Abnormalities of right ventricular function following Mustard's operation for transposition of the great arteries

Postoperative data were obtained at cardiac catheterization in twelve patients studied 6-29 months following Mustard's operation for transposition of the great arteries (TGA) to assess the incidence and severity of abnormalities of right ventricular (RV) function. Age at operation was 5-13 months in seven patients (infant group) and 19-25 months in the remaining five patients. RV end-diastolic volume (EDV) decreased in all patients following surgery and averaged 123% of normal in the postoperative group (NS). RV ejection fraction (EF) was depressed postoperatively averaging 0.45 (69% of normal (P less than 0.001) as was RV systolic output (78% of normal, P less than 0.01). LVEDV averaged 65% of normal (P less than 0.001), LVEF 0.67 (103% of normal, NS), and LV systolic output 67% of normal (P less than 0.001) following operation. Left atrial (systemic venous) volume was decreased in all postoperative patients averaging only 39% of normal (P less than 0.001). A high incidence (greater than 50%) of partial baffle obstruction was found and LV systolic output showed a significant negative correlation with baffle gradients. The low output postoperatively may be related to decreased LV filling pressure, a small LV reservoir, and thus a small atrial "booster pump." Pressure-velocity indices of RV contractile function in four patients showed a poor correlation with pump function. Long-term follow-up will be required to determine the clinical significance of the abnormalities of venous return and ventricular function.