Ventriculovascular interactions late after atrial and arterial repair of transposition of the great arteries

Objective The aim of this study was to compare atrial switch and arterial switch operations for the repair of transposition of the great arteries (TGA), assessing cardiac function and ventriculoarterial (VA) coupling based on cardiac magnetic resonance (CMR) data. Using CMR-derived wave intensity analysis, this study provides a noninvasive comparison of the 2 systemic ventricles and evaluates the subclinical hemodynamic burden of these operations. Methods Fifty-four patients (18 controls, 18 atrial switches, 18 arterial switches) were studied. Dimensional and functional data, including the ejection fraction (EF) and end-diastolic volume, were derived from CMR, as well as aortic distensibility. Wave intensity was computed from CMR according to a formulation based on changes in area and velocity, and the peaks of the 2 major systolic waves (forward compression wave [FCW], and forward expansion wave [FEW]) were measured as indicators of ventricular function. Results Both switches exhibited significantly increased end-diastolic volume and enlarged aortic root areas, and atrial switches were also characterized by significantly lower EF. Patients with TGA presented stiffer ascending aortas, particularly those repaired with an arterial switch. Both FCW and FEW were significantly lower in both TGA cohorts than the controls, suggesting compromised VA coupling, likely a result of increased impedance caused by the stiffer ascending aorta. A significant difference between switch type was noticed in terms of the FEW peak, which was lower in the atrial switch group. Conclusions These data highlight reduced aortic distensibility and abnormal VA coupling in repaired TGA. An intraoperational difference was noted in terms of EF and peak FEW, likely reflecting the different nature of the subaortic ventricle.