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US5129393A
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Dual chamber rate responsive pacemaker with variable refractory period
Assignee: Medtronic Inc
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Filing: 1990-08-14
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Granted: 1992-07-14
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Expires: 2010-08-14
Abstract
Abstract An improved atrial synchronous, dual chamber pacemaker provided with a variable refractory period during which the pacemaker is not responsive to the sensed atrial contractions. The atrial refractory period is varied as a function of measured atrial and ventricular rates, and corresponds to a predetermined proportion of the lesser of the average interval separating the ventricular contractions and the average interval separating atrial contractions. The invention is particularly beneficial in the context of a VDD type pacemaker.
Inventors
- 👤 Dennis A. Brumwell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:17
CPC Classifications
A; A61; A61N; A61N1/00; A61N1/18; A61N1/32; A61N1/36; A61N1/362; A61N1/365; A61N1/3621; A61N1/3622
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
278 words
A cardiac pacemaker, comprising: atrial sensing means for sensing contractions of the atrium; ventricular sensing means for sensing contractions of the ventricle; ventricular pulse generating means for generating ventricular pacing pulses; a-V interval determining means for determining an A-V interval initiated in response to sensing of an atrial contraction by said atrial sensing means and for triggering generation of a ventricular pacing pulse by said ventricular pulse generating means on the expiration of said A-V interval; V-V interval determining means for determining a V-V interval following generation of a ventricular pacing pulse by said ventricular pulse generating means and following sensing of a ventricular contraction by said ventricular sensing means, said V-V interval determining means also triggering said ventricular pulse generating means to generate a ventricular pacing pulse at the expiration of said V-V interval; sensor means for sensing physiologic demand for cardiac output and for varying the duration of said V-V interval and correspondence with said sensed demand for cardiac output; and refractory interval determining means for determining a variable refractory period for preventing a natural atrial contraction occurring therein from causing said pacemaker to initiate timing of said A-V interval, said refractory interval determining means comprising A-A interval measurement means for measuring the intervals separating proceeding atrial contractions and A-A interval averaging means for processing said measured A-A intervals to determine an average A-A interval and ventricular interval measuring means for measuring the intervals separately preceding previous ventricular contractions and V-V interval averaging means for processing said measured V-V intervals for determining an average V-V intervals, said refractory interval determining means defining said variable refractory as a function of both said average A-A and V-V intervals.
Claim 2
Dependent Claim
278 words
A cardiac pacemaker, comprising: atrial sensing means for sensing contractions of the atrium; ventricular sensing means for sensing contractions of the ventricle; ventricular pulse generating means for generating ventricular pacing pulses; a-V interval determining means for determining an A-V interval initiated in response to sensing of an atrial contraction by said atrial sensing means and for triggering generation of a ventricular pacing pulse by said ventricular pulse generating means on the expiration of said A-V interval; V-V interval determining means for determining a V-V interval following generation of a ventricular pacing pulse by said ventricular pulse generating means and following sensing of a ventricular contraction by said ventricular sensing means, said V-V interval determining means also triggering said ventricular pulse generating means to generate a ventricular pacing pulse at the expiration of said V-V interval; sensor means for sensing physiologic demand for cardiac output and for varying the duration of said V-V interval and correspondence with said sensed demand for cardiac output; and refractory interval determining means for determining a variable refractory period for preventing a natural atrial contraction occurring therein from causing said pacemaker to initiate timing of said A-V interval, said refractory interval determining means comprising A-A interval measurement means for measuring the intervals separating proceeding atrial contractions and A-A interval averaging means for processing said measured A-A intervals to determine an average A-A interval and ventricular interval measuring means for measuring the intervals separately preceding previous ventricular contractions and V-V interval averaging means for processing said measured V-V intervals for determining an average V-V intervals, said refractory interval determining means defining said variable refractory as a function of both said average A-A and V-V intervals.
Claim 3
Dependent Claim
39 words
A pacemaker according to claim 1 wherein said refractory interval defining means defines said variable refractory period as a function of the lesser of said average interval separating preceding atrial contractions and said average interval separating preceding ventricular contractions.
Claim 4
Dependent Claim
34 words
A pacemaker according to claim 2 wherein said variable refractory period is a specified percentage of the lesser of said average interval separating preceding atrial contractions and said average interval separating preceding ventricular contractions.
Claim 5
Dependent Claim
34 words
A pacemaker according to claim 1 or claim 2 or claim 3 wherein said variable refractory period is initiated in response to generation of a ventricular pacing pulse by said ventricular pulse generator means.
Claim 6
Dependent Claim
33 words
A pacemaker according to claim 4 wherein said variable refractory period is approximately 60% of the lesser of said average interval separating preceding atrial contractions and said average interval separating preceding ventricular contractions.
Claim 7
Dependent Claim
86 words
A pacemaker according to claim 1 wherein said V-V interval determining means defines a first, variable interval following generation of a ventricular pacing pulse by said ventricular pulse generator means, the duration of said variable interval determined by the physiologic demand for cardiac output as measured by said sensor means, said V-V determining means further defining a fixed interval following said variable interval, at the expiration of which said V-V interval defining means triggers generation of a ventricular pacing pulse by said ventricular pulse generator means.
Claim 8
Dependent Claim
35 words
A pacemaker according to claim 6 wherein said variable refractory period determined by said refractory interval determining means is initiated in response to expiration of said variable interval determined by said V-V interval determining means.
Claim 9
Dependent Claim
33 words
A pacemaker according to claim 7 wherein said variable refractory period is approximately 75% of the lesser of said average interval separating preceding atrial contractions and said average intervals separating preceding ventricular contractions.
Claim 10
Dependent Claim
29 words
A pacemaker according to claim 1 or claim 2 wherein said variable refractory period is initiated in response to sensing of an atrial contraction by said atrial sensing means.
Claim 11
Dependent Claim
33 words
A pacemaker according to claim 9 wherein said variable refractory period is approximately 75% of the lesser of said average intervals separating proceeding atrial contractions and said average intervals separating proceeding ventricular contractions.
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