Impact of pressure load caused by right ventricular outflow tract obstruction on right ventricular volume overload in patients with repaired tetralogy of Fallot

Objectives: In correction of tetralogy of Fallot (TOF), surgical strategies to minimize right ventricular outflow tract (RVOT) enlargement have recently been preferred. However, we may be confronted with residual pulmonary stenosis (PS) combined with pulmonary regurgitation (PR), and how the pressure load affects these patients is not evident. Methods: We compared 51 patients with PR and significant PS (PR with PS group) with 87 patients with PR without significant PS (PR group) using echocardiography and cardiac magnetic imaging. We evaluated the differences in parameters derived by magnetic resonance imaging between the 2 groups and the influence of the pressure load on right ventricular (RV) volume and function. Results: Although the PR fraction was similar between the 2 groups, the PR with PS group showed significantly smaller RV end-diastolic volume (136.7 ± 26.5 mL/m ² vs 151.2 ± 34.7 mL/m ²; P = .01), RV end-systolic volume (68.1 ± 23.7 mL/m ² vs 80.2 ± 27.5 mL/m ²; P = .01), and slightly better RV ejection fraction (51.1% ± 9.8% vs 47.6% ± 8.9%; P = .03) than the PR group. For influence of the pressure load, PR fraction (r = -0.18, P = .03), RV end-diastolic volume (r = -0.25, P = .003), and RV end-systolic volume (r = -0.24, P = .005) were decreased as peak pressure gradient of PS was higher. Linear regression analysis revealed that both PR fraction and peak pressure gradient of PS were independent predictors for RV volume. Conclusions: Our study demonstrated that the RV pressure load prevented RV dilatation from chronic PR without systolic dysfunction. It is suggested that a proper relief of RVOT obstruction with acceptable residual stenosis is more advantageous than aggressive RVOT enlargement in the long-term outcome of repaired TOF.