Severe right ventricular dilatation after repair of Tetralogy of Fallot is associated with increased left ventricular preload and stroke volume.

Abstract

Pulmonary regurgitation (PR) and right ventricular (RV) dilatation are common in repaired tetralogy of Fallot (rTOF). Left ventricular (LV) dysfunction is an important risk factor in rTOF. The effect of PR/RV dilatation on LV performance and RV-LV interactions in rTOF are incompletely understood. We examined LV responses and exercise capacity in rTOF, both before and after pulmonary valve replacement (PVR). Cardiac magnetic resonance imaging scans in 126 rTOF patients (age 17.3 ± 7.6 years) were analysed, comparing subjects with indexed RV end-diastolic volume (RVEDVi) <170 mL/m2 (mild/moderate dilatation, n = 95) and RVEDVi ≥170 mL/m2 (severe dilatation, n = 31). Indexed PR volume (PRVi), RV end-systolic (RVESVi), RV end-diastolic (RVEDVi), RV stroke volume (RVSVi), net pulmonary forward flow (NPFFi), LV end-diastolic (LVEDVi), LV end-systolic (LVESVi), LV stroke volume (LVSVi), RV and LV ejection fraction (EF), and diastolic septal curvature were obtained. Peak aerobic capacity (VO2 max) was measured. In a subset (n = 30), measures were obtained pre-and-post surgical PVR. Compared to those with mild/moderate RV dilatation, patients with severe RV dilation had greater PRVi (38 ± 12 vs. 24 ± 9 mL/m2, P < 0.0001), NPFFi (53 ± 9 vs. 44 ± 11 mL/m2, P < 0.0001), LVEDVi (87 ± 14 vs. 73 ± 13 mL/m2, P < 0.0001), LVESVi (39 ± 12 vs. 30 ± 8 mL/m2, P < 0.0001), and LVSVi (48 ± 7 vs. 43 ± 8 mL/m2, P = 0.002) but lower RV ejection fraction (46 ± 8 vs. 53 ± 7%, P < 0.0001). Septal curvature and VO2 max were similar in both groups. After PVR, there was no change in LVEDVi, LVSVi, septal curvature, or VO2 max. Chronic PR with severe RV dilatation is associated with increased NPFFi, LVEDVi, and LVSVi. This may potentially explain preserved exercise capacity in rTOF with severe PR and RV dilatation.