ASSESSMENT OF MYOCARDIAL CONTRACTILITY

摘要

A method for measuring changes in the ventricular contractile function uses the measurement of myocardial acceleration during the period of isovolumic contraction by Doppler echocardiography. This index is called IVA=isovolumic acceleration. During preload reduction by blocking the venous return to the heart (IVC occlusion) IVA is resistant to acute volume changes in the LV to up to 10% and up to 30% in the RV. Thus, IVA is not affected by preload changes in physiological range. During afterload increase, IVA remains constant until an un-physiological rise in blood pressure which in turn also affects contractility is achieved. In the LV an acute pressure rise of up to 30% and in the RV an acute pressure rise up to 50% does not affect the measured IVA. IVA is able to detect changes in contractile function during contractility modulation by infusion of dobutamine in animals and humans. IVA is able to detect non-invasively the force-frequency-relation.