title: Does functional capacity depend on the size of the shunt? A prospective, cohort study of adults with small, unrepaired ventricular septal defects.
abstract: Small ventricular septal defects (VSDs) are considered to have great prognoses and most remain unrepaired. However, we have recently demonstrated lower functional capacity in patients with small VSDs compared with healthy peers. Using magnetic resonance imaging scans, we determined whether the functional capacity was correlated to the size of the shunt.
  
  
  
  We included patients with unrepaired VSDs and healthy adults between 18 and 40 years of age in a prospective, cohort study. Functional capacity was previously determined using an incremental bicycle test, establishing peak oxygen uptake. Magnetic resonance imaging scans were performed using a 1.5-tesla Philips scanner. With electrocardiographically triggered flow measurements, we calculated mean cardiac output from the pulmonary trunk and ascending aorta as well as vessel diameters.
  
  
  
  In total, 29 patients with unrepaired VSDs (26.5 ± 6 years) and 25 controls (26.9 ± 5 years) completed both studies. Previously measured peak oxygen uptake was nearly 20% lower in patients compared with controls (P = 0.002). All patients had shunt ratios below 1.5, with mean QpQs of 1.2 ± 0.1. When correlating shunt size to functional capacity, a negative correlation was found between the shunt ratio and peak oxygen uptake (r  = −0.44, P = 0.020). Compared with controls, patients had increased forward and retrograde flow in the pulmonary trunk but comparable flows in the ascending aorta. Pulmonary diameter was also increased in patients (30.3 ± 4 mm) compared with controls (28.2 ± 3 mm; P = 0.041), whereas aortic dimensions were comparable.
  
  
  
  Our results demonstrate that, although small, unrepaired VSDs revealed reduced functional capacity that can be negatively correlated to the size of the shunt.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus N, Denmark.|Department of Clinical Medicine, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Marie
authors.initials: M
authors.lastname: Maagaard
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus N, Denmark.|Department of Clinical Medicine, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Johan
authors.initials: J
authors.lastname: Heiberg
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus N, Denmark.|Department of Clinical Medicine, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Asschenfeldt
authors.affiliation: Department of Clinical Medicine, Aarhus University Hospital, Aarhus N, Denmark.|The MR Research Centre, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Steffen
authors.initials: S
authors.lastname: Ringgaard
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus N, Denmark.|Department of Clinical Medicine, Aarhus University Hospital, Aarhus N, Denmark.
authors.forename: Vibeke E
authors.initials: VE
authors.lastname: Hjortdal
mesh_terms: D000328:Adult; D001011:Aorta / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D002302:Cardiac Output / Q000502:physiology; D016022:Case-Control Studies; D004562:Electrocardiography; D005080:Exercise Test / Q000379:methods; D005260:Female; D006345:Heart Septal Defects, Ventricular / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D012039:Regional Blood Flow / Q000502:physiology; D055815:Young Adult
keywords: Adult congenital heart disease (ACHD); Exercise testing ; Magnetic resonance imaging ; Small ventricular septal defects ; Unrepaired 