VENTRICULAR REMODELING AFTER ORTHOTOPIC CARDIAC TRANSPLANTATION

Objective: To determine quantitative changes in ventricular chamber vo lumes and left ventricular mass after orthotopic cardiac transplantati on. Material and methods: Right ventricular and left ventricular chamb er volumes and left ventricular muscle mass were quantified by electro n beam computed tomography in 10 patients at 1 month and 12 months aft er orthotopic cardiac transplantation. Results: During the study perio d, the mean right ventricular end-diastolic volumes increased from 117 +/- 26.1 cc to 143 +/- 25.3 cc (P < 0.005), and the mean left ventric ular end-diastolic volumes increased from 90 +/- 20.6 cc to 117 +/- 27 .3 cc (P < 0.001). Left ventricular stroke volume increased from 63 +/ - 16.5 cc at 1 month to 78 +/- 19.8 cc by 12 months (P < 0.005). These changes were associated with a concurrent reduction in global left ve ntricular muscle mass from 168 +/- 25.2 g to 145 +/- 16.3 g (P < 0.01) . The left ventricular end-diastolic volume/mass ratio, an index of wa ll tension, was abnormally low at 1 month but was in the normal range by 12 months (P < 0.0005). Both left ventricular and right ventricular ejection fractions were normal at all times and not significantly cha nged between the 1-month and 12-month studies. Conclusion: Significant right and left ventricular remodeling occurs between 1 month and 12 m onths after orthotopic cardiac transplantation, with progressive cavit y dilatation but reduction in global left ventricular muscle mass, The se adjustments, especially in the left ventricle, tend to reduce the v olume/mass ratio by 1 year and are compatible with normalization of ve ntricular wall tension between the early and late scan dates, Routine clinical measurements of ejection fraction alone mask the almost paral lel increases in stroke volume and end-diastolic volume during the fir st 12 months after orthotopic cardiac transplantation.