Myocardial Force-Velocity Relationships in Clinical Heart Disease

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Abstract
Myocardial force-velocity relationships were studied in 33 children and young people with varying heart lesions. From analysis of left ventricular pressures and consideration of left ventricular geometry, measured from biplane angiocardiograms, maximal contractile element velocity (Vmax) was determined by extrapolation of a stress-velocity plot to zero stress. The value of Vmax in each patient was compared with the assessment of cardiac function by usual hemodynamic criteria (left ventricular end-diastolic pressure [LVEDP], volume [LVEDV], and ejection fraction [EF]). In general, patients with normal LVEDP, LVEDV, and EF had values for Vmax above 3 circumferences/sec. Patients with elevated LVEDP or LVEDV or with EF below 0.5 had lower values for Vmax. Three patients whose usual catheterization data suggested normal ventricular function were found to have low Vmax. In all three, other evidence for myocardial abnormality was found. Several patients with excessive afterloads had impaired function by conventional criteria, yet had normal Vmax. Evaluation of myocardial mechanics in man with measurement of Vmax appears to aid significantly in evaluating patients with heart disease by giving an index to the state of the myocardium not available from routine catheterization data.