Method and apparatus for evaluating pacer battery status and stimulation effectiveness

• US 4,445,512 A
• Filed: 08/17/1982
• Issued: 05/01/1984
• Est. Priority Date: 02/20/1979
• Status: Expired due to Fees

• Current Assignee: Omikron Scientific Ltd.
• Original Assignee: Omikron Scientific Ltd.
• Inventors: Krupka, Yaakov, Feldman, Salomon, Yerushalmi, Shmuel
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US06/408,742
• Time in Patent Office: 623 Days
• Field of Search: 128/419 PG, 128/419 PT
• US Class Current: 607/29
• CPC Class Codes: A61N 1/37 Monitoring; Protecting

Abstract

A pacemaker of the inhibited demand type which is equipped with a battery and pacemaker efficiency evaluator. A magnetically initialized test circuit synchronizes the timing of test stimulating pulses with the natural R-wave or, the end of a basic pacemaker escape interval, thereby to enhance patient safety by avoiding competition during testing. The synchronized test circuit produces an alternating sequence of sensing and pacing periods which are maintained during the test. Upon actuation of the test, the first R-wave, or the end of the basic pacer interval, is sensed and a number of stimulating pulses is applied at the end of successive test intervals, which intervals are located between pacemaker output pulses, the duration of which indicates the battery status. This sequence of sensing, synchronization, an application of test pulses is repeated during the duration of the magnet test.

Claims

1. A method for evaluating the battery status and stimulating effectiveness of an inhibited type cardiac pacemaker system which issues periodic stimulating pulses between basic pacemaker intervals, said pacemaker system including magnet test means for performing said evaluating in a number of magnetic test intervals, means for activating said magnet test means, a synchronizer for coordinating the timing and sensing circuits of the pacemaker system, said system being capable of sensing periodic R-waves of a heart, which method comprises the step of:

(a) applying magnetic means to actuate said magnetic test means;

(b) sensing one of a first natural R-wave and the end of a first basic pacemaker interval;

(c) applying a predetermined number of consecutive asynchronous stimulation pulses, said asynchronous pulses being applied after a magnetic test interval which is shorter in duration than the basic pacemaker interval;

(d) sensing one of the next R-waves and end of a basic interval;

(e) applying again a sequence of a predetermined number of consecutive asynchronous stimulating pulses during the magnetic test intervals; and

(f) repeating steps (a) through (e) for the duration of the magnet test, whereby the length of the magnet interval and the heart response to the stimulating pulses being indicative of battery status and stimulation effectiveness, respectively.

2. A method as recited in claim 1, wherein a sequence of sensing periods follows two asynchronous stimulation pulses.

3. An inhibited demand pacer for applying stimulating pulses to a heart, said pacemaker including means for evaluating the status of a battery and the efficiency of stimulation, timing and sensing circuits for sensing periodic natural R-waves of the heart and for timing the application of stimulating pulses to the heart in the absence of a periodic R-wave, said pacer comprising:

magnetic test means for performing said evaluation in response to a magnetic field during successive magnetic test intervals;

synchronizing means for coordinating the timing and sensing circuits of the pacemaker;

means for actuating the magnetic test means so as to sense one of a first natural R-wave of the heart and the end of a first basic timing interval between stimulating pulses;

means for applying two or more consecutive asynchronous stimulation pulses, each at the end of a magnetic test interval which is shorter in duration than the basic timing interval;

means for synchronizing the stimulating pulses of the pacer with one of a next natural R-wave and the end of a next basic timing interval; and

means for repeating the stimulations during said evaluation until the end of the magnetic test period.