Background: The underlying mechanisms that contribute to global right ventricular (RV) dysfunction in patients with repaired tetralogy of Fallot are incompletely understood. We therefore sought to quantify regional RV abnormalities and to determine the relationship of these to global RV function and exercise capacity.
Methods and results: Clinical and cardiac magnetic resonance data from 62 consecutive patients with repaired tetralogy of Fallot were analyzed (median age at follow-up 23 years [limits 9 to 67 years]). Using cardiac magnetic resonance data, 3D RV endocardial surface models were reconstructed from segmented contours, and a correspondence between end diastole and end systole was computed with a novel algorithm. Regional RV abnormalities were quantified and expressed as segmental ejection fraction, spatial extent of dyskinetic area, displacement of dyskinetic area, and score of extent of late gadolinium enhancement. Regional abnormalities of function and hyperenhancement were greatest in the RV outflow tract (RVOT). These regional RVOT abnormalities correlated with global RV ejection fraction: RVOT ejection fraction r=0.64, P<0.0001; RVOT dyskinetic area r=-0.51, P<0.0001; RVOT displacement of dyskinetic area r=-0.49, P<0.0001; and RVOT late gadolinium enhancement score r=-0.33, P=0.01. Peak oxygen consumption during exercise correlated best with RVOT ejection fraction (r=0.56, P=0.0002) compared with the remainder of the RV (r=0.35, P=0.03). The only cardiac magnetic resonance variable independently predictive of aerobic capacity was RVOT ejection fraction (P=0.02).
Conclusions: A greater extent of regional abnormalities in the RVOT adversely affects global RV function and exercise capacity after tetralogy of Fallot repair. These regional measures may have important implications for patient management, including RVOT reconstruction, at the time of pulmonary valve replacement.