Detection of ventricular arrhythmias in real-time with a portable analog computer

Abstract

Recent studies on the occurrence of sudden death emphasize that many patients have ventricular premature contractions as prodromes of lethal arrhyhmlas. A portable, 6 ounce analog computer has been developed to detect tachycardias (heart rate 150 to 190 beats/min), bradycardias (heart rate less than 50 beats/min) and ventricular premature contractions. When preset limits are exceeded, acoustic warnings are sounded, and the patient may transmit his electrocardiogram by telephone, without additional equipment, to a receiving device that graphically reproduces the electrocardiogram in real-time. Hospital studies in 26 ambulatory patients with a variety of arrhythmias have been completed. Tachycardias and bradycardias were detected in every instance during 30 observation periods in six patients. Reproducible warnings were triggered in 19 of the 20 patients with ventricular premature contractions of various configurations during each of 5 observation periods (100 observations). In one patient, the electrical vector of the ventricular premature contraction closely resembled the normal QRS vector and was not detected. Appropriate electrode placement is essential to avoid initial Q waves and to maximize the difference between the vector of ventricular premature contraction and that of the normal QRS complex. No false positive acoustic alarms were sounded. Our results demonstrate that it is possible to detect ventricular premature contractions readily and reproducibly in ambulatory patients. Use of this detector may permit large scale monitoring of patients with a high risk of sudden death.