The Myocardium in Mitral Regurgitation

Abstract

Muscles (from the tensor tympani to the left ventricle [LV]) are in the business of generating force. In cardiac mechanics, the innate ability to generate force independently of preload is called contractility. A central tenet of cardiology is that the prognosis of most cardiac diseases is determined in large part by the health or disarray of the myocardium conferred by this property of contractility. Before the era of molecular biology, a search for the perfect index of contractility had become a Holy Grail of cardiology. Such an index would be independent of preload, afterload, and cardiac volume and mass; sensitive to changes in inotropy; reproducible; and easy to apply. Perhaps the most accurate of these is end-systolic stiffness (the modulus of systolic stress and strain),1 but the tedium of its clinical use is so daunting that it is rarely used. Thus, although dozens of indexes have been proposed, none fulfilled all of the above requisites, and the search was largely abandoned. Thus, the cardiology world has settled on ejection fraction (EF) with all of its foibles as the preferred index of cardiac function. It measures chamber …