch, Jeffrey; (New Hope, MN) ;
Peterson, Dean; (Rogers, MN) ; Bridgeman, John;
(Minneapolis, MN) ; Youngberg, Bruce R.; (Ramsey,
MN) |
Correspondence
Address: |
FISH & NEAVE
1251 AVENUE OF THE AMERICAS
50TH FLOOR
NEW YORK
NY
10020-1105
US
|
Family ID: |
27671077 |
Appl. No.: |
10/351736 |
Filed: |
January 24, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60351898 |
Jan 25, 2002 |
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60417110 |
Oct 8, 2002 |
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60379921 |
May 10, 2002 |
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60403720 |
Aug 14, 2002 |
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Current U.S.
Class: |
606/200 |
Current CPC
Class: |
A61B 2017/00575
20130101; A61B 17/12172 20130101; A61B 2017/12095 20130101; A61B
17/12122 20130101; A61B 2017/00243 20130101; A61B 17/0057 20130101;
A61F 2/0105 20200501; A61B 17/12022 20130101; A61F 2002/016
20130101; A61F 2230/008 20130101; A61F 2/011 20200501; A61F
2002/018 20130101; A61F 2230/0006 20130101; A61F 2230/0093
20130101; A61F 2230/005 20130101 |
Class at
Publication: |
606/200 |
International
Class: |
A61M 029/00 |
Claims
1. A blood filtration system for filtering blood flow from an
atrial appendage, comprising: a filter device that is configured
for deployment in the atrial appendage to intercept blood flow,
wherein the filter device has an elastic structure that expands to
its natural size from a compressed state when the device is
unconstrained; a tubular access sheath for establishing a
percutaneous pathway to the atrial appendage; and a delivery
instrument for delivering the device through a lumen of the access
sheath and for deploying the delivered device in the atrial
appendage, wherein the delivery instrument includes: a delivery
tube; and a movable tether that passes through the delivery tube,
and that is releasably attached to the device, wherein the tether
provides mechanical control over the delivery and deployment of the
device, and wherein the access sheath and the delivery tube
comprise releasable locks for controlling the relative movement of
the two.
2. The system of claim 1 wherein the access sheath comprises a tube
having a straight portion that curves into a distal portion at a
bend angle of about 90 degrees.
3. The system of claim 1 wherein the access sheath comprises a tube
having a substantially straight portion that curves into a first
distal portion at a first bend angle, and a second distal portion
that curves away from the first distal portion at an second bend
angle relative to the plane of the straight portion and the first
distal portion.
4. The system of claim 3 wherein the first bend angle is about 90
degrees.
5. The system of claim 1 wherein the access sheath has a length for
placing a distal sheath tip in the atrial appendage through the
body's vascular system.
6. The system of claim 1 wherein the tether wire comprises a
threaded fixture for rotatably attaching the filter device.
7. The system of claim 6 wherein a length of the tether wire near
the threaded fixture has a diameter that is substantially smaller
than the diameter of a proximal length of the tether wire to reduce
its coupling stiffness to the attached device.
8. The system of claim 1 wherein the delivery tube comprises a
tubular implant sheath that constrains the filter device to a
compressed state during the delivery of the device through the
lumen of the access sheath.
9. The system of claim 8 wherein the tether wire has a diameter
that is substantially smaller than the inner diameter of the
tubular implant sheath, wherein a length of the tether wire
proximate to the attached filter device is encased in a larger
diameter flexible coil to avoid buckling of the tether wire as it
is moved through the delivery tube.
10. The system of claim 9 wherein the flexible coil has a diameter
about the inner diameter of the tubular implant sheath, wherein the
flexible coil comprises a lumen that is in fluid communication with
the lumen of the delivery tube at its proximal end and wherein the
flexible coil lumen opens to flush ports about its distal end.
11. The system of claim 1 wherein the access sheath comprises a
valve assembly at its proximal end for sealably receiving the
delivery tube into the lumen of the access sheath.
12. The system of claim 11 wherein the valve assembly comprises
seals that are adjustably compressible against a surface of the
received delivery tube to control back bleeding.
13. The system of claim 11 wherein a releasable lock for coupling
the movement of the delivery tube and the access sheath is disposed
on the valve assembly.
14. The system of claim 13 wherein the releasable lock disposed on
the valve assembly is a luer fitting.
15. The system of claim 11 wherein the valve assembly comprises a
hemostasis valve.
16. The system of claim 11 wherein the valve assembly comprises a
radial compression valve.
17. The system of claim 11 wherein the valve assembly comprises a
port for passage of fluids through a lumen of the access
sheath.
18. The system of claim 1 wherein the delivery tube further
comprises a manifold at its proximal end, and wherein the tether
wire movably passes through the manifold.
19. The system of claim 18 wherein a proximal end of the tether
wire terminates in a knob, and wherein turning the knob turns the
tether wire to detach the device attached to the distal end of the
tether wire.
20. The system of claim 19 wherein the knob is a rotatable knob
mounted on the manifold.
21. The system of claim 18 wherein a casing is disposed on a length
of tether wire extending into the manifold to provide rigidity for
rotation and translation of the tether wire.
22. The system of claim 18 wherein a detachable stop is disposed on
the tether wire at a distance from its proximal terminal end, and
wherein the detachable stop acts against the manifold to limit the
translation of the tether wire into the manifold.
23. The system of claim 18 wherein a length of the casing has a
non-circular shape cross-section, and wherein the manifold
comprises a keyway that has a similar shape cross-section, wherein
the keyway allows the non-circular shape lengths of the casing to
slide through and restrains rotation of the non-circular shape
length of the casing.
24. The system of claim 22 wherein a length of tether wire abutting
the knob has a substantially round cross section that is free to
rotate in the keyway.
25. The system of claim 23 wherein the noncircular shape
cross-section includes a D-shape.
26. The system of claim 18 further comprising an actuator slidably
mounted on the manifold to reciprocally retract the delivery tube
into the manifold over the tether wire.
27. The system of claim 18 wherein the manifold comprises a port
for passage of fluids through a lumen of the delivery tube.
28. The system of claim 18 wherein a releasable lock for coupling
the movement of the delivery instrument and the access sheath is
disposed on the manifold, and wherein when lock is activated the
distal tips of the access sheath and the implant sheath are
approximately flush.
29. The system of claim 28 wherein the releasable lock disposed on
the manifold is a luer fitting.
30. The system of claim 28 wherein the second part of the
releasable lock disposed on the manifold is C-shape clip that
releasably catches on a cylindrical valve body on the access sheath
to prevent translation of the manifold relative to the access
sheath.
31. The system of claim 30 wherein the C-shape clip rotatably
catches on the cylindrical valve body on the access sheath to allow
rotation of the delivery tube in the access sheath.
32. The system of claim 1 wherein the filter device comprises: an
elastic wire frame, wherein the wire frame has a closed end,
wherein a threaded socket is disposed on about the wire frame's
longitudinal axis at about the closed end, wherein wire sections
extend radially from about the threaded socket to sides of the wire
frame, and wherein the wire sections act as springs to bias the
filter device to its natural size; and a blood-permeable filter
membrane disposed on at least the closed end of the wire frame,
wherein the closed end exterior surface of the filter device is
substantially flat.
33. The system of claim 32 wherein the wire sections that act as
springs have S-shapes.
34. The system of claim 32 wherein the wire frame has a cylindrical
shape with a diameter for interference fit in an atrial
appendage.
35. The system of claim 34 wherein the cylindrical shape is tapered
away from the closed end.
36. The system of claim 1 further comprising a dilator and needle
to make an opening in an atrial septum for transseptal access to
the atrial appendage.
37. A device for filtering blood flow from an atrial appendage,
comprising: an elastic wire frame, wherein the wire frame the has a
diameter for an interference fit in the atrial appendage, and
wherein the wire frame comprises wire sections radially extending
to the sides of the wire frame from its longitudinal axis that
serve as springs to bias the wire frame to its natural size when
compressed; a fixture disposed on the longitudinal axis of the wire
frame at about the plane of a proximal end of the wire frame, and
wherein the fixture has a structure for attachment of the device to
a tether wire; and a filter membrane that covers a proximal end of
the wire frame, wherein the filter membrane stretches across the
ostium of the atrial appendage to intercept blood flow
therethrough, and wherein the device presents a substantially flat
exterior surface along the plane of the proximal end of the wire
frame.
38. The device of claim 37 wherein the wire sections are S-shaped
wire sections that start from about the fixture at substantially
shallow angles to the longitudinal axis and lie in radial planes of
the wire frame.
39. The device of claim 38 wherein said fixture comprises a tubular
collar and an insert having a socket for attachment of the device
to a tether wire, and wherein the S-shape wire sections emanate
from the collar.
40. The device of claim 39 wherein a portion of the filter membrane
is held between the collar and the insert while other portions of
the filter membrane are attached to other portions of the wire
frame.
41. The device of claim 37 wherein the wire frame comprises a
chicken wire-like mesh.
42. The device of claim 41 wherein distal wire ends of the wire
frame are turned radially inward toward the longitudinal axis of
the wire frame to provide a traumatic tissue contact.
43. The device of claim 37 wherein the wire frame has conical
shape.
44. A device delivery system for implanting an self-expanding
device in an atrial appendage comprising: a delivery tube extending
into an implant sheath, wherein the delivery tube has an inner
diameter of about 30 to about 100 mils and the implant sheath has
an inner diameter larger than the diameter of a device in a compact
state that is contained in the implant sheath; a manifold disposed
on a proximal end of the delivery tube; a tether wire movably
passing through the manifold, wherein the tether wire has a fixture
attached to the device contained in the implant sheath, wherein the
attached device expands to its natural size on expulsion from the
implant sheath by translation of a length of the tether wire
through the delivery tube, and wherein the tether wire has a
coupling stiffness that allows the expelled device to attain its
natural unbiased state when deployed in an appendage while it is
still attached to the tether wire.
45. The device delivery system of claim 44 wherein a length of
tether wire near the fixture has a reduced diameter relative to the
diameter of a proximal length of the tether wire to reduce the
stiffness of the coupling to the attached device.
46. The device delivery system of claim 44 wherein a length of
tether wire extending into the implant sheath is encased in a
flexible coil to reduce buckling of the tether wire as it is
translated through the implant sheath.
47. The device delivery system of claim 46 wherein the flexible
coil has a lumen that is in fluid communication with the lumen of
the delivery tube and that has openings near the distal end of the
flexible coil.
48. The device delivery system of claim 44 wherein the delivery
tube has an inner diameter of about 45 mils, a proximal length of
the tether wire has a diameter of about 35 mils and a length of
tether wire near the threaded fixture has a reduced diameter of
about 10 mils.
49. The device delivery system of claim 44, wherein a casing is
disposed on a proximal length of tether wire extending from near
its distal end into the manifold to provide rigidity for
operator-controlled rotation and translation of the tether
wire.
50. The device delivery system of claim 49 further comprising a
releasable stop that acts against the manifold to limit translation
of the tether wire.
51. The device delivery system of claim 49 wherein a length of the
casing has non-circular cross-section, wherein the manifold has
keyway with a similar shape cross-section for allowing translation
of the tether wire and for restricting the rotation of the tether
wire.
52. The device delivery system of claim 21 wherein the keyway has a
D-shape.
53. The device delivery system of claim 44 wherein the manifold
comprises a Tuohy-Borst valve assembly.
54. The device delivery system of claim 44 further comprising an
access sheath for transseptal delivery of the device to an atrial
appendage, the access sheath comprising: a tube having compound
curvatures and a length to percutaneously place the distal tip of
the tube about the atrial appendage; and a valve assembly disposed
on the proximal end of the tube for sealably receiving the delivery
tube into the tube lumen.
55. The device delivery system of claim 54 wherein the compound
curvatures comprise a first curve of about 90 degrees and a second
curve of about 75 degrees away from the plane of the first
curve.
56. The delivery system of claim 54 further comprising releasable
locking structures for coupling together the translational movement
the delivery tube and the access sheath.
57. The delivery system of claim 56 wherein the releasable locking
structures are configured to allow rotational movement of the
delivery tube relative to the access sheath.
58. A method for implanting an self-expanding device in an left
atrial appendage using the device delivery system of claim 44,
comprising: inserting an access sheath percutaneously through the
body's vasculature into the left atrium, wherein the access sheath
has a valve assembly at its proximal end for sealably receiving the
delivery tube; directing the distal tip of the access sheath toward
the ostium of the left atrial appendage; attaching the device to
the tether wire; compacting the device and loading the device in
the implant sheath extending from the delivery tube; inserting the
delivery tube through the access sheath lumen so that the implant
sheath tip is at a deployment position; translating the tether wire
through the manifold to expel the compacted device from the implant
sheath so that the device self expands and deploys in its natural
unbiased state in the left atrial appendage; turning the tether
wire to detach the deployed device.
59. The method of claim 58 further comprising, assessing the
unbiased state of the deployed device prior to turning the tether
wire to detach the deployed device.
60. The method of claim 59, wherein assessing the unbiased state of
the deployed device comprises injecting radio opaque fluids through
the delivery lumen into the region of the left atrial appendage for
imaging.
61. The method of claim 58 wherein inserting an access sheath
comprises inserting an access sheath tube having compound
curvatures.
62. The method of claim 58 wherein inserting the delivery tube
through the access sheath lumen so that the implant sheath tip is
at a deployment position comprises advancing the implant sheath so
that its tip is about flush with the distal tip of the access
sheath.
63. The method of claim 62 further comprising using locking
structures to mechanically couple the delivery tube and the access
sheath, and moving the two together so that the implant sheath tip
is at the deployment position.
64. The method of claim 62 wherein the deployment position is
inside the atrial appendage.
Description
[0001] This application claims the benefit of U.S. provisional
application No. 60/351,898, filed Jan. 25, 2002, U.S. provisional
application No. 60/379,921, filed May 10, 2002, U.S. provisional
application No. 60/417,110, filed Oct. 8, 2002, and U.S.
provisional application No. 60/403,720, filed Aug. 14, 2002, all of
which are is hereby incorporated by reference in their entireties
herein.
BACKGROUND OF THE INVENTION
[0002] The invention relates to filtration of cardiac blood flow
between an atrial appendage and its associated atrium. The blood
filtration prevents the dispersal of thrombi, which may be formed
in the atrial appendage, into the body's blood circulation system.
In particular the invention relates to implant filter devices, and
apparatus for the percutaneous delivery and implantation of such
devices in the heart.
[0003] Structural heart disease or other cardiac conditions in a
patient can result in atrial fibrillation, which in turn causes
blood to pool or stagnate in the patient's atrial appendage.
Thrombi (i.e., blood clots) are prone to form in the atrial
appendages with stagnant blood. The blood clots may subsequently
break off and migrate to the brain leading to stroke, or to other
parts of the body causing loss of circulation to the affected
organ. The left atrial appendage (LAA), which is anatomically
disposed on top of the left atrium, happens to be a particularly
likely site for harmful blood clot formation. Thromboembolic events
such as strokes are frequently traced to blood clots from the
LAA.
[0004] The risk of stroke in patients with atrial fibrillation may
be reduced by drug therapy, for example, by using blood thinners
such as Coumadin. However, not all patients cannot tolerate or
handle the blood thinning drugs effectively. Alternative methods
for reducing the risk of stroke involve surgery to remove or
obliterate the LAA. Other proposed methods include using mechanical
devices to occlude the atrial appendage opening and thereby stop
blood flow from the atrial appendage into its associated
atrium.
[0005] Another prophylactic method for avoiding strokes or other
thromboembolic events caused by blood clots formed in atrial
appendages involves filtering harmful emboli from the blood flowing
out of the atrial appendages. Co-pending and co-owned U.S. patent
application Ser. No. 09/428,008, U.S. patent application Ser. No.
09/614,091, U.S. patent application Ser. No. 09/642,291, U.S.
patent application Ser. No. 09/697,628, U.S. patent application
Ser. No. 09/932,512, U.S. patent application Ser. No. 09/960,749,
U.S. patent application Ser. No. 10/094,730, U.S. patent
application Ser. No. 10/198,261, and U.S. patent application Ser.
No. 10/200,565, all of which are hereby incorporated by reference
in their entireties herein, describe filtering devices which may be
implanted in an atrial appendage to filter the blood flowing out of
the atrial appendage. The devices may be delivered percutaneously
to the heart through the body's blood vessels using common cardiac
catheterization methods. These catheterization procedures often
involve first deploying an access system to position an access
sheath through a patient's vascular system to the interior
locations in the patient's heart. The access sheath provides a
passageway through which implant devices are passed from outside
the patient's body to interior locations in the heart. Delivery of
the devices to the LAA may involve transseptal catheterization
procedures, in which access to the left atrium is gained from the
right atrium by puncturing the intervening septum. One or more
independent delivery systems may be used to deliver the devices
through the access sheath.
[0006] U.S. patent application Ser. No. 09/932,512, U.S. patent
application Ser. No. 10/094,730, and U.S. patent application Ser.
No. 10/200,565, disclose expandable implant devices which are small
and which can be delivered percutaneously by catheters to the
atrial appendages. The effectiveness or success of medical
procedures using the implant devices may depend on the proper
deployment and retention of the devices in a suitable orientation
in the atrial appendages. U.S. patent application Ser. No.
09/960,749 discloses a catheter apparatus having position guides.
U.S. patent application Ser. No. 10/198,260 discloses a catheter
apparatus having a device tether, which allows a deployed device to
be retrieved for repositioning as necessary.
[0007] Consideration is now being given to improving implant
devices and to improving catheterization apparatus including access
and delivery systems for the percutaneous delivery of such devices
through geometrically complex vascular paths leading, for example,
to the left atrial appendage.
SUMMARY OF THE INVENTION
[0008] The invention provides instrumentation for percutaneously
implanting filter devices in atrial appendages to filter blood
flowing between the atrial appendages and associated atrial
chambers. The filter devices are designed to prevent dispersal of
blood clots formed in the atrial appendages into the body's blood
circulation system.
[0009] The filter devices are self-expanding elastic or
compressible frames made from chicken wire-like mesh. The wire
frames are made of shape-memory alloy materials such as nitinol. A
typical device at its natural or expanded size may be about an inch
in diameter and about an inch long. The wire frames may have a
generally cylindrical or conical shape with a closed end. A
blood-permeable filter membrane covers the closed end. The
filter-membrane covered closed end extends across the ostium of a
subject atrial appendage in which a device is used. In one
embodiment, the filter membrane is made of a polyester weave or
knit having a nominal hole size of about 125 um. The filter
membrane filters harmful-sized emboli from the blood flow between
the appendage and the atrium.
[0010] The wire frame sides are shaped for an interference fit in
the subject atrial appendage in which the device is used. The
closed end wire sections may be S-shaped and serve as resilient
springs, which push or bias the cylindrical side portions of the
wire frame outward. Additionally, tissue-engaging barbs are
disposed on the wire frame to aid or encourage retention of the
device at its implant location. The wire frames have sockets or
other fixtures for attaching a delivery tether wire or shaft. The
attachment sockets are disposed about longitudinal frame axis at or
about the wire frames' closed ends. The wire frames are suitably
recessed to accommodate the attachment sockets so that closed ends
of the devices (the supported filter membranes) have a
substantially undulating or flat surface topography.
[0011] The filter devices may be percutaneously implanted in a
patient's atrial appendage. Inventive device delivery systems and
instrumentation may be used for the implant procedures. The
instrumentation includes a curved tubular access sheath. The
implant procedures involve introducing the access sheath into the
patient's blood vessels through a skin puncture and coursing it
through a patient's vascular system to the interior locations in
the patient's heart, for example, across the atrial septum. The
coursed access sheath establishes a channel or passageway for
device delivery to an atrial appendage through the patient's
vasculature.
[0012] The distal portions of the access sheath are curved. The
curvatures may be simple or compound. The curvatures take into
account the anatomical geometry of the heart and are designed to
provide a passageway leading directly to the subject atrial
appendage. In an embodiment, the access sheath is made from J-shape
tubing, with a distal portion that has a bend of about 90 degrees.
In another embodiment, the access sheath is made from similar
J-shape tubing, the distal portion of which has a further second
bend away from the J-shape plane.
[0013] In a transseptal device implantation procedure the suitably
curved access sheath may be set up across the septum so that its
distal end is directed toward the subject LAA. Access sheath may be
further advanced into the LAA itself if so desired.
[0014] A device delivery system may be used to move a filter device
through the pre-positioned access sheath. The delivery system
includes a delivery catheter tube that extends into a tubular
implant sheath. The filter device that is to be implanted is
attached to a tether wire or shaft passing through the delivery
catheter tube. The tether wire or shaft is made from flexible wire
material (e.g., nitinol). A threaded fixture at the end of the
tether wire may be used for device attachment. The attached filter
device is compressed to a narrow diameter size and confined in the
implant sheath extending from the delivery catheter tube.
[0015] The delivery catheter tube (with the device loaded in the
implant sheath) is inserted into the pre-positioned access sheath
leading to the subject atrial appendage. The implant sheath is
advanced through the access sheath to a suitable device deployment
location. The delivery system and access sheath may include
mechanical couplers or adapters to lock the delivery tube to the
access sheath. When locked together, the delivery catheter tube and
the access sheath may be moved together, for example, to place or
orient implant sheath in the suitable device deployment location.
The device is deployed by expelling it from the implant sheath at a
suitable location in or about the subject atrial appendage. On
expulsion from the confining implant sheath the filter device
self-expands to its useful size.
[0016] The delivery system may include remote actuators to expel or
uncover filter devices for deployment. In one embodiment, a knob or
handle is attached to the proximal end of the tether wire. The knob
may be manipulated to translate or turn the tether wire. The tether
wire is translated through the delivery tube to push the confined
implant device out of the implant sheath. The tether wire diameter
is selected to provide sufficient rigidity for transmitting
mechanical translation and rotational forces to the attached
implant device. Portions of the tether wire close to the attached
implant device have a reduced diameter to reduce the coupling
stiffness of the tether wire to the attached implant device. This
reduced coupling stiffness is advantageous in deploying the device
in its natural unbiased state while it is still attached to the
tether wire.
[0017] In another embodiment of the delivery system, additionally
or alternatively, the delivery tube is partially retractable over
the tether wire into a handle portion. A sliding actuator, which is
attached to the delivery tube, is disposed on the handle portion.
The filter device may be expelled from the implant sheath by
retracting delivery tube into the handle portion by activating the
actuator on the handle portion. In either embodiment, distal
portions of the tether wire adjoining the attached device may be
encased in a flexible elastomeric material coil, which occupies the
implant sheath lumen around the tether wire. The flexible coil
reduces any buckling tendencies, which a moving flexible tether
wire may have. Next, the tether wire may be detached by unscrewing
it from the deployed device by turning a knob attached to the
proximal end the tether wire. The delivery system may include
mechanical features or releasable stops to limit the translation or
rotation of the tether wire. Use of the releasable stops limits the
possibilities for inadvertent expulsion of the device from the
implant sheath and inadvertent release or loosening of the device
attachment.
[0018] Both the access sheath and the delivery system tubes have
suitable valve assemblies attached to their proximal ends to
prevent fluid leakage during the device implantation procedure. The
valve assemblies may include ports for injection of fluids through
the various tube lumens. For example, the delivery catheter tube
may be attached to a large bore Tuohy-Borst valve assembly. The
Y-arm of the valve assembly may be used for intermittent or
continuous fluid flushing and contrast injection or for continuous
blood monitoring during the implantation procedure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a partial cross sectional view of a heart
illustrating the position of the left atrial appendage relative to
the chambers of the heart and some of the major blood vessels.
[0020] FIG. 2 is a side elevational view of an inventive delivery
system including a delivery catheter tube having an implant sheath
attached to its distal end. The implant sheath contains an
unexpanded filter device attached to a distal flex coil end of a
tether wire passing through the delivery tube lumen.
[0021] FIG. 3a is an enlarged cross sectional view of a distal
section of the delivery system of FIG. 2 with the distal flex coil
end of a tether wire extending into the implant sheath in
accordance with the principles of the invention.
[0022] FIG. 3b is a side elevational view of the implant sheath of
FIG. 3a containing an unexpanded filter device attached the distal
flex coil end of the tether wire extending into the implant sheath
in accordance with the principles of the invention.
[0023] FIG. 3c is a side elevational view an unsheathed and
expanded filter device attached to the distal flex coil end of the
tether wire of FIG. 3a in accordance with the principles of the
invention.
[0024] FIGS. 4a and 4b respectively are a side elevational and a
cross-sectional view of a flexible coil portion that encases the
tether wire in accordance with the principles of the invention. The
inset in FIG. 4b is an enlarged view of section B of FIG. 4b
showing details of the mechanical attachment of flexible coil
portion and the encased tether wire.
[0025] FIG. 5 is an enlarged cross sectional view of the proximal
portion of the delivery system of FIG. 2.
[0026] FIGS. 6 and 7 respectively are a side elevational view and a
plan view of another catheter delivery system in accordance with
the principles of the invention. The delivery system includes a
delivery tube extending into a larger diameter implant sheath and a
tether wire having a control knob at its proximal end. The inset in
FIG. 7 is an enlarged view of section B showing details of the
mechanical attachment of flexible coil portion and the encased
tether wire.
[0027] FIG. 8 is a side view of the components of a transseptal
access system including a sheath, a dilator, a Brochenbrough needle
and an obturator in accordance with the principles of the
invention.
[0028] FIG. 9 is a plan view of an access system sheath in which
the sheath tip has a simple curvature in accordance with the
principles of the invention.
[0029] FIG. 10 is a plan view of an access system sheath in which
the sheath tip has compound curvatures in accordance with the
principles of the invention.
[0030] FIG. 11a is a side elevation view of the sheath tip portions
of the access system sheath of FIG. 10.
[0031] FIG. 11b is a rear elevation view of the access system
sheath of FIG. 10.
[0032] FIGS. 12a is a cross sectional view of a delivery system
tube inserted in an access system sheath in accordance with the
principles of the present invention. The delivery system tube is
partially inserted in the access system sheath.
[0033] FIGS. 12b is a view similar to that of FIG. 12b illustrating
the delivery system tube inserted in and locked with the access
system sheath. In the locked position the distal tips of the two
are about flush. Inset B is an enlarged view of the locking
portions of the delivery tube and the access system sheath.
[0034] FIG. 13a is a rear side elevational view of an expanded
filter device showing a filter membrane and portions of the
expandable wire frame on which the filter membrane is supported in
accordance with the principles of the invention.
[0035] FIG. 13b is a partial side elevational view of the expanded
wire frame structure of the filter device of FIG. 13a.
[0036] FIG. 13c is an enlarged cross sectional view of the central
portion B of the filter device of FIG. 13b illustrating the
attachment of the filter membrane to the wire frame structure in
accordance with the principles of the invention.
[0037] FIG. 13d is a cross sectional view of the expanded wire
frame structure of FIG. 13b sectioned at plane A-A, illustrating
barb elements suitable for engaging atrial appendage wall tissue to
secure the position of the deployed device in an atrial appendage
in accordance with the principles of the invention.
[0038] FIG. 13e is a side elevational view of a solid preform used
in fabricating the expanded wire frame structure of FIG. 13b in
accordance with the principles of the invention.
[0039] FIG. 14a is a side elevational view of another expanded
filter device showing a filter membrane and portions of an
expandable wire frame on which the filter membrane is supported in
accordance with the principles of the invention.
[0040] FIG. 14b is plan view of the proximal end of the device
shown in FIG. 14a.
[0041] FIG. 15a is a side elevational view of the expanded wire
frame structure of the device of FIG. 14a in accordance with the
principles of the invention.
[0042] FIG. 15b is an enlarged view of portion A of the wire frame
of FIG. 15a illustrating the detailed configuration of the wire
frame collar in accordance with the principles of the
invention.
[0043] FIG. 15c shows another side elevational view of the wire
frame of FIG. 15a, which has been rotated by about 15 degrees
around the device's cylindrical axis.
[0044] FIG. 15d is an enlarged view of a barb-carrying portion C of
the wire frame of FIG. 15c illustrating the disposition of a
tissue-engaging barb in accordance with the principles of the
invention.
[0045] FIG. 15e is an enlarged plan view of portion B of the wire
frame of FIG. 15c illustrating the details of the wire
configuration in the wire frame structure.
[0046] FIGS. 15g and 15f are rear elevational and rear side
elevational views of the wire frame of the filter device of FIG.
15a.
[0047] FIGS. 16a and 16b respectively are a side elevational view
and a plan view of another access system in accordance with the
principles of the present invention.
[0048] FIGS. 17a, 17b and 17c respectively are a side elevational
view, a plan view and a cross-sectional view of another delivery
system tube in accordance with the principles of the present
invention.
[0049] FIGS. 18a and 18b are respectively are a side elevational
view and a plan view of the delivery system tube of FIG. 17a and
the access system sheath of FIG. 16a in a locked position in
accordance with the principles of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0050] Devices for filtering or otherwise modifying blood flow
between a left atrial appendage (LAA) and its associated atrium may
be implanted in the LAA. A catheter access sheath is percutaneously
coursed through a blood vessel leading to the heart to gain access
to the LAA. A delivery system is used to move the device through
the access sheath into the LAA. The delivery system includes a
shaft or wire to control movement of the implant device.
[0051] Atrial fibrillation results in harmful clot formation
primarily in the LAA. Therefore, it is anticipated that the
invention will be mostly used for filtering blood flow from the
LAA. However, it will be understood that the invention may also be
used for the right atrial appendage and in general for device
placement across any aperture in the body through which blood
flows.
[0052] The implant filter devices may have adjustable sizes. A
compact or narrow size is used for percutaneous device delivery to
the atrial appendages, for example, by cardiac catheterization. The
devices include size-adjusting expansion mechanisms that allow the
device size to be enlarged in situ to an expanded size.
Alternatively, the devices may have self-expanding elastic
structures. The devices may be held in position in the atrial
appendage by outward contact pressure exerted by the outer
structures of the enlarged device against the atrial appendage
walls. This outward pressure provides an interference-like fit of
the device. The outward contact pressure may be a result of
designed springiness or elasticity of the device structure itself.
Alternate or additional mechanical means such as inflatable
balloons enclosed within the filter device also may be used to
generate the outward pressure.
[0053] In addition (or as an alternate) to the pressure generated
interference-like fit, tissue-engaging anchors may be used to hold
an implanted device in place. These anchors are generally disposed
on exterior device surfaces and engage atrial appendage wall tissue
when the device is deployed in an atrial appendage. The anchors may
be pins, hooks, barbs, wires with a traumatic bulb tips or any
other suitable structures for engaging appendage wall tissue.
[0054] A variety of filter devices have been disclosed in U.S.
patent application Ser. No. 09/428,008, U.S. patent application
Ser. No. 09/614,091, U.S. patent application Ser. No. 09/642,291,
U.S. patent application Ser. No. 09/697,628, and U.S. patent
application Ser. No. 09/932,512, U.S. patent application Ser. No.
10/094,730, and U.S. patent application Ser. No. 10/200,565, all
incorporated by reference herein. Other filter devices are
disclosed herein, for example, expandable devices 700 and 100.
These devices are described herein with reference to FIGS. 13a-13e,
FIGS. 14a and b, and FIGS. 15a-15g.
[0055] FIGS. 13a-13e show expandable filter device 700 having a
filter membrane cover 710. In FIG. 13a filter device 700 is shown
in its natural or expanded state. Filter membrane 710 is supported
on an elastic wire frame 720, which has the general shape of a
cylinder that is closed at one end. Filter membrane 710 covers the
closed cylinder end and extends along the sides of the cylindrical
wire frame 720. Filter device 700 includes an insert or pin 715
having a socket 716 that is suitably adapted for attaching filter
device 700 to a device tether or shaft (e.g., tether wire 410, FIG.
3c).
[0056] Device 700 may be expelled from the delivery tube at a
suitable deployment location in the atrial appendage where it
(device 700) can expand to its deployment state or natural size.
When device 700 is deployed in an atrial appendage, filter membrane
710 stretches across or covers the atrial ostium and intercepts
blood flowing in and out of the atrial appendage. Filter membrane
710 is made of blood-permeable material having fluid conductive
holes or channels extending across membrane 710. Filter membrane
710 may be fabricated from any suitable biocompatible materials.
These materials include, for example, ePFTE (e.g., Gortex.RTM.),
polyester (e.g., Dacron.RTM.), PTFE (e.g., Teflon.RTM.), silicone,
urethane, metal fibers, and other biocompatible polymers.
[0057] The hole sizes in the blood-permeable material may be chosen
to be sufficiently small so that harmful-size emboli are filtered
out from the blood flow between the appendage and the atrium.
Suitable hole sizes may range, for example, from about 50 to about
400 microns in diameter. In one embodiment, filter membrane 710 is
made of a polyester (e.g., Dacron.RTM.) weave or knit having a
nominal hole size of about 125 um. The open area of filter membrane
710 (i.e., the hole density) may be selected or tailored to provide
adequate flow conductivity for emboli-free blood to pass through
the atrial appendage ostium. Further, portions of filter membrane
710 may be coated or covered with an anticoagulant, such as heparin
or another compound, or otherwise treated so that the treated
portions acquire antithrombogenic properties to inhibit the
formation of hole-clogging blood clots.
[0058] FIG. 13b illustrates the structure of wire frame 720. Wire
frame 720 has a generally cylindrical structure that is closed at
one end (right end). Wire frame 720 may be designed to have a
lightweight open structure. For example, wire frame 720 may have an
open structure that resembles that of a chicken wire mesh. The wire
sizes in wire frame 720 may be suitably chosen with consideration
to the structural strength and elastic properties of the
fabrication material used (e.g., nitinol). In practice, the nitinol
wires that are used in wire frame 720 may have typical
cross-sectional dimensions, which range from a few mils to several
tens of mils (one mil.=one thousandth of an inch).
[0059] At the proximal end (right end) of wire frame 720, the frame
wires terminate in a cylindrical collar 722. Collar 722 is
preferably located within the back plane of wire frame 720 (i.e.,
to the left of the plane of filter membrane 710, FIG. 13b). The
cylindrical side portions of wire frame 720 are suitably shaped to
engage atrial appendage wall tissue and provide, for example, an
interference fit in the atrial appendage in which filter device 700
is deployed. Other portions of wire frame 720 may be shaped to
serve as resilient springs, which push or bias the cylindrical side
portions of wire frame 720 radially outward. FIG. 13b shows, for
example, S-shaped wire portions 723, serve as resilient springs to
expand wire frame 720 to its natural or unconstrained size.
S-shaped wire portions 723 emanate from wire collar 722, and lie in
the radial planes passing through passing through the cylindrical
axis of wire frame 720. The S-shape of wire portions 723 causes
collar 722 (and insert 716) to be geometrically recessed relative
to the back plane of wire frame 720.
[0060] In addition, to geometrical shape features designed to
retain or hold device 700 in position inside an atrial appendage,
wire frame 720 may have barbs 728 along its outer surface to engage
atrial appendage wall tissue. Barbs 728 may be distributed in any
suitable pattern on the outer surface. FIGS. 13b, 13c and 13d show,
for example, barbs 728 which are equally spaced along a
circumference of wire frame 720. Further, the diameter of
cylindrical wire frame 720 may be varied by design to enhance
device retention in an atrial appendage. For example, wire frame
720 may have an outwardly distending ridge 724 that is designed to
mechanically bias barbs 728 outward in an orientation suitable for
engaging appendage wall tissue.
[0061] The diameter of cylindrical wire frame 720 also may be
varied by design along its longitudinal axis to obtain device
shapes or structures that reduce the likelihood of traumatic or
undesirable tissue contact in device use. For example, the distal
wire ends (at left open end 726) of frame 720 may be turned
radially inwards toward the longitudinal frame axis. With the wire
ends turned inward only smooth or rounded wire portions 727 of
frame 720 may come in contact appendage walls. Thus, there is less
likelihood of sharp or pointed wire ends coming in contact with or
puncturing atrial appendage walls or other tissue. Alternatively or
additionally, the frame wires may terminate in atraumatic tips at
left open end 726 of wire frame 720.
[0062] Filter device 700 may be fabricated with different-sized
wire frames 720 as necessary or appropriate for use in different
sizes of atrial appendages. An exemplary wire frame at its natural
expanded size may be about an inch in diameter and about an inch
long. As mentioned earlier, wire frame 720 may be made of suitable
elastic material such as nitinol. Wire frame 720 may be made, for
example, by machining a solid preform from a nitinol tube by laser
cutting or other suitable machining processes. Other fabrication
methods such as braiding nitinol wires may be alternatively used.
FIG. 13e shows, for example, preform 730 fabricated by laser
cutting a nitinol tube. Wires 732 of preform 730 terminate in
cylindrical collar 722. Wires 732 may have attached stubs 734 which
when turned upwards form tissue-engaging barbs 728. Preform 730 may
be heat treated and shaped over a mandrel (not shown) to fabricate
wire frame 720 having a desired geometrical shape, for example, as
shown in FIG. 13b. In a compressed state, wire frame 720 returns to
a narrow diameter tubular shape (not shown) similar to that of
preform 730 that is convenient for fitting device 700 in a narrow
diameter catheter or delivery tube for percutaneous delivery.
[0063] FIG. 13c is an enlarged cross sectional view of the central
portion B of filter device 700 illustrating details of the
co-assembly of filter membrane 710, insert 715, and wire frame 720
in device 700. Portions of filter membrane 710 are held firmly
between the inner surfaces of cylindrical collar 722 and the outer
cylindrical surfaces of insert 715, which is inserted in
cylindrical collar 722. (Other portions of filter membrane 710 may
be tied (e.g., by suitable sutures or wire strands) or glued at one
or more places to wire frame 720 to hold filter membrane 710
against wire frame 720). Insert 715 has a threaded socket 716
(threads not shown) to which a mating screw or threaded tether wire
can be attached. Insert 715 may be made of any suitable rigid
materials that can be molded or machined to form threaded socket
716. Insert 715 may, for example, be made from hard plastics or
metals such stainless steel or titanium. Insert 715 may have a
diameter designed to provide a suitable interference fit in collar
722 to hold the filter device assembly together. Additionally or
alternatively, mechanical means, for example, cotter pin 717, may
be used to hold insert 715 in place. Alternative mechanical methods
such as riveting or the use of adhesives or epoxies also may be
used to hold insert 715 in place.
[0064] Device 700 as shown in FIGS. 13a and 13b has substantially
the same cylindrical diameter over substantial portions of its
cylindrical length. In other embodiments of the device, the
cylindrical diameter may vary by design. FIG. 14a shows an
expandable filter device 100 whose cylindrical diameter decreases
substantially over its (100) longitudinal axis.
[0065] FIG. 14a shows filter device 100 in its expanded state.
Filter device 100 has a generally cone-like cylindrical shape that
is closed at one end. Filter device 100 includes a filter membrane
110 covering portions of a wire frame 120 and includes other
structures or features, which are the same or similar to the
corresponding structures in filter 700 described above. For
brevity, the description of device 100 herein is generally limited
only to its features that may differ significantly from the
corresponding structures or features of device 700.
[0066] In its expanded state wire frame 120 has a generally
cone-like cylindrical structure, which is closed at one end (right
end). FIGS. 15a-15f, illustrate the structure of exemplary wire
frame 120, which may be made from a laser-cut solid nitinol tube
preform. The varying cylindrical diameter of wire frame 120 is
chosen to give device 100 a conical shape in consideration of the
typical shapes of atrial appendages in which the device is likely
to be used.
[0067] At the right end of wire frame 120, wires 120w that form
wire frame 120 terminate in cylindrical collar 122. FIG. 15b shows
an enlarged view of collar 122 and portions of attached wires 120w.
Wires 120w are shown, for example, as approaching and terminating
at collar 122 at a suitable shallow angle relative to the
longitudinal axis of wire frame 120.
[0068] Filter device 100 includes a cylindrical insert 115 having a
socket 116 that is suitably configured for attaching filter device
100 to a device tether or shaft (similar to insert 715 in device
700, FIG. 13c). Insert 115 is attached to collar 122 of wire frame
120 (FIG. 14a). Collar 122 may have holes 129 suitable for
receiving, for example, cotter pins to fasten insert 115 in
position. FIG. 14b shows, for example, the relative radial sizes of
wire frame 120, insert 115 and socket 116.
[0069] The positioning of collar 122 along the longitudinal axis of
wire frame 120 may be suitably chosen with consideration to the
exterior surface topography presented by deployed device 120 to
atrial blood flow. The recessed location of collar 122 may reduce
or minimize the extension or protrusion of insert 115 normal to the
back plane of device 100. Atrial appendage implant devices with few
or little back plane protuberances may be desirable as such devices
are unlikely to impede or disrupt blood flow through the
atrium.
[0070] In preferred embodiments of either device 700 or 100, their
respective wire frame structures 720 or 120 are shaped so that
annular portions of their proximal surfaces (closed end) are
concave or dimpled toward the distal end of the device (see, e.g.,
FIG. 13b and FIG. 14a). This concavity allows wire frame collar 722
(122) to be positioned along the longitudinal axis of wire frame
720 (120) at or about the closed-end back plane (e.g., back plane
120b, FIGS. 14a and 15a). With the wire collars so disposed, filter
membrane 710 (110), which is held between the collar 722 (122) and
insert 715 (115), may be supported over the closed end of wire
frame 722 (122) in a substantially flat configuration (see e.g.,
FIG. 13a and FIG. 14a). Further, inserts 715 and 115 may have
suitably small axial dimensions so that they do not protrude from
or do not extend substantially beyond the devices' closed-end back
planes (120b). Devices 700 or 100 of these preferred embodiments,
when deployed in an atrial appendage, present a relatively flat
proximal surface topography that does not protrude into the atrium
or significantly disturb atrial blood flow past the appendage
opening.
[0071] The concavity of portions of the back surface of the wire
frames also may give portions of the wire frames an S-shape. These
portions (e.g., sections 723, FIG. 13a, sections 123, FIGS. 14a and
15a) may serve as S-shaped resilient springs that push the
cylindrical side portions of the wire frames radially outward to
engage atrial appendage walls. Wire portions 123c, for example,
with reference to FIGS. 15c, form the chicken-wire mesh-like
cylindrical sides portions of wire frame 120. At one end each
S-shaped wire section 123 is attached to collar 122. The other end
of each S-shaped wire section 123 is connected to wire portions
123c. FIG. 15e shows an enlarged view of an exemplary mechanical
transition from a S-shaped wire section 123 to distal chicken-wire
mesh-like wire portions 123c. S-shaped sections 123 may lie in
radial planes that intersect each other along the longitudinal
frame axis (FIG. 15g)
[0072] Filter devices 100 or 700 (or other expandable devices) may
be implanted in a patient's atrial appendage using percutaneous
catheterization procedures. The catheterization procedures involve
first deploying an access system to position an access sheath
through a patient's vascular system to the interior locations in
the patient's heart, (e.g., to the atrial appendage). The access
sheath provides a passageway through which medical instrumentation
such as probes or implant devices are passed from outside the
patient's body to interior locations in the heart. Independent
delivery systems may be used to deliver the probes or devices
through the access sheath. The inventive delivery systems that may
be used can be of one or more types (e.g., delivery system 200, 800
or 800A).
[0073] FIGS. 8 and 9 show access system kit 500 which may be used
to establish a passageway for device delivery to an atrial
appendage through a patient's vasculature. Access system kit 500
includes access sheath 510, dilator 520, obturator 540, and
Brochenbrough needle 530. Access sheath 510 has a tubular
structure. Access sheath 510 tubing may be made of any suitable
flexible materials. Access sheath 510 may, for example, be made
from braided wire tubing having a plastic outer coat. In the
example, the braided wire may be stainless steel and the plastic
outer coat may be any suitable plastic polymeric material such as
urethane. The distal end or tip of the access sheath is made of
curved tubing which can be stiffened or straightened as necessary
during the insertion of the access sheath through the vasculature
and across the cardiac septum. The curved shape of the access
sheath tip may be designed to take into account the anatomical
geometry of the vasculature and the heart.
[0074] The diameter of the tubing used to fabricate access sheath
510 is selected to be sufficiently large to allow convenient
passage of probes or tubular portions of the implant device
delivery systems (e.g., FIG. 2 delivery catheter tube 200) through
it. An exemplary access sheath 510 is made from French size 12 (4
mm diameter) tubing. Other French size tubing (smaller or larger
than French size 12) may be used as needed for different sizes of
probes or implant devices. Further, the interior walls of the
tubing material may be lined with lubricious material such as PTFE
(e.g., Teflon.RTM.) for easier sliding passage of probes or implant
device delivery systems through access sheath 510. The liner
material may extend through the distal end of the tubing material
to form a soft distal tip 512. The proximal end of the stainless
tube is connected to valve assembly with fluid seals acting against
tubes or catheters that may be inserted into the access sheath to
prevent the leakage of fluids during use. For example, a hemostasis
valve assembly 514 is attached to the proximal end of the sheath
tube. Valve 514 may, for example, have a conventional hard plastic
material shell construction with silicone material valve seals.
Optional port 515 on the proximal end of access sheath 510 provides
fluid communication with access sheath 510 lumen. A stopcock valve,
for example, a three-way valve 516, may be used to control the flow
of fluids through port 515.
[0075] Access system kit 500 components Brochenbrough needle 530,
dilator 520, and obturator 540 may be conventional components
suitably adapted to fit in access sheath 510 for use in conjunction
with access sheath 510. Brochenbrough needle 530 is a hollow curved
tube. Needle 530 may be made of any suitable material such as a
stainless steel tube. Valve 532 seals the proximal end of the tube.
The distal end of the tube is sharpened to form a needle tip 532.
Obturator 540 is made from a length of a suitable solid wire having
a blunt end 542. An exemplary obturator 540 is made from 14 mils
diameter stainless steel wire. Obturator 540 is designed to slide
through needle 520 with blunt end 542 extending out of needle tip
532. In use, the extension of blunt end 542 through needle tip 532
prevents needle tip 532 from causing inadvertent punctures of
surrounding tissue or tubing. Dilator 520 is another curved hollow
tube like-structure that can fit in access sheath 510. Dilator 520
also, may, for example, be made with from stainless steel tubing.
Dilator 520 is designed to fit through access sheath 510 over
needle 530.
[0076] Access system kit 500 may be used in a transseptal
catheterization procedure for implanting filter devices, for
example, in a patient's LAA. In such a catheterization procedure,
access sheath 510, dilator 520, and needle 530 may be
conventionally prepared for introduction into a patient's vascular
system, for example, by flushing them with saline solution to
remove air from their lumen. A conventional short introducer sheath
or needle may be used to make a puncture opening, for example, in
the right femoral vein (or artery), through which Brochenbrough
needle 530 is introduced into the patient's vasculature.
Alternatively, a puncture opening made by the sharpened needle tip
532 it self may be used to introduce needle 530 into the patient's
vasculature.
[0077] Next, a length of conventional guide wire may be advanced
through needle 530 (or the introducer sheath) ahead of the needle
tip into the femoral vein. The guide wire may, for example, be a
standard 35 mils diameter steel wire. Access sheath 510 and dilator
520 are then advanced over the guide wire through the femoral vein
into the right superior vena cava. Dilator tip 522 may extend out
of access sheath 510, for example, by about three quarters of an
inch. Access sheath 510 and dilator 520 are advanced sufficiently
into the right atrium through the right superior vena cava so that
the dilator tip 522 is in close proximity to the atrial septum
separating the right atrium from the left atrium. Next, the guide
wire may be withdrawn and replaced by needle 530. Needle 530 (with
obturator 540 extending through it) is advanced through dilator 520
so that needle tip 532 extends slightly out of dilator tip 522.
Obturator 540 is then withdrawn to expose sharpened needle tip
532.
[0078] Next, needle 530, dilator 520, and access sheath 510 may be
advanced, either sequentially or together, to puncture the septum,
dilate the puncture opening, and advance access sheath 510 through
the dilated septal opening into the left atrium. Once access sheath
is set up across the septum, needle 530 and dilator 520 may be
withdrawn.
[0079] A suitable septal puncture location may often be found
within the thin walled dimpled region of the atrial septum (fossa
ovalis), which is below the position of the LAA on the left atrium
(FIG. 1). After advancing access sheath 510 through the dilated
septal opening into the left atrium, access sheath 510 tip is
reoriented and redirected from the direction of its entry into the
left atrium toward the subject LAA. The curved shape of the distal
access sheath 510 tip is advantageous in reorienting and
redirecting it toward the subject atrial appendage. The curved
shape may facilitate moving the access sheath through angles and in
placing the access sheath in an orientation from which an implant
device may be delivered directly into the subject atrial appendage.
The sheath tip curvatures may be suitably designed to ease access
to atrial appendages, which are anatomically disposed in the remote
or awkward upper reaches of the corresponding atria. The suitable
designed geometrical curvatures of the sheath tip may be simple or
compound.
[0080] In one embodiment, access sheath 510 tip has a simple
geometric curvature (e.g., J-shape). The length of the access
sheath tubing may be chosen to have the ability to position distal
end 512 in the atrial appendage. An exemplary access sheath 510 of
this embodiment may have a length of about 33 inches (FIG. 9). The
distal tip portion 510c of this exemplary sheath is a curved arc,
which may have a radius of about a few inches (e.g., 2 inches).
Distal tip portion 510c may be about one quarter of circle long. In
another embodiment, access sheath 510 tip may have a geometrically
compound curved shape. FIG. 10, 11a and 11b show an exemplary
access sheath 510 in which the sheath tip has two adjoining tip
portions 510a and 510b. Portion 510a may have a radius of curvature
of about a few inches, and may like portion 510c (FIG. 10) be about
one quarter of circle long. Adjoining portion 510b may be a short
stub-like portion, which extends from portion 510a and orients
sheath exit opening (distal end 512) in a direction that is about
normal or away from the plane containing curved portion 510a (FIGS.
11a and 11b).
[0081] With reference to and in continuation of the preceding
description of a transseptal access procedure using access system
kit 500, it will be understood that suitably curved access sheath
510 may be set up across the septum so that its distal end 512
points toward the subject LAA. Access sheath 510 may be further
advanced into the LAA itself. In some procedures, access sheath 510
may be advanced so that distal end 512 is placed deep inside the
LAA. Once access sheath 510 is placed in suitable position across
the septum, it may be used as a passageway for delivery of filter
devices to the LAA from outside the patient's body. Suitable
delivery systems may be used to move the filter devices through
hemostatic valve assembly 514.
[0082] During the transseptal access sheath positioning or set-up
procedure described above, blood flow in needle 530 lumen may be
sampled through valve 534, for example, to confirm the position of
needle tip 532 in either the right or the left atrium. Additionally
or alternatively, fluids may be injected into the heart through
access sheath 510 using through port 515 for diagnostic or other
purposes. For example, radio opaque dyes may be injected into the
left atrial appendage to size the appendage to determine or select
the appropriate or suitable implant device size. A selected device
may be implanted in the LAA through the through the passage way
formed by pre-positioned access sheath 510.
[0083] Inventive delivery systems may be used to implant the device
through access sheath 510. FIG. 2 and FIGS. 3a-3c, show, for
example, a delivery system 200 that may be used to deliver and
position implant devices (e.g., filter device 700 and device 100)
in a patient's LAA through access sheath 510. Delivery system 200
includes delivery catheter tube 220 that distally extends into a
tubular implant sheath 230. The proximal end of delivery tube 220
is slidably connected to a hollow handle or manifold assembly 210.
Delivery tube 220 may be partially retractable into manifold
assembly 210. A tether wire 410 passes through hollow handle 210
and delivery tube 220 into implant sheath 230 (FIGS. 3a-3c). The
distal portions of tether wire 410 may be encased in a flexible
material, for example, distal flex coil 420 whose diameter is
selected to fit inside implant sheath 230. The distal end of tether
wire 410 terminates in fixture 430 suitable for attaching an
implant device (FIG. 3a). Fixture 430 may, for example, be a
threaded screw, which can be screwed into threaded socket 716 to
attach, for example, filter device 700 (FIG. 13a). The proximal end
of tether wire 410 is attached to a rotatable knob 260 mounted on
handle 210. Rotatable knob 260 may be manually rotated to turn
fixture 430.
[0084] The implant device selected for implantation in the patient
is attached to distal tether wire fixture 430, compressed or
compacted to a narrow diameter size and loaded in implant sheath
230. Implant devices having threaded sockets (e.g., device 700
insert 715, FIG. 13a) may be attached (or detached) to tether wire
410 by turning rotatable knob 260. Handle or manifold assembly 210
may be fitted with a mechanical safety cap 280 to cover rotatable
knob 260 to prevent inadvertent unthreading or detachment of an
attached device. To gain access to knob 260, an operator must first
remove safety cap 280. The attached device is compressed in size
(e.g. compressed device 700a, FIG. 3b) to fit in implant sheath
230. The walls of implant sheath 230 restrain compressed device
700a from expanding during device delivery. For deployment in situ,
compressed device 700a is expelled from implant sheath 230 from a
suitable deployment position in or about the subject LAA.
[0085] Compressed device 700a may be unconstrained or expelled from
the implant sheath 230 for deployment by retracting delivery tube
220 over tether wire 410 into handle 210. Delivery system 200
includes external control mechanisms, which may be activated to
retract delivery tube 220 over tether wire 410. In an embodiment of
delivery system 200, the proximal end of delivery tube 220 is
attached to reciprocating sheath actuator 240. Sheath actuator 240
may slide along handle or manifold assembly 210 to partially
retract delivery tube 220 into manifold 210 or to further extend
delivery tube 220 from manifold 210. Additionally, manifold 210 may
be fitted with an optional actuator lock 290 to prevent inadvertent
movement of sheath actuator 240. Movement of sheath actuator 240,
may be enabled only after actuator lock 290 must be removed.
[0086] Sheath actuator 240 may have suitable hemostatic fluid seals
(e.g., rubber seals 242, FIG. 5) acting against the surface of
tether wire 410 passing through handle 210. The fluid seals may
prevent fluid leakage from delivery tube 220 as sheath actuator 240
is moved along handle 210 over a length of tether wire 410. Sheath
actuator 240 also may include an optional pipe fitting, for
example, female luer fitting 245, in fluid communication with
delivery tube 220 lumen. Fitting 245 may, for example, be used to
flush delivery tube 220 with saline solution prior to use to remove
air from delivery tube 220 lumen. Fitting 245 also may be used to
sample blood or for infusion of drugs and other fluids into
delivery tube 220 during use.
[0087] In the device implantation procedure, delivery system 200 is
inserted into pre-positioned access sheath 510 through hemostasis
valve assembly 514. Delivery tube 220 is advanced through access
sheath so that implant sheath 230 extends out of access sheath tip
512 toward the subject LAA.
[0088] The length of catheter delivery tube 220 (and that of tether
wire 410) desired for a catheterization procedure may be chosen or
determined by consideration of length of the vascular pathway to
the atrial appendage. Catheter delivery tube 220 lengths of about
80 cms. to 125 cms. may be appropriate for most adult
catheterization procedures. Implant sheath 230 may have a length
sufficient to axially cover distal flex coil 420 and the compressed
implant device. The diameter of delivery catheter tube 220 and
implant sheath 230 are kept small in consideration of the size of
typical vascular pathways and the flexibility required for delivery
catheter tube 220 and implant sheath 230 to traverse access sheath
510.
[0089] In an exemplary delivery system 200, the inside diameter of
delivery tube 220 may be about 45 mils. Implant sheath 230, which
constrains unexpanded filter devices, may have a larger diameter of
about 90 mils to accommodate the larger diameter of an unexpanded
filter device. (It will be understood that in practice a wide range
delivery tube 220 and implant sheath diameters may be used as
appropriate). In the example, tether wire 410, which passes through
delivery tube 220, has a diameter smaller than 45 mils so that it
can easily slide through delivery tube 220. An embodiment of tether
wire 410 is made from a nitinol or other metal wire having a
diameter of about 35 mils over most of its length. A metal wire of
this diameter may be sufficiently stiff or rigid to allow for its
smooth passage through delivery tube 220, and for mechanically
coupling the motion of knob 260 to that of a filter device attached
to the other end of tether wire 410. However, a distal section 432
of tether wire 410 of this embodiment may have a reduced diameter
of about 10 mils (FIG. 3a). The diameter decreases gradually from a
proximal section 436 diameter (35 mils) to a distal section 432
diameter (10 mils) over a taper section 434. Taper section 434 may
have a length, for example, of about 1 to 2 cms.
[0090] This manner of wire diameter reduction lessens the coupling
stiffness between tether wire 410 and a filter device attached to
fixture 430. The lessening of coupling stiffness may allow the
filter device deployed in an atrial appendage to be detached or
released from device tether 410, without significant recoil.
Recoilless release or release with minimum recoil is desirable as
recoil may cause the deployed device to tip or dislodge from its
pre-release position in the atrial appendage. The reduced coupling
stiffness also allows the attached filter device to deploy in its
natural unbiased state in the atrial appendage while still attached
to the tether wire. These features may be advantageously used to
assess the suitability of an implant deployment prior to detachment
of tether wire 410. The deployed device may be viewed in its
unbiased state while it is still attached to tether wire 410. An
improperly or unsuitably deployed device may be retrieved, for
example, by extending implant sheath 230 over still-attached tether
wire 410 to recapture the device or by pulling the device back into
implant sheath 230 with still-attached tether wire 410.
[0091] FIG. 3c shows a distal section of tether wire 410 of the
aforementioned embodiment. FIG. 3c also shows an expanded filter
device (e.g., device 700) attached to the distal end of tether wire
410. Portion 410b represents the section of tether wire 410 with
the wire diameter reduced to about 10 mils. Portion 410b is encased
in distal flex coil 420. The latter may be made of coiled or molded
plastic elastomer material. Flex coil 420 is designed to have a
diameter to occupy the luminal space between the inner walls of
implant sheath 230 and tether wire portion 410b. By taking up the
dead space in implant sheath 230, distal flex coil 420 may prevent
reduced diameter wire tether portion 410b from buckling when tether
wire 410 is moved relative to implant sheath 230.
[0092] In some cases of the device implantation procedure using
delivery system 200, access sheath 510 may be pre-positioned such
that sheath tip 512 is itself advanced into the subject atrial
appendage. In other cases, access sheath 510 may be pre-positioned
such that sheath tip 512 is outside or at the atrial appendage
opening. In either instance, implant sheath 230 may be advanced out
of access sheath tip 512, for example, to the back of the subject
LAA, in preparation for device deployment. Then access sheath 510
may be partially retracted to pull access sheath tip 512 clear of
the subject atrial appendage (if necessary) for device deployment.
Access sheath 510 may be pulled back a sufficient distance so that
tip 512 is back at the opening of the atrial appendage or is
completely out of the atrial appendage. Next, the compressed
implant device contained in the implant sheath 230 may be deployed
in the atrial appendage by retracting implant sheath 230 to uncover
compressed implant device 700a. Implant sheath 230 may be retracted
over tether wire by sliding sheath actuator 240 backward over
manifold 210 to retract delivery tube 210 into manifold 210 (e.g.,
FIGS. 2 and 5).
[0093] As implant sheath 230 is retracted, the implant device
(e.g., device 700) expands in situ to its natural size. As filter
device 700 expands, filter membrane 710 extends across the atrial
appendage ostium to intercept blood flow. In the expanded device,
cylindrical side portions of wire frame 720 press radially outward
in opposition to the interior walls of the atrial appendage.
Additionally, wire frame 720 features such as barbs 728 engage
atrial appendage wall tissue. The outward contact pressures, which
may be resisted by atrial wall muscle tissue, and the engagement of
appendage wall tissue by barbs 728, secure the expanded device in
an implant position. After filter device 700 is suitably expanded
in situ, it may be released or detached from tether wire 410. To
release filter device 700, first, safety cap 280 is removed to gain
access to release knob 260. Next, release knob 260 may be turned or
rotated to unscrew fixture 430 from socket 715 to release filter
device 700 from tether wire 410.
[0094] It will be understood that suitable external imaging
techniques may be used during the catheterization procedure to
monitor the in vivo position of the components of the access system
and the device delivery system. These techniques may include but
are not limited to techniques such as radiography or fluoroscopy,
echocardiography including transesophageal echocardiography, and
ultrasound. It will also be understood that the various components
of the device delivery system and the access system may include
materials having suitable properties (e.g., radio-opacity) that
make it possible to monitor the in-vivo component positions using
the appropriate external imaging techniques.
[0095] For some assessment or imaging techniques, port 514 on
access sheath 510 may be used to inject fluids into the heart
including, for example, radio opaque dyes, at any suitable times in
the procedure including when delivery catheter tube 210 extends
through access sheath 510. In delivery system 200, delivery tube
220 lumen may be used to transmit fluids. For such use, flex coil
portions in which distal portions of tether wire 410 are encased
may include flush ports to allow fluids to be injected into the
heart or atrial appendage through delivery tube 220 lumen. FIGS.
4a-4b show a coil 620, which may be used to encase the distal
narrow diameter portions of tether wire 410. Coil 620 may be made
of soft polymeric materials (including, for example, thermoplastic
electrometric resins that may be sold commercially under the trade
name PEBAX.RTM.). The outer diameter of coil 620 (like that of coil
420) may be about the same as the inner diameter of implant sheath
230. Coil 620 includes axial lumen 622 that leads to flush ports
624 near the distal end of coil 620. An exemplary lumen diameter
may be about 75 mils. Proximal end portions 628 of coil 620 may be
designed for mechanical connection with delivery tube 220. For
example, proximal end portions 628 may be tapered to provide
interference fit in delivery tube 220 (FIGS. 4a and 4b, delivery
tube 220 not shown). Tether wire 410, which may have a diameter of
about 35 mils or less, passes through delivery tube 220 and through
coil 620 so that device-attachment fixture 430 extends out of coil
620. A mechanical restraint, for example, a cylindrical plug or
stop 626 that fits in axial lumen 622, may be used to hold coil 620
in position over tether wire 410. Cylindrical plug 626 may be glued
to tether wire 410 with suitable adhesives or epoxy material 627
(FIG. 4b inset). Fluid connectivity around plug 626 between
delivery tube 220 lumen and axial lumen 622 may be provided by
grooves and holes 629 fashioned in proximal end portions 628 of
coil 620. Fluids that are injected into delivery tube 220 lumen
(e.g., through fitting 245, FIG. 2) may pass through holes 629 into
lumen 622 and are discharged from flush ports 624. This fluid
pathway may, for example, be used to inject radio opaque dyes into
atrial appendages around implant devices that are still attached
tether wire 410. Such radio opaque dye injection may be
advantageous in assessing the positioning of expelled or deployed
devices in the atrial appendage before tether wire 410 is detached.
If the position of the expelled device is not appropriate, sheath
actuator 240 may be activated to slide implant sheath 230 forward
over tether wire 410 to recapture the device for repositioning or
withdrawal as desired.
[0096] In other embodiments of the device delivery system, tether
wire 410 itself may be used as the primary means to control
movement of the attached implant device in and out of implant
sheath 230. FIGS. 6 and 7 show, for example, delivery system 800 in
which the movement of tether wire 410 through delivery catheter
tube 220 controls the movement of the attached implant device in or
out of implant sheath 230 (implant device not shown). For brevity,
the description of delivery system 800 herein is generally limited
only to some of its features that may differ significantly from the
corresponding structures or features of delivery system 200.
[0097] Device delivery system 800 includes delivery catheter tube
220 that distally extends into a tubular implant sheath 230. The to
be implanted device is attached to tether wire 410 and is contained
in implant sheath 230. A radial compression valve assembly 810 is
mounted or connected to the proximal end of delivery catheter tube
220. Radial compression valve assembly 810 may, for example, be a
large bore Touhy Borst valve assembly. The side-arm or Y-arm 814 of
the Touhy Borst valve assembly allows intermittent or continuous
flushing and contrast injection, and also allows for continuous
blood monitoring through delivery tube 220 lumen. A multi-way
stopcock 816 may be attached to Y-arm 814 to regulate or control
the flow of fluids through Y-arm 814.
[0098] Tether wire 410 slidably passes through valve assembly 810
and delivery tube 220 into implant sheath 230. Touhy Borst valve
assembly 810 seals permit unimpeded translational or rotational
movement of tether wire 410, whose proximal end is attached to a
control handle or knob 820. In use knob 820 may be manipulated to
translate or rotate tether wire 410 as necessary at appropriate
steps in the device implantation procedure. For example, to insert
or deploy an attached device in the subject atrial appendage,
tether wire 410 may be translated forward through hemostatis valve
assembly 810 to push the attached device out of implant sheath 230.
A rotational motion of tether wire 410 may be used to unthread and
detach the deployed device.
[0099] Proximal portions of tether wire 410 leading to control knob
820 optionally may be clad by stiffening material or tube 822.
Stiffening tube 822 may provide mechanical rigidity for
transmitting, for example, control knob 820 rotation or torque to
the threaded fixture 430 over the length of tether wire 410.
[0100] It will be understood that the various components of device
delivery system 800 (e.g., knob 820, valve assembly 810, delivery
tube 220, stopcock 816, etc.) may be mutually attached or connected
using suitable adhesives, glues, and epoxy materials, and/or
conventional fittings. Some or all sections of deliver system 800
may be fabricated using off-the-shelf components or alternatively
may be fabricated as single pieces using techniques such as
injection molding. For example, pipefitting or locking nut 812 may
be used to connect delivery tube 220 to threaded portions of valve
assembly 810.
[0101] Delivery system 800 and access sheath 510 may optionally
include fittings or other coupling mechanisms, which allow them to
be mechanically coupled. The coupling mechanism may, for example,
be a manually adjustable mechanical lock. The coupling mechanisms
may, for example, include threaded nut connectors, bayonet
connectors, pin connectors, screwed flanges, or any other suitable
connectors which can be used to lock the access sheath and the
delivery system together. The suitable connectors may include
pipefittings such as leur fittings.
[0102] FIGS. 12a-12d show, for example, access sheath 510 and
delivery system 800 with lock fittings or adapters 550a and 850a,
respectively. Fitting 550a may, for example, be a socket or female
adapter fashioned in hemostasis valve 514 at the distal hub of
access sheath 510. Fitting 850a may be a pin or male adapter
disposed over delivery tube 220 adjacent to valve assembly 810.
Fittings 550a and 850a may have matching structures and dimensions
that allow access sheath 510 and delivery system 800 to be
mechanically coupled or joined together. Matching lock fittings
550a and 850a may be designed to be capable of ready and repeated
physical engagement or disengagement (with or without the use of a
tool). Access sheath 510 and delivery system 800 may be moved
together when joined or combined by the coupling mechanism, or
independently when the coupling mechanism is inactive. Mechanically
coupling delivery system 800 to access sheath 510 may be
advantageous in obtaining a stable passageway for moving implant
devices attached to a tether wire. The mechanical coupling also may
be useful in predetermining and fixing the relative positions of
implant sheath 230 and access sheath tip 512, and in moving the two
together.
[0103] FIGS. 12a and 12b show delivery system 800 and access sheath
510 in use, for example, during a catheterization procedure, with
delivery catheter tube 220 inserted in access sheath 510 through
hemostasis valve 514 with matched luer fittings 850a and 550a
separated and disconnected. In this state both delivery catheter
tube 220 and access sheath 510 can be moved independently. In
routine operation, delivery catheter tube 220 may be advanced
through access sheath 510 until fitting 850a locks in fitting 550a.
When locked together, the distal end of implant sheath 230 may, for
example, be flush with access sheath tip 512 (or at separation
distance which is predetermined by the positioning of fitting 850a
along the length of delivery tube 220).
[0104] FIGS. 12c and 12d show delivery system 800 and access sheath
510 with fittings 850a and 550a locked together. In the locked
state both delivery catheter tube 200 and access sheath 510 move
together in a mechanically joined or combined fashion. An implant
device (e.g., device 100) may be deployed, for example, in the
subject LAA, by retracting the delivery tube/access sheath
combination over wire 410 to unsheathe the self-expanding implant
device (FIG. 3, LAA not shown).
[0105] Other types of locks and/or valve assemblies may be
incorporated in access system sheath 510 and delivery system tube
800. The configurations of these other types of locks and valves
may provide different or additional operational features. For
example, FIGS. 16a-18b show another access system sheath 510A and
another delivery system 800A. Again for brevity, the description of
delivery systems 800A and access system 510A herein is generally
limited only to those features that may differ significantly from
the corresponding structures or features of delivery systems 200
and 800 and access system 510.
[0106] Access system sheath 510A, shown in FIGS. 16a and 16b, may
have a radial compression valve assembly 514A at its proximal hub.
Radial compression valve assembly 514A may have any suitable
conventional design. Valve 514A may, for example, have a Touhy
Borst design with a cylindrical body 514c that houses a suitable
radial shaft seal (not shown). The shaft seal may, for example, be
made from a cylinder or ring of silicone material. A knurled knob
514k, which rotates on threaded portions of cylinder body 514c, may
be used to controllably compress the shaft seal against a passing
shaft or tube (e.g., delivery tube 220). The use of rotary valve
514A having an adjustable shaft seal may be advantageous in
controlling back bleeding during the manipulation of the delivery
tube or other instrumentation (e.g., guide wires) through access
sheath 510A.
[0107] Access system sheath 510A may be used with a suitably
adapted delivery system, for example, delivery system 800A shown in
FIGS. 17a-17c. Delivery system 800A and access system sheath 510
may be locked together using suitable snap-on locking arrangements.
The locking arrangement may restrict the relative translation
and/or rotation of the two systems. A snap-on locking arrangement
may include, for example, a C-shaped clip 852 that is disposed on
the distal ends of delivery system valve assembly 810 (FIG. 17a).
Further, cylinder body 514c of valve 514A at the distal end of
access sheath 510 may be provided with suitable detents, grooves,
holes or rings, to receive and hold the tips of C-shaped clip 852.
For example, ring 552 on cylinder body 514C may be designed to
receive and slidably hold the tips of C-shaped clip 852. Ring 552
may be immovably fixed on cylinder body 514c, or alternatively ring
552 may be rotatably mounted on cylinder body 514c. Like luer-type
lock fittings 550a and 850a (FIGS. 12a-12b), C-shaped clip 852 may
be designed to be capable of ready and repeated physical engagement
or disengagement with ring 552.
[0108] In operation, delivery system 800A may be mechanically
locked with access system 510A by suitably advancing delivery
system 800A so that tips of C-shaped clip 852 catch or snap behind
ring 552. The exemplary C-shape locking mechanism may mechanically
couple delivery system 800A to access sheath 510A to obtain a
stable passageway for moving implant devices attached to a tether
wire, while allowing desirable rotational motion of delivery tube
220 and delivery system 800A. For example, C-shape clip 852 when
locked prevents the linear or translation movement of delivery
system 800A relative to access system sheath 510A. The rotational
motion of delivery tube 220 passing through rotary valve 514A may
remain unconstrained as the tips of C-shape clip 852 may slid
around ring 552 (or alternatively ring 552 may rotate around
cylindrical body 514c). Further, open spacing 852a that is
delimited by C-shape clip 852 provides operator access to knob
514k. This access may be advantageously used to adjust knob 514k,
for example, to control back bleeding during the device
implantation or other procedures.
[0109] FIGS. 18a and 18b show delivery system 800A and access
sheath 510A in use, for example, during a catheterization
procedure, with delivery catheter tube 220 (not seen) inserted in
access sheath 510A through rotary valve 514A with C-shape clip 852
locked on cylindrical body 514c. In the locked state both delivery
system 800A and access sheath 510A may be moved together linearly.
Delivery catheter tube 220 and delivery system 800A may be rotated
as necessary or advantageous, for example, to orient or position
the implant device (e.g., device 100) attached to the distal end of
tether wire 410. Access to knurled knob 514k through spacing 852a
allows the operator to adjust the radial or shaft seal of valve 514
around catheter tube 220 to allow free rotation and/or control back
bleeding.
[0110] The design of systems 800A and 510 may incorporate other
optional features involving operator use of the systems. For
example, FIGS. 17a-18b show an additional locking clip 890 mounted
on tether wire casing 822. Clip 890 may have a suitable releasable
or detachable structure. Clip 890 may, for example, be a plastic
flag or tab which is releasable, mounted in a slot running along
casing 822 tube. Clip 290A acts as a stop against the distal end of
Touhy Borst valve or manifold assembly 810. Clip 890 may be mounted
at suitable distance along wire casing 822 to limit the length of
tether wire 410 that can be inserted in delivery tube 220. By
limiting the inserted length of tether wire 410, clip 890 may
prevent premature expulsion and deployment of the implant device
attached to the end of tether wire 410. In use, clip 890 may be
removed or released by an operator after combination of access
sheath 510A/delivery tube 800A has been suitably placed (e.g., in a
subject LAA) for device deployment. Then the operator may extend
additional lengths of tether wire 410 through delivery tube 220 to
push the tethered device out of the constraining implant sheath 230
for device deployment. The deployed device may be released by
turning control knob 820.
[0111] Delivery system 800A and tether wire 410 may include
suitable features to prevent inadvertent release of the device
attached to the distal end of tether wire 410. For example,
proximal hub 832 of Touhy Borst assembly 810 (e.g., at the end
opposite from clip 852) may include a D-shaped lumen or keyway for
the passage of tether wire 410/casing 822. FIG. 19c shows, for
example, D-shape keyway 815 that is located to the left of washer
819 and silicone seal 817. Portions or lengths of tether wire
410/casing 822 may have a suitable cross-section that allows it to
slide through keyway 815 but which prevent its rotation. For
example, casing length 822D may have a D-shaped cross-section that
allows sliding passage of tether wire 410/casing 822 through keyway
815 but one that prevents rotation. Further, casing 822 at its
extreme distal end portions abutting knob 820 may have a suitable
cross-section that can rotate through the keyway 815. For example,
short casing length 822R may have a round cross-section. In use,
tether wire 410 is restrained from turning while casing length 822D
is in keyway 815, which, may correspond to when the attached device
is within implant sheath 230. Tether wire 410 can be turned only
when knob 820 is pushed up against connector 812 so that round
cross-section casing length 822R is within keyway 815. The length
of tether wire 410 may be designed so when knob 820 is pushed up
against connector 812 the implant device is pushed out of implant
sheath 230. Thus the device may be detached by unscrewing tether
wire 410 only after it has been has been expelled from implant
sheath 230 by pushing knob 820 up against up against connector 812.
The operator may, for example, release the deployed device by
turning knob 820.
[0112] It will be understood that the foregoing is only
illustrative of the principles of the invention, and that various
modifications can be made by those skilled in the art without
departing from the scope and spirit of the invention. It will be
understood that terms like "distal" and "proximal", "left" and
"right", and other directional or orientational terms are used
herein only for convenience, and that no fixed or absolute
orientations are intended by the use of these terms.
* * * * *