Clinical evaluation of left ventricular function using the cardiac helical fiber model: an echocardiographic study

The cardiac helical fiber concept was introduced in 1969 and was shown mathematically to provide better approximations of normal ejection fractions compared with the conventional circumferential fiber model. The clinical applicability of this concept was evaluated noninvasively by M-mode and two-dimensional echocardiography in 55 subjects: 10 with aortic insufficiency, 10 with congestive cardiomyopathy, eight with hypertension, eight who were long-distance runners, 12 who were active and seven who were sedentary normals. Comparison of myocardial shortening by the circumferential and helical fiber models showed that the former discriminated only two groups of subjects, while endocardial and epicardial helical shortening discriminated three and four groups, respectively. Regression analyses suggest that more than 90% (r2 = 0.92) of variation in ejection fraction may be accounted for by variation in endocardial shortening, and that more than 75% (r2 = 0.77) of variation in observed endocardial shortening may be accounted for by variation in epicardial contraction. The study demonstrates that the helical fiber length concept may be useful for the noninvasive evaluation of left ventricular function in man.