ASSESSMENT OF RIGHT-VENTRICULAR REGIONAL CONTRACTION AND COMPARISON WITH THE LEFT-VENTRICLE IN NORMAL HUMANS - A CINE MAGNETIC-RESONANCE STUDY WITH PRESATURATION MYOCARDIAL TAGGING

Objective-Right ventricular regional contractility has been thought to be difficult to assess precisely. Cine magnetic resonance imaging wit h presaturation myocardial tagging was employed to quantitate the cont raction of the right ventricular free wall and to identify normal perf ormance compared with the left ventricle. Methods-Nine normal voluntee rs, aged 27-39 years, were examined in a 1 5 Tesla superconductive mag net, and short arris and four-chamber sections at the midventricular l evel were imaged with cine magnetic resonance sequences. Tags, applied at end diastole as two parallel black lines, intersected the mid-port ion of the free wall, dividing it into upper, centre, and lower segmen ts in the short axis section, and anterior, middle, and posterior segm ents in the four-chamber section. From a series of cine magnetic reson ance images at 50 ms intervals over a cardiac cycle, end diastolic, an d early, mid-, and end systolic images were chosen for calculation of the endocardial, epicardial, and mean percent fractional shortenings ( %FS) in the six segments. Results-There was (1) a gradual increase in %FS in systole in both sections (P < 0.001, < 0.005); (2) a poor trans mural gradient of contractility; (3) a predominance of meridional shor tening (whole length, mean end systolic %FS (SD): short axis, 17.4 (3. 1)%; four-chamber, 30.1 (4.1)%; P < 0.001) in contrast to dominant cir cumferential shortening in the left ventricular lateral wall; (4) lowe r predominance of contractility in the short axis section (P < 0.001), and a middle dip of contractility in the four-chamber section (P < 0. 005). Conclusions-Heterogeneity of contractility was closely correlate d with the myocardial fibre architecture, and with wall stress determi ned by its thickness and curvature. It was proved that right ventricul ar regional function could be analysed non-invasively using cine magne tic resonance imaging with myocardial tagging.