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Figure 5 | Cardiovascular Ultrasound

Figure 5

From: Myocardial contractility in the echo lab: molecular, cellular and pathophysiological basis

Figure 5

Load changes at constant contractility (left) and contractility changes at constant load (right). Left panel. The graph shows how two additional pressure-volume loops appear with an acute increase in afterload or preload. Contractility is quantified by the ESPVR slope: the Ees (end systolic elastance). Right panel. Increased contractility, is reflected in higher myocardial fiber shortening velocity, with a more highly developed tension peak and a steeper pressure rise, when preload, after load, and heart rate are constant: Ees moves upward and to the left. The left ventricular emptying fraction or ejection fraction (LVEF) is reflected in the ability of the left ventricle to empty. Because myocardial contractility is an important determinant of LVEF, LVEF and contractility are frequently considered to be interchangeable. But they are not the same: thus it is possible to have low LVEF despite normal contractility when LV afterload is excessive. Alternatively, LVEF may be nearly normal despite decreased myocardial contractility if LV afterload is low. (Modified from Little WC. Assessment of normal and abnormal cardiac function. Chapter 15, page 480. In Braunwald Zipes Libby Heart disease, 6th edition, W. B Saunders Company, 2001)

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