DIGITAL SIGNAL-PROCESSING CHIP IMPLEMENTATION FOR DETECTION AND ANALYSIS OF INTRACARDIAC ELECTROGRAMS

The adoption of digital signal processing (DSP) microchips for detecti on and analysis of electrocardiographic signals offers a means for inc reased computational speed and the opportunity for design of customize d architecture to address real-time requirements. A system using the M otorola 56001 DSP chip has been designed to realize cycle-by-cycle det ection (triggering) and waveform analysis using a time-domain template matching technique, correlation waveform analysis (CWA). The system d igitally samples an electrocardiographic signal at 1000 Hz, incorporat es an adaptive trigger for detection of cardiac events, and classifies each waveform as normal or abnormal. Ten paired sets of single-chambe r bipolar intracardiac electrograms (1-500 Hz) were processed with eac h pair containing a sinus rhythm (SR) passage and a corresponding arrh ythmia segment from the same patient. Four of ten paired sets containe d intraatrial electrograms that exhibited retrograde atrial conduction during ventricular pacing; the remaining six paired sets of intravent ricular electrograms consisted of either ventricular tachycardia (4) o r paced ventricular rhythm (2). Of 2,978 depolarizations in the test s et, the adaptive trigger failed to detect 6 (99.8% detection sensitivi ty) and had 11 false triggers (99.6% specificity). Using patient depen dent thresholds for CWA to classify waveforms, the program correctly i dentified 1,175 of 1,197 (98.2% specificity) sinus rhythm depolarizati ons and 1,771 of 1,781 (99.4% sensitivity) abnormal depolarizations. F rom the results, the algorithm appears to hold potential for applicati ons such as real-time monitoring of electrophysiology studies or detec tion and classification of tachycardias in implantable antitachycardia devices.