Objectives Despite excellent survival in patients after the arterial switch operation, reintervention is frequently required and exercise capacity is decreased in a substantial number of patients. This study relates right-sided imaging features in patients long-term after the arterial switch operation to exercise capacity and ventilatory efficiency to investigate which lesions are functionally important. Methods Patients operated in the UMC Utrecht, the Netherlands (1976-2001) and healthy controls underwent cardiac magnetic resonance imaging and cardiopulmonary exercise testing within 1 week. We measured main, left, and right pulmonary artery cross-sectional areas, pulmonary blood flow distribution, peak oxygen uptake, and minute ventilation relative to carbon dioxide elimination. Results A total of 71 patients (median age, 20 [12-35] years, 73% were male) and 21 healthy controls (median age, 26 [21-35] years, 48% were male) were included. Main, left, and right pulmonary artery areas were decreased compared with controls (190 vs 269 mm2/m2, 59 vs 157 mm2/m2, 98 vs 139 mm2/m2, respectively, all P <.001); however, pulmonary blood flow distribution was comparable (P =.722). Peak oxygen uptake and minute ventilation relative to carbon dioxide elimination were 88% ± 20% and 23.7 ± 3.8, respectively, with 42% and 1% of patients demonstrating abnormal results (â‰84% and ≥ 34, respectively). The main pulmonary artery area significantly correlated with peak oxygen uptake (r = 0.401, P =.001) and pulmonary blood flow distribution with minute ventilation relative to carbon dioxide elimination (r = -0.329, P =.008). Subanalysis (<18, 18-25, >25 years) showed that the main pulmonary artery area was smaller in older age groups. In multivariable analysis, the main pulmonary artery area was independently associated with peak oxygen uptake (P =.032). Conclusions In adult patients after the arterial switch operation, narrowing of the main pulmonary artery is a common finding and is the main determinant of limitation in functional capacity, rather than pulmonary branch stenosis.

arterial switch operation, exercise capacity, magnetic resonance imaging, pulmonary artery stenosis, transposition of great vessels
dx.doi.org/10.1016/j.jtcvs.2015.07.101, hdl.handle.net/1765/88856
The Journal of Thoracic and Cardiovascular Surgery
Department of Cardiology

Baggen, V.J.M, Driessen, M.M.P, Meijboom, F.J, Sieswerda, G.T, Jansen, N.J.G, Van Wijk, S.W.H, … Breur, J.M.P.J. (2015). Main pulmonary artery area limits exercise capacity in patients long-term after arterial switch operation. The Journal of Thoracic and Cardiovascular Surgery, 150(4), 918–925. doi:10.1016/j.jtcvs.2015.07.101