The right ventricle provides systemic circulation in individuals with congenitally corrected transposition of the great arteries (CCTGA) and in those with complete transposition who have had an atrial switch repair (DTGA). The aim of this study was to evaluate how the systemic right ventricle adapts to increased workload and oxygen demand during exercise.
From November 2005 through December 2015, 3,358 adult patients with congenital heart disease were treated at our institution; we identified 48 (26 females, 22 males; median age, 25.4 ± 8.1 yr) who met the study criteria; 37 had DTGA and atrial switch repair, and 11 had CCTGA. We studied their echocardiographic and cardiopulmonary exercise test results. A control group consisted of 29 healthy sex- and age-matched volunteers.
On exercise testing, oxygen uptake at anaerobic threshold, peak oxygen uptake, peak heart rate, and percentage of maximal heart rate were significantly lower in the group with systemic right ventricle than in the control group (all P <0.001); in contrast, the peak ventilatory equivalent for carbon dioxide was higher in the study group (P=0.013). Impaired systemic right ventricular function reduced peak oxygen uptake. The peak heart rate was lower in the CCTGA group than in the DTGA group.
Our results indicate that reduced exercise capacity is related to impaired systemic right ventricular function, severe tricuspid valve regurgitation, and chronotropic incompetence. There was no correlation between cardiopulmonary exercise test results and time after surgery. Chronotropic efficiency is lower in individuals with CCTGA than in those with DTGA.
