Myocardial Contractility, Afterload Mismatch and Ventricular Dysfunction
Although abnormalities in right ventricular function and/or the pulmonary vascular bed can be of pathophysiologic importance, it is more commonly an alteration of one or more determinants of left ventricular function which create an adverse hemodynamic status in the cardiac disease states encountered in man. Of the four major factors which control left ventricular function, i.e. heart rate, myocardial contractility, preload or end-diastolic fiber stretch, and afterload or the force which resists shortening, the latter is now appreciated as playing a particularly critical role in the mechanisms underlying heart failure. For example, the interdependence of wall shortening and afterload, at any given preload, has allowed understanding of the favorable influence of vasodilating agents in treating congestive heart failure. Moreover, the serial application of both invasive and non-invasive diagnostic techniques has provided improved insight into the role of afterload in chronic valvular heart disease, the potential for improving left ventricular shortening by valve surgery, and the relation between postoperative changes in afterload and regression of hypertrophy.
KeywordsAortic Stenosis Mitral Regurgitation Wall Stress Myocardial Contractility Mitral Valve Surgery
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