Right ventricular myocardial function after atrial switch operation for transposition of the great arteries

Postoperative right ventricular (RV) myocardial function was evaluated in 6 patients who underwent atrial switching for simple transposition of the great arteries (TGA). The average age at study was 5.5 years. RV function was evaluated at rest and during administration of methoxamine by cardiac catheterization and RV angiography. The data were compared with left ventricular function in a control group, which consisted of 6 patients, 3 with functional murmur and 3 with pulmonary valvar stenosis. During stress, the TGA group showed a significant increase in end-diastolic pressure, minute work index and end-diastolic and end-systolic volume indexes, along with a significant decrease in ejection fraction. The control group also showed an increase in these variables except for ejection fraction during stress, which did not change. The slope of the work-function curve for the TGA group was lower than that for the control group (p = 0.02). The TGA group had a lower slope of the peak systolic pressure-volume relation than the control group (p = 0.005). There was no significant correlation between the slope of the peak systolic pressure-volume relation and age at repair or study. This study shows that RV pump dysfunction observed in postoperative TGA patients may be caused by depressed myocardial function.