Method and apparatus using windows and an index value for identifying

Abstract

A method and apparatus for identifying cardiac arrhythmias. In the preferred embodiment the invention is embodied in an implantable pulse generator. The IPG features a system to analyze the sensed ECG. The system utilizes an algorithm able to quantify continuously the sensed cardiac rhythm. The algorithm features essentially two parts, a pre-diagnostic program ('PDP'), which is able to discriminate up to 95% of all sensed rhythms, and a diagnostic program ('DP'), which is able to discriminate the remaining sensed rhythms. The pre-diagnostic program is relatively quicker and draws less energy as compared to the diagnostic program. The pre-diagnostic program functions by regularly measuring the dv/dt of the sensed ECG. These values are then converted into an index value to thereby quantify the sensed cardiac rhythm. After any noise is rejected, the algorithm permits an automatic discrimination of normal sinus rhythm from atrial fibrillation, atrial flutter, ventricular tachycardia, ventricular fibrillation and ventricular flutter. In cases where other rhythms are sensed, the algorithm then utilizes the diagnostic program. The diagnostic program compares a series of sensed values from the sensed ECG to a series of references values. Through the various values examined, a discrimination among various arrhythmias is accomplished.