The future of adult patients after Mustard or Senning repair for transposition of the great arteries.

BACKGROUND: After Mustard or Senning repair for transposition of the great arteries (d-TGA), qualitative assessment of the systemic right ventricle remains difficult. We wanted to evaluate the relationship between demographic and echocardiographic variables, and exercise performance.
METHODS: In 22 consecutive d-TGA patients (9 Mustard and 13 Senning) a standard transthoracic echocardiogram was performed. Peak oxygen consumption (peak VO2, ml/kg/min) was obtained by a bicycle stress test. Cardiac index (CI) at rest, 50 W, and 100 W was calculated from cardiac output, obtained by CO2 rebreathing.
RESULTS: The group of patients consisted in 15 male and 7 female with a median age of 21 (range 17-34) years. On echocardiographic evaluation, right ventricular function was normal in one, slightly impaired in 11, moderately impaired in 9, and severely impaired in one. Peak VO2 was 27.4+/-7.9 ml/kg/min, which was 64+/-16% of predicted values in normals. CI at rest, 50 Watt, and 100 Watt, were 2.7+/-0.5, 5.6+/-1.2, and 6.8+/-1.1 l/min/m2, respectively. No relationship between echocardiographic parameters and exercise capacity was found. Age correlated significantly with CI at 50 and 100 W (rho=-0.44, P=0.045 and rho=-0.77, P=0.0001, respectively). Finally, simple regression analysis identified a linear relationship between age and CI at 100 W (bèta=-0.54 and R2=0.29, P=0.014).
CONCLUSIONS: Maximal exercise capacity is reduced in adult patients after Mustard or Senning repair. Standard echocardiographic 2D-measurements are insufficient to determine the reduction in their functional capacity. The inverse relationship between age and the cardiac indices suggests an age dependent and progressive diminution of systemic ventricular function.