Long-term assessment and serial evaluation of cardiorespiratory exercise performance and cardiac function in patients with atrial switch operation for complete transposition

Background. At present, a considerable number of patients survive who under went an atrial switch operation for correction of complete transposition. O ur study aimed to assess their long-term exercise performance and the seria l evolution of cardiac function, Methods: We studied 22 patients 5 to 17 ye ars after an atrial switch operation, and followed them serially for 3.5 +/ - 2 years after the first evaluation. Cardiorespiratory exercise function w as assessed by analysis of gas exhange and by determination of the ventilat ory anaerobic threshold. Echocardiography was performed on all evaluations. Results: All patients were in Class I of the classification of the New Yor k Heart Association at all assessments. Ventilatory anaerobic threshold, ho wever, was significantly lower than normal. It averaged 77.9% +/- 13.7 of t he normal mean value at the initial evaluation, and remained stable when re -evaluated later (76.2 +/- 13.7%). At the initial study, the increase in ox ygen uptake during graded exercise was below the 95% confidence limit in 6 of the patients, and was below this level in 10 patients at re-assessment. The subnormal values for oxygen uptake during submaximal exercise were asso ciated with moderate to severe haemodynamic dysfunction. At echocardiograph y, 15 of 17 patients studied twice had mild to moderate right ventricular d ilation and tricuspidregurgiation, which remained virtually the same at rea sssesment. A stable sinus rhythm was initially present in 17 patients, and persisted in 15 patients during follow-up. Conclusion: At medium term follo w-up, cardiorespiratory exercise performance remains stable in patients aft er atrial switch repair. Serial exercise testing appears useful, because in individual patients in the present study, a decreasing exercise tolerance correlated with development of haemodynamic sequels.