Global Left Ventricle Function Research Articles

The dynamic twisting of the left ventricle: a computer study.

A mathematical analysis which relates the dynamic twisting motion of the heart around its longitudinal axis to the mechanical function of the left ventricle (LV) is presented. The study thus extends our earlier model which relates the micro-scale sarcomere dynamics, the fibrous structure of the myocardium, and the electrical transmural activation wave to the global LV function. The analysis demonstrates that although the angular twisting motion of the heart moderates the sarcomere length (SL) and the strain rate distributions throughout the myocardium, the global characteristics of the LV function are almost independent of the twisting phenomenon. The endocardial sarcomeres are nevertheless subjected to higher strains and higher (negative) strain rates than the corresponding (positive) epicardial sarcomeres. Utilizing the sarcomere stress length area to predict oxygen demand, it is shown that the twisting motion of the heart produces the metabolic gradient across the LV wall. In spite of the moderating effect of the twist, a larger than normal gradient in oxygen demand is predicted for cases of concentric hypertrophy.

Quantitative frame by frame analysis of regional contraction and lengthening on left ventricular cineangiograms: application to the study of normal left ventricles and left ventricles with mitral valve prolapse.

This work attempted to study the segmental wall motion on left ventriculograms, in terms of segmental shortening, velocity of segmental shortening, and temporal sequences of various events in systole as well as in diastole. The ability of such a method to characterize patterns of normal regional wall motion and to detect mild abnormalities such as isolated asynchronisms, was tested on two groups of patients. Group I included 25 patients presenting evidence of a normal left ventricle (LV) after left heart catheterization. Group II consisted of 21 patients suffering from an isolated pure idiopathic mitral valve prolapse (MVP), with no mitral insufficiency and with an unaffected global LV function. In all patients left ventriculography was filmed in the right anterior oblique view at a rate of 50 frames/s. For each patient a cycle was chosen, distant from any premature beat, with acceptably contrasted outlines, and a quantitative frame by frame study of the motion of 10 segments was performed using a semiautomated method derived from the Stanford method. In the control group (Group I), analysis of the segmental motion by means of this method demonstrates a mild nonuniformity of the normal wall motion. This is principally marked by a stronger and faster contraction in anterolateral segments (segments 7, 8, 9) and by a shorter duration of the contraction in this region. In contrast the MVP group (Group II), exhibited a frank asynergy of the anterolateral region occurring from end systole to early diastole.(ABSTRACT TRUNCATED AT 250 WORDS)