A Noninvasive Technique for the Determination of Velocity of Circumferential Fiber Shortening in Man

Abstract

Velocity of circumferential fiber shortening (V as determined by analysis of left ventricular cineangiocardiograms has been proposed as a measure of left ventricular myocardial contractility. In this study, a noninvasive ultrasonic technique was used to measure the rate of shortening of the left ventricular internal minor axis throughout ejection in 61 patients. These measurements permitted calculation of mean Vcr. In 23 patients with normal left ventricular function, mean V CF averaged 1.45 ± 0.08 circumferences/sec (mean SE). Tn contrast, mean V in 38 patients with impaired left ventricular function was significantly depressed (0.91 ±0.09 circumferences/see, P <0.001). In 17 patients, adequate resolution of septal and posterior wall thicknesses permitted measurement of midwali radius at 50-msec intervals throughout the cardiac cycle. These measurements permitted computation of instantaneous and peak V Values for peak V CF at the midwall were generally similar to those observed for mean V at the internal axis. In patients with normal left ventricular function, peak V CF averaged 1.58 ± 0.23 circumferences/sec. This study has demonstrated the feasibility of measuring the velocity of left ventricular circumferential fiber shortening in man by a noninvasive method. Initial studies indicate that this approach may prove useful in the detection and serial evaluation of left ventricular performance in patients with heart disease.