Measurement of left ventricular mean circumferential fiber shortening velocity and systolic ejection rate by computerized radionuclide angiocardiography

Abstract

Recently attention has focused on ejection phase indexes as clinically relevant measures of left ventricular contractility. Using an Anger camera interfaced to a dedicated computer with injection of radionuclide (technetium 99m) into a wedged pulmonary arterial catheter we have developed a method for measuring left ventricular mean circumferential fiber shortening velocity and mean systolic ejection rate. For determination of mean fiber shortening velocity an area of interest coincident with the left ventricular minor axis is constructed and a time-activity curve obtained. In 31 patients radionuclide-determined values for mean fiber shortening velocity and mean systolic ejection rate correlated ( r = 0.90, P < 0.001 and r = 0.98, P < 0.001, respectively) with values for these indexes obtained from left cineventriculography. Left ventricular ejection fraction correlated with mean fiber shortening velocity and systolic ejection rate ( r = 0.60, P < 0.001 and r = 0.92, P < 0.001, respectively). No patient with a normal mean fiber shortening velocity or systolic ejection rate had a diminished ejection fraction. Because these radionuclide measurements do not require left heart catheterization, they can be frequently repeated.