Can we use the end systolic volume index to monitor intrinsic right ventricular function after repair of tetralogy of Fallot?

Background: After tetralogy of Fallot (ToF) repair the right ventricle (RV) is commonly exposed to abnormal volume load resulting from pulmonary regurgitation (PR) leading to progressive RV dilatation. The objective of this study was to assess the relationship between RV volumes, especially the end systolic volume index (ESVi), and RV contractility in patients after ToF repair and significant PR and to determine whether RV dilatation reflects intrinsic RV dysfunction in these patients.

Methods: Twenty-nine ToF patients were studied 11.6 (range: 1.9-30.1) years after repair with the pressure-volume conductance system. The patient cohort was divided into two groups according to the median ESVi (group 1: ESVi<34.7 ml/m(2)(×1.18), n = 14; group 2: ESVi ≥ 34.7 ml/m(2)(×1.18), n = 15).

Results: The slope of the end systolic pressure-volume relationship (end systolic elastance, Ees) was higher in group 1 compared to group 2 both at baseline and during dobutamine infusion (0.87 ± 0.36 vs. 0.46 ± 0.28 mm Hg/ml and 1.50 ± 0.77 vs. 0.92 ± 0.37 mm Hg/ml; P<0.005 and P = 0.02, respectively). Overall, Ees at baseline correlated significantly with ESVi and also with the end diastolic volume index (r = -0.64, and P<0.001 for both). Receiver operating characteristic curve analysis revealed that ESVi was superior to RV ejection fraction (EF) in predicting an Ees in the lowest quartile of the study group (area under curve ESVi vs. EF: 0.84 (0.64-0.95) vs. 0.68 (0.47-0.85); P = 0.015).

Conclusion: ESVi is a valid estimate of intrinsic RV function in repaired ToF patients with residual PR and in this respect seems superior to EF. These data underscore the importance of serial ventricular volume assessment in the follow-up of these patients.