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Claims  |
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What is claimed is:
1. A method of percutaneously implanting a defibrillation lead within the
intrapericardial space of a patient's heart, the defibrillation lead
having a distal electrode, a body, and proximal connection means capable
of making electrical contact to an implantable defibrillation device, the
method comprising the steps of:
distending the pericardium from the epicardium by injecting a small volume
of fluid into the pericardium, so that pericardial effusion results;
percutaneously perforating the pericardium by advancing a perforation
device having a lumen therethrough towards the distended pericardium until
the fluid flows out of the lumen, thereby indicating that the pericardium
wall has been perforated;
inserting a guide wire into the pericardium through the lumen of the
perforation device until a distal end thereof is positioned within the
pericardium;
enlarging the perforated opening in the pericardium by inserting an
introducer over the guide wire and into the tissue; and
inserting the distal electrode of the defibrillation lead within the
introducer until the distal electrode is likewise positioned within the
pericardium.
2. The method of claim 1 wherein the step of distending the pericardium
comprises:
transvenously attaching a screw-in catheter to the right atrial lateral
wall;
advancing a stylet having a tip through the catheter until the tip contacts
the atrial wall;
puncturing the atrial wall with the tip of the stylet; and
infusing the small volume of fluid through the catheter into the
pericardium.
3. The method of claim 1 wherein the step of perforating the pericardium
comprises:
plugging the lumen of the perforation device with a relatively rigid rod
prior to inserting the perforation device, the rigid rod preventing tissue
coring as the perforation device is inserted;
inserting the perforation device and rod only until a tip of the
perforation device is abutted against the pericardium;
removing the rigid rod from the lumen; and
perforating the pericardium at the point where the perforation device tip
is abutted against the pericardium, thereby making an opening in the
pericardium through which the perforation device tip may be inserted.
4. The method of claim 3 wherein the step of perforating the pericardium at
the point where the perforation device is abutted against the pericardium
further comprises inserting a cutting device into the lumen and cutting an
opening through the pericardium wall using the cutting device.
5. The method of claim 1 wherein the step of inserting the guide wire into
the distended pericardium comprises inserting the guide wire into the
distended pericardium from a sub-xiphoid position.
6. The method of claim 1 wherein the step of inserting the guide wire into
the distended pericardium comprises inserting the guide wire into the
distended pericardium from an intercostal position.
7. The method of claim 1 further comprising the step of tunneling the body
of the defibrillation lead to a desired tissue location, whereat the
proximal connection means of the defibrillation lead may be connected to a
desired defibrillation device.
8. The method of claim 1 wherein the step of inserting the distal electrode
into the pericardium further comprises the step of anchoring the distal
electrode within the pericardium.
9. The method of claim 8 wherein the step of anchoring the distal electrode
within the pericardium comprises the step of stimulating a fibrosis
attachment site within the pericardium whereat the distal electrode may be
anchored.
10. The method of claim 9 wherein the defibrillation lead further comprises
a heating element at its distal tip, and wherein the step of anchoring the
distal electrode within the pericardium further comprises acutely
attaching the distal electrode to the heart by selectively energizing the
heating element.
11. The method of claim 8 wherein the step of anchoring the distal
electrode within the pericardium comprises the step of capturing an
autologous blood clot on the distal electrode and coagulating it to the
pericardium.
12. The method of claim 11 further comprising the step of creating a small
lesion on the pericardium to promote adhesion of the coagulated blood clot
thereto.
13. The method of claim 12 wherein the steps of coagulating the blood clot
and creating a small lesion of the pericardium further comprise
selectively applying energy from an external source to the site of
attachment.
14. The method of claim 13 wherein the step of applying external energy to
the site of attachment comprises directing microwave energy from an
external microwave source on the site of attachment.
15. The method of claim 13 wherein the step of applying external energy to
the site of attachment comprises directing laser energy form an external
laser source to the site of attachment.
16. The method of claim 13 wherein the defibrillation lead further
comprises a heating element at its distal tip at the site of attachment
and electrical means for directing electrical energy to the heating
element, and wherein the step of applying external energy to the site of
attachment comprises applying electrical energy to the heating element
through said electrical means.
17. The method of claim 1 wherein the defibrillation lead comprises a
deployable defibrillation lead having a retracted position wherein the
distal electrode thereof is maintained in a retracted position, and a
deployed position wherein the distal electrode is extended so as to
provide a larger electrode surface area, and further wherein the step of
inserting the distal electrode of the defibrillation lead comprises
inserting the distal electrode through the introducer while in its
retracted position and extending the distal electrode to its deployed
position after the distal electrode has been inserted within the
pericardium.
18. A method of positioning at least one defibrillation lead within the
pericardium of a mammal, the defibrillation lead having deployable distal
electrode means for selectively placing an electrode in contact with a
desired tissue area when the electrode is deployed, and for selectively
maintaining the electrode in a retracted position, thereby facilitating
the movement and positioning of the electrode until the electrode is
positioned at a desired tissue location, the method comprising the steps
of:
(a) injecting a fluid between the heart and the pericardium, thereby
extending the pericardium away from the heart;
(b) percutaneously inserting a guide wire having a lumen therethrough into
the extended pericardium at a desired tissue contact location until the
fluid injected between the heart and the pericardium flows out of the
lumen, thereby indicating that the pericardium wall has been perforated;
(c) placing a sheath introducer into the pericardium over the guide wire;
(d) inserting the electrode, in its retracted position, within the
pericardium through the sheath introducer; and
(e) deploying the electrode within the pericardium, whereby the electrode
makes contact with a large tissue area at the desired tissue contact
location within the pericardium.
19. The method of claim 18 wherein the step of injecting a fluid between
the heart and the pericardium comprises:
transvenously attaching a screw-in catheter to the right atrial lateral
wall of the heart;
advancing a stylet through the catheter until a tip of the stylet contacts
the atrial wall;
puncturing a small hole in the atrial wall with the tip of the stylet; and
injecting the fluid through the catheter and through the punctured hole in
the atrial wall into the space between the heart and the pericardium.
20. The method of claim 18 wherein the step of percutaneously inserting the
guide wire comprises inserting the guide wire into the distended
pericardium from a sub-xiphoid position.
21. The method of claim 18 wherein the step of deploying the electrode
further comprises recording the ECG of said mammal to aid in correctly
positioning the electrode.
22. A method for anchoring a distal electrode of a defibrillation lead
within the pericardium comprising the steps of:
(a) capturing an autologous blood clot on the distal electrode;
(b) inserting the distal electrode within the pericardium; and
(c) coagulating the blood clot to tissue within the pericardium.
23. The method of claim 22 wherein step (c) further comprises creating a
small lesion in the tissue at the desired attachment site within the
pericardium to promote adhesion of the coagulated blood clot thereto.
24. The method of claim 23 wherein step (c) further comprises applying
external energy to the desired attachment site to create said lesion.
25. The method of claim 24 wherein said defibrillation lead further
comprises electrical means for directing electrical energy to the distal
electrode thereof, and wherein the step of applying external energy to the
site of attachment comprises applying electrical energy to the site of
attachment through said electrical means.
26. The method of claim 24 wherein the step of applying external energy to
the site of attachment comprises guiding microwave energy from an external
source to the site of attachment.
27. The method of claim 24 wherein the step of applying external energy to
the site of attachment comprises selectively guiding electromagnetic
energy from an external source to the site of attachment.
28. A system for implanting a defibrillation lead in a mammal, the mammal
having a heart surrounded by a pericardium, the system comprising:
a defibrillation lead having a deployable distal electrode that selectively
assumes a retracted position adapted to promote the positioning of the
distal electrode without having the distal electrode becoming entangled
with body tissue, and an extended position adapted to promote contact with
body tissue over a large area, the defibrillation lead having deployment
means for extending the distal electrode to its extended position;
means for injecting a fluid between the heart and the pericardium, thereby
extending the pericardium away from the heart;
a perforation device having a lumen therethrough, the perforation device
being sub-xiphoidally inserted toward the extended pericardium until the
fluid flows out of the lumen, thereby indicating that the extended
pericardium wall has been perforated; and
insertion means for inserting the defibrillation lead, with its deployable
distal electrode in its retracted position, into the pericardium until the
distal electrode is positioned at a desired location within the
pericardium.
29. The system of claim 28 wherein the defibrillation lead comprises
anchoring means for anchoring the distal electrode to the body tissue.
30. The system of claim 29 wherein said anchoring means comprises means for
capturing a blood clot on the distal electrode and means for coagulating
said blood clot to desired tissue within the pericardium.
31. The system of claim 30 further comprising means for making a small
lesion within the pericardium, said blood clot adhering to said small
lesion as coagulation occurs.
32. The system of claim 29 wherein said anchoring means comprises a heater
element within the distal electrode and means for applying electrical
energy thereto, and wherein heat generated by said heater element creates
a fibrosis attachment site within the pericardium whereat the distal
electrode is anchored.
33. The system of claim 28 wherein the perforation device comprises:
a blunt needle having a removable, rigid rod therethrough, the rod being
capable of preventing tissue coring as the needle is advance into the
pericardium.
34. The system of claim 28 wherein the perforation device comprises:
a housing; and
a cutting device within the housing, the cutting device having a sharp
cutting tip, a rigid body portion and a flexible, compressible coupling
portion located between the body portion and the tip, the coupling portion
being capable of transferring longitudinal forces from the body portion to
the tip while in the housing, and further being capable of buckling
without the lateral support of the housing.
35. The system of claim 28 wherein the perforation device comprises:
a percutaneous insertion needle;
a catheter having a blunt soft tip, the catheter being guided to the
pericardium over the insertion needle;
a cutting device recessed with the catheter;
means for applying suction between the catheter tip and the pericardium so
that the pericardium is pulled into the catheter tip and impaled on the
cutting device, thereby perforating the pericardium.
36. The system of claim 35 wherein the perforation device further
comprises:
a remotely activated fixation device located within the catheter for
fixating the catheter tip against the pericardium when the fixation device
is activated.
37. A defibrillation lead system comprising:
a sheath;
means for passing said sheath through a pericardium surrounding a heart
from a percutaneous position;
a defibrillation lead having a distal electrode, said defibrillation lead
being of a size that allows it to be slidably inserted through said sheath
until said distal electrode resides within the pericardium; and
means for anchoring said distal electrode to a desired location within the
pericardium, said anchoring means comprising means for stimulating a
fibrosis attachment site.
38. The lead system of claim 37 wherein said anchoring means comprises
means for capturing a blood clot on said distal electrode and means for
coagulating said blood clot to a desired attachment site within the
pericardium.
39. The lead system of claim 38 wherein said anchoring means further
comprises means for creating a small lesion in the body tissue at the
desired attachment site, which small lesion promotes the adhesion of the
coagulated blood clot thereto.
40. The lead system of claim 37 wherein said anchoring means comprises
means for passing platelets or whole blood near said distal electrode and
means for coagulating said platelets or whole blood to a desired
attachment site within the pericardium.
41. The lead system of claim 40 wherein said anchoring means further
comprises means for creating a small lesion in the body tissue at the
desired attachment site, which small lesion promotes the adhesion of the
coagulated blood clot thereto. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to implantable defibrillation leads
and electrodes, and more particularly to methods for the sub-xiphoid
implantation of deployable defibrillation electrodes, and means for
anchoring the same to tissue within the pericardium.
The pericardium is a membranous sac that encloses the heart. It consists of
an outer layer of dense fibrous tissue and an inner serous layer, termed
the epicardium, which directly surrounds the heart. Throughout the
description and claims that follow, the phrase "within the pericardium" or
"within the pericardial space" is used to mean any of the body tissue or
fluid found inside of the dense outer layer of the pericardium, including
the outer surface of the heart, but not including the interior of the
heart.
In recent years a serious effort has been undertaken to implant automatic
defibrillators in certain patients at high risk of experiencing
ventricular fibrillation or other heart disorders. When fibrillation or
related heart malfunctions are sensed by such devices, a large
defibrillation shock is automatically delivered to the heart in an attempt
to stimulate the heart back to a normal or near normal beating pattern.
The advantage of such implanted devices is that the life-saving
defibrillation shocks are delivered without any undue delay, as would
otherwise exist if external defibrillation pulses had to be delivered by
paramedics (or other medical personnel) who were summoned to the aid of a
heart-failing patient.
In order to minimize the energy of a defibrillation pulse, and thereby
improve the efficacy of the defibrillation system, it is preferred that
the defibrillation electrodes be in direct contact with the heart tissue.
Further, it is generally preferred that the electrodes cover large and
strategic areas of the heart, thereby allowing the delivered electrical
energy to be efficiently distributed throughout the fibrillating region.
Attempts at placing the defibrillating electrodes on the inside of the
heart, either in the atria or the ventricles, or both, similar to
stimulating electrodes used with pacemakers, have proven less than
satisfactory.
Accordingly, implantable defibrillation electrodes are preferably placed
around the exterior of the heart. Because of the large surface area
covered by such electrodes, they are typically referred to as "patch
electrodes", often resembling patches that are placed on the heart.
Although there are some shortcomings associated with placement of
defibrillation electrodes directly on the epicardial or endocardial
surfaces, the advantages are overwhelming.
In order to make the best possible contact with the heart tissue, it is
often desirable that implantable defibrillation electrodes be placed
within the pericardium, or within the pericardial space. Unfortunately,
however, pericardial placement of defibrillation leads is a dangerous and
difficult procedure that has heretofore generally required traumatic and
endangering surgery, usually open-chest surgery. Needless to say, not all
patients are suitable candidates for open-chest surgery, and even for
those that are, the risks, trauma, and danger associated with such surgery
make this procedure of electrode placement less than ideal.
In an attempt to minimize the problems associated with open-chest surgery
for the placement of epicardial defibrillation leads, it has been
suggested in the art to implant epicardial defibrillation leads
transvenously. Such an approach is described in patent application Ser.
No. 07/128,326, filed Dec. 3, 1987, entitled "Method For Transvenous
Implantation of Objects into the Pericardial Space of Patients," jointly
invented by the applicant named herein and Clyde D. Elliott. This prior
application, including the methods and leads described therein (hereafter
referred to as the "transvenous implantation approach"), is hereby
incorporated herein by reference.
In accordance with the transvenous implantation approach described in the
above-referenced prior application, a guide wire and a catheter are
inserted into the heart transvenously, with the aid of an introducer, as
required. Once in the heart, the atrial lateral wall is punctured, making
a hole therein, through which the non-deployed defibrillation electrode is
inserted, thereby entering the pericardial space. The non-deployed
electrode is further positioned within the pericardial space to a desired
position, and then the electrode is deployed so as to better contact a
larger surface area of the outside of the heart.
The transvenous implantation approach also suffers from several drawbacks.
For one, a fairly good size hole must be made in the atrial wall, and the
trauma and long term effects of such a hole are uncertain. Further, the
approach is generally limited to an introducer not much larger than a Fr
14. (A FR 14 instrument is approximately 4.7 millimeters in diameter.)
Additionally, the introducer's path is somewhat tortuous, resulting in
challenging lead placement. Moreover, once the lead is placed, the ensuing
connection of the lead to the site of the implanted defibrillator is
non-trivial.
From the venous location of the lead, the lead connector must then be
tunneled to the defibrillator site, generally in the abdomen. These
limitations place severe restrictions on the geometry and flexibility of
the electrode and the deployment system. For small, easily deployed lead
systems, the transvenous implantation approach offers a very viable
alternative to open chest surgery, particularly if a long tunneled lead is
not objectionable. However, in the event very large surface electrodes are
desired, or if tunneling is undesirable, the transvenous approach is
probably no more effective, and perhaps less effective, than a more direct
surgical approach. What is needed, therefore, is a method and system for
placing defibrillation leads in the propitious pericardial space that
avoids the major problems associated with both the open-chest surgery
approach and the transvenous implantation approach. The present invention
advantageously addresses this need.
SUMMARY OF THE INVENTION
The disadvantages and limitations of the background art discussed above are
overcome by the present invention. With this invention, a method and
system for positioning an epicardial defibrillation electrode(s) within
the pericardial space are disclosed. Advantageously, the present invention
recognizes that a small sub-xiphoid or other percutaneous access into the
mediastinum (the space bounded by the two pleural membranes, the
pericardium and the diaphragm) can be used to provide a direct access to
the pericardium, through which an introducer can be placed.
Such a sub-xiphoid or other introducer can easily be twice the diameter of
a subclavian venous introducer, yet its placement can be less painful and
cause less damage. Hence, this percutaneous direct access to the
pericardial space is preferable over the transvenous implantation approach
because it presumably (1) is easier to achieve, and (2) affords more
latitude in the lead choice, placement and design, and (3) will entail
less mortality and morbidity.
One of the most critical considerations of the method and system of the
present invention lies in gaining direct percutaneous access to the
pericardial space without puncturing or otherwise damaging the heart. This
is because, in the absence of a pericardial effusion, any attempt to
introduce a sharp object percutaneously with the intent of piercing the
pericardium would almost certainly also invade the myocardium.
To address this concern, the present invention includes means for
distending the pericardium from the heart by injecting a small volume of
fluid into the pericardium, thus creating a pericardial effusion. This
injection extends the pericardium away from the heart. A conventional
needle having a lumen therethrough is then inserted from the desired
percutaneous location into the body tissue until a tip thereof punctures
the distended pericardium at a selected location.
Several means are available for the accurate detection of the moment that
the needle tip enters the pericardium before it cuts the epicardium. Among
the possibilities are (1) fluoroscopic guidance, (2) monitoring of the
force resisting the needle advancement, (3) ECG recording using the needle
as an electrode, and (4) pressure monitoring. Perhaps the simplest method
may be the most precise and reliable. That is, the egress of the injected
fluid through the needle lumen signals that the pericardial space has been
entered and that further insertion of the needle can be stopped (else the
needle may puncture the heart).
A guide wire is next inserted into the pericardium through the lumen of the
needle, whereupon the needle may be removed. A suitable sheath or
introducer is then placed over the guide wire and inserted into the tissue
until a distal end thereof is positioned within the pericardium. The
defibrillation lead, with its electrode in a retracted position, is next
inserted through the sheath or introducer until the electrode is likewise
positioned within the pericardium, whereupon the electrode is deployed in
order to make contact with a large area of tissue within the pericardium.
The preferred percutaneous position from which access to the pericardium is
attempted in accordance with the present invention is a sub-xiphoid
position. However, it is to be understood that other access paths to the
pericardium from a percutaneous location could also be used, such as
intercostal access.
The present invention thus includes a method of implanting defibrillation
leads within the pericardial space of a mammal that includes the following
steps: (a) distending the pericardium; (b) inserting guide means into the
distended pericardium from a desired percutaneous position, such as a
sub-xiphoid position; (c) inserting the defibrillation lead(s) into the
pericardium following these guide means, where following the guide means
may include inserting the lead within the guide means or over the guide
means, or where the guide means may include two elements and the lead is
inserted over one and within the other; and (d) tunneling the body of the
defibrillation lead to a desired tissue location, whereat it may be
connected to a desired defibrillation device.
Further, the present invention includes a method of positioning
defibrillation leads within the pericardium of a mammal. The
defibrillation lead(s) used with such a method preferably has a deployable
distal electrode means for selectively placing an electrode in contact
with a large tissue area when the electrode is deployed, and for
selectively maintaining the electrode in a retracted or non-deployed
position when the electrode is being inserted through a narrow opening.
This method of positioning includes the steps of: (a) injecting a fluid
between the heart and the pericardium, thereby extending the pericardium
away from the heart; (b) percutaneously, e.g., sub-xiphoidally, inserting
guide means into the extended pericardium to a desired tissue contact
location; (c) inserting the electrode, in its retracted position, within
the pericardium by following the guide means; and (d) deploying the
electrode within the pericardium, thereby making contact with a large
tissue area at the desired tissue contact location within the pericardial
space.
Moreover, the present invention includes a method for anchoring a distal
electrode of a defibrillation lead within the pericardial space. This
anchoring method comprises the steps of: (a) capturing an autologous blood
clot on the distal electrode; (b) inserting the distal electrode within
the pericardium; and (c) coagulating the blood clot to tissue within the
pericardium.
Further, the present invention may be characterized as a system for
implanting one or more defibrillation leads in a mammal, such as a human,
the mammal having a heart surrounded by a pericardium. The defibrillation
lead(s) used in such a system preferably has a deployable distal electrode
that selectively assumes a retracted or extended position, the retracted
position being adapted to promote the positioning of the distal electrode
without having the distal electrode becoming entangled with body tissue,
and the extended position being adapted to promote contact with body
tissue over a large surface area.
However, it is to be emphasized that the implanting system works equally
well with non-deployable electrodes. This implanting system includes:
means for injecting a fluid between the heart and the pericardium, thereby
extending the pericardium away from the heart; means for percutaneously
inserting a guide means into the extended pericardium; sheath means for
directing a sheath introducer into the pericardium over the guide means;
insertion means for inserting the defibrillation lead, with its deployable
distal electrode in its retracted position, into the pericardium through
the sheath; and deployment means for extending the distal electrode to its
extended position once it is positioned as desired within the pericardium.
The present invention is further characterized as a defibrillation lead
system that includes: a sheath; means for percutaneously, e.g.,
sub-xiphoidally, inserting a distal end of the sheath into the pericardial
space surrounding the heart; a defibrillation lead having at least one
distal electrode, the defibrillation lead being of a size that allows it
to be slidably inserted through the sheath until the distal electrode(s)
resides within the pericardial space; and means for anchoring the distal
electrode to a desired location within the pericardial space.
As will be evident from the description that follows, it is a feature of
the present invention to provide a simple, safe and efficacious method and
system of implanting one or more defibrillation electrodes into the
propitious pericardial space of a mammalian heart.
It is another feature of the invention to provide such a method of
epicardial defibrillation electrode placement that is less traumatic and
dangerous than prior methods used for this purpose, such as open-chest
surgery or transvenous implantation techniques.
It is yet another feature of the invention to provide a flexible
implantation method and system that allows a wide range of different types
and sizes of electrodes to be implanted in the pericardial space.
It is still a further feature of the invention to provide a means for
anchoring a defibrillation electrode to a desired tissue location within
the pericardium. Advantageously, this anchoring means utilizes natural
bonding mechanisms or agents, such as coagulated blood, to effectuate the
desired adhesion between the lead and the pericardium.
DESCRIPTION OF THE DRAWINGS
These and other advantages of the present invention are best understood
with reference to the drawings, in which:
FIG. 1 is a simplified diagram of a mammalian heart surrounded by a
pericardium, and further shows a defibrillation electrode positioned
therein and connected to an implantable defibrillation device;
FIG. 2A is a simplified diagram of the heart of FIG. 1 prior to placement
of the electrode in the pericardial space;
FIG. 2B is a diagram as in FIG. 2A illustrating a distended pericardium
resulting from injecting a fluid into the pericardial space through a
fixation catheter that has been attached transvenously to the interior of
the atrial wall;
FIG. 3A is a schematic perspective view of the fixation catheter of FIG. 2B
prior to its attachment to the atrial wall;
FIG. 3B is a schematic perspective view, shown partially in cross section,
showing the fixation catheter of FIG. 2B after its attachment to the
atrial wall, and further illustrating a J-tip guide wire puncturing the
atrial wall to form a hole through which the fluid used to distend the
pericardium may be injected;
FIG. 4 is a simplified schematic drawing illustrating the manner of making
sub-xiphoid access with a needle to the pericardium;
FIG. 5A is an expanded view of the sub-xiphoidally inserted needle tip of
FIG. 4 as the needle tip just makes contact with the pericardial wall;
FIG. 5B is a view as in FIG. 5A after the needle tip has punctured the
pericardial wall, and further illustrates the fluid in the pericardial
space egressing via the lumen in the needle;
FIG. 5C is a view similar to FIG. 5A wherein a special perforation device
is inserted in the lumen of the needle to aid in cutting through the
pericardial wall;
FIG. 5D is a view as in FIG. 5C where the perforation device has punctured
through the pericardial wall;
FIG. 6A is a view as in FIG. 5B further illustrating a guide wire or stylet
inserted through the lumen of the needle into the pericardial space;
FIG. 6B is a view as in FIG. 6A further depicting a catheter inserted into
the pericardial space over the needle and guide wire;
FIG. 6C is an elevated view of the distal tip of an expanding pleated
sheath or catheter that may optionally be used to gain access into the
pericardial space;
FIG. 7 shows the distal end of one type of defibrillation lead that could
be used with the present invention, showing the electrode thereof in a
partially retracted position;
FIG. 8 is an electrical schematic diagram of the lead of FIG. 7;
FIG. 9 is an exploded view of a section of the pericardial space and heart
as in FIGS. 5A through 6B further illustrating the electrode of FIGS. 7
and 8 positioned within the pericardial space adjacent the heart;
FIGS. 10A | | |
