M-mode echocardiography: reproducibility of serial left ventricular measurements in subjects with normal ventricles and patients with congestive cardiomyopathy.

Serial measurements of left ventricular short axis dimensions were made to determine reproducibility in ten normal subjects and in ten patients with congestive cardiomyopathy without asynergic wall motion, conduction abnormalities, or arrhythmias. Three echocardiograms were performed over a period of three weeks in each subject. In the congestive cardiomyopathy group, mean coefficients of variation for diastolic and systolic left ventricular dimensions (LVlDd, LVlDs) and fractional shortening (FS) were 3.5%, 4.3% and 10.3% respectively. In the normal subjects they were slightly less; LVlDd (2.2%), LVlDs (3.1%) and FS (8.0%) but the difference was not statistically significant. Coefficients of variation for calculated diastolic and systolic volumes in the normal ventricle group (Teichholz formula) were 5.0% and 7.1% respectively and for ejection fraction, stroke volume and cardiac output 5.8%, 9.8% and 11.8%. The results demonstrate that M-mode echocardiography is a reliable technique for serial quantitative studies of left ventricular dimensions in both normal subjects, and in selected patients with congestive cardiomyopathy. M-mode echocardiography may be used to assess the responses of patient groups but not of individual patients to interventions which change ventricular volume and cardiac output in subjects with normal left ventricles in whom good quality endocardial echoes are recorded.