title: Left ventricular dysfunction discriminated noninvasively beat by beat.
abstract: To discriminate left ventricular (LV) dysfunctional beats noninvasively, simultaneous systolic time intervals (STI), acceleration ballistocardiograms (BCG) and respiratory cycle were recorded in 102 men with no history of cardiac disease and in 20 men with proved myocardial infarction or systemic hypertension. Thirty-six measurements were made on each heartbeat on a maximum of 20 beats per patient. The ratio of preejection period to LV ejection time (ET) varied significantly with the respiratory cycle in normal men, but not in men with proved myocardial infarctions or systemic hypertension. The BCG I-wave amplitude varied significantly with respiration in all 3 groups. Various statistical methods identified 9 primary variables of the 36, which differed significantly in a training group of 275 heartbeats in 19 normal, vs 46 beats in 5 coronary patients. A nonlinear quadratic discriminant function based on these primary variables identified 87% of the heartbeats as "normal" in the normal men and 98% as "coronary" in the coronary men. A test group of normal men older than 40 years showed 89% of 97 heartbeats "normal" and in hypertensive men 67% of 85 beats "normal." Comparison by patients showed a range of "coronary" beats in the training normal group from 0 to 50%, the older normal group 0 to 33%, and in the hypertensive patients 0 to 88%. The appropriate use of quadratic discriminant analysis to multivariable data may yield information not otherwise seen. A beat-by-beat identification of dysfunctional beats at rest may lead to a sensitive index that is prognostically useful.
mesh_terms: D000328:Adult; D000368:Aged; D001450:Ballistocardiography; D003327:Coronary Disease / Q000503:physiopathology*; D004562:Electrocardiography; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000503:physiopathology; D012119:Respiration; D013318:Stroke Volume; D013599:Systole