Beat-to-beat variation in echocardiographic measurements of left ventricular dimensions and function

M-mode echocardiography was used to explore the extent of spontaneous variation in left ventricular dimensions and indices of systolic and diastolic function. Extended records made in 26 subjects at rest were digitized and analyzed by computer. We found considerable beat-to-beat variation, in that measurements of five or more consecutive cycles were necessary to provide representative values for minor axis dimensions, while the degree of scatter for derived indices of function was greater. This has to be recognized when serial echocardiography is used to study the progress of disease or the effects of treatment.