U.S. patent application number 10/154737 was filed with the patent office on 2002-10-03 for pmr device and method.
This patent application is currently assigned to SCIMED LIFE SYSTEMS, INC.. Invention is credited to DeVore, Lauri, Ellis, Louis, Hendrickson, Gary L..
Application Number | 20020143289 10/154737 |
Document ID | / |
Family ID | 21884497 |
Filed Date | 2002-10-03 |
United States Patent
Application |
20020143289 |
Kind Code |
A1 |
Ellis, Louis ; et
al. |
October 3, 2002 |
PMR device and method
Abstract
A catheter having an elongate shaft including a proximal and a
distal end. The shaft includes a conductor. An electrode is
disposed at the distal end of the shaft and is connected to the
conductor. The electrode has a generally annular, cross-sectional
shape. The annular shape defines an opening within the electrode.
An insulator surrounds the conductor. In accordance with the method
of the present invention, a crater wound can be formed through the
endocardium and into the myocardium of a patient's heart.
Collateral damage to the myocardium can be made by infusing
pressurized fluid into the crater wound.
Inventors: |
Ellis, Louis; (St. Anthony,
MN) ; Hendrickson, Gary L.; (Big Lake, MN) ;
DeVore, Lauri; (Seattle, WA) |
Correspondence
Address: |
Glenn M. Seager
CROMPTON, SEAGER & TUFTE, LLC
Suite 895
331 Second Avenue South
Minneapolis
MN
55401
US
|
Assignee: |
SCIMED LIFE SYSTEMS, INC.
|
Family ID: |
21884497 |
Appl. No.: |
10/154737 |
Filed: |
May 23, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10154737 |
May 23, 2002 |
|
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09035736 |
Mar 5, 1998 |
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6416490 |
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60064210 |
Nov 4, 1997 |
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Current U.S.
Class: |
604/22 ; 606/41;
607/113 |
Current CPC
Class: |
A61B 2018/00148
20130101; A61B 2018/00279 20130101; A61B 2017/00867 20130101; A61B
18/1492 20130101; A61B 2018/126 20130101; A61B 17/3468 20130101;
A61B 2018/1425 20130101; A61B 90/39 20160201; A61B 2018/1253
20130101; A61B 2018/00392 20130101; A61B 2017/00296 20130101; A61B
2017/320084 20130101; A61B 2018/0016 20130101; A61B 2018/162
20130101; A61B 2218/002 20130101; A61M 2025/0089 20130101; A61B
2017/00247 20130101; A61B 18/1477 20130101; A61F 2/2493 20130101;
A61B 17/3478 20130101 |
Class at
Publication: |
604/22 ; 606/41;
607/113 |
International
Class: |
A61B 017/20; A61F
007/12; A61B 018/18 |
Claims
What is claimed is:
1. A catheter assembly, comprising: an elongate shaft having a
proximal end and a distal end, and including a conductor; an
electrode disposed at the distal end of the shaft and connected to
the conductor, the electrode having a generally annular transverse
cross-sectional shape, the annular shape defining an opening within
the electrode, the electrode having a distal end; an insulator
surrounding the conductor.
2. A catheter assembly in accordance with claim 1, wherein a stop
is disposed in the opening proximally a predetermined distance from
the distal end of the electrode.
3. A catheter assembly in accordance with claim 1, wherein the
shaft defines a lumen in fluid communication with the opening.
4. A catheter assembly in accordance with claim 3, further
comprising a needle disposed within the opening and in fluid
communication with the lumen.
5. A catheter assembly in accordance with claim 1, wherein the
insulator includes polyethylene.
6. A catheter assembly in accordance with claim 1, wherein the
insulator includes polyimide.
7. A catheter assembly in accordance with claim 1, wherein the
shaft includes a stainless steel hypotube.
8. A catheter assembly in accordance with claim 1, wherein the
shaft includes a Nitinol hypotube.
9. A catheter assembly in accordance with claim 1, further
comprising a radiofrequency generator connected to the
conductor.
10. A catheter assembly in accordance with claim 1, wherein the
annular shape is generally circular.
11. A catheter assembly in accordance with claim 1, wherein the
annular shape is continuous.
12. A catheter assembly in accordance with claim 1, wherein the
annular shape is discontinuous.
13. A catheter assembly in accordance with claim 12, wherein the
annular shape is formed by a plurality of electrodes positioned in
an array.
14. A catheter assembly in accordance with claim 1, wherein the
electrode includes a plurality of distally projecting members.
15. A catheter assembly in accordance with claim 14, wherein the
electrode is serrated to grab tissue.
16. A catheter assembly in accordance with claim 1, further
comprising a second electrode.
17. A catheter assembly in accordance with claim 16, wherein the
electrode comprises a needle.
18. A method of performing PMR, comprising the steps of: providing
a catheter including an elongate shaft having a proximal end and a
distal end, and a generally annularly shaped electrode disposed at
the distal end; advancing the electrode to proximate the
endocardium of the patient's heart; energizing the electrode; and
advancing the electrode into the myocardium to wound the
myocardium.
19. The method in accordance with claim 18, further comprising the
step of providing a lumen through the shaft.
20. The method in accordance with claim 19, further comprising the
step of delivering contrast medium to the distal end through the
lumen.
21. The method in accordance with claim 19, further comprising the
step of delivering a drug to the distal end through the lumen.
22. The method in accordance with claim 19, further comprising the
step of delivering saline to the distal end through the lumen.
23. A method of performing PMR, comprising the steps of: forming a
hole through the endocardium and into the myocardium having a width
and a depth, wherein the width of the hole is greater than the
depth; infusing a fluid into the hole.
24. A catheter, comprising: a shaft having a distal end and a
proximal end; and a radiopaque marker disposed proximate the distal
end, the marker having an asymmetrical shape, such that the marker
appears in mirror image when viewed from opposite sides of the
shaft.
Description
RELATED APPLICATIONS
[0001] The present application is related to U.S. Provisional
Patent Application Serial No. 60/064,210, filed on Nov. 4, 1997,
and entitled TRANSMYOCARDIAL REVASCULARIZATION GROWTH FACTOR
MEDIUMS AND METHOD, U.S. patent application Ser. No. 08/812,425,
filed on Mar. 6, 1997, entitled TRANSMYOCARDIAL REVASCULARIZATION
CATHETER AND METHOD, U.S. patent application Ser. No. 08/810,830,
filed Mar. 6, 1997, entitled RADIOFREQUENCY TRANSMYOCARDIAL
REVASCULARIZATION APPARATUS AND METHOD, and U.S. patent application
Ser. No. ______ filed on Mar. 5, 1998, and entitled EXPANDABLE PMR
DEVICE AND METHOD herein incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to medical devices
for forming holes in heart chamber interior walls in percutaneous
myocardial revascularization (PMR) procedures. More specifically,
the present invention relates to intravascular PMR devices having
generally annular tips.
BACKGROUND OF THE INVENTION
[0003] A number of techniques are available for treating
cardiovascular disease such as cardiovascular by-pass surgery,
coronary angioplasty, laser angioplasty and atherectomy. These
techniques are generally applied to by-pass or open lesions in
coronary vessels to restore and increase blood flow to the heart
muscle. In some patients, the number of lesions are so great, or
the location so remote in the patient vasculature that restoring
blood flow to the heart muscle is difficult. Percutaneous
myocardial revascularization (PMR) has been developed as an
alternative to these techniques which are directed at by-passing or
removing lesions. Heart muscle may be classified as healthy,
hibernating and "dead". Dead tissue is not dead but is scarred, not
contracting, and no longer capable of contracting even if it were
supplied adequately with blood. Hibernating tissue is not
contracting muscle tissue but is capable of contracting, should it
be adequately resupplied with blood. PMR is performed by boring
channels directly into the myocardium ofthe heart.
[0004] PMR was inspired in part by observations that reptilian
hearts muscle is supplied primarily by blood perfusing directly
from within heart chambers to the heart muscle. This contrasts with
the human heart, which is supplied by coronary vessels receiving
blood from the aorta. Positive results have been demonstrated in
some human patients receiving PMR treatments. These results are
believed to be caused in part by blood flowing from within a heart
chamber through patent channels formed by PMR to the myocardial
tissue. Suitable PMR holes have been burned by laser, cut by
mechanical means, and burned by radio frequency current devices.
Increased blood flow to the myocardium is also believed to be
caused in part by the healing response to wound formation.
Specifically, the formation of new blood vessels is believed to
occur in response to the newly created wound.
SUMMARY OF THE INVENTION
[0005] The present invention pertains to a device and method for
performing percutaneous myocardial revascularization (PMR). The
device of the present invention can be used to form crater wounds
in the myocardium of the patient's heart. A crater wound can be
viewed as a wound having a width greater than its depth, whereas a
channel wound is one having a depth greater than its width. A hole
in the myocardium is a volumetric removal of tissue. The device can
also be used to form channel wounds, but the configuration of the
device's electrode(s) makes the device particularly suitable for
creating crater wounds.
[0006] In the preferred form of the method in accordance with the
present invention, a crater wound is made through the endocardium
and into the myocardium. The wound, and thus the healing response,
including angiogenisis and subsequent perfusion of tissue is
enhanced by collateral damage to the myocardium. The collateral
damage is preferably induced by directing pressurized saline,
contrast media, drug or a combination into the crater site through
the endocardium and into the myocardium. This causes the vessels,
capillaries and sinuses to rupture. By creating the collateral
damage, the number of wounds which need to be made during the PMR
procedure can be substantially reduced as the size of each wound is
increased in view of the collateral damage. Additionally, and
arguably as significant as the reduction in the number of wounds
which must be formed during the procedure, is the reduction of the
likelihood of a myocardial perforation. This reduction is possible
because the holes can be limited in depth to just through the
endocardium. Once the endocardium is perforated, pressure from
infused fluid can rupture the myocardial vessels without further
ablation or removal of tissue.
[0007] In a preferred embodiment, a catheter in accordance with the
present invention includes an elongate shaft having a proximal end
and a distal end, and a conductor extending therethrough. An
electrode is disposed at the distal end of the shaft and connected
to the conductor. The electrode has a generally annular transverse
cross-sectional shape. The annular shape defines an opening within
the electrode. An insulator surrounds the elongate shaft.
[0008] A stop is disposed in the opening a predetermined distance
proximally of the distal end of the electrode. The shaft preferably
defines a lumen in fluid communication with the opening through the
electrode. In one embodiment, a needle can be disposed within the
opening and be in fluid communication with the lumen to deliver
contrast media, growth factors or drugs to the wound.
[0009] In another embodiment, the annular shape of the electrode is
generally circular. The annular shape can be continuous or in an
alternate embodiment, discontinuous and formed from a plurality of
discrete electrodes positioned in an array. The electrode can also
include a serrated edge that produces a plurality of electrode
contact points.
[0010] A method for performing PMR in accordance with the present
invention includes providing a catheter having an elongate shaft
including a proximal end and a distal end. A generally annular
shaped electrode is disposed at the distal end of the shaft. The
electrode is advanced to proximate the endocardial surface of the
myocardium of the patient's heart. The electrode is energized and
advanced into the myocardium to form an annular shaped crater
wound. Depth is controlled by a mechanical stop.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cross-sectional, perspective view of an annular
shaped crater wound in a patient's myocardium formed by a device in
accordance with the present invention;
[0012] FIG. 2 is a perspective, cross-sectional view of a catheter
in accordance with the present invention;
[0013] FIG. 3 is a cross-sectional view of the catheter of FIG. 2
in use;
[0014] FIG. 4 is a perspective, cross-sectional view of an
alternate embodiment of the catheter in accordance with the present
invention;
[0015] FIG. 5 is a cross-sectional view of the catheter of FIG. 4
in use;
[0016] FIG. 6 is a perspective view of the distal end of yet
another alternate embodiment of a catheter in accordance with the
present invention;
[0017] FIG. 7 is a perspective view of yet another alternate
embodiment of the catheter in accordance with the present
invention;
[0018] FIG. 8 is a perspective view of yet another alternate
embodiment of the catheter in accordance with the present
invention;
[0019] FIG. 9 is a perspective view of yet another alternate
embodiment of the catheter in accordance with the present
invention;
[0020] FIG. 10 is a cross-sectional view of the catheter of FIG.
8;
[0021] FIG. 11 is a cross-sectional view of the catheter of FIG.
8;
[0022] FIG. 12 is a cross-sectional view of the catheter of FIG.
8;
[0023] FIG. 13 is a top view of a crater formed in the
endocardium;
[0024] FIG. 14 is a cross-sectional view of the crater of FIG.
12;
[0025] FIG. 15 is a front view of a catheter electrode in
accordance with the present invention;
[0026] FIG. 16 is a back view of the electrode of FIG. 14;
[0027] FIG. 17 is a side view of the electrode of FIG. 14;
[0028] FIG. 18 is a front view of yet another embodiment of an
electrode in accordance with the present invention; and
[0029] FIG. 19 is a back view of the electrode of FIG. 17.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Referring now the drawings wherein like reference numerals
refer to like elements throughout the several views, FIG. 1 is a
perspective, partial cross-sectional view of a heart wall 10 having
an annular hole 12 formed in the myocardium by a catheter made in
accordance with the present invention. FIG. 2 is a perspective,
partial cross-sectional view of a catheter 20 in accordance with
the present invention. Catheter 20 includes a shaft 21 having a
proximal end and a distal end. Shaft 21 preferably includes an
elongate hypotube sandwiched between an inner insulator 24 and an
outer insulator 26. Hypotube 22 can be formed from stainless steel
or Nitinol or other conductive material. It can be desirable to use
a Nitinol hypotube as the highly flexible material can act as a
shock absorber while catheter 20 is pressured against the beating
heart during the PMR procedure. Insulators 24 and 26 may be formed
from, for example, polyethylene, polyimide or PTFE. Those skilled
in the art would appreciate that other biocompatible materials can
be used to form these elements. The distal end of hypotube 22 is
preferably left uninsulated to form an annularly-shaped electrode
23.
[0031] A stop 28 is preferably disposed within shaft 21. Stop 28
preferably defines a lumen 30 extending therethrough. Stop 28
includes a distal end 32 spaced a predetermined distance from a
distal end 34 of electrode 23. This predetermined distance can be
used to control the depth of holes 12 formed in the myocardium of a
patient's heart. Those skilled in the art will recognize the
non-conductive, biocompatible materials available to form stop 28,
for example PEPI.
[0032] In view of the discussion below regarding the use of
catheter 20, those skilled in the art of catheter construction
would recognize the various possibilities for manifolds to be
disposed at the proximal end of catheter 20, and that a suitable
radio frequency (RF) generator can be conductively connected to
hypotube 22 to deliver RF energy to electrode 23.
[0033] FIG. 3 is a cross-sectional view of catheter 20 in use. In
FIG. 3, electrode 23 has been energized with RF energy and advanced
into heart wall 10 to form hole 12. As shown by the arrows,
contrast medium, growth factor or other drugs are being infused
through lumen 30 into hole 12, and then into myocardium 10. It can
be noted that in FIG. 3 that distal end 32 of stop 28 is spaced a
predetermined distance from distal end 34 of electrode 23 such that
the depth of hole 12 is approximately equal to its width. The
predetermined distance can be varied such that shallower holes or
craters are formed, or alternatively the distance can be increased
to form channels.
[0034] FIG. 4 is a perspective, partial cross-sectional view of
catheter 20 modified to include a hypotube 36 extending distally
from lumen 30. The distal end of hypotube 36 includes a sharpened
end 38, and a lumen defined therethrough in fluid communication
with lumen 30. Hypotube 36 can also act as a bi-polar ground
[0035] FIG. 5 is a cross-sectional view of catheter 20 including
hypotube 36. This view is similar to that of FIG. 3, except that
rather than infusion fluid into hole 12, as shown by the arrows,
fluid is directed into the myocardium.
[0036] FIG. 6 is an alternate embodiment of a catheter 120 in
accordance with the present invention. Many elements of catheter
120 are similar to that of catheter 20 as shown in FIG. 2. Rather
than shaft 121 including a hypotube 22, shaft 121 includes a
plurality of elongate conductive members 122 embedded in a tubular
insulator 124. A distal portion of members 122 is preferably left
uninsulated to form a generally annularly shaped array of
electrodes 123. A stop 128 is disposed within tubular member 124.
Stop 128 defines a lumen 130 extending therethrough. Stop 128
includes distal end 132 spaced a predetermined distance proximally
of distal ends 134 at electrodes 123 to control the depth of the
holes created by catheter 123. It can be appreciated by those
skilled in the art that catheter 120 can be used in substantially
the same manner to perform PMR as catheter 20 shown in FIG. 3. A
plurality of electrodes, having a surface area less than a
continuous annular electrode requires less energy to arc or ablate.
A plurality of electrodes will also tend to grab tissue,
stabilizing the electrode on a moving heart wall.
[0037] FIG. 7 is a perspective view of a modified embodiment of
catheter 20 of FIG. 2. In particular, the distal end of hypotube 22
has been serrated to form a serrated electrode 40. Serrating
electrode 40 changes the surface of the electrode contacting the
tissue and thus reduces the power needed to arc. Serrated electrode
40 will also grab tissue, securing electrode 40 to a moving heart
wall during crater formation.
[0038] FIG. 8 is a view of yet another embodiment of catheter 20 in
accordance with the present invention. To catheter 20 has been
added a second grounded or return electrode 31 to form a bi-polar
RF PMR catheter. It can be appreciated that this electrode can also
be added to catheter 120 of FIG. 6 and catheter 20 of FIG. 7 to
make each of these embodiments bi-polar as well.
[0039] FIG. 9 is a perspective view of yet another embodiment of a
catheter 210 in accordance with the present invention disposed
within a guide catheter 212. Catheter 210 includes an elongate
shaft 214. Elongate shaft 214 is preferably formed from an elongate
tubular, and conductive member such as a stainless steel or Nitinol
hypotube. Shaft 214 defines an infusion lumen therethrough. The
wall of the lumen and the exterior shaft 214 are preferably
insulated, by a layer of, for example, polyethylene. An electrode
216 is connected to shaft 214 by solder or another conductive
connection.
[0040] Electrode 216 can be formed from a wire or ribbon shaped
member which extends distally from shaft 214 to a generally
linearly and transversely extending distal end 218. All but distal
end 218 of electrode 216 can be insulated with, for example, PTFE
to focus RF energy at end 218. Electrode 216 can be partially or
completely surrounded by a hood 220 extending from shaft 214. Hood
220 preferably defines an infusion lumen in fluid communication
with the infusion lumen of shaft 214. All or a portion of electrode
216 can be disposed in the infusion lumen. Hood 220 includes a
distal end 222. Distal end 218 could be plated with gold or other
radiopaque material to act as a marker.
[0041] FIG. 10 is a cross-sectional view of hood 220 showing
electrode 218 extending distally beyond distal end 222. By
contrast, in FIG. 11, electrode 216 is entirely disposed proximally
of end 222. In FIG. 12, distal end 218 of electrode 216 is disposed
flush with end 222 of hood 220. The relative positioning of hood
220 and electrode 216 can have an effect on the depth of craters
formed by catheter 210, as explained in more detail below.
[0042] FIG. 13 is a view directly into a crater 223 formed by a
typical electrode 218 viewed from a perspective perpendicular to a
surface 224 of endocardium 226. Crater 223 extends into myocardium
228 of a patient's heart. FIG. 14 is a cross-sectional view of
crater 223 of FIG. 13.
[0043] The depth D of crater 223 is a function of the power
delivered to electrode 216 and the relative position of the
electrode 216 to distal end 222 of hood 220. The more power
delivered to electrode 216, the greater the depth of crater 223.
With respect to the position of electrode 216 relative to hood 220,
the position of electrode distal end 218 relative hood distal end
222 of FIG. 10 creates the deepest crater. The positioning shown in
FIG. 11 would create the shallowest, whereas the positioning of
FIG. 12 would create a crater of intermediate depth.
[0044] The width W of crater 223 is a function of the transverse
extent of distal end 218 of electrode 216, and the power delivered
to the electrode. The greater the transverse extent of distal end
218, the greater the width of crater 223. The more power that is
delivered to electrode 216, the wider will be crater 223.
[0045] In use, catheter 210 is preferably advanced percutaneous to
the endocardium of a patient's heart. This route will normally be
by way of the femoral artery and the aorta to the left ventricle.
Distal end 222 is brought into contact with the endocardium,
preferably, such that the perimeter of distal end 222 is entirely
in contact with the endocardium. Electrode 216 disposed in one of
the positions shown in FIGS. 10-12, is energized to form a crater.
A fluid under pressure is then forced into the crater by way of the
infusion lumen through shaft 214 and hood 220. This fluid can be
saline, contrast media, a drug or any combination of these. By
forcing fluid under pressure into the myocardium, the vessels,
capillaries, and sinuses will be collaterally damaged within an
area 230 about crater 223. This will increase the healing response
by angiogenisis associated with the crater. The likelihood of
perforating the myocardium is reduced as the depth of the crater
need only be sufficient to penetrate the endocardium.
[0046] The following are exemplary technical specifications for
catheter 210 as configured in FIG. 12:
[0047] A. Output power vs. impedance specifications-channel or
crater making PMR device;
[0048] 1. Output power vs. impedance is preferably flat across a
wide range of impedance values for desired therapeutic power
level.
[0049] 2. Exemplary power requirements: a) output power
approximately 30-40 watts into 100 to 10,000 ohms; b) output
voltage approximately 1,200 to 2,000 V P-P into approximately 100
to 10,000 ohms; c) output current approximately 100 to 300 ma P-P
into about 100 to 10,000 ohms voltage is preferably large enough to
sustain cutting effect for a given electrode while delivery current
as low as possible.
[0050] B. The RF wave form is preferably 500 KHz or higher
unmodulated continuous sine wave.
[0051] C. The delivery type can be mono-polar delivery with small
area dispersive electrode for lower power applications.
[0052] D. RF delivery control.
[0053] 1. Preferably fixed power to provide cutting effect.
[0054] 2. Delivery controlled by application timer preferably fixed
at about 0.6 to 1.0 seconds.
[0055] It can be appreciated, that angiogenisis is also stimulated
by the thermal injury creating the crater, and fluid pressure
entering the myocardium from the left ventricle through the
endocardium by way of the crater. Hemorrhaging of the
subendocardial vasculature may also occur in response to adjacent
tissue ruptures or ablation.
[0056] FIG. 15 is a front view of an elongate electrode 300 having
an angled distal end 302. Disposed on the front of electrode 300 is
an asymmetrical radiopaque marker 304. Marker 304 could be formed
from, for example, gold or platinum. As electrode 300 is rotated
180.degree. around its longitudinal axis, electrode 300 will appear
as shown in FIG. 16. FIG. 16 is a fluoroscopic back side view of
electrode 300 wherein marker 304 appears in mirror image to its
position FIG. 15.
[0057] FIG. 17 is a side view of electrode 300 rotated 90.degree.
round about its longitudinal axis relative to its position in FIG.
15. It can be appreciated that by providing an asymmetrical marker
band, the relative rotational position of the catheter or electrode
in a patient can be determined by fluoroscopy.
[0058] FIGS. 18 and 19 are views of the front and back,
respectively of electrode 300 including an alternate marker 306
configured as an F. It can be appreciated that various asymmetrical
marker configurations can be used in accordance with the present
invention.
[0059] It is noted several times above that contrast media can be
infused into the holes, craters, wounds, or channels formed during
a PMR procedure. Normal contrast media formulations will tend to
dissipate rapidly into the patient's blood stream as the patient's
heart continues to beat. In order to retain the contrast media
within the crater for an extended period of time, a mixture of 498
Loctite.TM. adhesive can be radiopaque loaded with platinum or
other biocompatible radiopaque material to a weight percentage
sufficient to be visible under fluoroscopy.
[0060] In use, the catheters of the present invention can be
advanced percutaneously to a chamber of a patient's heart, for
example, the left ventricle. The percutaneous route for advancement
will generally be by way of the femoral artery and the aorta. The
electrode is then brought into close proximity with the chamber
wall. The electrode is energized and repeatedly plunged into the
myocardium to form a plurality of holes.
[0061] Numerous advantages of the invention covered by this
document have been set forth in the foregoing description. It will
be understood, however, that this disclosure is, in many respects,
only illustrative. Changes may be made in details, particularly in
matters of shape, size, and arrangement of parts without exceeding
the scope of the invention. The inventions's scope is, of course,
defined in the language in which the appended claims are
expressed.
* * * * *