The Right Ventricle and Exercise Capacity in Adults with Repaired Tetralogy of Fallot: Passive Bystander or Active Participant?

Exercise intolerance is a hallmark symptom in adults with tetralogy of Fallot (TOF). This may be attributed to impairments in right ventricular (RV) function, augmentation in RV load, and their effect on left ventricular (LV) hemodynamics. To elucidate these mechanisms, we examined oxygen uptake (VO2) and cardiac hemodynamics in TOF and healthy controls at rest and during exercise. At peak exercise, VO2 was lower in TOF. This was partially attributed to lower heart rate in conjunction with a blunted exercise-induced change in LV stroke volume from rest to compensate for the chronotropic incompetence. Additionally, at peak exercise, pulmonary-RV was higher in TOF. Additionally, at peak exercise, in TOF, pulmonary-RV coupling negatively correlated with VO2 , changes in LV end-diastolic volume, and changes in LV SV from rest. These findings reveal the reliance of LV hemodynamics on the interplay between RV systolic load and function during exercise in TOF.