Measurement of Mean Circumferential Fiber Shortening Rate Using Radionuclide Blood Pool Scan

Abstract

Ejection phase indices of left ventricular performance are standard parameters for the evaluation of myocardial contractility. Recently, ejection fraction and ejection rate are easily obtained from radionuclide gated cardiac blood pool scan. No method, however, is available for determining the mean circumferential fiber shortening rate (Vcf) precisely. Velocity indices are relatively independent of alternation in resting filling pressure and volume, and responsive to changes in heart rate. We measured the left ventricular mean circumferential fiber shortening velocity using gamma camera interfaced to a computer after injection of radionuclide to evaluate its significance for detecting left ventricular dysfunction, especially in patients With coronary heart disease. Radionuclide-determined values for mean fiber shortening rate correlated (r=0.79) with values for this index obtained from echocardiography. Left ventricular ejection fraction correlated with mean fiber shortening rate. There was a strong relationship between the value of mean fiber shortening rate and the severity of myocardial impairment by the NYHA(New York Heart Association) functional class (r=0.84). In summary, these data indicate that gated cardiac blood pool scan provides a noninvasive, accurate and simple method to measure the mean circumferential fiber shortening rate and it can be utilized in a variety of cardiac disorders.