title: Main pulmonary artery area limits exercise capacity in patients long-term after arterial switch operation.
abstract: OBJECTIVE
  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 mm(2)/m(2), 59 vs 157 mm(2)/m(2), 98 vs 139 mm(2)/m(2), 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 (≤ 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.
authors: Department of Cardiology, Erasmus MC, Rotterdam, The Netherlands; Department of Cardiology, UMC Utrecht, Utrecht, The Netherlands.
authors: Vivan J M
authors: VJ
authors: Baggen
authors: Department of Cardiology, UMC Utrecht, Utrecht, The Netherlands; ICIN-Netherlands Heart Institute, Utrecht, The Netherlands.
authors: Mieke M P
authors: MM
authors: Driessen
authors: Department of Cardiology, UMC Utrecht, Utrecht, The Netherlands.
authors: Folkert J
authors: FJ
authors: Meijboom
authors: Department of Cardiology, UMC Utrecht, Utrecht, The Netherlands.
authors: Gertjan Tj
authors: GT
authors: Sieswerda
authors: Department of Pediatric Intensive Care, Wilhelmina Children's Hospital, UMC Utrecht, Utrecht, The Netherlands.
authors: Nicolaas J G
authors: NJ
authors: Jansen
authors: Department of Cardiology, UMC Utrecht, Utrecht, The Netherlands.
authors: Sebastiaan W H
authors: SW
authors: van Wijk
authors: Department of Cardiology, UMC Utrecht, Utrecht, The Netherlands.
authors: Pieter A
authors: PA
authors: Doevendans
authors: Department of Radiology, UMC Utrecht, Utrecht, The Netherlands.
authors: Tim
authors: T
authors: Leiner
authors: Department of Pediatric Cardiothoracic Surgery, Wilhelmina Children's Hospital, UMC Utrecht, Utrecht, The Netherlands.
authors: Paul H
authors: PH
authors: Schoof
authors: Department of Pediatric Physical Therapy and Exercise Physiology, Child Development and Exercise Center, Wilhelmina Children's Hospital, UMC Utrecht, Utrecht, The Netherlands.
authors: Tim
authors: T
authors: Takken
authors: Department of Pediatric Cardiology, Wilhelmina Children's Hospital, UMC Utrecht, Utrecht, The Netherlands. Electronic address: h.breur@umcutrecht.nl.
authors: Johannes M P J
authors: JM
authors: Breur
mesh_terms: D000293:Adolescent; D000328:Adult; D000069278:Arterial Switch Operation; D057791:Cardiac Imaging Techniques; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011651:Pulmonary Artery / Q000033:anatomy & histology* / Q000503:physiopathology*; D012039:Regional Blood Flow; D013997:Time Factors; D055815:Young Adult
keywords: arterial switch operation; exercise capacity; magnetic resonance imaging; pulmonary artery stenosis; transposition of great vessels