Cardiac pacer

• US 3,903,897 A
• Filed: 03/09/1973
• Issued: 09/09/1975
• Est. Priority Date: 03/11/1972
• Status: Expired due to Term

• Current Assignee: Telectronics Pacing Systems, Inc (Abbott Laboratories Incorporated)
• Original Assignee: David John Woollons, Michael John English
• Inventors: Woollons, David John, English, Michael John
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US05/339,537
• Time in Patent Office: 914 Days
• Field of Search: 128/404,418,419P,419R,2.6A,2.6F,2.6R
• US Class Current: 607/9
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/29 for permanent or long-term implantation
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence

Abstract

In a cardiac pacer of the synchronous type and having both atrial and ventricular electrode systems, the atrial electrode senses atrial signals and the ventricular electrode is used to sense the QRS complex and this is used to gate out the QRS complex from the atrial signal and allow the atrial electrode to discriminate against the QRS complex and sense only the P-wave. Consequently the atrial electrode system can be within the heart, and there can be a single catheter with both the atrial and the ventricular electrodes spaced apart on it.

Claims

1. A synchronous cardiac pacer comprising:

atrial electrode means which is adapted so that it can be arranged in relation to an atrium of a heart in order to sense the naturally occurring P-wave of said heart and produce a corresponding sensed P-wave signal;

ventricular electrode means which is adapted so that it can be arranged in relation to a ventricle of said heart in order to sensE the naturally occurring QRS complex of said heart and produce a corresponding sensed QRS signal;

gating means which has an output connection to said ventricular electrode means and respective input connections from said atrial electrode means and ventricular electrode means so as to receive said P-wave and QRS signals without disturbing the phase relationship between them, and which responds to said Pwave and QRS signals by blocking any similar signal variations which occur simultaneously so that only a pure P-wave signal without any QRS complex component passes to the output connection;

pulse generating means which is connected in the P-wave channel comprising said atrial electrode means, said gating means, said output connection and said ventricular electrode means to produce a pulse signal corresponding to said P-wave signal, whereby a pure P-wave pulse signal is applied to said ventricular electrode means as a stimulating signal for said heart; and

delay means which is connected in said P-wave channel and introduces an appropriate atrio-ventricular delay in said Pwave signal.

2. A cardiac pacer as claimed in claim 1 in which said gating means comprises a logic gate.

3. A cardiac pacer as claimed in claim 2 in which said P-wave and QRS signals are converted to corresponding pulse signals by respective means connected between said electrode means and said inputs of the logic gate so that pulse signals are received at the latter and pass to said output connection.

4. A cardiac pacer as claimed in claim 1 in which said pulse generating means is connected in said output connection between said gating means and said ventricular electrode means.

5. A cardiac pacer according to claim 1 in which said delay means is connected in said output connection between said gating means and said ventricular electrode means.

6. A cardiac pacer according to claim 5 in which second gating means is connected in said output connection between said delay means and said ventricular electrode means to control the passage of said pure P-wave signal to the latter, said second gating means having a control input, a blocking pulse generating means producing a blocking pulse of fixed length in response to each QRS signal connected to said control input for preventing the passage of said pure P-wave signal through said gating means.

7. A cardiac pacer according to claim 1 in which a single catheter designed for insertion in the heart carries both the atrial electrode means and the ventricular electrode means.

8. A cardiac pacer according to claim 7 in which the catheter is designed for pervenous insertion, the ventricular electrode means being formed on the extreme end of the catheter and the atrial electrode means being formed at a distance spaced from that end.

9. A cardiac pacer according to claim 8 in which the distance between the electrode means is substantially 12cm.

10. A cardiac pacer according to claim 8 in which each electrode means comprises at least two poles, axially spaced apart along the catheter.

11. A cardiac pacer according to claim 10 in which the spacing between the poles of each electrode means is substantially 1cm.

12. A cardiac pacer according to claim 8 in which an end cap on the catheter forms one pole and a second pole on the catheter is spaced axially from said end cap, these two poles comprising ventricular electrode means.

13. A cardiac pacer according to claim 1 in which said pulse generating means includes means for generating said pure P-wave pulse signal at a fixed minimum lower rate in the event of the P-wave signal from the atrial electrode means falling below that rate or vanishing.

14. A cardiac pacer according to claim 1 in which said pulse generating means includes means for generating said pure P-wave pulse signal at a normally fixed upper limiting rate in the event of the P-wave signal from the atrial electrode means rising above that rate.

15. A cardiac pacer according to claim 14 in which said pulse generating means includes means for omitting a pulse of the pure P-wave pulse signal at the upper limiting rate each time this signal falls behind the sensed P-wave signal by an amount exceeding a predetermined value.