U.S. patent number 3,902,501 [Application Number 05/372,269] was granted by the patent office on 1975-09-02 for endocardial electrode.
This patent grant is currently assigned to Medtronic, Inc.. Invention is credited to Paul Citron, Eugene A. Dickhudt.
United States Patent |
3,902,501 |
Citron , et al. |
September 2, 1975 |
Endocardial electrode
Abstract
A medical electrode uniquely adapted for use as an endocardial
electrode. An electrical conductor is encased in a material which
is generally inert to body fluids and terminates at an exposed
electrically conductive tip. A plurality of pliant tines extend
from the electrode adjacent the tip and form an acute angle with
the electrode body. Provision is made for holding the tines against
the electrode body during insertion while allowing their release
when the tip is in position. The released tines cooperate with the
heart tissue, particularly the trabeculae found in the ventricles
and the right atrial appendage, to maintain the electrode tip in
position.
Inventors: |
Citron; Paul (New Brighton,
MN), Dickhudt; Eugene A. (St. Paul, MN) |
Assignee: |
Medtronic, Inc. (Minneapolis,
MN)
|
Family
ID: |
34312054 |
Appl.
No.: |
05/372,269 |
Filed: |
June 21, 1973 |
Current U.S.
Class: |
607/126 |
Current CPC
Class: |
A61N
1/057 (20130101) |
Current International
Class: |
A61N
1/05 (20060101); A61n 001/04 () |
Field of
Search: |
;128/418,419P,404,2.5F,407-409,242-244,325,344,345,348-350,DIG.16,2.6E |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
schaldach, "New Pacemaker Electrodes," Trans: Am. Society For
Artificial Internal Organs, Vol. 17, 1971, pp. 29-35. .
Wende et al., "Neve intrakardicle Schrittmacherelektrode," Deutsche
Medizinische Wochenschrift, Nr. 40, 2, Oct. 1970, pp. 2026-2028.
.
Pieper, "Registration of Phesic Changes of Blood Flow by Means of
Catheter Type Flowmeter," Review of Sci. Instr., Vol. 29, No. 11,
Nov. 1958, pp. 965-967..
|
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Cohen; Lee S.
Attorney, Agent or Firm: Schwartz; Lew Sivertson; Wayne
A.
Claims
What is claimed is:
1. In an endocardial lead of the type having an electrical
conductor encased in a material which is generally inert to body
fluids, the conductor terminating at an exposed electrically
conductive electrode tip, the improvement which comprises:
nonconducting tine means extending from said encasing material and
away from said tip from a location adjacent said tip for
cooperating with heart tissue, to hold the tip in position, said
tine means forming a generally acute angle with said encasing
material and being entirely of a pliant material having sufficient
rigidity to maintain said angle when said tine means are
unrestrained, but sufficiently pliant to prevent penetration of
said heart tissue, said pliant material being generally inert to
body fluids.
2. The lead of claim 1 wherein the improvement further comprises
means external to said encasing material for releasably restraining
said tine means in a position overlying said encasing material.
3. The lead of claim 2 wherein said restraining means comprises
shroud means for accepting at least the end portion of said tine
means.
4. The lead of claim 3 wherein said restraining means further
comprise means cooperating with said shroud means for effecting the
release of said tine means at a point spaced from said shroud
means.
5. The lead of claim 3 wherein the improvement further
comprises:
inflatable means underlying said tine means when said tine means
are in said restrained position; and
means spaced from said inflatable means for selectively inflating
said inflatable means.
6. The lead of claim 4 wherein said tine means are
non-metallic.
7. An endocardial lead which comprises:
elongated electrically conductive means;
flexible catheter means surrounding said electrically conductive
means and having a lumen substantially parallel to and coextensive
with said electrically conductive means;
electrically conductive tip means at one end of said catheter means
and electrically connected to said electrically conductive means;
and
nonconducting tine means extending from said catheter means and
away from said tip from a point adjacent said tip means for
cooperation with heart tissue, to hold the tip in position, said
tine means forming a generally acute angle with said catheter means
and being entirely of a pliant material having sufficient rigidity
to maintain said angle when said tine means are unrestrained, but
sufficiently pliant to prevent penetration of said heart tissue,
said pliant material being generally inert to body fluids.
8. The lead of claim 7 further comprising means for releasable
restraining said tines in a position wherein they overlie said
catheter means.
9. The lead of claim 8 wherein said restraining means comprises
shroud means for accepting at least the end portion of said tine
means.
10. The lead of claim 9 wherein said restraining means further
comprises means cooperating with said shroud means for effecting
the release of said tine means at a point spaced from said shroud
means.
11. The lead of claim 9 wherein said catheter means comprises a
balloon catheter, the balloon underlying the tines when the tines
are in the restrained position.
12. The lead of claim 11 wherein said elongated electrically
conductive means comprises a coiled electrical conductor having a
void central portion, said lumen coinciding with said void central
portion.
13. The lead of claim 11 wherein said elongated electrically
conductive means is positioned substantially at the center of the
cross section of said catheter means and said lumen lies off the
center of said cross section.
14. In a medical lead of the type in which an electrical conductor
is positioned within a catheter and terminates at an exposed
electrically conductive electrode tip, the improvement which
comprises:
nonconducting tine means including a plurality of tines each
extending from said catheter and away from said tip from a point
adjacent said tip and forming an acute angle with said catheter for
cooperating with heart tissue to hold the tip in position, said
tine means being entirely of a pliant material having sufficient
rigidity to maintain said angle when said tine means are
unrestrained, but sufficiently pliant to prevent penetration of
said heart tissue;
means for releasably restraining said tine means in a position
wherein said tine means overlie said catheter; and
means underlying said tine means when said tine means are in said
restrained position and inflatable from a point spaced from said
restraining means for releasing said tine means from said
restraining means upon inflation.
15. The medical lead of claim 14 wherein the angle formed by said
tine means and said catheter is approximately 45.degree..
16. The medical lead of claim 14 wherein said pliant tine means
material comprises a material which is relatively inert to body
fluids, at least a portion of said material being radiopaque.
17. The medical lead of claim 16 wherein the radiopaque material
portion is a material treated with a material selected from the
group consisting of carbon, barium sulfate or Tantalum.
Description
BACKGROUND OF THE INVENTION
Electrical stimulation of heart action is well-known and has been
employed to counter a variety of heart dysfunctions. Dependent upon
the particular dysfunction, optimal placement of the electrical
contact point or points may vary. However, optimal electrode
placement has often been sacrificed to other considerations such as
minimization of the surgical risk and reliability of the electrode
securement. To date, the greatest number of electrodes have been
ventricular electrodes with the transvenous-endocardial approach
coming into the fore in recent years.
The advantages of a reliable electrical contact with the atrium are
well-known. Such a contact would allow atrial pacing or atrial
synchronized pacing thereby preserving the contribution of the
atrial contraction in the overall cardiac output. Additionally, an
atrial contact would be advantageously employed for arrhythmia
management and other purposes which may not be accomplished through
ventricular electrical stimulation. For reasons well-known to those
skilled in the art, the greatest advantages can be obtained through
an electrical contact with the right atrium, the right atrial
appendage providing a suitable site.
An attempt to accomplish transvenous or endocardial atrial pacing
is described in Smyth et. al. "Permanent Transvenous Atrial Pacing,
An Experimental and Clinical Study", The Annals of Thoracic
Surgery, Volume 11, No. 4, Apr. 19, 1971, pages 360-70. Here, a
J-shaped catheter with a flange near the tip was inserted into the
right atrial appendage through a transvenous approach. The catheter
was straightened by the insertion of a stylet. When the stylet was
withdrawn, the catheter assumed its preformed J shape for placement
of the electrode tip in the atrial appendage. There was no attempt
to artificially secure the electrode tip in position, the atrial
trabeculae and shape of the catheter being relied upon to maintain
it in location until the heart tissue itself enveloped and fixed
the tip. The metal parts of the catheter may be radiopaque to
facilitate placement by viewing through fluoroscopy.
A sensing atrial endocardial electrode is described in Portsmann
et. al., "P Wave Synchronous Pacing Using Anchored Atrial Electrode
Implanted Without Thoractomy", The American Journal of Cardiology,
Volume 30, July 11, 1972, pages 74-76. A J-shaped applicator
catheter was used to direct the electrode tip into the right atrial
appendage. The electrode however, had two fine wire hooks
positioned at its tip each ending in a relieving loop. The hooks
were held back by the applicator catheter to spring out and anchor
the electrode in the trabeculae of the right atrial appendage when
the electrode tip left the end of the applicator catheter.
In the applicator catheter technique described above, the
applicator catheter was radiopaque so that it could be viewed as it
was inserted into the right atrial appendage. It is imperative with
the double hook tip that the electrode be properly placed before
the hooks are released. The placement was checked not only through
fluoroscopy but also by extending the tip slightly beyond the end
of the applicator catheter to take a threshold measurement. The tip
had to be extended sufficiently to take an accurate measurement
while still retaining the hooks within the applicator catheter.
Because of its size, it is extremely difficult to accomplish this
test measurement without also releasing the hooks. Additionally,
the metallic nature of the hooks, their sharp points and spring
action creates the possibility that the hooks may perforate the
wall of the appendage if the catheter tip is not precisely
positioned. Also, the configuration and rigidity of the hooks make
it extremely difficult to remove the electrode without damage to
the heart tissue while its metallic properties severely limit its
utility as a pacing electrode.
SUMMARY OF THE PRESENT INVENTION
The present invention provides an electrode uniquely adapted for
use as an atrial endocardial electrode. The electrode may be
positioned in the right atrial appendage through the use of a
J-shaped catheter known to the prior art. Alternatively, a J-shaped
stylet may be employed which is held in a straightened position by
the walls of the vein used to approach the heart, the stylet
assuming its J-shape upon entry into the right atrium. A plurality
of pliant non-conductive tines are provided at the tip of the
electrode to cooperate with the heart tissue, particularly the
trabeculae found in the right atrial appendage, to maintain the
electrode tip in electrical contact with the heart tissue while
allowing a removal of the electrode should that prove necessary.
Provision is also made for holding the tines against the electrode
body during insertion while allowing their release when the tip is
in position and after a test threshold measurement. Although the
electrode is discussed in the context of the right atrial
appendage, it is suitable for use in any portion of the heart
having the requisite cooperating tissue and may be employed as
either a sensing or pacing electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a preferred embodiment of the present invention.
FIG. 2 shows a cross section of the preferred embodiment of FIG. 1
taken along the line 2--2 in FIG. 1.
FIG. 3 shows a cross section of another preferred embodiment taken
along the line 2--2 in FIG. 1.
FIG. 4 illustrates apparatus which may be used with the preferred
embodiment of FIG. 1.
FIG. 5 shows a component of another preferred embodiment of the
present invention.
FIG. 6 shows a preferred embodiment of the present invention which
utilizes the component of FIG. 5, the tines being in a restrained
position.
FIG. 7 shows the embodiment of FIG. 6 with the tines
unrestrained.
FIG. 8 shows another preferred embodiment of the present
invention.
FIG. 9 shows still another preferred embodiment of the present
invention.
FIG. 10 shows a further preferred embodiment of the present
invention.
FIG. 11 shows a portion of the preferred embodiment of FIG. 10.
FIG. 12 shows a portion of the preferred embodiment of FIG. 10.
FIG. 13 shows an additional preferred embodiment of the present
invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to FIG. 1, there is shown a body member 10
terminating at an exposed electrically conductive tip 11 and a
plurality of tines 12 extending at an acute angle from the body
member 10 from a position adjacent the tip 11. The electrically
conductive tip 11 may be of any material suitable for the
environment; platinum-iridium, for example. The tines 12 are of a
pliant material which is generally inert to body fluids; silicone
rubber or polyurethane, for example. The tines 12 may be attached
to the body member 10 in any convenient manner. For example, the
tines may extend from, and be unitary with, a disc 13 which disc is
held in position between the body member 10 and tip 11.
Alternatively, the member 13 may be in the form of a ring which
lies over either the body member 10 or tip 11 and is adhered
thereto in any convenient manner. The tines 12 may take any angle
with the body member 10, their purpose being to cooperate with the
body tissue, particularly the trabeculae of the right atrial
appendage, to maintain the tip 11 in electrical contact with the
body tissue. It can be seen that an acute angle formed by the tines
12 and the body member 10 will have the greatest tendency to push
against and become involved with the cooperating trabeculae and
maintain the tip 11 in electrical contact. It has been found, that
an angle of approximately 45.degree. maintains the necessary
electrical contact is a very efficient manner. Further, any number
of tines may be used, three having proven to be adequate in most
situations.
Referring now to FIG. 2 wherein there is shown a cross section of a
preferred embodiment of the body member 10 of FIG. 1 taken along
the line 2--2. In this embodiment, an elongated electrical
conductor 15 runs substantially the length of the body member 10
and makes electrical contact with the tip 11. The conductor 15 is
encased within a catheter 16 of a material which is generally inert
to body fluids.
It is desirable that the catheter -- conductor combination be made
as flexible as possible. To accomplish this purpose while providing
the necessary rigidity for insertion of the electrode, a stylet
lumen 19 is provided, the stylet being within the lumen 19 during
insertion of the electrode and being withdrawn after placement is
accomplished. In a preferred embodiment, the stylet which is placed
into the lumen 19 has a J configuration similar to that of the
prior art applicator catheters. During insertion, the stylet is
maintained in a "straightened" configuration by the walls of the
vessel through which insertion is accomplished. When the electrode
tip reaches the atrium, the stylet assumes its J configuration
thereby allowing an easy insertion into the appendage. When the
placement of the electrode tip is accomplished, the stylet is
withdrawn. In this embodiment, the electrical conductor can be of
any known type, one preferred form being a multistrand wire of
platinum, for example, commonly referred to as "tinsel wire."
A second preferred form for the body member 10 is illustrated in
FIG. 3. Here, the electrical conductor is a coiled member 17 which
again runs substantially the length of the body member 10. The coil
17 is encased in a catheter 16 substantially identical to that
shown in FIG. 2. The central portion of the coil 17 is left at
least partially void to form a lumen 18 for the insertion of a
stylet, the stylet serving essentially the same function in this
embodiment as in the embodiment of FIG. 2. Further, in both the
embodiments of FIG. 2 and FIG. 3, the lumens 19 and 18 may be lined
with Teflon or any other appropriate material to facilitate the
insertion and removal of the stylet.
Referring now to FIG. 4, there is again shown an electrode body
portion 10 this time at the end farthest from the tip 11. In some
applications, a pin type connection to an external stimulator or
sensing device is desired. For this purpose, the body portion 10
commonly has an enlarged segment 20 from which extends the
connecting pin 21. If it is desired to insert the electrode through
the use of the J-shaped applicator catheter known to the prior art,
the catheter must be made sufficiently large to slide back over the
enlarged portion 20 or, alternatively, some other system for
removal of the catheter must be provided. Here, the applicator
catheter is shown at 22 of a size not sufficiently large to be
withdrawn over the enlarged portion 20. A cutting tool 23 is shown
adjacent the enlarged portion 20 and extending forward of the
enlarged portion with a wedge 24 and a knife blade 25. The cutting
tool 23 may be separate from the electrode body 10 or may be
attached thereto in any convenient manner. In operation, the wedge
portion 24 slips under the edge of the applicator catheter 22 and,
as the applicator catheter 22 is drawn toward the cutting tool 23,
the wedge will direct the catheter 22 into contact with the knife
blade which will then cut and separate it thus allowing the removal
of the applicator catheter over the enlarged portion 20.
The electrode shown in the embodiment of FIG. 1 may be successfully
inserted into the right atrial appendage through a transvenous
approach using the stylet technique of either FIGS. 2 or 3 or the
J-shaped applicator catheter technique. In the applicator catheter
technique, the tines 12 are not exposed during insertion. In the
stylet technique of either FIGS. 2 or 3, however, the tines are
non-restrained or extended during the entire operation. Although
the electrode may be successfully positioned in this condition, it
is found that the blood flow tends to draw the electrode tip into
the ventrical. For this reason, some means of restraining the tines
during insertion is desirable.
Referring now to FIG. 5, there is shown a balloon catheter similar
to the balloon catheters used for other applications. Specifically,
the catheter body 10 has a portion 30 which is inflatable from an
end 32. The inflation is accomplished through a lumen similar to
the stylet lumen 19 and 18 of FIGS. 2 and 3 respectively. Indeed,
the inflation can be accomplished through the stylet lumens 19 and
18, the lumens being made sufficiently large to accomodate the
stylet while allowing a passage for air to inflate the balloon. The
ballooning feature of the electrode body 10 may be accomplished in
any known manner. Referring now to FIG. 6, there is shown an
electrode having a body 10 and a tip 11 as described with reference
to the embodiment of FIG. 1. The body 10 is composed of a balloon
catheter as illustrated in FIG. 5 with the ballooning or inflatable
part lying adjacent the tip 11. A hold down shroud 31 is positioned
near the tip 11 and is adapted to receive at least the ends of the
tines 12 to restrain them in a position wherein they overlie the
inflatable portion 30 of the electrode body 10. With the tines in
this restrained position, a stylet may be inserted into a lumen
such as that illustrated in FIGS. 2 or 3 and the electrode inserted
through a transvenous approach without any interference from the
extended tines. When the electrode tip is believed to be in an
acceptable position as viewed by fluoroscopy, a test measurement
can be made. If the site of the electrode tip proves satisfactory,
the balloon 30 can be inflated from the end of the electrode still
outside the body causing the tines to withdraw from the shroud 31
and extend into their normal unrestrained position as illustrated
in FIG. 7. With the tines freed from the shroud 31 the inflating
pressure can be released and the balloon 30 will deflate to a
normal configuration. The shroud 31 may take any shape which can
accept at least the end portions of the tines 12. A ring which is
attached to the body by spaced tethers is an example of an obvious
modification of the shroud 31.
An alternative shroud to the shroud 31 of FIG. 7 is illustrated at
35 in FIG. 8. This shroud 35 again is adapted to accept at least
the end portion of the tines 12 to restrain them in a position
wherein they overlie the body of the electrode 10. A line 36 is
attached to the shroud 35 at 37, and when the tip is properly
positioned, a force on the line 36 will cause the shroud 35 to
withdraw thus freeing the tines 12 to assume their extended
unrestrained position. A similar approach is illustrated in FIG. 9
wherein a stylet 40 is shown having a coiled portion 41 which
coiled portion is wrapped around the tines causing them to lie flat
against the body member 10. Again, when the tip 11 is properly
positioned, the stylet will be withdrawn thereby freeing the tines
for interaction with the trabeculae of the right atrial appendage,
for example.
Referring now to FIG. 10, there is shown another preferred
embodiment of the present invention. Specifically, there is shown
an electrode body 10 composed of a connecting portion 50, a central
portion 51 and an end portion 52 which lies between the tip 11 and
the shroud 53. The cross section of the central portion 51 may be
as illustrated in FIG. 3. That is, the electrical conductor is a
coiled member 17 having a void lumen forming central portion 18,
the conductor extending from the tip 11 back to the connecting
portion 50. The connecting portion 50 is similar to that
illustrated in FIG. 4 with the connecting pin 54 making an
electrical contact with the electrical conductor 17 and having a
lumen coincident with the lumen 18 of the conductor 17. With this
configuration, it is possible to insert a stylet 55 through the end
of the connecting pin 54 to abut the tip 11. Inasmuch as the
electrical conductor is a coiled member it can be stretched or
elongated by applying a pressure against the tip 11 with the stylet
55. Since the electrical conductor is typically uniform throughout
its length, the location at which the electrode body will give or
elongate can be controlled to the durometer or diameter of the
electrode body, or both. For reasons to be explained more fully
below, it is desired that the portion 52 of the electrode body 10
"give" before the central portion 51 or the connecting portion 50.
Therefore, the portion 52 is illustrated as having a smaller
diameter than either the central portion 51 or the connecting
portion 50. Alternatively, the material comprising the portion 52
may have a lower durometer than either of the other portions of the
electrode body 10 or it may have a lower durometer and diameter, as
desired.
FIG. 11 illustrates the embodiment of FIG. 10 with the tines 12
having at least their ends restrained by the shroud 53 in a manner
substantially identical to that illustrated in FIG. 6. With the
tines in their restrained position, the electrode can be inserted
and positioned and, when a proper positioning is obtained as
described above, the stylet is forced against the tip 11 causing
the portion 52 to stretch as illustrated in FIG. 12 thereby
releasing the tines 12 from the shroud 53. With the tines released,
the stylet is removed thereby allowing the portion 52 to assume its
normal shape as illustrated in phantom at FIG. 12.
As stated with regard to the shroud 31 of FIGS. 6 and 7, the shroud
53 of FIGS. 10-12 may take the form of a ring connected to the
electrode body by means of a plurality of tethers. Such a ring
shroud is illustrated at 60 in FIG. 13. As can be seen, the shroud
60 has a ring or a "doughnut" configuration and is held in place by
means of tethers 61 which perform essentially as the spokes of a
wheel, the tethers 61 being positioned so as not to interfere with
the restraining and release of the tines 12.
From the above, it can be seen that the present invention provides
a new medical electrode uniquely adapted for use as an endocardial
electrode. The electrode provides means for cooperating with the
heart tissue, particularly the trabeculae of the ventricles and
right atrial appendage, to provide an artificial fixation until
such time as a natural fixation has occurred. The tines are of a
pliant material which is sufficiently rigid to accomplish their
purpose without having the snapping action and sharp points
attendant in the prior art devices. Further, the present invention
provides a system for positioning the electrode and making any
necessary test measurements prior to its being finally positioned,
the position of the tip with regard to the inserting devices being
much less critical in the present invention than in the prior art
devices because the tines may be selectively released independently
of the insertion device.
Obviously, many modifications and variations of the present
invention are possible in light of the above teaching. An example
of such a modification would be to make the body member 10 or the
tines 12, or both, radiopaque to facilitate the positioning by
observation of the electrode through X-ray, fluoroscopy, etc. We
have found that this can be accomplished through impregnation with
carbon, barium sulfate or Tantalum. Of course, any suitable
substance and method will be acceptable for this purpose. It is
therefore to be understood that, within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described.
* * * * *