Stress Echocardiographic Evaluation for D-Transposition of the Great Arteries after Atrial Redirection: Unmasking Early Signs of Myocardial Dysfunction and Baffle Stenosis

Abstract

The authors used semisupine cycle ergometry stress echocardiography to assess cardiac function and unmask baffle stenosis in patients with d-transposition of the great arteries after atrial redirection surgery. This was a retrospective review of semisupine cycle ergometry stress echocardiography performed in 53 patients (64% male; mean age, 24.0years; 90% Mustard procedure) and 56 healthy control subjects. Incremental exercise to volitional fatigue was performed. Hemodynamic data, echocardiographic cardiac dimensions, area change, tissue Doppler velocities, strain, ventricular synchronization, and superior vena cava flow velocities before and immediately after exercise are reported. Patients had lower exercise capacity (870 vs 1,854 J/kg, P<.001) and peak heart rates (132 vs 167 beats/min, P<.001). Stroke volume index did not increase with exercise (45 vs 47mL/m2, P=.400). Cardiac index increased in both groups with exercise (3.0 vs 6.1 and 2.9 vs 7.0L/min/m2, P<.001) and was higher in control subjects (P=.006). Right ventricular diastolic and systolic areas decreased significantly with exercise in both the short-axis and four-chamber views. Right and left ventricular contraction time shortened with exercise (405 vs 247 and 338 vs 217msec, P<.001) and remained synchronous (ratio of right ventricular to left ventricular contraction time=0.080). Doppler velocities in patients with baffle obstruction were higher in the lower superior vena cava with exercise compared with nonobstructed patients (1.87 vs 1.46m/sec, P=.020) and normalized after catheter intervention (1.49 vs 1.46m/sec, P=.800). Patients with d-transposition of the great arteries have lower exercise capacity and peak heart rates. The systemic right ventricle presents a lesser but qualitatively normal systolic response and decreased diastolic filling. Semisupine cycle ergometry stress echocardiography unmasked SVC obstruction.