ASSESSMENT OF SYSTOLIC AND DIASTOLIC LV FUNCTION BY MR MYOCARDIAL TAGGING

Heart failure has been divided into several different forms depending on etiology, clinical course and pathophysiology of left ventricular ( LV) dysfunction. Systolic and diastolic dysfunction are characterized by a reduced cardiac output with normal (= diastolic dysfunction) or d epressed (= systolic dysfunction) LV pump function. New diagnostic tec hniques such as magnetic resonance imaging (MRI) allow to determine no ninvasively LV 3D motion by labelling specific myocardial regions (= m yocardial ''tagging'') with a rectangular or radial grid. From the def ormation of this grid rotational and translational motion of the heart can be derived. A ''wringing'' motion of the left ventricle has been described during systole which includes a clockwise rotation at the ba se and a counter-clockwise rotation at the apex. During diastole, an ' 'untwisting'' motion has been demonstrated. In the normal heart, diast olic ''untwisting'' occurs primarily during isovolumic relaxation, ana logous to the systolic ''wringing'' which takes place mainly during is ovolumic contraction. A prolongation of the ''untwisting'' motion was found in the hypertrophied (aortic stenosis) and hibernating myocardiu m. Thus, heart failure is associated with profound alterations in the mechanical function of the heart which are manifested by changes in sy stolic ''wringing'' and diastolic ''untwisting'' motion.