System and method for reliably detecting atrial events of a heart using only atrial sensing

• US 6,052,617 A
• Filed: 07/01/1998
• Issued: 04/18/2000
• Est. Priority Date: 07/01/1998
• Status: Expired due to Term

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Kim, Jaeho
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US09/108,902
• Time in Patent Office: 657 Days
• Field of Search: 607/4, 607/5, 600/515, 600/518, 600/521
• US Class Current: 600/518
• CPC Class Codes: A61N 1/395 for treating atrial fibrillation
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock

Abstract

An atrial defibrillator including a cardioverter for applying cardioverting electrical energy to atria of a heart when the atria are in need of cardioversion and an atrial arrhythmia detector for detecting if the atria are in need of cardioversion includes a continuous monitoring system for causing the atrial arrhythmia detector to initiate a detection. The monitoring system includes a sense amplifier for sensing atrial activity of the heart and an A wave detector for detecting A waves from the sensed atrial activity. The A wave detector has a first threshold and a selectable second threshold higher than the first threshold. A threshold selector is responsive to each detected A wave for activating the second threshold for a finite time period commencing a delay time period after each detected A wave. The A wave detector provides an indication of each detected A wave, and an atrial arrhythmia detection is initiated when the A wave detection rate exceed a predetermined limit.

Claims

1. A system for detecting A waves of a heart while avoiding detection of R waves, the system comprising:

sensing means for sensing atrial activity of the heart;

an A wave detector for detecting A waves from the sensed atrial activity, said A wave detector having a first threshold and a selectable second threshold higher than the first threshold; and

threshold selection means responsive to each detected A wave for selecting the second threshold for a finite time period commencing a delay time period after each detected A wave.

2. A system as defined in claim 1 wherein the threshold selection means includes a one-shot circuit for activating the second threshold for the finite time period.

3. A system as defined in claim 1 wherein the threshold selection means are arranged to activate the second threshold for a finite time period of about 100 milliseconds.

4. A system as defined in claim 1 wherein the threshold selection means further includes a delay circuit for providing a control signal the delay time period after each detected A wave for commencing the finite time period.

5. A system as defined in claim 1 wherein the delay time period is between about 50 and 100 milliseconds.

6. An atrial defibrillator comprising:

a cardioverter for applying cardioverting electrical energy to atria of a heart when the atria are in need of cardioversion;

an atrial arrhythmia detector for detecting if the atria are in need of cardioversion; and

a system for causing the atrial arrhythmia detector to initiate a detection including sensing means for sensing atrial activity of the heart, an A wave detector for detecting A waves from the sensed atrial activity, the A wave detector having a first threshold and a selectable second threshold higher than the first threshold, threshold selection means responsive to each detected A wave for selecting the second threshold for a finite time period commencing a delay time period after each detected A wave, the A wave detector providing an indication of each detected A wave; and

means responsive to the A wave detection indications for causing the atrial arrhythmia detector to initiate a detection.

7. An atrial defibrillator as defined in claim 6 wherein the threshold selection means includes a one-shot circuit for activating the second threshold for the finite time period.

8. An atrial defibrillator as defined in claim 6 wherein the threshold selection means are arranged to activate the second threshold for a finite time period of about 100 milliseconds.

9. An atrial defibrillator as defined in claim 6 wherein the threshold selection means further includes a delay circuit for providing a control signal the delay time period after each detected A wave for commencing the finite time period.

10. A method of detecting A waves of a heart while avoiding detection of R waves as A waves, the method including the steps of:

sensing atrial activity of the heart;

detecting A waves from the sensed atrial activity with a first threshold or with a second threshold higher than the first threshold; and

selecting the second threshold in response to each detected A wave for a finite time period commencing a delay time period after each detected A wave.

11. In an atrial defibrillator having a cardioverter for applying cardioverting electrical energy to atria of a heart when the atria are in need of cardioversion and an atrial arrhythmia detector for detecting if the atria are in need of cardioversion, a method of causing the atrial arrhythmia detector to initiate a detection including the steps of:

sensing atrial activity of the heart;

detecting A waves from the sensed atrial activity with a first threshold or with a second threshold higher than the first threshold;

selecting the second threshold in response to each detected A wave for a finite time period commencing a delay time period after each detected A wave;

determining a rate of A wave detections; and

causing the atrial arrhythmia detector to initiate a detection responsive to the rate of A wave detections.