title: Differential regurgitation in branch pulmonary arteries after repair of tetralogy of Fallot: a phase-contrast cine magnetic resonance study.
abstract: BACKGROUND
  The importance of pulmonary regurgitation (PR) after repair of tetralogy of Fallot (TOF) is increasingly recognized, but little is known regarding its underlying mechanisms. This phase-contrast cine magnetic resonance (PC MR) study was performed to evaluate the relative contribution of each lung to total regurgitant volume.
  
  
  RESULTS
  Twenty-two patients with significant PR underwent a PC MR 3 to 16 years after repair of TOF. Regurgitant fraction of the main pulmonary artery was 39+/-10%. Regurgitant fraction of the left pulmonary artery (LPA; 46+/-18%) was greater than that of the right pulmonary artery (34+/-16%; P=0.002). The average contribution of the LPA to the total regurgitant flow volume was 54+/-19%, whereas its average contribution to the total forward flow volume was 44+/-13% (P=0.002). In 4 patients, regurgitant flow in the LPA accounted for 75% to 100% of the total regurgitant flow. There was a linear relationship between regurgitant fraction and fraction of the regurgitant flow duration in the main pulmonary artery (P<0.001) and right pulmonary artery (P=0.001) but not in the LPA (P=0.129).
  
  
  CONCLUSIONS
  PR after repair of TOF is commonly associated with differential regurgitation in the branch pulmonary arteries, which is usually greater in the LPA. Although the cause of this disparity requires further investigation, those patients with a significant unilateral contribution to total PR may be amenable to localized techniques to reduce regurgitation.
authors.affiliation: Department of Diagnostic Imaging, The University of Toronto School of Medicine, Hospital for Sick Children, 555 University Ave, Toronto, Ontario, Canada M5G 1X8.
authors.forename: I-Seok
authors.initials: IS
authors.lastname: Kang
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Redington
authors.forename: Leland N
authors.initials: LN
authors.lastname: Benson
authors.forename: Christopher
authors.initials: C
authors.lastname: Macgowan
authors.forename: Emanuela R
authors.initials: ER
authors.lastname: Valsangiacomo
authors.forename: Kevin
authors.initials: K
authors.lastname: Roman
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Kellenberger
authors.forename: Shi-Joon
authors.initials: SJ
authors.lastname: Yoo
mesh_terms: D000293:Adolescent; D001783:Blood Flow Velocity; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008168:Lung / Q000098:blood supply; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D011651:Pulmonary Artery / Q000503:physiopathology; D011652:Pulmonary Circulation; D011665:Pulmonary Valve Insufficiency / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D013771:Tetralogy of Fallot / Q000601:surgery*; D014654:Vascular Patency