[Study on the medium normalized velocity of circumferential lengthening of the fiber using ultrasound. II. Use of the construction of left-ventricle performance curves]. FT Studio della velocita media normalizzata di allungamento circonferenziale della fibra mediante ultrasuoni

Telediastolic pressure and volume can readily be employed as expressions of sarcomere length when constructing ventricular performance curves for the normal heart. In pathological hearts, however, these parameters are rendered inadequate as a result of altered compliance, which means that diastolic lengthening of the muscle fibre cell must be determined from telediastolic stress and linear compliance, corrected for wall thickness (muscle fibre stretch, strain index). Ventricular performance curves were constructed for normal subjects and patients with hypertrophic subaortic stenosis, using the normalised mean rate of circumferential lengthening of the fibre as the expression of fiber strength. Comparison was made with the mean circumferential shortening rate and the ejection fraction as the expression of ventricular effort. It was found that both normal subjects and stenosis patients lay on the same curve, the latter acting low down through having short sarcomeres.