title: Total isovolumic time relates to exercise capacity in patients with transposition of the great arteries late after atrial switch procedures.
abstract: BACKGROUND
  Systemic right ventricular systolic dysfunction is common late after atrial switch surgery for transposition of the great arteries. Total isovolumic time is the time that the ventricle is neither ejecting nor filling and is calculated without relying on geometric assumptions. We assessed resting total isovolumic time in this population and its relationship to exercise capacity.
  
  
  METHODS
  A total of 40 adult patients with transposition of the great arteries after atrial switch - and 10 healthy controls - underwent transthoracic echocardiography and cardiopulmonary exercise testing from January, 2006 to January, 2009. Resting total isovolumic time was measured in seconds per minute: 60 minus total ejection time plus total filling time.
  
  
  RESULTS
  The mean age was 31.6 plus or minus 7.6 years, and 38.0% were men. There were 16 patients (40%) who had more than or equal to moderate systolic dysfunction of the right ventricle. Intra- and inter-observer agreement was good for total isovolumic time, which was significantly prolonged in patients compared with controls (12.0 plus or minus 3.9 seconds per minute versus 6.0 plus or minus 1.8 seconds per minute, p-value less than 0.001) and correlated significantly with peak oxygen consumption (r equals minus 0.63, p-value less than 0.001). The correlation strengthened (r equals minus 0.73, p-value less than 0.001) after excluding seven patients with exercise-induced cyanosis. No relationship was found between exercise capacity and right ventricular ejection fraction or long-axis amplitude.
  
  
  CONCLUSIONS
  Resting isovolumic time is prolonged after atrial switch for patients with transposition of the great arteries. It is highly reproducible and relates well to exercise capacity.
authors: Adult Congenital Heart Centre and Centre for Pulmonary Hypertension, Royal Brompton Hospital, London, United Kingdom. Edgar_Tay@nuhs.edu.sg
authors: Edgar L W
authors: EL
authors: Tay
authors: Derek
authors: D
authors: Gibson
authors: Ryo
authors: R
authors: Inuzuka
authors: Manjit
authors: M
authors: Josen
authors: Rafael
authors: R
authors: Alonso-Gonzalez
authors: Georgios
authors: G
authors: Giannakoulas
authors: Wei
authors: W
authors: Li
authors: Konstantinos
authors: K
authors: Dimopoulos
authors: Michael A
authors: MA
authors: Gatzoulis
mesh_terms: D000328:Adult; D006348:Cardiac Surgical Procedures; D016022:Case-Control Studies; D004452:Echocardiography; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D013997:Time Factors; D014188:Transposition of Great Vessels / Q000503:physiopathology* / Q000601:surgery; D016278:Ventricular Function, Right