U.S. patent application number 10/639614 was filed with the patent office on 2004-04-22 for healing transmyocardial implant.
This patent application is currently assigned to HeartStent Corporation. Invention is credited to Tweden, Katherine S., Vanney, Guy P..
Application Number | 20040077988 10/639614 |
Document ID | / |
Family ID | 22495012 |
Filed Date | 2004-04-22 |
United States Patent
Application |
20040077988 |
Kind Code |
A1 |
Tweden, Katherine S. ; et
al. |
April 22, 2004 |
Healing transmyocardial implant
Abstract
A transmyocardial implant establishes a blood flow path through
a myocardium between a heart chamber and a lumen of a coronary
vessel residing on an exterior of the heart. The implant includes a
coronary portion sized to be received within the vessel. A
myocardial portion is sized to pass through the myocardium into the
heart chamber. A transition portion connects the coronary and
myocardial portions for directing blood flow from the myocardial
portion to the coronary portion. The coronary portion and the
myocardial portion have an open construction for permitting tissue
growth across a wall thickness of the coronary portion and the
myocardial portion. The myocardial portion includes an agent for
controlling a coagulation cascade and platelet formation.
Inventors: |
Tweden, Katherine S.;
(Mahtomedi, MN) ; Vanney, Guy P.; (Blaine,
MN) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER
LLP
1300 I STREET, NW
WASHINGTON
DC
20005
US
|
Assignee: |
HeartStent Corporation
Minneapolis
MN
|
Family ID: |
22495012 |
Appl. No.: |
10/639614 |
Filed: |
August 11, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10639614 |
Aug 11, 2003 |
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10095165 |
Mar 8, 2002 |
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10095165 |
Mar 8, 2002 |
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09141284 |
Aug 27, 1998 |
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6406488 |
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Current U.S.
Class: |
604/8 |
Current CPC
Class: |
A61F 2/07 20130101; A61F
2/958 20130101; A61F 2002/91558 20130101; A61F 2002/9155 20130101;
A61F 2250/0067 20130101; A61F 2002/91533 20130101; A61F 2/915
20130101; A61F 2230/0054 20130101; A61F 2/2493 20130101; A61F 2/94
20130101; A61B 17/04 20130101; A61B 2017/00252 20130101; A61F 2/06
20130101; A61F 2/064 20130101; A61F 2002/828 20130101; A61B 17/11
20130101; A61F 2/91 20130101; A61F 2220/0008 20130101 |
Class at
Publication: |
604/008 |
International
Class: |
A61F 002/06 |
Claims
What is claimed:
1. A transmyocardial implant for defining a blood flow pathway
directly from a left ventricle to a coronary vessel, the implant
comprising: a coronary portion sized to be received within the
vessel; a myocardial portion sized to pass through the myocardium
into the left ventricle; a transition portion connecting the
coronary and myocardial portion for directing blood flow from the
myocardial portion to the coronary portion; at least the coronary
portion and the myocardial portion having an open construction for
permitting tissue growth across a wall thickness of the coronary
portion and the myocardial portion; and at least the myocardial
portion including an agent for controlling a coagulation cascade
and platelet activation.
2. An implant according to claim 1 further comprising an agent for
encouraging healing.
3. An implant according to claim 1 further comprising a porous
lining in at least the myocardial portion with the porous lining
have pores smaller than openings of the open construction of the
myocardial portion.
4. An implant according to claim 1 wherein the porous lining
contains the agent.
5. An implant according to claim 1 wherein the agent is
heparin.
6. An implant according to claim 1 wherein the agent is an
anti-coagulant.
7. An implant according to claim 1 wherein the agent is an
anti-platelet.
8. An implant according to claim 2 wherein the agent for
encouraging healing is a growth factor.
9. An implant according to claim 1 wherein the coronary portion is
expandable from a first diameter to an enlarged second
diameter.
10. An implant according to claim 1 wherein the myocardial portion
is expandable from a first diameter to an enlarged second
diameter.
11. An implant according to claim 1 wherein the transition portion
permits articulation between the coronary portion and the
myocardial portion.
12. A transmyocardial implant for defining a blood flow pathway
directly from a left ventricle to a coronary vessel, the implant
comprising: a coronary portion sized to be received within the
vessel; a myocardial portion sized to pass through the myocardium
into the left ventricle; a transition portion connecting the
coronary and myocardial portion for directing blood flow from the
myocardial portion to the coronary portion; and the myocardial
portion including a construction to facilitate tissue integration
and including an agent for controlling a coagulation cascade and
platelet activation.
13. An implant according to claim 12 wherein the coronary portion
includes an open structure to facilitate growth of vascular
endothelial cells along the coronary portion.
14. An implant according to claim 12 wherein the myocardial portion
includes a porous structure for facilitating growth of vascular
endothelial cells into the myocardial portion.
15. An implant according to claim 14 wherein the porous structure
includes a fabric liner.
16. An implant according to claim 14 wherein the myocardial portion
further includes a wall structure for facilitating growth of
structural cells into the interior of the myocardial portion.
17. An implant according to claim 16 wherein the wall structure is
an open cell construction of the myocardial portion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention pertains to an implant for passing blood flow
directly between a chamber of the heart and a coronary vessel. More
particularly, this invention pertains to such an implant with an
enhance design for promoting a healed layer of cells on an interior
of the implant.
[0003] 2. Description of the Prior Art
[0004] Commonly assigned U.S. Pat. No. 5,755,682 issued May 26,
1998 and commonly assigned and co-pending U.S. patent application
Ser. No. 08/882,397 filed Jun. 25, 1997, entitled "Method and
Apparatus for Performing Coronary Bypass Surgery", and filed in the
name of inventors Mark B. Knudson and William L. Giese (published
as PCT International Application Publication No. WO 98/06356) both
teach an implant for defining a blood flow conduit directly from a
chamber of the heart to a lumen of a coronary vessel. In one
embodiment, an L-shaped implant is received within a lumen of a
coronary artery and passed through the myocardium to extend into
the left ventricle of the heart. The conduit is rigid and remains
open for blood flow to pass through the conduit during both systole
and diastole. The conduit penetrates into the left ventricle in
order to prevent tissue growth and occlusions over an opening of
the conduit. The '682 patent and '397 application also describe an
embodiment where a portion of the implant passing through the heart
wall is an open structural member lined by polyester (e.g.,
Dacron). A further embodiment discloses a portion of the implant in
a coronary vessel as being an open cell, balloon-expandable
stent.
[0005] U.S. Pat. No. 5,429,144 to Wilk dated Jul. 4, 1995 teaches
implants which are passed through the vasculature in a collapsed
state and expanded when placed in the myocardium so as not to
extend into either the coronary artery or the left ventricle. The
described implants close once per cycle of the heart (e.g., during
diastole in the embodiment of FIGS. 7A and 7B or during systole in
the embodiment of FIGS. 2A and 2B). Either of these two designs may
be lined with a graft.
[0006] Commonly assigned and co-pending U.S. patent application
Ser. No. 08/944,313 filed Oct. 6, 1997, entitled "Transmyocardial
Implant", and filed in the name of inventors Katherine S. Tweden,
Guy P. Vanney and Thomas L. Odland, teaches an implant such as that
shown in the aforementioned '397 application and '682 patent with
an enhanced fixation structure. The enhanced fixation structure
includes a fabric surrounding at least a portion of the conduit to
facilitate tissue growth on the exterior of the implant.
[0007] PCT International Application Publication No. WO 98/08456
describes a protrusive stent to form a passageway from the heart to
a coronary vessel. The stent is described as wire mesh or other
metal or polymeric material and may be self-expanding or pressure
expandable. The application describes the stent may be covered by a
partial or complete tubular covering of material including
polyester, woven polyester, polytetraflouroethylene, expanded
polytetraflouroethylene, polyurethane, silicone, polycarbonate,
autologous tissue and xenograft tissue.
[0008] Biocompatibility is an important design feature. Solid metal
implants are formed of material (e.g., titanium or pyrolytic
carbon) with low incidents of thrombus and platelet activation.
While such materials are proven in use in a wide variety of
products (e.g., heart valve components), they do not facilitate
full healing. By "healing", it is meant that over time, the
patient's cells grow over the material of the implant so that blood
flowing through the implant is exposed only (or at least primarily)
to the patient's cells rather than to a foreign material.
SUMMARY OF THE INVENTION
[0009] According to a preferred embodiment of the present
invention, a transmyocardial implant is disclosed for establishing
a blood flow path through a myocardium between a heart chamber and
a lumen of a coronary vessel residing on an exterior of the heart.
The implant includes a coronary portion sized to be received with
the vessel. A myocardial portion is sized to pass through the
myocardium into the heart chamber. A transition portion connects
the coronary and myocardial portions for directing blood flow from
the myocardial portion and into the coronary portion. The coronary
portion and the myocardial portion have an open construction for
permitting tissue growth across a wall thickness of the coronary
portion and the myocardial portion. The myocardial portion includes
an agent for controlling the coagulation cascade and platelet
activation, and promoting healing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side-elevation view of a transmyocardial implant
according to the present invention shown in place defining a blood
flow path from a left ventricle to a coronary artery;
[0011] FIG. 2 is a cross-sectional view of the implant of FIG.
1;
[0012] FIG. 3 is a view of an alternative embodiment of the implant
of FIG. 1 illustrating a portion of the implant expandable within a
coronary artery;
[0013] FIG. 4 is a view similar to FIG. 3 showing a transition
portion of open cell construction;
[0014] FIG. 5 is a side section view of an alternative embodiment
of FIG. 3 showing a balloon catheter admitted into the implant
through an access port; and
[0015] FIG. 6 is a side sectional view of an expandable implant
with a balloon catheter removable through a myocardial portion of
the catheter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] With initial reference to FIG. 1, a conduit 10 is shown in
the form of an L-shaped tube. The conduit 10 may be formed of
titanium or other biocompatible material. The material of the
conduit 10 is preferably radially rigid material in order to
withstand contraction forces of the myocardium. By way of
non-limiting example, the tube will have an outside diameter
D.sub.O of about 3 millimeters and an internal diameter D.sub.I of
about 2.5 millimeters to provide a wall thickness of about 0.25
millimeters.
[0017] The tube 10 has a coronary portion 12 sized to be received
within the lumen of a coronary vessel such as the lumen 80 of a
coronary artery 82 distal to an obstruction 81 as illustrated in
FIG. 1. The conduit 10 has a myocardial portion 14 extending at a
right angle to the axis of portion 12. The myocardial portion 14 is
sized to extend from the coronary artery 82 directly through the
myocardium 84 and protrude into the left ventricle 83 of a
patient's heart.
[0018] The coronary portion 12 has a first opening 16. The
myocardial portion 14 has a second opening 18 in communication with
an interior 20 of the implant 10. Therefore, blood can freely flow
through the implant 10 between the left ventricle 83 and the lumen
80 of the coronary artery 82. Blood flows axially out of opening 16
parallel with the axis of lumen 80.
[0019] The longitudinal axis of the coronary portion 12 is aligned
with the axis of the lumen 80. Sutures 24 secure the artery 82 to
the coronary portion 12. The proximal portion 82a of the coronary
artery is ligated by sutures 85.
[0020] The coronary and myocardial portions 12, 14 have an open
lattice construction 12a, 14a to define a plurality of open cells
12b, 14b extending through the wall thickness of the implant 10.
Preferably, the coronary and myocardial portions 12, 14 are joined
by a transition portion 13 in a 90.degree. bend between portions
12, 14. While transition portion 13 can have an open lattice
construction as portions 12, 14, transition portion 13 will
preferably have smaller open areas in such an open construction or,
as illustrated, will be of solid construction. Such construction
permits the transition portion to deflect high velocity blood flows
from the myocardial portion 14 into the coronary portion 12. A
lattice construction with large open cells in the transition
portion could result in the high velocity flow damaging tissue (not
shown) overlying the transition portion.
[0021] Any one or all of the coronary portion 12, transition
portion 13 and myocardial portion 14 could be formed in final size
as rigid units or could be formed in small diameter sizes which are
subsequently expanded to full size. For example, FIG. 3 illustrates
a coronary portion 12' which is formed tapering from the transition
portion 13' to a reduced diameter open end 16'. The taper permits
ease of insertion into a coronary artery. Following such insertion,
the tapered coronary portion 12' may be expanded to full size
illustrated by the phantom lines in FIG. 3. Such expansion can be
performed using balloon-tipped catheters as is conventional in
stent angioplasty. A collapsed and subsequently expanded implant 10
where all portions 12, 13 and 14 are expanded can permit use as a
percutaneously deployed implant. The present drawings illustrate a
presently preferred surgically deployed implant. In the surgical
application, the artery 82 is ligated. The implant 10 is passed
through the epicardium and myocardium on a side of the artery
82.
[0022] FIG. 5 illustrates a balloon 100 placed in a tapered
coronary portion 12. A lead 102 from the balloon 100 is passed
through an opening 113' in the transition portion 13'. The opening
113' can be closed with a plug 115' after the balloon 100 and lead
102 are withdrawn through the opening 113'.
[0023] Alternatively, in a transition portion 13" with open cell
construction (FIG. 4), the balloon lead can be passed through the
openings of the transition portion 113". FIG. 6 illustrates passing
the lead 102 through opening 18 of the myocardial portion. The lead
102 can be pulled upwardly from the exterior of the heart to remove
the balloon 100. Alternatively, the lead 102 can be pulled through
a catheter (not shown) adjacent end 18 in the left ventricle.
[0024] In either percutaneous or surgical implants, a flexible
transition portion 13 (as would be achieved with a stent lattice
construction) permits relative articulation between the coronary
and myocardial portions 12, 14 to ensure the coronary portion is
axially aligned with the lumen 80. Absent such articulation, such
axial alignment is achieved by accurately controlling the position
of the myocardial portion 14 such that the coronary portion 12 is
axially aligned with the lumen 80 following implantation.
[0025] The open cell construction of the coronary and myocardial
portions 12, 14 permit tissue growth through the open cells 12c,
14c following implant. The healing procedure in the coronary
portion 12 is the same as that in coronary stents. Vascular
endothelial cells grow over to coat the structural material 12a of
portion 12.
[0026] In portion 14, myocardial tissue, if not obstructed, will
grow through the cells 14c. Furthermore, the myocardium is highly
thrombogenic. Therefore, uncontrolled contact between the
myocardium 82 and the implant interior 20 can result in thrombosis
of the implant 10. Further, it is believed that the epicardium
(i.e., outer layer of the myocardium) has a greater density of
myocardial growth cells which contribute to healing.
[0027] To control growth in the myocardial portion 14, a liner 30
is provided in the myocardial portion 14. The liner 30 is any
porous material for accepting tissue growth and, preferably, is a
polyester fabric (e.g., Dacron). The porous liner 30 has interstial
spaces smaller than the open cells 12c, 14c. The liner 30 is shown
on an interior of the myocardial portion 14 but could also or
alternatively surround the exterior.
[0028] The liner 30 has an upper end 32 secured through any
suitable means (e.g., sutures not shown) to the upper end of the
myocardial portion 14. A lower end 34 is folded over the opening of
the myocardial portion 14 and secured to the exterior of the
portion 14 by sutures 36. The myocardial portion 14 is sized to
protrude into the left ventricle 83 with only the folded over liner
material exposed to the interior of the left ventricle 83.
[0029] The liner 30 acts as a porous substrate into which tissue
may grow. To prevent thrombus, the liner 30 is impregnated with an
agent for controlling coagulation cascade and platelet activation
and adhesion. An example of such an agent is heparin but could be
any anticoagulant or antiplatelet. Also, an agent such as a basic
fibroblast growth factor could be used to accelerate healing.
[0030] The agent permits structural cells to grow on the liner by
limiting thrombus formation which, uncontrolled, would occlude the
implant. Due to the open construction, the structural, healing
cells of the epicardium can grow onto the liner. Subsequently,
endothelial cells can grow on the structural cells.
[0031] Therefore, the structure described promotes a three-stage
healing process:
[0032] 1. the drug agents control healing by minimizing coagulation
and platelet activation which would otherwise be stimulated by
agents from the myocardium; and
[0033] 2. structural cells grow into and on the liner 30 now lined
with the thrombus to initially heal and form a vascular bed;
and
[0034] 3. endothelial cells grow over the structural cells.
[0035] In the transition portion 13, an open cells structure will
permit tissue growth as in the coronary portion 12. Such growth may
also occur in the solid construction. Alternatively, the liner 30
can be extended into the transition portion 13. Additionally, the
open cell structure in the transition portion 13 can permit
articulation between the coronary portion and the myocardial
portion. Such a structure is shown in FIG. 4. The open transition
portion 13" is formed by a coil 13a" between the coronary portion
12" and the myocardial portion 14". This structure permits bending
at the transition portion. As a result, the coronary portion can be
axially aligned in the artery without first accurately positioning
the myocardial portion.
[0036] Having disclosed the present invention in a preferred
embodiment, it will be appreciated that modifications and
equivalents may occur to one of ordinary skill in the art having
the benefits of the teachings of the present invention. It is
intended that such modifications shall be included within the scope
of the claims appended hereto. For example, the liner 30 can take
many constructions including PTFE, expanded-PTFE, polyurethane,
polypropylene or any biologically compatible paving material or
natural tissue. Further, restenosis of the coronary portion 12 can
be prevented with radioactivity therapy (such as providing the
coronary portion with a short half-life beta emitter). Also, the
liner 30 may be either a resorbable or non-resorbable material.
Genetically engineered cells can be transformed to secrete
anticoagulants and other agents to keep the blood fluid (such as
tissue plasminogen activator and smooth muscle cells altered to
express nitric acid).
* * * * *