U.S. patent number 3,924,639 [Application Number 05/489,187] was granted by the patent office on 1975-12-09 for cardiac pacer lead system for interim pacing during pacer changeover.
This patent grant is currently assigned to Cordis Corporation. Invention is credited to Stanley R. Hess.
United States Patent |
3,924,639 |
Hess |
December 9, 1975 |
Cardiac pacer lead system for interim pacing during pacer
changeover
Abstract
In the cardiac pacer lead assembly disclosed herein, a mass of a
conductive silastic is cast about the flexible metallic lead,
adjacent its connection with the pacer. A jacket of insulating
silastic is cast over the conductive silastic and this jacket
extends to the usual insulating sheath covering the flexible lead.
By inserting a needle-like element through the insulating jacket
and into the conductive silastic, a physician can establish a
connection for interim pacing, i.e. when the lead is disconnected
from a pacer being replaced and the replacement is not yet
connected.
Inventors: |
Hess; Stanley R. (Miami,
FL) |
Assignee: |
Cordis Corporation (Miami,
FL)
|
Family
ID: |
23942757 |
Appl.
No.: |
05/489,187 |
Filed: |
July 17, 1974 |
Current U.S.
Class: |
607/122; 439/86;
174/74R |
Current CPC
Class: |
A61N
1/0587 (20130101) |
Current International
Class: |
A61N
1/05 (20060101); A61N 001/04 () |
Field of
Search: |
;128/418,419P,419PS,419C,419E,404 ;339/DIG.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
84,040 |
|
Aug 1971 |
|
DT |
|
1,469,132 |
|
Jan 1967 |
|
FR |
|
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Cohen; Lee S.
Attorney, Agent or Firm: Kenway & Jenney
Claims
What is claimed is:
1. A pacer interconnection and lead system for use with an
implantable cardiac pacer, which system facilitates interim pacing
of a patient's heart during pacer replacement, the pacer having a
connector terminal through which signals are coupled for pacing the
heart of a patient, said pacer interconnection and lead system
comprising:
a flexible, electrical lead;
over said lead, for a majority of its length, an insulating
sheath;
at one end of said lead, an electrode adapted to contact cardiac
tissue for applying stimulating pulses thereto;
at the other end of said lead, a connector adapted to engage said
pacer terminal for coupling stimulating signals generated by said
pacer to said electrode;
in the region of the juncture of said lead and said connector, a
mass of conductive, rubbery material electrically interconnected
with said lead;
an insulating rubbery jacket extending over said conductive mass
from said insulating sheath;
auxiliary connection means including a needle-like conductive
element insertable through said jacket to establish electrical
contact with said conductive rubbery mass to permit interim pacing
of a patient's heart during replacement of a pacer; and
guide means for directing said needle-like element into said
conductive rubbery mass without directly contacting said lead.
2. A lead system as set forth in claim 1 wherein the lead is
helically coiled.
3. A lead system as set forth in claim 2 wherein said sheath is
tubular and loosely encloses said helically coiled lead.
4. A lead systems as set forth in claim 1 wherein said conductive
material is a conductive silicone rubber.
5. A lead system as set forth in claim 4 wherein said jacket is an
insulating silicone rubber.
Description
BACKGROUND OF THE INVENTION
This invention relates to cardiac pacing and more particularly to a
cardiac pacer lead system permitting cardiac pacing to be
maintained essentially continuously during pacer replacement,
especially with unipolar pacers.
While research continues to go forward on developing batteries and
other power sources which will provide longer life in a cardiac
pacemaker, present practice in most cases is to plan and provide
for periodic replacement of the pacemaker unit with its integral
batteries. For this reason, among others, the pacer unit itself is
typically implanted in a location remote from the patient's heart.
The location is selected so that access to the pacer itself can be
obtained by means of a relatively simple surgical procedure as
compared with that required when the pacer and stimulating
electrode are initially installed or placed.
The battery powered pacer unit is typically connected to the lead
and electrode assembly by means of some sort of separable connector
so that, after a preselected interval or upon the occurrence of
some change indicating battery failure, the pacer circuit itself
can be replaced while retaining the originally installed electrode
and lead assembly. While such an arrangement facilitates the
replacement of the pacer unit, some problems have still remained
with respect to the patients who require essentially continuous
pacing. If pacing is not maintained while the substitute pacer is
installed, the attending physician will be under considerable
pressure to work quickly. Thus, a danger exists that the connector
might not be properly assembled or sealed, due to the haste
required. Likewise, the need for the essentially continuous
presence of the pacemaker circuit may render it difficult to test
stimulation thresholds or pacer sensitivity in the case of standby
pacing. In the past, in certain cases a temporary system had to be
installed consisting of a pervenous lead and an external pacemaker
to provide stimuli to the heart during the replacement of a
permanent pacemaker. This method is employed for those patients who
are suspected to suffer from standstill of the heart when
stimulation is disrupted.
Among the several objects of the present invention may be noted the
provision of a cardiac pacer lead system which facilitates pacer
replacement by permitting connection to the cardiac electrode of a
second pacer or monitor unit before the pacer being replaced is
disconnected; the provision of such a lead system which permits
threshold and sensitivity testing, either with an implantable pacer
unit in place or removed; the provision of such a lead system which
does not reduce lead reliability; the provision of such a lead
system which is readily and easily used to provide interim pacing;
and the provision of such a lead system which is of relatively
simple and inexpensive construction. Other objects and features
will be in part apparent and in part pointed out hereinafter.
SUMMARY OF THE INVENTION
Briefly, a lead system in accordance with the present invention is
adapted for use with an implantable cardiac pacer having a terminal
through which signals are coupled for pacing the heart of a
patient. A flexible electrical lead is employed which has an
insulating sheath over a majority of its length. At one end of the
lead, an electrode is provided which is adapted to contact cardiac
tissue for applying stimulating pulses thereto. At the other end of
the lead, there is provided a connector adapted to engage the pacer
terminal. Typically, at a point close to the juncture of the
connector and the lead, there is provided a mass of conductive
rubbery material, which material is electrically interconnected
with the lead. An insulating jacket of a nonconductive rubbery
material extends over the conductive mass from the lead sheath. The
jacket is shaped to engage the case of the pacer and form a seal
around the contact between the connector and the pacer terminal. As
the conductive mass can be electrically contacted by a needle-like
element inserted through the insulating jacket, interim pacing is
facilitated during replacement of the pacer.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side view, with parts broken away, of a lead system in
accordance with the present invention, showing the connection of
the lead system with a cardiac pacemaker; and
FIG. 2 is a view, taken on the line2--2 of FIG. 1, showing the
cross-section of the proximal end of the lead system and showing
also the method of connecting to the lead for interim pacing.
Corresponding reference characters indicate corresponding parts
throughout the several views of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1,there is indicated at 11 generally a
conventional cardiac pacemaker. As is understood, such a device
incorporates suitable timing circuits and batteries for energizing
of those circuits for an appropriate length of time, e.g. several
years. In both standby and continuous pacing systems, pacing can be
accomplished with a single electrical lead extending to the
patient's heart, a metallic portion of the pacemaker case serving
as a remote ground or reference potential. However, it should be
understood that the invention can also be applied advantageously to
bipolar pacing.
Stimulating pulses generated by the pacer 11 are applied to the
patient's heart through a suitable electrode 13. In the embodiment
illustrated, electrode 13 is of the type which is adapted to be
surgically attached to the outside of the patient's heart, i.e. a
so-called epicardial electrode. As indicated previously, an
alternative method of applying stimulating pulses is through a
pervenous electrode, i.e. an electrode which is inserted through a
vein and which is caused to be lodged in one of the chambers of the
patient's heart. Electrode 13 is coupled with the pacer 11 by means
of a flexible insulated electrical lead comprising a coiled wire 15
residing within a tubular insulating sheath 17 of silicone
rubber.
A jack 21 constitutes the output terminal of the pacer 11 and at
the proximal end of the lead, the helical conductor 15 is attached
to a connector pin 19 which is adapted to establish electrical
contact with the jack. In accordance with the practice of the
present invention, a plug of a conductive silicone rubber is cast
around the helical conductor 15 essentially at the point of its
juncture with the connector pin 19. Preferably, the conductive
silicone rubber is in direct intimate contact with the turns of the
coiled wire 15 so that good electrical contact is established.
Preferably, the end of the plug 25 is shaped so as to receive the
end of the tubular lead sheath 17, as illustrated.
Over the conductive closure 25 is case a jacket 27 of an insulating
silicone rubber or plastic substance. Preferably, the jacket 27
extends over and is sealed to the tubular sheath 17 and, at the
opposite end, extends partially over the connector pin 19. The
portion of the jacket 27 around the pin 19 is preferably shaped, as
illustrated, so as to contact and effect a seal with the case of
the pacer 11.
The lead system described above facilitates interim cardiac pacing
during pacer replacement by permitting an alternative connection to
be established to the cardiac electrode 13, using a needle-like
element to engage the conductive silicone rubber plug 25.
Preferably, this is done utilizing a tool 30 which acts as a
templet, guiding the needle-like piercing element as illustrated in
FIG. 2. Referring now to FIG. 2, the interim contact device
comprises a yoke-like member 31, the lower portion of which is
bifurcated so as to straddle the connector portion of the lead
system. A needle-like element 33 extends from the member 31 into
the hollow of the yoke-like portion, so as to pierce the sheath 27
and the plug 25 when the member 31 is placed over the connector
portion of the lead assembly. The needle-like member 33 is
preferably mounted off center, as illustrated in FIG. 2, so that it
does not directly contact the coiled wire 25, thereby avoiding any
damage to the wire. However, by passing into the conductive plug 25
as illustrated, the needle-like element 33 establishes an
electrical connection to the pacing electrode 13. A terminal 35
extending from the tool 30 is provided for connection to external
pacing apparatus, e.g. through a suitable clip or connector (not
shown). As will be understood by those skilled in the art, external
pacers of various types are known, being commonly used for
temporary pacing following cardiac surgery and the like. If the
pacer being replaced is a standby type, the external pacer can be
operated either in the standby mode or at a fixed rate higher than
the natural heartbeat or rhythm of the patient. In the standby
mode, both pacers can operate simultaneously, either pacer
responding to naturally occurring heartbeats. In the absence of a
natural heartbeat, the first to generate a stimulating pulse will
be detected by the other and control its operation. In the case of
a pacer which operates continuously, the external pacer is
appropriately left turned off until the connector is separated, at
which time the external pacer can be turned on without delay since
the connection to the stimulating electrode can be pre-established.
It can thus be seen that, in either case, substitution of
pacemakers is greatly facilitated since a connection for interim
pacing can be established before disconnecting the original pacer
and interim pacing can be provided by an external device while the
installation of the replacement pacer proceeds on a deliberate and
un-hurried basis.
While interim pacing of standby and continuous pacers has been
described by way of example, since each of these types of pacing
can be effected with a single lead, it can be seen by those skilled
in the art that the present invention can also be adapted to other
pacemakers in which a pair of leads are employed, i.e. by providing
respective plugs of conductive silastic adjacent around the
respective leads adjacent their connection to the pacer circuitry.
Thus, connections can be established for interim pacing while the
original pacemaker unit itself is still in place.
In view of the foregoing, it may be seen that several objects of
the present invention are achieved and other advantageous results
have been attained.
As various changes could be made in the above constructions without
departing from the scope of the invention, it should be understood
that all matter contained in the above description or shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
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