Myocardial strain: can we finally measure contractility?

The measurement of myocardial performance is of critical importance for the diagnosis and management of the patient with cardiac disease. Despite decades of investigation, the search for the optimal method to measure the contractile properties of the myocardium still continues. Extrapolations from experiments in isolated muscle preparations and the intact animal heart have resulted in invasive measurements of myocardial function such as peak positive dp/dt, cardiac output, and maximal elastance (1–3). The two former procedures can now also be measured noninvasively, but they are highly dependent upon the loading conditions of the heart and have not been routinely used in clinical practice. The latter is an accurate measurement of the intrinsic contractility of the left ventricle but is impractical for clinical assessment given the need for simultaneous measurement of pressure and volume under varying preload and afterload conditions (3).