Dual chamber rate responsive pacemaker

• US 4,932,406 A
• Filed: 09/23/1988
• Issued: 06/12/1990
• Est. Priority Date: 09/23/1988
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Vascular (Medtronic Plc)
• Inventors: Berkovits, Barouh V.
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/249,046
• Time in Patent Office: 627 Days
• Field of Search: 128/419 P, 128/419 PG, 128/419 D
• US Class Current: 607/22
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

A pacemaker which operates in an atrial synchronized modality when the sensed atrial rate is within a physiologic range and which paces at a sensor determined rate when the atrial rate is above or below the physiologic range.

Claims

1. A cardiac pacer for implantation in the body of a patient, comprising:

atrial sensing means for detecting atrial depolarizations;

means for defining an upper rate;

monitoring means responsive to the detection of atrial depolarizations by said sensing means for determining the rate of said atrial depolarizations;

ventricular pulse generating means for generating ventricular stimulus pulses;

means responsive to detection of an atrial depolarization by said sensing means for triggering said ventricular pulse generating means to generate a stimulus pulse at a predetermined A-V interval thereafter;

sensor means for estimating the demand of said patient'"'"'s body for oxygenated blood;

rate determining means responsive to said sensor means for defining a ventricular pacing rate based on the estimation of the demand of said patient'"'"'s body for oxygenated blood by said sensor means; and

mode switching means for switching said pacer between a first mode in which said responsive means is enabled to trigger said ventricular pulse generating means to generate ventricular stimulating pulses in response to and at said predetermined A-V interval after the detection of said atrial depolarizations by said sensing means and a second mode in which said responsive means is prevented from triggering said ventricular pulse generator in response to the detection of atrial depolarizations and in which said rate determining means triggers generation of ventricular stimulus pulses by said ventricular pulse generating means at said ventricular pacing rate, said mode switching means responsive to said monitoring means for switching from said first mode to said second mode in response to determination of a rate of atrial depolarizations which exceeds said upper rate, said mode switching means switching between said second mode and said first mode in response to said monitoring means measuring a rate of atrial depolarizations less than said upper rate, said atrial monitoring means operative to monitor the rate of said atrial depolarizations in both said first and second modes.

2. A pacer according to claim 1 wherein said mode switching means further comprises rate incrementing means operative while said pacer is in said second mode and activated in response to the detection of a rate of atrial depolarizations below said upper rate, by said monitoring means, said rate incrementing means triggering said ventricular pulse generating means at an increasing rate, said increasing transition rate gradually increasing from said ventricular rate defined by said rate determining means until equal to the rate of atrial depolarizations determined by said monitoring means, said mode switching means thereafter switching the operation of said pacer from said second mode to said first mode.

3. A pacemaker according to claim 1 or claim 2 wherein said mode switching means further comprises rate decrementing means activated in response to the detection of a rate of atrial depolarizations in excess of said upper rate, by said monitoring means, said rate decrementing means triggering said ventricular pulse generating means at a decreasing transition rate, said decreasing transition rate gradually decreasing from said upper rate to said ventricular rate defined by said rate determining means.

4. A cardiac pacer for implantation in the body of a patient, comprising:

atrial sensing means for detecting the occurrence of atrial depolarizations;

means for defining an upper rate;

monitoring means for determining the rate of atrial depolarizations;

ventricular pulse generating means for generating ventricular stimulus pulses;

means responsive to the detection of an atrial depolarization by said sensing means for triggering said ventricular pulse generating means to generate a ventricular stimulus pulse at a predetermined A-V interval thereafter;

fallback rate defining means for defining a ventricular pacing fallback rate lower than said upper rate; and

mode switching means for switching the operation of said pacer between a first mode in which said responsive means triggers generation of a ventricular stimulus pulse by said ventricular pulse generating means in response to and at said predetermined A-V interval after the detection of an atrial depolarization by said sensing means and a second mode in which said responsive means is prevented from triggering generation of ventricular stimulus pulses and in which said fallback rate defining means triggers said ventricular pulse generating means to generate ventricular stimulus pulses at said fallback rate, said mode switching means operative to switch the operation of said pacer from said first mode to said second mode in response to the detection of a rate of atrial depolarizations in excess of said upper rate, by said monitoring means, and switching the operation of said pacer from said second mode to said first mode in response to the detection of a rate of atrial depolarizations less than said upper rate, by said monitoring means, said monitoring means further comprising rate incrementing means activated when said pacemaker is in said second mode, and in response to the detection of a rate of atrial depolarizations less than said upper rate by said monitoring means, said rate incrementing means defining an increasing transition rate, said increasing transition rate gradually increasing from said fallback rate defined by said fallback rate defining means until equal to the rate of atrial depolarizations determined by said monitoring means, said mode switching means thereafter operative to switch the operation of said pacer from said second mode to said first mode.

5. A pacemaker according to claim 4 further comprising rate decrementing means, said rate decrementing means activated in response to the detection of a rate of atrial depolarizations in excess of said upper rate by said monitoring means, said rate decrementing means triggering said ventricular pulse generating means at a decreasing transition rate, said decreasing transition rate gradually decreasing from said upper rate to said fallback rate.