4 Non-invasive assessment of left ventricular contractility by means of transoesophageal echocardiography

Abstract

While assessment of ventricular loading conditions is readily accessible at the patient's bedside, evaluation of contractile function is remarkably more complicated. The difficulty in obtaining contractility measurements in patients is directly related to the intimate interrelation between inotropic state and ventricular loads at the level of the intact organism. Despite the inherent problems in measuring contractility, it is of crucial importance in experimental research as well as in clinical medicine to separate the effects of a primary change in load from a primary change in contractility, whenever a clinical situation with severe left ventricular dysfunction presents itself. The most useful approaches for assessing contractility in clinical medicine involve transoesophageal echocardiography. By providing estimations of clinically important but previously inaccessible physiological parameters, this technology paved the way for a more quantitative assessment of cardiac function. Three different non-invasive techniques to measure left ventricular contractility by means of echocardiography have been applied in humans: (1) the reconstruction of the end-systolic pressure-volume relation; (2) the end-systolic meridional wall stress-rate-corrected mean velocity of fibre shortening relation; and (3) the pre-concept of preload-adjusted maximal power.