Cardiac rhythm management system with prevention of double counting of events

• US 6,754,534 B2
• Filed: 03/07/2001
• Issued: 06/22/2004
• Est. Priority Date: 04/19/1999
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Esler, James A.
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Assistant Examiner(s): Oropeza, Frances P.
• Application Number:
  US09/801,295
• Publication Number:
  US 20010041919A1
• Time in Patent Office: 1,203 Days
• Field of Search: 600/509, 600/515, 600/516, 600/518, 600/519, 607/4, 607/5, 607/9, 607/14, 607/15, 607/25, 607/28
• US Class Current: 607/27
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence

Abstract

A cardiac rhythm management system recognizes patterns of interval durations, distinguishing between events in different heart chambers even though signals associated with those different heart chambers are processed using a commonly shared sensing circuit. A therapy delivery algorithm ignores intervals between cardiac events occurring in different heart chambers when determining a cardiac rate upon which the delivery of therapy is based. This reduces the risk of inappropriate delivery of therapy to the patient. Delayed conduction left ventricular beats are not erroneously recognized as a subsequent right ventricular beat, preventing such short intervals from inappropriately triggering a defibrillation countershock. The system detects cardiac events, obtains a current interval between a current cardiac event and a previous cardiac event, and classifies the current interval into at least first and second categories, based on a duration of the current interval. The system determines timing of delivery of output energy based on whether a previous interval is in the first category and the current interval is in the second category. The system then stores the current interval as the previous interval.

Claims

1. A method including:

(a) computing a current interval between successive cardiac events obtained from a commonly shared first sensing channel that is coupled to two different heart chambers on different sides of a heart to detect the events occurring in at least one of (1) both right and left ventricles, and (2) both right and left atria;

(b) classifying each of a previous and the current intervals as “

long”

if the interval is longer than a first duration, and as “

short”

if the interval is shorter than the first duration;

(c) incrementing a counter value, if the previous interval is long and the current interval is short and the counter value is less than a maximum counter value;

(d) decrementing the counter value, if the counter value exceeds a minimum counter value and either (1) the previous interval is long and the current interval is long, or (2) the previous interval is short and the current interval is short;

(e) leaving the counter at its existing value, if either (1) the previous interval is long and the current interval is long, or (2) the previous interval is short and the current interval is short; and

(f) determining timing of delivery of therapy based on intervals between cardiac events, but ignoring the current interval if the counter value is equal to the maximum counter value.

2. The method of claim 1, further including (g) storing the current interval as the previous interval and repeating steps (a)-(f).

3. The method of claim 1, in which (b) includes one of (1) classifying each of the previous and current intervals as “

long”

if the interval is equal to the first duration, or (2) classifying each of the previous and current intervals as “

short”

if the interval is equal to the first duration.

4. A method including:

(a) computing a current interval between successive cardiac events obtained from a commonly shared first sensing channel that is coupled to two different heart chambers on different sides of a heart to detect the events occurring in at least one of (1) both right and left ventricles, and (2) both right and left atria;

(b) classifying each of a previous and the current intervals as “

long”

if the interval is longer than a first duration, and as “

short”

if the interval is shorter than a second duration that is shorter than the first duration, and as “

medium”

if the interval is between the first and second durations;

(c) incrementing a counter value, if the previous interval is long and the current interval is short and the counter value is less than a maximum counter value;

(d) decrementing the counter value, if the counter value exceeds a minimum counter value and either (1) the previous interval is long and the current interval is long, or (2) the previous interval is short and the current interval is short, or (3) the previous interval is short and the current interval is medium, or (4) the previous interval is medium and the current interval is short, or (5) the previous interval is long and the current interval is medium, or (6) the previous interval is medium and the current interval is long, or (7) the previous interval is medium and the current interval is medium;

(e) leaving the counter at its existing value, if either (1) the previous interval is long and the current interval is long, or (2) the previous interval is short and the current interval is short; and

(f) determining timing of delivery of therapy based on intervals between cardiac events, but ignoring the current interval if the counter value is equal to the maximum counter value.

5. The method of claim 4, further including (g) storing the current interval as the previous interval and repeating steps (a)-(f).

6. The method of claim 4, in which (b) includes one of (1) classifying each of the previous and current intervals as “

long”

if the interval is equal to the first duration, or (2) classifying each of the previous and current intervals as “

medium”

if the interval is equal to the first duration.

7. The method of claim 4, in which (b) includes one of (1) classifying each of the previous and current intervals as “

short”

if the interval is equal to the second duration, or (2) classifying each of the previous and current intervals as “

medium”

if the interval is equal to the second duration.