title: Power loss and right ventricular efficiency in patients after tetralogy of Fallot repair with pulmonary insufficiency: clinical implications.
abstract: OBJECTIVE
  To quantify right ventricular output power and efficiency and correlate these to ventricular function in patients with repaired tetralogy of Fallot. This might aid in determining the optimal timing for pulmonary valve replacement.
  
  
  METHODS
  We reviewed the cardiac catheterization and magnetic resonance imaging data of 13 patients with tetralogy of Fallot (age, 22 ± 17 years). Using pressure and flow measurements in the main pulmonary artery, cardiac output and regurgitation fraction, right ventricular (RV) power output, loss, and efficiency were calculated. The RV function was evaluated using cardiac magnetic resonance imaging.
  
  
  RESULTS
  The RV systolic power was 1.08 ± 0.62 W, with 20.3% ± 8.6% power loss owing to 41% ± 14% pulmonary regurgitation (efficiency, 79.7% ± 8.6%; 0.84 ± 0.73 W), resulting in a net cardiac output of 4.24 ± 1.82 L/min. Power loss correlated significantly with the indexed RV end-diastolic and end-systolic volume (R = 0.78, P = .002 and R = 0.69, P = .009, respectively). The normalized RV power output had a significant negative correlation with RV end-diastolic and end-systolic volumes (both R = -0.87, P = .002 and R = -0.68, P = .023, respectively). A rapid decrease occurred in the RV power capacity with an increasing RV volume, with the curve flattening out at an indexed RV end-diastolic and end-systolic volume threshold of 139 mL/m(2) and 75 mL/m(2), respectively.
  
  
  CONCLUSIONS
  Significant power loss is present in patients with repaired tetralogy of Fallot and pulmonary regurgitation. A rapid decrease in efficiency occurs with increasing RV volume, suggesting that pulmonary valve replacement should be done before the critical value of 139 mL/m(2) and 75 mL/m(2) for the RV end-diastolic and end-systolic volume, respectively, to preserve RV function.
authors.affiliation: Division of Cardiology, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. fogel@email.chop.edu
authors.forename: Mark A
authors.initials: MA
authors.lastname: Fogel
authors.forename: Kartik S
authors.initials: KS
authors.lastname: Sundareswaran
authors.forename: Diane
authors.initials: D
authors.lastname: de Zelicourt
authors.forename: Lakshmi P
authors.initials: LP
authors.lastname: Dasi
authors.forename: Tom
authors.initials: T
authors.lastname: Pawlowski
authors.forename: Jack
authors.initials: J
authors.lastname: Rome
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Yoganathan
mesh_terms: D000293:Adolescent; D000328:Adult; D006328:Cardiac Catheterization; D002302:Cardiac Output; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects; D006801:Humans; D008279:Magnetic Resonance Imaging; D009200:Myocardial Contraction; D011237:Predictive Value of Tests; D011665:Pulmonary Valve Insufficiency / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D011666:Pulmonary Valve Stenosis / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D012189:Retrospective Studies; D013771:Tetralogy of Fallot / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D018497:Ventricular Dysfunction, Right / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D016278:Ventricular Function, Right; D017725:Ventricular Pressure; D055815:Young Adult