U.S. patent application number 09/883658 was filed with the patent office on 2001-11-01 for implant delivery system.
Invention is credited to Ahern, John E., Gambale, Richard A., Parascandola, Michael.
Application Number | 20010037117 09/883658 |
Document ID | / |
Family ID | 22592001 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010037117 |
Kind Code |
A1 |
Gambale, Richard A. ; et
al. |
November 1, 2001 |
Implant delivery system
Abstract
The present invention provides an implant delivery system for
placing interior defining implants in the human body. The devices
comprise elongate shafts and a mechanism at the distal end of the
shaft for engaging and retaining the implant in place on the shaft
during delivery through the vessels and insertion of the distal end
of the shaft into tissue. Some embodiments of the devices are
configured to have a plurality of implants and configured to
deliver the implants sequentially to a plurality of locations. One
embodiment employs a flexible outer tube at its distal end that
compresses and crinkles to a larger diameter upon being compressed
lengthwise to engage the inside surface of the implant. Another
embodiment utilizes a tubular delivery shaft having a circular
cross section with segments of oval shaped cross sections which
serve to engage the inside of implant located on the shaft. A cam
slidable within the shaft engages the oval areas, deforming them to
a circular shape which permits the implants to be released. Another
embodiment provides delivery force by pressurizing fluid filling
the shaft lumen to move a plunger at the distal end of the shaft
which carries the implant to be delivered. A feature of the
invention provides for monitoring of the depth to which an implant
is delivered within tissue by monitoring pressure changes
experienced near the distal tip of the shaft. Another feature of
the delivery devices provides for drug delivery at the implant site
by compressing a drug filled bladder by the expansion of an
adjoining bladder. Also disclosed is the use of an electromagnetic
guidance system to accurately navigate the delivery devices to the
implant delivery sites.
Inventors: |
Gambale, Richard A.;
(Tyngsboro, MA) ; Ahern, John E.; (Melrose,
MA) ; Parascandola, Michael; (Londonderry,
NH) |
Correspondence
Address: |
John F. Perullo
Kirkpatrick & Lockhart LLP
75 State Street
Boston
MA
02109-1808
US
|
Family ID: |
22592001 |
Appl. No.: |
09/883658 |
Filed: |
June 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09883658 |
Jun 18, 2001 |
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09163884 |
Sep 30, 1998 |
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6248112 |
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Current U.S.
Class: |
606/108 |
Current CPC
Class: |
A61B 2017/00247
20130101; A61B 2090/062 20160201; A61F 2/2493 20130101; A61B
2018/00392 20130101; A61M 25/06 20130101; A61F 2/95 20130101; A61F
2/88 20130101; A61B 17/3478 20130101; A61B 34/20 20160201; A61B
2090/064 20160201; A61B 17/3468 20130101; A61B 2034/2051 20160201;
A61B 2017/00243 20130101 |
Class at
Publication: |
606/108 |
International
Class: |
A61F 002/06 |
Claims
1. A delivery device for a hollow implant comprising: an elongate
shaft having proximal and distal ends and a lumen at least one
deformable surface adjacent to the distal end that can be deformed
to contact an inside surface of an implant and reformed to release
the implant.
2. An implant delivery device as defined in claim 1 wherein the
deformable surface is common with the shaft.
3. An implant delivery device as defined in claim 3 wherein the
deformable surface is a section of the shaft having an oval cross
sectional shape that is deformable to have a circular
cross-sectional shape.
4. An implant delivery device as defined in claim 3 further
comprising: a cam slidable within the lumen of the shaft that is
selectively engageable with the oval sections to deform them to a
round cross-sectional shape.
5. A method of implanting an implant device in the human body
comprising: providing a shaft generally circular in cross-sectional
shape, having a lumen and proximal distal ends and at least one
segment having an oval cross-sectional shape; placing a tubular
implant over the shaft such that the inside diameter of the tube
becomes caught on the oval section of the shaft; navigating the
shaft and associated implant tube to the intended delivery site
within a patient; deforming the oval segment to circular
cross-sectional shape to permit the tubular implant to slide over
the segment and off the shaft.
6. An implant delivery device as defined in claim 1 further
comprising: a collapsible sleeve having a proximal end and a distal
end and being mounted around the distal end of the shaft defining
the deformable surface.
7. An implant delivery device as defined in claim 6 further
comprising: a push tube mounted over the shaft and slidable
relative to the shaft and joined to the proximal end of the sleeve
such that longitudinal movement of the push tube relative to the
shaft places an axial load on the sleeve.
8. An implant delivery device as defined in claim 7 wherein
movement of the push tube in a distal direction relative to the
shaft places the sleeve in axial compression resulting in collapse
of the sleeve and the formation of multiple folds having peaks that
define a diameter that is larger than the diameter of the unloaded
sleeve.
9. A method of implanting an implant device in the human body
comprising: providing a shaft having a distal end and a collapsible
sleeve having a surface mounted around its distal end; placing a
hollow implant over the collapsible sleeve; placing an axial load
on the sleeve to collapse it and cause the formation of a plurality
of folds along its surface thereby engaging the interior of the
implant; navigating the shaft and associated implant tube to the
intended delivery site within a patient; placing the sleeve in
tension to remove the folds and release the implant from engagement
with the implant.
10. An implant delivery device comprising A tubular shaft having a
lumen and proximal and distal ends; a plunger having a proximal
side and a distal side configured to hold an implant and the
plunger being in slidable and fluid tight engagement with the lumen
at the distal end of the shaft such that pressurization of fluid
contained with in the lumen causes the plunger to move in a distal
direction.
11. An implant delivery device as defined in claim 10 further
comprising: A pullwire joined to the distal end of the tube and
extending proximally through the proximal end and arranged such
that placing the wire in tension causes the distal end of the shaft
to be deflected away from the axis defined by the shaft.
12. An implant delivery device as defined in claim 9 further
comprising: a source of pressurized fluid in fluid
communicationwith the proximal end of the shaft.
13. A method of delivering an implant comprising: providing a
tubular shaft having a lumen and proximal and distal ends; a
plunger having a proximal side and a distal side configured to hold
an implant and the plunger being in slidable and fluid tight
engagement with the lumen at the distal end of the shaft; placing
an implant on the distal side of the plunger; navigating the distal
end tubular shaft and implant through a patient's vasculature to an
implantation site; connecting the proximal end of the shaft to a
source of fluid to be pressurized: filling the lumen with fluid and
pressurizing the fluid to cause distal movement of the plunger to
drive the implant into the intended implantation site.
14. An implant delivery device comprising: an outer delivery shaft
having a lumen; an inner shaft having a lumen a first bladder with
perfusion ports sealed around the shaft, defining an interior with
a volume and containing a therapeutic substance within the interior
and; a second bladder sealed around the shaft in close proximity to
the first bladder and in fluid communication with the lumen.
15. An implant delivery device as defined in claim 14 wherein the
second bladder is laterally displaced form the first bladder a
minimal distance such that inflation of the second bladder causes
significant contact with the first bladder so that deformation of
the first bladder occurs.
16. An implant as defined in claim 14 wherein the second bladder is
located within the interior of the first bladder such that
inflation of the second bladder causes expulsion of the therapeutic
substance through the perfusion ports.
17. A method of delivering an implant and a therapeutic substance
to a treatment site within a patient comprising: providing a shaft
having a lumen, proximal and distal ends, an inner tube within the
shaft lumen having a lumen and a first bladder having a volume and
perfusion ports and containing a therapeutic substance and a second
bladder in fluid communication with the tube lumen, and an implant
releasably attached to the distal end of the shaft; navigating the
shaft, tube and implant to the implantation site within a patient;
releasing the implant at the implantation site; inflating the
second bladder to reduce the volume of the first bladder and cause
expulsion of the therapeutic substance in the area of the released
implant.
18. A delivery system for implanting a device in tissue in a
patient comprising: a shaft having proximal and distal ends and
means for temporarily restraining an implant at the distal end; a
depth monitor mechanism having a sensor at the distal end of the
shaft and indicator means joined to the proximal end of the
shaft.
19. A delivery system for implanting a device in tissue in a
patient as defined in claim 18 wherein the depth monitor operates
by sensing pressure at the distal end of the shaft.
20. A delivery system for implanting a device in tissue in a
patient as defined in claim 19 further comprising: a plurality of
sensors spaced longitudinally along the shaft adjacent the distal
end.
21. A method of monitoring the placement depth of an implant
delivery device within tissue comprising: providing an implant
delivery device having proximal and distal ends and a plurality
pressure sensors each, with independent output, longitudinally
spaced and placed at known distances along the shaft; advancing the
distal end shaft into tissue; observing which sensors record a
pressure change in conjunction with the known placement of the
sensors on the shaft to determine the position of the shaft.
22. An implant delivery system for placing a device in a patient
comprising: a shaft having proximal and distal ends; a mechanism
for releasably retaining an implant at the distal end of the shaft;
a navigation system having components internal and external to the
patient including sensors mounted on the shaft.
23. A catheter for accessing the left ventricle of the heart to
promote revascularization of the myocardium by mechanical means
comprising: an implant configured to promote revasclarization of
myocardial tissue a shaft having proximal and distal ends; a
mechanism for releasably retaining the implant at the distal end of
the shaft; a navigation system having components internal and
external to the patient including sensors mounted on the shaft.
Description
FIELD OF THE INVENTION
[0001] This invention relates to delivery devices for implants
placeable within tissue of the human body. Specifically, the
invention relates to delivery of implants configured to aid in the
restoration of blood flow to myocardial tissue of the heart. The
invention includes a mechanism to monitor the position of the
device and deliver drugs.
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.
[0003] Although ischemia can occur in various regions of the body,
often tissue of the heart, the myocardium, is affected by ischemia
due to coronary artery disease, occlusion of the coronary artery,
which otherwise provides blood to the myocardium. Muscle tissue
affected by ischemia can cause pain to the individual affected.
Ischemia can be treated, if a tissue has remained viable despite
the deprivation of oxygenated blood, by restoring blood flow to the
affected tissue.
[0004] Treatment of myocardial ischemia has been addressed by
several techniques designed to restore blood supply to the affected
region. Coronary artery bypass grafting 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 others have
reported varying degrees of success with various methods of
piercing the myocardium to restore blood flow to the muscle, 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, hypodermic tube and
physically stretching the channel after its formation. Reportedly,
many of these methods still 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, Jun. 1981,
pp.253-260. The laser was said to form channels in the tissue 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 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 transmyocardial revascularization (TMR)
in a non-laser catheterization procedure, there does not appear to
be evidence that such procedures have been put into practice. For
example, 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 is also
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. The authors noted
that such treatment could be an approach to management of diffused
coronary heart disease after alternative methods of administration
have been developed.
SUMMARY OF THE INVENTION
[0010] The present invention provides a delivery system for placing
implants within tissue in the human body. The implant delivery
system of the present invention provides several novel features,
which are useful in delivering implants into tissue.
[0011] In one aspect of the invention a delivery device is provided
that is especially configured to carry multiple tubular shaped
implants at its distal end, engaging the implants by their inside
surfaces. The delivery devices are inserted percutaneously into a
patient and navigated to the site where the implant is to be
located. The delivery systems of the present invention are
particularly well suited for delivering implants into the
myocardium to perform transmyocardial revascularization (TMR).
Implants such as stents may be placed by the delivery device into
the myocardial tissue to a proper depth to encourage
revascularization of ischemic tissue. In such a procedure,
positioning the implants into the proper depth within the
myocardium is important to the success of the procedure because it
has been observed that areas of the myocardium closer to the
endocardial surface and to the epicardial surface are more likely
to be responsive to revascularization. Additionally, spacing of the
implants relative to one another in an area of ischemic tissue is
important to the success of the revascularization process and
avoiding undesirable side effects of placing foreign objects in the
muscle tissue of the myocardium. Additionally, it may be desirable
to deliver a therapeutic substance to the implant location, before,
after or during delivery of the implant to promote
revascularization activity such as angiogenesis. The features of
the present invention address these concerns as will be discussed
in greater detail below.
[0012] Reaching the intended implant delivery location with the
delivery devices of the present invention first requires placement
of a guide catheter prior to navigation of a deliverable catheter
into the left ventricle. A steerable catheter that is placeable
within the left ventricle and positionable in multiple locations
with one catheterization is disclosed in U.S. application Ser. No.
09/073,118 filed May 5, 1998, the entirety of which is herein
incorporated by reference. The delivery devices as described herein
are insertable through the lumen of the delivery catheter and are
extendible pasts its distal end to place the implants within the
myocardial tissue. The delivery catheter provides directional
control so that the delivery devices of the present invention can
deliver multiple implants to a variety of locations within a given
area of ischemic tissue.
[0013] In one embodiment of a delivery device of the present
invention the device comprises a catheter having a compressible
sleeve at its distal end which forms into a plurality of random
folds when it is compressed expanding its diameter and serving to
capture the inside surface of any tubular object placed over it.
The crinkle tube may be formed from a polymer such as polyethylene
terethalate (PET). The crinkle tube can securely retain tubular
implants over its crinkle, radially expanded surface to a
sufficient degree such that delivery into tissue does not push the
implant off of the delivery device. Additionally, the crinkle tube
catheter may be used in conjunction with an outer catheter shaft
having a plurality of interior projections which engage a plurality
of implants in cue while the crinkle tube shaft delivers the
implants from the distal end of the catheter sequentially.
[0014] In another embodiment, a tubular implant is maintained on
the catheter behind an oval shaped segment of the catheter which
presents a larger profile than the inside diameter of the tubular
implant. A member is slidable within the catheter engages the oval
portion to deform into a round shape, thereby permitting the
implant to slip off the distal end of the shaft. Simultaneously
with deformation of the oval to a circle shape, the inner member
causes arms to protrude from the interior of the catheter and to
engage the implant and push it in a distal direction so that it
becomes implanted in the tissue. Additionally, the catheter has the
ability to carry multiple implants over its shaft. The implants
waiting in cue are also maintained in position on the shaft by a
oval shape segment of the shaft that can be deformed to a circular
shape thereby permitting advancement of the next implant.
[0015] In yet another embodiment of the delivery system, the
delivery catheter comprises an elongate shaft that contains
pressurized fluid within its lumen to motivate a plunger located at
the distal end of the shaft and attached to a single implant
attachment device. When fluid within the lumen of the delivery
catheter is pressurized, the plunger moves from its position
against proximal stops distally to its position against distal
stops. That length of travel is sufficient to push the implant
attached to the plunger into the intended tissue location. The
benefit of the fluid pressure delivery system is the reduction in
moving components needed to cause distal movement of the implant at
the distal end of the catheter from the proximal end of the
catheter which is manipulated outside of the patient.
[0016] Another feature of the present invention includes a dual
bladder drug delivery system which may be associated with the
delivery catheters discussed above. The dual bladder arrangement
provides a first bladder which contains a therapeutic substance
near the distal end of the delivery catheter and a second bladder
arranged near the first bladder so as to impinge upon the space of
the first bladder when the second bladder is inflated. The second
bladder is inflated with an inexpensive fluid simply to cause the
evacuation of the first bladder, which contains a therapeutic
substance to be delivered. The first bladder may be provided with a
series of perfusion ports through which the therapeutic substance
can be forced through when pressurized by the reducing volume
imposed by the inflation of the second bladder.
[0017] The benefit of the system is to avoid the waste of expensive
therapeutic substances by filling an entire full length lumen with
the substance in order to force it from the distal end of a
delivery catheter. With the dual bladder delivery system, an
expensive fluid can be used to occupy the space along the full
length of the delivery catheter, yet its pressurization force can
be applied to deliver a small quantity of the therapeutic substance
maintained only at the distal end of the catheter.
[0018] Another feature of the present invention is a depth monitor,
which may be applied to any of the above delivery catheters. The
depth monitor uses changes in pressure being measured at the distal
end of the catheter to signal the operator that the distal end of
the catheter has been placed within myocardial tissue to a certain
depth sufficient to implant the device. This depth monitoring is
accomplished by providing one or a plurality of pressure ports at
the distal end of the catheter that will be inserted into tissue in
order to deliver the implant that it carries. The pressure port(s)
are spaced a known distance from the distal end of the delivery
catheter. The interior lumen of the catheter can transmit the
pressure experienced at the distal end of the catheter through
individual lumens to the proximal end where a pressure monitoring
device for each pressure port is attached to the proximal end of
the delivery device. When the distal end of the delivery catheter
is in the left ventricle, pressure readings at the distal end will
be dynamic. However, after the distal end of the delivery catheter
enters the tissue to implant the device, the pressure ports become
covered with surrounding tissue resulting in dampened or static
signal. The most proximal pressure port when covered by the
surrounding tissue, will act likewise and signals the operator that
the distal end of the delivery catheter has been placed to a
sufficient depth within the tissue to deliver the implant.
[0019] Another feature of the present invention is a navigation
system utilizing magnetic fields transmitted over the body to
identify the location within a patient of a catheter having sensing
electrodes that interact with the electromagnetic coils. Computer
software processes the information obtained from the magnetic
pick-up coils and places the catheter on a virtual image of the
heart to give the operator a general idea of where the catheter is
located and what areas of ischemic tissue have been treated with
implant devices. Because the delivery devices of the present
invention are capable of delivering more than one implant to an
area of ischemic tissue with one catheterization, a navigation
system helping to guide the placement of the delivery catheter and
implants is helpful.
[0020] It is an object of the present invention to provide an
implant delivery system that is simple and effective to use. It is
yet another object of the present invention to provide an implant
delivery system that is suitable for varying implant devices to the
myocardium of the heart that will aid in revascularization of
ischemic tissue.
[0021] It is yet another object of the invention to provide an
implant delivery device that operates to grasp a tubular shaped
implant by its inside surface. The implant may be inserted into
tissue. It is another object of the invention to provide an implant
delivery device that utilizes fluid pressure through the delivery
catheter to insert the implant into the subject tissue.
[0022] It is yet another object of the invention to provide an
implant delivery device that includes a dual bladder drug delivery
system that reduces waste of expensive therapeutic substances in
its application to a treatment site through a catheter.
[0023] It is still another object of the invention to provide a
depth monitor capable of being associated with a delivery device
that utilizes pressure sensed at the distal end of the catheter to
reliably determine the location of the distal end of the
device.
[0024] It is yet another object of the invention to provide a
navigation system that is capable of identifying the location of a
catheter delivering mechanical TMR inducing devices, within the
human heart so that the catheter can be moved to various locations
delivering multiple devices with one insertion into the heart.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] 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:
[0026] FIG. 1 shows a sectional illustration of the left ventricle
of a human heart;
[0027] FIG. 2A-2D illustrate the steps of percutaneously delivering
an implant to an area of the myocardium;
[0028] FIG. 3A is a partial sectional illustrational of the crinkle
tube delivery device;
[0029] FIG. 3B is a detail of the crinkle tube in compression;
[0030] FIG. 3C is a detail of the crinkle tube in tension;
[0031] FIG. 3D is a partial sectional illustration of the crinkle
tube device delivering an implant;
[0032] FIG. 3E is a partial sectional illustration of the crinkle
tube device being withdrawn from the implant location;
[0033] FIG. 3F is a partial sectional illustration of a delivery
device having a depth monitor;
[0034] FIG. 4A-4C are partial sectional illustrations of a multiple
implant device;
[0035] FIG. 5A is a partial sectional view of a oval tube delivery
device;
[0036] FIG. 5B is a sectional view taken along the line 5B-5B of
FIG. 5A;
[0037] FIG. 5C is a sectional view taken along the line 5C-5C of
FIG. 5A;
[0038] FIG. 6A is a partial sectional view of an oval tube delivery
device;
[0039] FIG. 6B is a sectional view taken along the line 6B-6B of
FIG. 6A;
[0040] FIG. 60 is a sectional view taken along the line 6C-6C of
FIG. 6A;
[0041] FIG. 7A is a partial sectional view of an oval tube delivery
device;
[0042] FIG. 7B is a sectional view taken along the line 7B-7B of
FIG. 7A;
[0043] FIG. 7C is a sectional view taken along the line 7C-7C of
FIG. 7A;
[0044] FIG. 8 is a sectional view of a pressurized fluid delivery
device;
[0045] FIG. 9A is a sectional view of a double bladder therapeutic
substance delivery device;
[0046] FIG. 9B-9C are sectional views of the double bladder
therapeutic substance delivery device.
[0047] DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
[0048] FIG. 1 shows a sectional illustration of the left ventricle
2 of a human heart 1. Several implants 8 are placed within the
myocardium 4 adjacent the endocardial surface 6. As shown in FIGS.
2A-2D, access to the endocardial surface 6 of the myocardium 8 is
gained through a steerable delivery catheter 36 inserted into the
left ventricle 2. It is through the delivery catheter 36 that the
delivery devices of the present invention are inserted to carry the
individual implants into the myocardial tissue 8. The steerable
delivery catheter 36. It is noted, throughout the description of
the delivery devices and their associated methods, "proximal"
refers to the direction along the delivery path leading external of
the patient and "distal" refers to the direction leading internal
to the patient.
[0049] To access the left ventricle of the heart percutaneously, a
guide catheter (not shown) may be navigated through the patient's
vessels to reach the left ventricle 2 of the heart 1. A barbed tip
guidewire 34 may then be inserted through the guide catheter and
into the ventricle where it pierces the myocardium 4 and becomes
anchored within the tissue. After anchoring the guidewire, the
steerable delivery catheter 36 may be advanced over the guidewire
to become positioned within the ventricle in close proximity to the
endocardium to facilitate delivery of implants. To facilitate
delivery of multiple implants, the guidewire lumen of the delivery
catheter 36 may be eccentrically located on the catheter.
Therefore, when the catheter is rotated about the guidewire, the
center of the catheter will rotate through a circular path as
demonstrated in FIGS. 2C and 2D, to encompass a broader delivery
area with only a single guidewire placement. The outside diameter
of the delivery catheter is preferably less than 0.100 inch.
Additionally, the delivery catheter may be provided with steering
capability by means of a pull wire extending the length of the
catheter and attached at its distal end such that pulling on the
wire from the proximal end causes the distal tip of the catheter to
be deflected. Therefore, the steering capability provides a broader
range of delivery area with a single catheterization. A detailed
description of the construction of a delivery catheter for reaching
multiple sites within the left ventricle is described in U.S.
patent application Ser. No. 09/073,118 filed May 5, 1998, the
entire disclosure of which is herein incorporated by reference.
[0050] FIG. 3A shows a partial cut-away view of a preferred
delivery device 10 for the TMR implants 8. The delivery device 10
shown in FIG. 3A may be used with a guide catheter 12 rather than
the steerable catheter 36 discussed above. A delivery device 10
comprises an elongate solid shaft 14 having a sharp obturator head
16 at its distal end. The obturator head 16 is formed at the distal
end of the core wire 14 by any convenient means of building a mass
at the end of a core wire. For example, several thin and small
sleeves and springs may be amassed at the distal end and melted
together to form a bulbous tip which is later ground to form a
sharp, piercing tip 18. Included within the mass of melted
materials that form the distal obturator head 16, should be a
radiopaque material such as gold or platinum to make the distal
area of the device visible under fluoroscopy. Heat bonded to the
proximal end 20 of the obturator head 16 is a flexible crinkle tube
22, shown in detail in FIG. 3B, formed from polyethylene
terephthalate (PET): Attached to the proximal end 24 of the crinkle
tube 22 by heat bonding is push tube 26 which is formed from a
closely wound spring having a PET shrink tube formed around its
outer surface filing in the voids created by the coils. The crinkle
tube 22 collapses under compressive load to form a random pattern
of folds 28, which serve to increase the overall diameter of the
crinkle tube such that it comes into frictional contact with the
inside diameter of a hollow or generally tubular implant 8 that is
placed over it. When placed in tension as shown in FIG. 3C, the
crinkle tube elongates and returns to a low diameter configuration
without folds. The configuration of the crinkle tube is manipulated
by relative movement of the core wire 14 having its obturator 16
joined to the distal end 25 of the crinkle tube relative to the
push tube 26, which is joined to the proximal end of the crinkle
tube 24. The shaft and push tube are slidable relative to each
other and controllable from the proximal end of the device by a
handle 38 and core wire extension 30. Movement of the handle and
push tube in a distal direction and movement of the core wire and
its extension in the proximal direction compress the crinkle tube
22 to capture the interior of an implant 8 for delivery into tissue
as shown in FIG. 3A. It is in this large diameter, crinkled
configuration that the delivery device must maintain to restrain
the implant during delivery into tissue. As shown in FIGS. 3D and
3E after delivery into tissue, the crinkle tube may be placed in
tension, to withdraw the plurality of folds that engage the
interior of the implant 8. With the crinkle tube 22 placed in a low
profile configuration, the core wire extension 30 is advanced
distally within the handle 38 and handle 38 advanced distally into
the associated guide catheter 12 as shown in FIG. 3D. After
reducing the profile of the crinkle tube 22 the implant easily
slides off of the crinkle tube 22 over the obturator 16 as the
device is withdrawn from the tissue as shown in FIG. 3E.
[0051] An alternative embodiment of the crinkle tube delivery
device may be additionally equipped with a pressure dependent depth
monitor. The depth monitor may be comprised of at least one
pressure port 21, shown in FIGS. 3B and 3F, formed in the push tube
26 adjacent its distal end 27 and location of the crinkle tube 22
and implant. Pressure sensed through the port 21 is transmitted
through lumen defined by the push tube and is detected by a
pressure detector 31 joined to the handle 38. Readings from the
pressure detector may be shown on a hydraulic gauge or electronic
readout.
[0052] The location of the pressure port 21 is a significant factor
in interpreting the pressure information for proper implant
delivery. When the pressure port is open to the left ventricle,
pressure readings are dynamic. However, when the pressure port 21
is submerged and covered by tissue, pressure readings drop or
become static. With placement of the pressure port just proximal of
the implant mounting location on the push tube, a significant
pressure dampening during delivery of an implant will signal the
operator that, not only has the pressure port become embedded in
the tissue, but also the implant, located distal to the pressure
port, has become sufficiently imbedded in the tissue. Thus the
implant can be released from the delivery device and into the
tissue. Multiple pressure ports spaced along the distal end of the
delivery device can provide an indicator of how deep the delivery
device is in the tissue because as each successive pressure is
monitored.
[0053] FIG. 4A shows a variation of the crinkle tube delivery
device, which is configured to sequentially delivery several
preloaded implants 8. The multiple implant delivery device 34
operates much the same way as the single implant delivery device
described above. The crinkle tube 22 grips the most distal implant
8 only, while the other implants wait in cue within the guide
catheter 12 and over the push tube 26. The additional implants are
restrained in their relative positions behind the most distal
implant by resilient fingers 44 which project inwardly from the
interior wall 46 of guide catheter 12. After the most distal stent
is urged out of the guide catheter by the distal movement of the
core wire and push shaft, as shown in FIG. 4B, the core wire and
push shaft may be retracted back into the guide catheter as the
remaining stents are indexed distally by the sliding distal
movement of index cue 40 which may be manually slidable within the
guide catheter 12 by indexing shaft 42. As the core wire 14 and
push tube 26 are withdrawn proximally back into the guide catheter,
the area of the crinkle tube 22 resides in the interior of the
newly placed most distal stent. The push tube and core wire are
again moved relative to each other to cause compression along the
crinkle tube 22 so that the folds 28 of the crinkle tube 22 contact
the interior surface of the next implant 8 to be delivered. The
next implant to be delivered is preferably placed in a different
location, spaced apart from the first implant by movement of the
guide catheter 12 to a new area.
[0054] FIGS. 5A-C shows another embodiment of the implant delivery
device 50. The device operates to maintain an implant 8 over its
outer shaft 54 by having a distal oval area where the shaft defines
an oval cross-sectional shape, as shown in FIG. 5B, that defines a
diameter that is larger than the circular shape of the tubular
implant 8, to thereby preventing the implant from sliding off the
end of the outer shaft 54. Additionally, the proximal oval area 68
on the outer shaft 54 maintains the implant 8 that is second in
line in its mounted configuration on the catheter shaft. The
natural tendency of the shaft 54 to maintain an oval shape at these
areas serves to lock the implants 8 in place on the shaft as is
shown in FIG. 5A. It is in this locked configuration that the most
distal implant is navigated to the myocardium. The oval areas of
the outer shaft 54 lock the implants in place so that they do not
move as they are navigated to the tissue location.
[0055] FIGS. 6A-C shows an implant 8 being delivered from the oval
shaft embodiment 50. Once the delivery device is adjacent the
tissue to be penetrated, the shaft 52 is advanced distally causing
the sharpened distal tip 70 of the shaft to emerge from the distal
end 72 of the delivery device. The sharpened distal tip 70 pierces
tissue as it is advanced in a distal direction to facilitate
insertion of the implant 8 into the tissue. Also with the distal
movement of the shaft 52, the distal cam 56 moves into engagement
with the distal shims 62, thereby causing the naturally oval area
66 to be elastically deformed into a round shape as is shown in
FIG. 6B. The round configuration of the outer shaft 54 in this area
permits the round implant to slide off the distal end of the
device. Further distal movement of the shaft 52 causes distal
movement of the split tube 76, which is engaged by the proximal cam
60 joined to the shaft 52 . The vanes 78 of the split tube move
distally and curve radially outward through radial passages 80
formed into the sidewall of the outer shaft 54 to engage the
interior of the most distal implant. The natural curvature of the
vanes and the presence of biasing member 84 underneath the vanes
urge them in a radially outward direction so that as they are moved
distally within the shaft 54 the vanes are urged out of the radial
passages 80 that are formed in the tube. Though the vanes serve to
push the implant into the desired tissue location, their radial
extent from the catheter shaft 54 could potentially interfere with
the passage of the proximal end 9 of the implant over the vanes.
Therefore, to ensure that the implants are not hindered as they are
pushed off the catheter shaft, the implants used with the present
embodiment of delivery device should be configured to have a
proximal opening that is larger than the distal opening and as
large as the maximum extent of the natural extent of the vanes.
[0056] During delivery into the myocardium the proximal oval area
68 is maintained in the oval configuration to lock in place on the
shaft 52 the implants 8 that are in cue to be delivered. However,
after delivery of an implant into tissue, the shaft is retracted
proximally within the shaft 54 to shield the sharp distal tip 70
from tissue during movement of the shaft to the next location, as
shown in FIG. 7A. Distal movement of the shaft 52 also causes the
proximal cam 60 to engage the proximal shim 62 located on the inner
surface of the outer shaft lumen directly adjacent the proximal
oval area 68, which forces the shaft to become circular temporarily
in that area, as shown in FIG. 7C. Thus the secondary implants
become free to cue forward, the next implant 8 moving up to be the
next delivered. The arrangement of cams on the shaft dictates that
when the proximal oval area is deformed to be round, the distal
oval area remains in its undeformed oval configuration to prevent
continued distal movement of implants 8 distally on the shaft until
they are ready to be delivered into tissue.
[0057] FIG. 8 is partial sectional view of another embodiment of
the delivery device of the present invention that uses pressurized
fluid to provide the implantation force needed to insert a
self-piercing stent into myocardial tissue. The fluid pressure
delivery device 90 comprises an elongate shaft 92 having at least
one lumen 94, which carries the pressurized fluid 96 such as water
or saline. The fluid and a pressurization source are joined to the
lumen at proximal luer fitting 98. The shaft may have a guidewire
lumen 99 containing a barbed tip guidewire 34, as with the delivery
catheter 36 described above . The barbed tip guidewire implanted
within adjacent tissue helps provide leverage to resist movement of
the distal tip 100 of the catheter when when substantial fluid
force is being applied to the tissue surface by the entering
implant 8.
[0058] The distal portion 102 of the lumen 94 is configured as a
track 104 to receive a slidable plunger 106 that forms a fluid
tight seal with the track. Fluid pressure within the lumen 94
creates a force against the plunger causing it to slide distally.
The plunger has joined to its distal face a catch member 108 that
is configured to be releasably engagable with the interior of an
implant 8 with which the device is intended to deliver into tissue.
The extent of travel of the plunger within the track 104 is limited
by proximal stops 110 and distal stops 112 that engage the plunger
to limit its movement so that it does not become disassociated from
the shaft lumen 94 when travel is maximized. To avoid the necessity
of attaching a piercing member to the plunger, self-piercing
implants are preferred for use with the present embodiment, such as
shown in FIG. 8. Examples of self piercing implants intended for
placement in the myocardium are described in U.S. patent
application Ser. No. 09/073,118, filed May 5, 1998.
[0059] FIGS. 9A-9C show a double bladder therapeutic substance
delivery system 110 that may be employed with the implant delivery
systems of the present invention that can be configured to have an
open lumen through their lengths. In particular the crinkle tube 22
and oval shaft 50 embodiments may be configured to employ the
therapeutic substance delivery system 110. FIG. 9A shows a double
bladder system 110 positioned within the central lumen 112 of a
tube 111 of an implant delivery system similar to the crinkle tube
delivery device. It is noted that other implant delivery sytems or
catheter devices not disclosed herein may employ the therapeutic
substance delivery system or the system could be deployed alone
through a conventional catheter having a lumen.
[0060] The drug delivery system shown in FIGS. 9A-9C employs a
first flexible bladder 114 filled with a therapeutic substance and
mounted about a tube,116 and in close longitudinal proximity to
(FIG. 9B), or surrounding (FIG. 9C) a second flexible bladder 118
attached to the shaft 116 and inflatable with a conventional medium
such as saline. The second bladder 118 is in fluid communication
with a lumen 120 that extends through shaft 116 via a port 122.
Expansion of the second bladder 118 within a confined space such as
within a lumen 112 adjacent the first bladder 114 (FIG. 9B) or from
within the first bladder (FIG. 9C) applies pressure to the first
bladder, reducing its volume which increases fluid pressure in the
first bladder sufficiently to cause the therapeutic substance to be
ejected through tiny orifices 124 to the intended treatment
site.
[0061] The bladders may be similar to dilatation balloon in their
shape, size and manner of attachment to the shaft 116. The bladders
may be made from a strong but flexible material such as PVC or
Nylon. The bladders may be approximately the same size so that
volume reduction of the first bladder corresponds to the volume
expansion of the second bladder. The first bladder may be filled
with a therapeutic substance during the process of joining it the
bladder to the shaft. After bonding the proximal neck 130 to the
shaft, the catheter may be oriented so that the distal neck 132 is
elevated. In this orientation, the therapeutic substance can be
injected, by a syringe, inserted between the distal neck and the
shaft, without the chance of the substance running out of the
bladder or contaminating the bonding area between the distal neck
and the shaft. After filling the bladder 114 with the substance,
the distal neck is bonded to the shaft.
[0062] A plurality of tiny orifices 124 may be preformed in the
drug bladder prior to use of the device and either prior or after
being filled with the substance and bonded. Because the orifices
are small, on the order of 0.001", and the substance within the
first bladder is not pressurized it is expected that most
therapeutic substances can be formulated to have a sufficiently
high viscosity that the substance will not leak out from the
orifices in the absence of pressure applied by the second bladder.
For this reason, an alternative method of prefilling the first
bladder with a therapeutic substance may comprise the steps of
piercing the surface of a bladder with a tiny syringe needle and
injecting the substance through the bladder wall.
[0063] Another aspect of the invention utilizes electromagnetic
guidance technology to provide a guidance system for use with an
implant delivery system such as the systems discussed above. U.S.
Pat. No. 5,769,843 (Abela), the entirety of which is incorporated
herein by reference, discloses such a guidance system for
positioning a laser catheter within the ventricle of the heart. An
electromagnetic guidance system would be especially useful in the
delivery of multiple mechanical implants to an area of ischemic
myocardial tissue such as is described above. The delivery devices
of the present invention may be equipped with two non-coplanar
magnetic sensing coils in the distal ends of their shafts to
cooperate with three sets of three magnetic fields generating
external coils located outside the patient. The sensing coils of
the catheter receive tthe electromagnetic field and thus, with
assistance with from a computer can be located within the
patient.
[0064] From the foregoing, it will be appreciated that the
invention provides delivery devices for delivering implants and
therapeutic substances to the myocardium. The invention is
particularly advantageous for delivering devices and therapeutic
substances to promote TMR and angiogenesis within ischemic
myocardial tissue. The implants are simple and readily insertable
into the intended tissue location with a minimum of steps. The
delivery systems are simple to operate to implant the devices
quickly.
[0065] 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. Having thus described the invention what we desire to
claim and secure by letters patent is:
* * * * *