U.S. patent application number 10/951735 was filed with the patent office on 2005-03-17 for implant and agent delivery device.
This patent application is currently assigned to C. R. Bard, Inc.. Invention is credited to Forcucci, Stephen J., Forde, Sean, Gambale, Richard A., Weiser, Michael F..
Application Number | 20050060019 10/951735 |
Document ID | / |
Family ID | 34119620 |
Filed Date | 2005-03-17 |
United States Patent
Application |
20050060019 |
Kind Code |
A1 |
Gambale, Richard A. ; et
al. |
March 17, 2005 |
Implant and agent delivery device
Abstract
The present invention provides a system (178) for delivering a
therapeutic agent in combination with an implantable device (2) to
maximize a therapeutic benefit offered by each. Preferably, the
therapeutic agent is contained within a solid matrix form such as a
pellet or gel to facilitate its handling and to regulate its rate
of dissipation into the tissue after delivery. The implant device
(2) is specially configured to receive and retain the matrix but
permit blood to interact with the matrix so that the agent can be
released to the blood in and around the device and the surrounding
tissue. A delivery system (178) comprises an implant delivery
device having an obturator (180) capable of piercing the tissue and
an agent matrix delivery device (210) to place a matrix form, such
as a pellet, into the interior of the implant (2) after it has been
implanted. Preferably, the implant delivery device (180) and the
matrix delivery device (210) are contained in one apparatus to
facilitate delivery of the pellet into the embedded implant. The
present invention is useful for treating tissue in any area of the
body, especially ischemic tissue experiencing reduced blood flow.
The present devices and methods are especially useful for treatment
of ischemia of the myocardium. In treatment of the myocardium, the
present implant device and matrix combination may be delivered
surgically through the epicardium of the heart.
Inventors: |
Gambale, Richard A.;
(Tyngsboro, MA) ; Forcucci, Stephen J.; (Medford,
MA) ; Weiser, Michael F.; (Groton, MA) ;
Forde, Sean; (Watertown, MA) |
Correspondence
Address: |
KIRKPATRICK & LOCKHART LLP
75 STATE STREET
BOSTON
MA
02109-1808
US
|
Assignee: |
C. R. Bard, Inc.
Murray Hill
NJ
|
Family ID: |
34119620 |
Appl. No.: |
10/951735 |
Filed: |
September 28, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10951735 |
Sep 28, 2004 |
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10048694 |
Jun 10, 2002 |
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10048694 |
Jun 10, 2002 |
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PCT/US00/21215 |
Aug 3, 2000 |
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60147094 |
Aug 4, 1999 |
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60148475 |
Aug 12, 1999 |
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Current U.S.
Class: |
623/1.11 ;
424/422; 623/1.42 |
Current CPC
Class: |
A61F 2/06 20130101; A61F
2/2493 20130101; A61F 2220/0016 20130101; A61F 2/88 20130101; A61F
2250/0067 20130101 |
Class at
Publication: |
623/001.11 ;
424/422; 623/001.42 |
International
Class: |
A61F 002/06 |
Claims
1. A tissue implant comprising: a porous body having an interior
and proximal and distal ends; wherein the proximal end of the
implant is adapted to permit insertion of an agent carrying matrix
into the interior of the implant after the implant has been placed
in host tissue.
2. An implant as defined in claim 1 wherein the implant comprises a
spring coil.
3. An implant as defined in claim 2 wherein the coil is
substantially a constant diameter throughout its length.
4. An implant as defined in claim 2 wherein the coil is tapered,
reducing in diameter from its proximal end to its distal end.
5. An implant as defined in claim 2 further comprising: a central
region lying between the proximal and distal ends of the implant
wherein coils that define the proximal and distal ends are of a
smaller diameter than the coils of the central region.
6. An implant as defined in claim 5 wherein the coils that define
the proximal region may be expanded temporarily to permit insertion
of an agent carrying matrix into the interior of the implant, then
released to return to a smaller diameter to retain the matrix
within the interior of the implant.
7. An implant as defined in claim 5 wherein the proximal coils are
compressed to a smaller diameter configuration after delivery of an
agent substance carrying matrix into the interior of the implant
through the proximal coils.
8. An implant as defined in claim 1 further comprising a
therapeutic substance carrying matrix residing in the interior of
the implant.
9. An implant as defined in claim 8 wherein the matrix is a solid
form.
10. An implant as defined in claim 8 wherein the matrix is a
pellet.
11. An implant as defined in claim 9 wherein the matrix is a
gel.
12. An implant as defined in claim 10 wherein the pellet is
substantially cylindrically shaped.
13. An implant as defined in claim 10 wherein the pellet is
substantially cone shaped to facilitate entry into and frictional
engagement with the interior of the implant.
14-18. (Canceled)
19. A method of treating tissue comprising: delivering a tissue
implant defining an interior into tissue; inserting into the
interior of the tissue implant a matrix carrying a therapeutic
agent; securing the matrix in the interior of the implant so that
the therapeutic agent is permitted to be released to surrounding
tissue.
20. A method of delivering an implant and agent carrying matrix
into tissue comprising: providing a tissue implant device defining
an interior, an agent carrying matrix and a combination implant and
agent matrix delivery device having proximal and distal ends and an
interior; loading the delivery device with a tissue implant and
agent matrix; positioning the delivery device adjacent tissue to be
treated; delivering the tissue implant device into tissue while
maintaining communication of the interior of the implant with the
interior of the delivery device; delivering the agent matrix into
the interior of the implant from the interior of the delivery
device; withdrawing the delivery device and leaving the implant and
matrix in the tissue.
21. A method of delivering an implant and agent matrix as defined
in claim 20 wherein the implant is secured after delivery of the
agent matrix to prevent the matrix from leaving the interior of the
implant while permitting the agent to be released into surrounding
tissue.
22. A method of delivering an implant and agent matrix into tissue
as defined in claim 20 wherein the implant is carried external to
the delivery device and the matrix is carried internal to the
delivery device during delivery.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to delivery of a therapeutic
agent into tissue in combination with an implant device.
Specifically, the agent is contained in a matrix form capturable
within the implant device to provide the therapeutic advantages
provided by both in a single treatment.
BACKGROUND OF THE INVENTION
[0002] Tissue becomes ischemic when it is deprived of adequate
blood flow. Ischemia causes pain in the area of the affected tissue
and, in the case of muscle tissue, can interrupt muscular function.
Left untreated, ischemic tissue can become infarcted and
permanently non-functioning. Ischemia can be caused by a blockage
in the vascular system that prohibits oxygenated blood from
reaching the affected tissue area. However, ischemic tissue can be
revived to function normally despite the deprivation of oxygenated
blood because ischemic tissue can remain in a hibernating state,
preserving its viability for some time. Restoring blood flow to the
ischemic region serves to revive the ischemic tissue. Although
ischemia can occur in various regions of the body, often myocardial
tissue of the heart is affected by ischemia. Frequently, the
myocardium is deprived of oxygenated blood flow due to coronary
artery disease and occlusion of the coronary artery, which normally
provides blood to the myocardium. The ischemic tissue causes pain
to the individual affected.
[0003] Treatment of myocardial ischemia has been addressed by
several techniques designed to restore blood supply to the affected
region. A conventional approach to treatment of ischemia has been
to administer anticoagulants with the objective of increasing blood
flow by preventing formation of thrombus in the ischemic
region.
[0004] Another conventional method of increasing blood flow to
ischemic tissue of the myocardium is coronary artery bypass
grafting (CABG). One type of CABG involves grafting a venous
segment between the aorta and the coronary artery to bypass the
occluded portion of the artery. Once blood flow is redirected to
the portion of the coronary artery beyond the occlusion, the supply
of oxygenated blood is restored to the area of ischemic tissue.
[0005] Early researchers, more than thirty years ago, reported
promising results for revascularizing the myocardium by piercing
the muscle to create multiple channels for blood flow. Sen, P. K.
et al., "Transmyocardial Acupuncture--A New Approach to Myocardial
Revascularization", Journal of Thoracic and Cardiovascular Surgery,
Vol. 50, No. 2, August 1965, pp. 181-189. Although researchers have
reported varying degrees of success with various methods of
piercing the myocardium to restore blood flow to the muscle (which
has become known generally as transmyocardial revascularization or
TMR), many have faced common problems such as closure of the
created channels. Various techniques of perforating the muscle
tissue to avoid closure have been reported by researchers. These
techniques include piercing with a solid sharp tip wire, or coring
with a hypodermic tube. Reportedly, many of these methods produced
trauma and tearing of the tissue that ultimately led to closure of
the channel.
[0006] An alternative method of creating channels that potentially
avoids the problem of closure involves the use of laser technology.
Researchers have reported success in maintaining patent channels in
the myocardium by forming the channels with the heat energy of a
laser. Mirhoseini, M. et al., "Revascularization of the Heart by
Laser", Journal of Microsurgery, Vol. 2, No. 4, June 1981, pp.
253-260. The laser was said to form channels in the tissue that
were clean and made without tearing and trauma, suggesting that
scarring does not occur and the channels are less likely to
experience the closure that results from healing. U.S. Pat. No.
5,769,843 (Abela et al.) discloses creating laser-made TMR channels
utilizing a catheter based system. Abela also discloses a magnetic
navigation system to guide the catheter to the desired position
within the heart. Aita patents U.S. Pat. Nos. 5,380,316 and
5,389,096 disclose another approach to a catheter based system for
TMR.
[0007] Although there has been some published recognition of the
desirability of performing TMR in a non-laser catheterization
procedure, there does not appear to be evidence that such
procedures have been put into practice. U.S. Pat. No. 5,429,144
(Wilk) discloses inserting an expandable implant within a preformed
channel created within the myocardium for the purposes of creating
blood flow into the tissue from the left ventricle.
[0008] Performing TMR by placing stents in the myocardium also is
disclosed in U.S. Pat. No. 5,810,836 (Hussein et al.). The Hussein
patent discloses several stent embodiments that are delivered
through the epicardium of the heart, into the myocardium and
positioned to be open to the left ventricle. The stents are
intended to maintain an open channel in the myocardium through
which blood enters from the ventricle and perfuses into the
myocardium.
[0009] Angiogenesis, the growth of new blood vessels in tissue, has
been the subject of increased study in recent years. Such blood
vessel growth to provide new supplies of oxygenated blood to a
region of tissue has the potential to remedy a variety of tissue
and muscular ailments, particularly ischemia. Primarily, study has
focused on perfecting angiogenic factors such as human growth
factors produced from genetic engineering techniques. It has been
reported that injection of such a growth factor into myocardial
tissue initiates angiogenesis at that site, which is exhibited by a
new dense capillary network within the tissue. Schumacher et al.,
"Induction of Neo-Angiogenesis in Ischemic Myocardium by Human
Growth Factors", Circulation, 1998; 97:645-650.
SUMMARY OF THE INVENTION
[0010] The present invention provides a system for delivering a
therapeutic agent in combination with an implantable device to
maximize a therapeutic benefit offered by each. Preferably, the
therapeutic agent is contained within a solid matrix form such as a
pellet or gel to facilitate its handling and to regulate its rate
of dissipation into the tissue after delivery. The implant device
is specially configured to receive and retain the pellet but permit
blood to interact with the pellet so that the agent can be released
to the blood in and around the device and the surrounding tissue. A
delivery system comprises an implant delivery device having an
obturator capable of piercing the tissue and an agent matrix
delivery device to place a matrix form, such as a pellet, into the
interior of the implant after it has been implanted. Preferably,
the implant delivery device and the pellet delivery device are
contained in one apparatus to facilitate delivery of the pellet
into the embedded implant.
[0011] The present invention is useful for treating tissue in any
area of the body, especially ischemic tissue experiencing reduced
blood flow. The present devices and methods are especially useful
for treatment of ischemia of the myocardium. In treatment of the
myocardium, the present implant device and pellet combination may
be delivered surgically through the epicardium of the heart.
[0012] With specific agents and a particular configuration of the
implant device, revascularization by angiogenesis and vessel
recruitment can be encouraged in the ischemic tissue by use of the
present invention. A wide range of therapeutic agents conducive to
revascularization can be introduced via the matrix pellet
including: growth factors; gene therapies or other natural or
engineered substances that can be formed or added to the pellet.
The pellet formation is well known in the medical field and
typically comprises an inert powder pressed together to form a
tablet or pill-like article.
[0013] The implant device also provides therapeutic benefit to the
subject tissue in several ways. First the structure of the implant
device provides an interior cavity within the tissue which permits
blood to pool, mix with the agents of the matrix and coagulate. The
coagulation occurs in and around the device as part of the
coagulation cascade, that will eventually lead to new vessel
formation and recruitment. Furthermore, the presence of a device in
the moving tissue of a muscle such as the myocardium, creates an
irritation or injury to the surrounding tissue which further
promotes an injury response and the coagulation cascade that leads
to new vessel growth. Additionally the implant causes a foreign
body response, which causes inflammation attracting macrophages,
which cause secretion of growth factors. Suitable implant devices
should be flexible, define an interior, be anchorable within tissue
and permit fluid such as blood to transfer between the surrounding
tissue and the interior of the device. Examples of tissue implant
devices are disclosed in pending U.S. patent application Ser. Nos.
09/164,163, 09/164,173, 09/211,332 and 09/299,795, all of which are
herein incorporated by reference. Delivery of therapeutic agents in
a pellet form are discussed in pending U.S. application Ser. Nos.
08/993,586 and 09/116,313 and 09/159,834, all of which are herein
incorporated by reference.
[0014] It is an object of the present invention to provide an agent
delivery system that permits the delivery of an agent in
combination with an implant device into tissue.
[0015] It is another object of the present invention to provide an
implant device configured to retain an agent matrix form, such as a
pellet, containing a therapeutic substance while it is implanted in
tissue.
[0016] It is another object of the invention to provide a delivery
method for sequentially delivering the implant device and a matrix
containing a therapeutic substance that is relatively simple and
effective.
[0017] It is another object of the present invention to provide a
method for delivering an implant device and matrix containing a
therapeutic agent that utilizes a simplified delivery device.
[0018] It is yet another object of the present invention to provide
a dual step delivery system contained in one apparatus and
associated method for sequentially delivering an implant then an
agent suspending matrix form into the interior of the implant
device placed in the tissue.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The foregoing and other objects and advantages of the
invention will be appreciated more fully from the following further
description thereof, with reference to the accompanying
diagrammatic drawings wherein:
[0020] FIG. 1. is a side view of an implant device configured to
accept a matrix;
[0021] FIG. 2. is a side view of an implant device containing a
matrix;
[0022] FIG. 3 is a side view of an alternate embodiment of the
tissue implant device;
[0023] FIG. 4 is a partial sectional view of the tissue implant
device shown in FIG. 3;
[0024] FIG. 5A. is a partial sectional side view of an implant
delivery device delivering an implant device;
[0025] FIG. 5B. is a partial sectional side view of the implant
delivery device shown in FIG. 5A, delivering an agent carrying
matrix into the implanted device;
[0026] FIG. 5C. is a detail of the distal tip of an implant
delivery device shown in FIG. 5B delivering an agent matrix into an
implant.
DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
[0027] FIG. 1 shows a side view of an implant device 2 of the
present invention. In a preferred embodiment the implant device 2
comprises a flexible helical coil having a plurality of individual
coils 4 that define an interior 6. The device preferably has a
distal region 8 and proximal region 10. The coils at the distal
region 8 define a diameter that is smaller than that defined by the
coils of proximal region 10. However, an agent carrying matrix,
such as a pellet, may be inserted through proximal opening 12 into
the proximal region 10 of the implant. The coils 4 of the distal
region 8 are sized smaller than the pellet so that the pellet
cannot slip out of the implant through the distal region. In the
present application, proximal is understood to mean the direction
leading external to the patient and distal is understood to mean a
direction leading internally to the patient.
[0028] It should be noted that the agent carrying matrix may, but
need not be a pellet form. A pellet may comprise a pill or tablet
like article formed from inert substances compressed together; the
substances are normally absorbable in the body. The pellet may be
formed with a radiopaque seed to provide radiographic visibility of
the implant location. In a preferred embodiment the pellet may have
a generally cylindrical shape having a diameter on the order of
0.060 inch and a thickness of 0.028 inch.
[0029] FIG. 2 shows the implant device 2 implanted in tissue 3 and
having captured with its interior 6 an agent carrying matrix 14,
such as a pellet. The implant device maintains a cavity 18 within
the tissue defined by the interior 6 of the device where the matrix
may reside and blood may pool and mix with agents contained in the
matrix 14. After the device is implanted in tissue, by steps which
will be described in detail below, a tail 16 joined to the proximal
end 22 of the device 2 serves to prevent the device from migrating
out of the tissue. The tail may comprise a variety of
configurations but should extend to have a profile that is greater
than the diameter of the coils along the body 24 of the device. The
tail projects into the tissue and is submerged beneath the surface
26 of the tissue 3 to prevent axial migration as well as rotation
of the device, which could permit the device to move from the
tissue location.
[0030] In one implant embodiment shown in FIG. 2, the pellet may be
maintained in position within the interior 6 of the device 2 by
reducing the diameter of the coils 4 of the proximal portion 10 of
the device after the matrix 14 has been inserted. As mentioned
above, the coils of the distal portion 8 are pre-formed to have a
diameter that is smaller than the lateral extent of the pellet to
prevent distal migration out of the device. The proximal portion
coils 10 may be reduced in diameter by crimping by sterilized
forceps after the implant device and matrix are delivered to the
tissue. The reduced diameter coils of the proximal portion 10 and a
distal portion 8 of the device leave a capturing portion 28 at the
center of the device where the matrix will reside. The matrix may
move slightly within this capturing portion 28 but will not migrate
from either the proximal end 12 or distal end 13 of the device.
[0031] Preferably, the matrix is restrained in the implant by a
close or a friction fit between the pellet and the inside diameter
of the coils 4. So configured, there would be no clearance around
an installed matrix and the implant device coils. The friction fit
permits the matrix to be delivered into the device and retained
without crimping the proximal coils behind the matrix to retain it,
thereby eliminating an additional step after delivery. In this
case, the implant device may be configured to have coils of
approximately constant diameter. When a matrix, such as a pellet,
is configured to have zero clearance with the inside diameter of
the device, the pellet may be shaped to have a smaller profile
distal end (leading edge) to be more easily insertable into the
narrow opening of the device. An example of such a shape would be a
cone shape pellet (not shown).
[0032] In treating the myocardium of the heart a preferred device
length is on the order of approximately 7 mm-8 mm. The device may
be made from any implantable material such as surgical grades of
stainless steel or a nickel titanium alloy. The filament of
material from which the coils are formed may have any
cross-sectional shape. A round filament may have a diameter on the
order of 0.006 inch to 0.010 inch.
[0033] Alternatively, the implant may be formed from a filament
having a rectangular cross-sectional shape. FIG. 3 shows an
embodiment of a tubular implant device 40 formed from a filament 42
of rectangular cross-section such as a strand of flat wire. As
shown in FIG. 4, the coil is formed so that the major
cross-sectional axis 47 of the rectangular wire is oriented at an
acute angle to the longitudinal axis 50 of the coil 40. The
orientation gives each turn 46 of the coil a projecting edge 44,
which tends to claw into tissue to serve as an anchoring mechanism
for the device. The implant device may have coils of substantially
the same diameter sized to closely surround a matrix inserted into
the implant interior. At least the most distal coil 54 should be
wound to a smaller diameter that will frictionally engage the
surface of the obturator delivery device as is discussed in detail
below.
[0034] In addition to being retained by surrounding coils of the
device, the matrix is supported in position within the device and
within the capturing portion 28 by herniation points 20 of the
surrounding tissue 3, as shown in FIG. 2. After insertion of the
device, surrounding tissue attempts to resume its previous
position, collapsing around the individual coils 4 of the device
and tending to herniate at points 20 through the spaces between the
coils 4. The herniation points extending into the interior 6 of the
device 2 engage the matrix 14 to help maintain it is position so
that it does not migrate through either end or through the spaces
between the coils 4.
[0035] With implants of the first embodiment in which the proximal
coils are crimped after pellet delivery, it has proven desirable to
have approximately 0.002 inch of clearance between the matrix and
the inside diameter of the coils 4 in the larger coiled proximal
region 10 (as well as the captured portion 28--after the proximal
coils 10 have been crimped). Therefore, the preferable inside
diameter of the coils 4 through a proximal region 10 is on the
order of 0.065 inch. It has also been found desirable to have the
restraining coils of small diameter, such as those at the distal
portion 8, to be approximately 0.002 inch smaller in inside
diameter than the diameter of the matrix. Therefore, the preferable
inside diameter for distal coils 8 is approximately 0.055 to 0.056
inch. Likewise, it is preferable to have spacing between adjacent
coils 4 of the implant device 2 to be no more than approximately
0.026 inch so that the matrix does not migrate through the space
between the coils. In preferred implant embodiments having coils of
constant diameter, the coils may define an inside diameter of
approximately 0.061-0.062 inch to closely surround a pellet of
0.060 inch diameter.
[0036] The implant devices 2 and 40 of the present invention are
preferably delivered to their intended tissue location surgically.
FIGS. 5A-5C show an example of a surgical delivery device 178 that
may be used to deliver the implants into tissue such as that of the
myocardium of the heart. The delivery device 178, shown in FIG. 5A,
is, generally, a hollow rigid tubular structure formable or
machined from a polymer that comprises an obturator 180 for
delivering the implant and a matrix delivery tube 210 for
delivering the agent matrix 14. Both are independently advanceable
and retractable through the interior 174 of the device 178 to a
distal port 172. The distal end 181 of the device 178 is shown in
detail in FIG. 5C.
[0037] The obturator includes a spring loaded main shaft 182, by
which it can be gripped and manipulated by a threaded knob 183. The
obturator 180 also includes a reduced diameter device support
section 184 having a sharp distal tip 186 adapted to pierce tissue.
The diameter of the shaft segment 184 is selected to fit closely
within the interior 6 of the devices 2 and 40. Preferably, the
obturator is configured so that the device is held onto the
obturator only by a close frictional fit. The reduced diameter
distal coil of an implant frictionally engages the support section
184. The proximal end of the segment 184 may terminate in a
shoulder (not shown) formed at the junction of a proximally
adjacent, slightly enlarged diameter portion 190 of the shaft. When
the implant device 2 is mounted on the obturator 180, the proximal
end of the device may bear against the shoulder. Alternatively, the
distal end of the device support segment 184 may include a radially
projecting pin (not shown) dimensioned to project and fit between
adjacent turns of the coils 4. The pin engages the coils in a
thread-like fashion so that after the assembly has been inserted
into the tissue, the obturator 180 can be removed simply by
unscrewing the obturator to free it from the implanted coil.
Alternatively, the tip of the distal most coil of the implant may
be deformed to project radially inward so as to catch a small
receiving hole formed in the distal end of the support segment
184.
[0038] The matrix delivery tube 210 has slidable within its
interior lumen 214 a push rod 216. The push rod is slidably
controllable by slide 220, slidably mounted to the exterior of the
body 200 of the device 178. A matrix pellet is sized to be retained
in the lumen 214 of the delivery tube by the resilient force of the
radially flexible tube against the matrix. The restraining force of
the tube on the pellet can be easily over come by advancement of
the pushrod through the delivery tube 210. Advancement of slide 220
serves to move both the delivery tube 210 and pushrod 216 together
in unison in the distal direction through the interior 174 until
distal end 234 bottoms out against distal stop 236, an annular
ridge encircling the exit port 172 of the device. After the distal
end bottoms against the stop, distal movement of the delivery tube
stops, but pushrod 216 keeps advancing distally to push matrix
pellet 14 through the tube, out of the exit port 172 and into the
interior 6 of the implanted device 2. Conical surface 238 captures
the distal end 234 of the delivery tube and ensures alignment with
the exit port 172.
[0039] Retraction spring 240 surrounds pushrod 216 and is
restrained between proximal end 244 of delivery tube 210 and slide
220. The spring, therefore, causes delivery tube to advance
distally with movement of slide and pushrod and compresses when
delivery tube bottoms out and pushrod is advanced further.
Advancement of the pushrod relative to the delivery tube serves to
eject the matrix from the tube. After the matrix pellet 14 is
pushed out of delivery tube, as shown in FIG. 5C, the slide may be
released to permit pushrod to return to its retraced position.
Delivery tube may be returned to its proximal position by proximal
movement of the slide.
[0040] Prior to delivery of an implant and matrix, the obturator
180 is advanced distally to a delivery position, as shown in FIG.
5A, by screwing knob 183 so that knob threads 188 engage threaded
sleeve 190. The delivery position of the obturator is reached after
the threads of the knob have been advanced entirely through the
threaded sleeve. In the delivery position, the support segment 184
of the obturator is advanced past the distal end 181 of the
delivery device. In this configuration implant devices 2 or 40 may
be manually loaded onto the support segment 184. Once mounted, the
implant and underlying support segment 184 remain distal to the
distal end 181 of the delivery device until the implant is placed
in tissue and released
[0041] In use, the intended tissue location is first accessed
surgically, such as by a cut-down method. In the delivery position
of the delivery device, the implant may be delivered into tissue by
manually advancing the delivery device to the tissue location. With
application of a delivery force, the sharp tip 176 of the obturator
pierces the tissue permitting the obturator and implant to be
pushed inward into the tissue until the distal end 181 of the
device contacts the tissue indicating that the support segment 184
and implant have been fully inserted into the tissue. The
advancement of the obturator and implant into the tissue may be
aided by rotating the screw knob while applying the delivery force.
The rotation may serve to provide a screwing action between the
mounted implant and tissue being penetrated that will facilitate
insertion. Retractable projecting barbs or vacuum suction may be
added to the distal end of the delivery device to help maintain
position of the distal end of the device on the tissue 26 during
the matrix pellet delivery step that follows.
[0042] After the implant is placed in the tissue the obturator is
disengaged by unscrewing the knob 183. Retraction spring 192
positioned around obturator shaft 182 so as to be biased between
the inside surface 194 of knob 183 and proximal end 196 of body 200
is compressed while the obturator is advanced to the delivery
position and thus serves to bias the obturator proximally so that
threads 188 remain at the edge of engagement with threaded sleeve
190. Rotation of the knob 194 in the counter-clockwise direction
causes the threads 188 to immediately engage the threaded sleeve,
permitting the assembly to be unscrewed, which causes obturator to
be rotated and moved proximally. Rotation and proximal withdrawal
of the obturator also causes the implant to be released from
frictional engagement with the support region 184 of the obturator.
The implant remains in the tissue as the obturator is with drawn.
Release of the threads 188 from threaded sleeve 190 permits spring
to expand to quickly force the obturator shaft fully proximally to
complete disengagement from the implant. The delivery tube then may
be advanced to deliver the matrix. After the obturator is
withdrawn, distal pressure is maintained on the body of the
delivery device to ensure that the tapered portion 193 of the
distal end 181 remains in the proximal end 12 of the implant to
provide a pathway for the matrix delivery.
[0043] The delivery tube, preloaded with a matrix pellet may then
be advanced distally by movement of the slide 220 as described
above. During discharge of the matrix 14, the distal end of the
device 181 should remain in position on the epicardial tissue
surface 26 over the implant 2 to ensure tapered portion 193 remains
in engagement with the implant 2, which ensures alignment of the
exit port 172 with the interior 6 of the device 2, 40. After the
matrix pellet is advanced into the interior of the implant, the
slide is moved proximally, aided by the retraction spring to
withdraw the pushrod and delivery tube. The delivery device may
then be with drawn from the site.
[0044] From the foregoing it should be appreciated that the
invention provides an agent delivery system for delivering an agent
carrying pellet and implant device in combination. The invention is
particularly advantageous in promoting angiogenesis within an
ischemic tissue such as myocardial tissue of the heart. The
delivery system is simple to use and requires a minimum of steps to
practice.
[0045] It should be understood, however, that the foregoing
description of the invention is intended merely to be illustrative
thereof and that other modifications, embodiments and equivalents
may be apparent to those skilled in the art without departing from
its spirit.
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