Right ventricular function in children with tetralogy of Fallot before and after aortic-to-pulmonary shunt.

Abstract

Right and left ventricular volume variables were obtained in 43 tetralogy patients undergoing diagnostic cardiac catheterization. The patient population consisted of 25 preoperative patients (group 1) and 18 patients who had undergone aortic-to-pulmonary shunt procedure (group 2). Volumes were calculated from biplane cineangiocardiograms using Simpson's rule method for the right ventricle (RV) and the area-length methods for the left ventricle (LV). In group 1, RV end-diastolic volume (RVEDV) was not different from normal in the total group and averaged 93 +/- 4% (SEM) of normal. In patients with hemoglobin (Hgb) greater than or equal to 16 g%, however, this variable was significantly (P = 0.044) less than normal. Right ventricular ejection fraction was normal and RV systolic index was significantly (P less than 0.001) reduced, averaging 3.35 +/- 0.18 (SEM) L/min/m2. Left ventricular volume variables in this group were not significantly different from RV volume variables. In group 2, RVEDV in patients with Hgb greater than or equal to 16 g% was significantly (P = 0.037) less than normal, but was normal in patients with Hgb less than 16 g%. Right ventricular ejection fraction averaged 0.52 +/- 0.03 in this group and was significantly (P less than 0.001) less than normal. Right ventricular systolic index (RVSI) averaged 3.51 +/- 0.24 L/min/m2 and was significantly (P = 0.009) less than normal. RVSI in patients with Hgb less than 16 g% averaged 3.90 +/- 0.31 and was not different from normal. In contrast, this variable in patients with Hgb greater than or equal to 16 g% averaged 3.21 +/- 0.34 and was significantly (P = 0.005) less than normal. Left ventricular end-diastolic volume (LVEDV) and LV systolic output in group 2 were significantly higher than RVEDV and RV systolic output. Right ventricular and LV ejection fractions in group 2 were not different. The relatively decreased ejection fraction fraction in tetralogy patients, as compared with patients with valvular pulmonic stenosis and similar volumes and pressures, suggests that the decreased ejection fraction was not due to decreased preload or increased afterload and might be due to impaired ventricular function secondary to chronic hypoxia. Early corrective surgery in these patients might reverse this process. However, patients with severe tetralogy who have small ventricular volume and reduced output might benefit from shunt procedure rather than complete correction.