Haemodynamic, ventilatory and peripheral determinants during exercise of repaired Tetralogy of Fallot

Abstract

Pulmonary valve replacement (PVR) for patients with repaired Tetralogy of Fallot (TOF) and pulmonary regurgitation (PR) improves functional status without definitive improvement of peak VO2 despite correction of the haemodynamic lesion. We aim to study cardiorespiratory and peripheral profiles during exercise test before and after PVR to understand this improvement. Patients with TOF and severe PR performed a cardiopulmonary exercise testing (CPET) and a cardiac MRI for the measurement of ventricular volumes and pulmonary regurgitation fraction (FR) before and after PVR. Fifteen patients (mean age 33 ± 13 years) were included. CPET was performed 6 months before and 25 ± 2 months after PVR. Following PVR: significant improvement in NYHA functional class ( P = 0,006) without significant improvement in peak VO 2 (26 ± 6 to 25 ± 6,9 mL/kg/min, P = 0,36) nor maximal workload (114 ± 30 to 118 ± 30 Watt, P = 0,31) with unchanged maximal heart. Patients had a moderate hyperventilation without pejorative criterion (VE/VCO 2 nadir 31 ± 3 to 32 ± 7, P = 0,61) without pulmonary limitation (maximal breathing reserve 31 ± 23 to 21 ± 17%, P = 0,27) despite a restrictive pattern in spirometric results. Nevertheless, we found a significant improvement in peak oxygen pulse (9,9 ± 2,5 to 11 ± 4, P = 0,04) and a significant postponed ventilatory anaerobic threshold (VAT) after PVR (05:28 ± 2:00 to 6:57 ± 1:53 min, P = 0,002; 61 ± 20 to 75 ± 18 Watt, P = 0,006). PR (FR: 46 ± 14 to 5,6± 9,7%, P < 0,001), RV end-diastolic volume (156 ± 39,4 to 92 ± 32 mL/m 2 , P = 0,002) and RV end-systolic volume (89 ± 32 to 50 ± 28 mL/m2, P = 0,004) decreased. Despite the lack of improvement in the peak VO 2 , hemodynamic improvement was observed by the significant improvement in oxygen pulse and peripheral capacity associated with an improvement in functional capacity. It can be assumed that the peak VO 2 is not the best marker for the evaluation of aerobic capacity and that our evaluation could be based on the VAT in these patients.