U.S. patent number 4,579,119 [Application Number 06/553,260] was granted by the patent office on 1986-04-01 for method and apparatus for multiplexed dipole/quadrupole for stimulation/sensing.
This patent grant is currently assigned to Cordis Corporation. Invention is credited to Frank J. Callaghan.
United States Patent |
4,579,119 |
Callaghan |
April 1, 1986 |
Method and apparatus for multiplexed dipole/quadrupole for
stimulation/sensing
Abstract
A system is provided for cardiac pacing and sensing. A lead
carrying three electrodes is introduced into a cardiac chamber. Two
of the electrodes are connected to the output of a pulse generator
and are disconnected from the pulse generator output during
sensing. All three of the electrodes are connected to the input of
a sensing amplifier during sensing and two of the electrodes are
disconnected from the input during pacing.
Inventors: |
Callaghan; Frank J. (Miami,
FL) |
Assignee: |
Cordis Corporation (Miami,
FL)
|
Family
ID: |
24208767 |
Appl.
No.: |
06/553,260 |
Filed: |
November 18, 1983 |
Current U.S.
Class: |
607/13 |
Current CPC
Class: |
A61N
1/365 (20130101) |
Current International
Class: |
A61N
1/365 (20060101); A61N 001/36 () |
Field of
Search: |
;128/784,785,786,419D,419P,419PG,642 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Gerstman; George H.
Claims
What is claimed is:
1. In a system for cardiac pacing including means for generating
pacing pulses and means for sensing cardiac response, the
improvement comprising:
a lead for introduction into only one cardiac chamber, said lead
including means for pacing and sensing within one chamber, said
means including three electrodes for location within said one
chamber;
switching means coupled to said pulse generating means and said
sensing means;
said switching means for connecting two of said electrodes to said
pulse generating means during pacing and being operable to connect
all three of said electrodes to said sensing means during sensing
whereby the polarization as seen by the electrodes is reduced
sufficiently so that the electrodes can read the cardiac evoked
response.
2. In the system as described in claim 1, said switching means
being operable to disconnect said sensing means from at least two
of said electrodes during pacing and to disconnect said pulse
generating means from said electrodes during sensing.
3. In a system as described in claim 1, said electrodes being in
the form of a distal tip electrode and two spaced ring electrodes,
with wires extending from said tip and rings to said switching
means, said wires being carried internally within a lead cover.
4. In a system as described in claim 1, said pulse generating means
including two output lines and said sensing means including two
input lines; said switching means being operable to connect two of
said electrodes to said two output lines during pacing and to
connect the same two of said electrodes to one of said input lines
during sensing.
5. In a system as described in claim 4, wherein the other of said
three electrodes is connected to the other of said input lines
during pacing and sensing.
6. In a system as described in claim 1, said pulse generating means
including a first output line and a second output line; said
sensing means including a first input line and a second input line;
said three electrodes including a first electrode for connection by
said switching means to said first output line during pacing and
for connection to said first input line during sensing, a second
electrode for connection by said switching means to said second
output line during pacing and for connection to said first input
line during sensing; and a third electrode for connection by said
switching means to said second input line during pacing and
sensing.
7. In a system as described in claim 6, said electrodes being in
the form of a distal tip electrode and two spaced ring electrodes,
with wires extending from said tip and rings to said switching
means, said wires being carried internally within a lead cover.
8. A cardiac pacing process in which a pulse generator provides
pacing pulses and means are provided for sensing cardiac response,
including the steps of:
introducing into only one cardiac chamber a lead including means
for pacing and sensing within one chamber, said means including
three electrodes for location within one chamber;
connecting two of said electrodes to said pulse generator during
pacing;
disconnecting said two electrodes from said pulse generator during
sensing;
connecting all three electrodes to said sensing means during
sensing whereby the polarization potential as seen by the
electrodes is reduced sufficiently so that the electrodes can read
the cardiac evoked response; and
disconnecting at least two of said electrodes from said sensing
means during pacing.
9. A cardiac pacing process as described in claim 8, wherein said
one of three electrodes is connected to said sensing means during
pacing and sensing.
10. A cardiac pacing process as described in claim 8, including the
step of providing one of the electrodes at the distal tip of the
lead and providing the other two electrodes as spaced rings on the
lead.
Description
BACKGROUND OF THE INVENTION
The present invention concerns a novel system for cardiac pacing
and sensing.
In both unipolar and bipolar cardiac pacing, in which a lead is
located in a cardiac chamber, after a current pulse is applied
polarization charges exist in solution at the electrode-electrolyte
interface. These charges are electrolytic ions which are intrinsic
to the volume conductor. Anions are found surrounding the anode
while cations are established at the cathode. As a result, during
sensing it is often difficult to sense the evoked cardiac response
because the polarization voltages may be greater than the cardiac
signals. In effect, the sensing circuit of the pacer is unable to
determine whether the pulse provided by the pacer has been an
effective stimulus because the pulse that was provided results in a
polarization charge that masks the cardiac response. It has been
determined to be the pacer's sensing circuit that is effectively
unable to determine the response.
The use of a three-electrode configuration in the atrium for the
purpose of reducing cross-sensing (i.e., cross-talk) from the
ventricle during sensing has been suggested prior to this
invention. I have discovered that by using three electrodes in
either of the cardiac chambers, all three electrodes may be used
for sensing and two of the same three electrodes may be used for
pacing with the result that in addition to alleviating the
cross-talk problem as previously noted, the polarization problem is
also alleviated. I have found that by using the three electrodes,
the polarization potential as seen by the electrodes is reduced
sufficiently so that the electrodes readily can "read" the cardiac
evoked response.
Other objects and advantages of the present invention will become
apparent as the description proceeds.
SUMMARY OF THE INVENTION
In accordance with the present invention, a system is provided for
cardiac pacing and sensing including means for generating pacing
pulses and means for sensing cardiac response. The improvement
comprises a lead for introduction into a cardiac chamber, with the
lead carrying three electrodes. Switching means are coupled to the
pulse generating means and the sensing means, with the switching
means being operable to connect two of the electrodes to the pulse
generating means during pacing and being operable to connect all
three of the electrodes to the sensing means during sensing.
In the illustrative embodiment, the switching means are operable to
disconnect the sensing means from at least two of the electrodes
during pacing and to disconnect the pulse generating means from the
electrodes during sensing.
In the illustrative embodiment, the pulse generating means include
two output lines and the sensing means include two input lines. The
switching means operate to connect two of the electrodes to the two
output lines during pacing and to connect the same two of the
electrodes to one of the input lines during sensing. The other of
the three electrodes is connected to the other of the input lines
during both pacing and sensing.
In the illustrative embodiment, the electrodes are in the form of a
distal tip electrode and two spaced ring electrodes, with wires
extending from the tip and rings to the switching means. The wires
are carried internally within a lead cover.
A more detailed explanation of the invention is provided in the
following description and claims, and is illustrated in the
accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
The drawing is a schematic diagram of a system for cardiac pacing
and sensing constructed in accordance with the principles of the
present invention.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT
Referring to the drawing, a cardiac lead 1 is schematically
illustrated therein. Cardiac lead 1 is adapted for introduction
into one of the cardiac chambers. Conventionally, lead 1 will be a
straight lead if used in the ventricle and will have a J-shape if
used in the atrium.
Lead 1 comprises a plastic lead cover carrying three wires 2, 3 and
4, internally. Wire 2 is electrically connected to a distal tip
electrode 2'; wire 3 is electrically connected to a spaced ring
electrode 3'; and wire 4 is electrically connected to another
spaced ring electrode 4'. The use of tip and ring electrodes on
plastic leads in cardiac pacing and sensing is well-known in the
art.
Conventionally, cardiac pacers comprise a pulse generator 6 for
generating pacing pulses and a sensing amplifier 8 for sensing
cardiac response. In accordance with the present invention, pulse
generator 6 has output lines 10 and 11 for providing the basic
pulses and sense amplifier 8 has input lines 12 and 13 for
detecting the cardiac response. A multiplexer 14 is provided for
connecting and disconnecting the electrodes to the pulse generator
6 and sense amplifier 8 in a novel manner. In its schematic form,
multiplexer 14 has switch contacts 16 and 17 which are connected,
respectively, to output lines 10 and 11 of pulse generator 6.
Multiplexer 14 also has switch contacts 18 and 19 which are both
connected to sense amplifier input line 12. Wire 2 is connected to
switch arm 20 and wire 3 is connected to switch arm 21.
During pacing, switch arms 20 and 21 engage contacts 16 and 17,
respectively, as illustrated. In this manner, electrodes 2' and 3'
are coupled to outputs 10 and 11, respectively, of the pulse
generator 6 and are effectively disconnected from the sense
amplifier 8. However, electrode 4' is always connected to input 13
of sense amplifier 8.
During sensing, switch arms 20 and 21 will engage contacts 18 and
19. In this manner, electrodes 2' and 3' will be connected to input
12 of sense amplifier 8 and will be effectively disconnected from
pulse generator 6.
Since the cardiac response detection is differential, it does not
matter which input of sense amplifier 8 is used for connection to
electrode 4' so long as electrode 4' is connected to a different
input from electrodes 2' and 3'.
Although a multiplexer 14 is illustrated with discrete switches,
this is by example only and the multiplexer may take the form of a
unit containing discrete solid state devices, discrete mechanical
devices or it may be the form of a software routine utilizing a
microprocessor-based system.
By using three electrodes for sensing and two of the same three
electrodes for pacing, both the problem of cross-talk between
chambers and the problem of polarization is alleviated.
Although an illustrative embodiment of the invention has been shown
and described, it is to be understood that modifications and
substitutions may be made by those skilled in the art without
departing from the novel spirit and scope of the present
invention.
* * * * *