System for the detection of cardiac events

• US 8,038,624 B2
• Filed: 08/18/2003
• Issued: 10/18/2011
• Est. Priority Date: 09/20/2002
• Status: Active Grant

• Current Assignee: Angel Medical Systems, Inc.
• Original Assignee: Angel Medical Systems, Inc.
• Inventors: Fischell, David R., Fischell, Robert E., Johnson, Steven R., Harwood, Jonathan, Fischell, Tim A.
• Primary Examiner(s): EVANISKO, GEORGE ROBERT
• Application Number:
  US10/642,245
• Publication Number:
  US 20040059238A1
• Time in Patent Office: 2,983 Days
• Field of Search: 607/4, 607/5, 607/9, 607/14, 600/508, 600/510, 600/515, 600/516, 600/518, 600/519, 600/513
• US Class Current: 600/508
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02455 provided with high/low alarm devices
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61B 5/7465 Arrangements for interactive communication between patient and care services, e.g. by using a telephone network telemetry of measured physiological signal A61B5/0002

Abstract

Disclosed is a system for the detection of cardiac events (a guardian system) that includes an implanted device called a cardiosaver, a physician'"'"'s programmer and an external alarm system. The system is designed to provide early detection of cardiac events such as acute myocardial infarction or exercise induced myocardial ischemia caused by an increased heart rate or exertion. The system can also alert the patient with a less urgent alarm if a heart arrhythmia is detected. Using one or more detection algorithms, the cardiosaver can detect a change in the patient'"'"'s electrogram that is indicative of a cardiac event within five minutes after it occurs and then automatically warn the patient that the event is occurring. To provide this warning, the guardian system includes an internal alarm sub-system (internal alarm means) within the cardiosaver and/or an external alarm system (external alarm means). If the guardian system is put into a pacemaker, the algorithm can utilize a different analysis of the electrogram depending on whether or not the pacemaker is actually pacing the heart.

Claims

1. A system for assessing cardiac function, the system comprising:

(a) means for receiving a first plurality of user input ST segment and PQ segment offset times and durations and receiving a corresponding plurality of R-R interval ranges, wherein each of the ST and PQ segment offset times specifies an offset time from an R wave peak for one of the R-R interval ranges;

(b) electrical circuitry means for determining an R-R interval between a prior beat and a current beat, thereby generating a current R-R interval;

(c) processor means for determining an R wave peak of the current beat;

(d) processor means for selecting both a current beat PQ offset time and duration, and a current beat ST offset time and duration from the user input PQ and ST offset and duration times according to the current R-R interval;

(e) processor means for computing ST-segment deviation of the current beat as equal to an average value of an ST segment of the current beat minus an average value of a PQ segment of the current beat, wherein the average values of the ST and PQ segments are based on the current beat ST and current beat PQ segment offset times and durations;

(f) means for determining a baseline ST deviation value; and

,

(g) processor means for assessing cardiac function based upon the difference between the baseline ST deviation value and the ST-segment deviation of the current beat.

2. The system of claim 1 wherein the current beat PQ and ST offset times are in the PQ and ST segments respectively closest to the R wave peak of the current beat.