Late results of surgical treatment of transposition of the great arteries.

In summary, many of these patients have achieved a normal working capacity, but as a group there is a statistically significant reduction when compared to healthy children (p < 0.01). There was no significant difference between the group of patients who had their Mustard operation in infancy and later. As yet, there is no suggestion that the older patients, or those with the longest time interval between the operation and the exercise test, have a progressive reduction in working capacity. The decreased working capacity and moderate increase in ventilation suggests restricted cardiac output on exercise. This could be related to the abnormal heart rate response rather than indicating poor ventricular function. Equally, a restricted cardiac output on exercise may be due to inefficiency of atrial transport, tricuspid regurgitation or unmasked pulmonary vascular obstructive disease. Further studies may clarify these points. This study demonstrated that the exercise performance of asymptomatic patients 6-13 years after Mustard's operation was somewhat diminished, compared with a group of normal children. Nevertheless, these patients did lead and enjoy a normal life. Only longitudinal studies may bring the final answer to the important question: How many patients will be alive with normal or near normal exercise tolerance 40-50 years after Mustard's operation? Until such an answer is available, we believe that the Mustard operation should be used in the treatment of TGA, while the alternative techniques are carefully explored.