title: Quantification of aortic flow by phase-contrast magnetic resonance in patients with bicuspid aortic valve.
abstract: OBJECTIVE
  Bicuspid aortic valve (BAV) causes complex flow patterns in the ascending aorta (AAo), which may compromise the accuracy of flow measurement by phase-contrast magnetic resonance (PC-MR). Therefore, we aimed to assess and compare the accuracy of forward flow measurement in the AAo, where complex flow is more dominant in BAV patients, with flow quantification in the left ventricular outflow tract (LVOT) and the aortic valve orifice (AV), where complex flow is less important, in BAV patients and controls.
  
  
  RESULTS
  Flow was measured by PC-MR in 22 BAV patients and 20 controls at the following positions: (i) LVOT, (ii) AV, and (iii) AAo, and compared with the left ventricular stroke volume (LVSV). The correlation between the LVSV and the forward flow in the LVOT, the AV, and the AAo was good in BAV patients (r = 0.97/0.96/0.93; P < 0.01) and controls (r = 0.96/0.93/0.93; P < 0.01). However, in relation with the LVSV, the forward flow in the AAo was mildly underestimated in controls and much more in BAV patients [median (inter-quartile range): 9% (4%/15%) vs. 22% (8%/30%); P < 0.01]. This was not the case in the LVOT and the AV. The severity of flow underestimation in the AAo was associated with flow eccentricity.
  
  
  CONCLUSIONS
  Flow measurement in the AAo leads to an underestimation of the forward flow in BAV patients. Measurement in the LVOT or the AV, where complex flow is less prominent, is an alternative means for quantifying the systolic forward flow in BAV patients.
authors.affiliation: Division of Cardiology, Fondazione Cardiocentro Ticino, Via Tesserete 48, Lugano CH-6900, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Muzzarelli
authors.forename: P
authors.initials: P
authors.lastname: Monney
authors.forename: K
authors.initials: K
authors.lastname: O'Brien
authors.forename: F
authors.initials: F
authors.lastname: Faletra
authors.forename: T
authors.initials: T
authors.lastname: Moccetti
authors.forename: P
authors.initials: P
authors.lastname: Vogt
authors.forename: J
authors.initials: J
authors.lastname: Schwitter
mesh_terms: D000328:Adult; D001021:Aortic Valve / Q000002:abnormalities* / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000502:physiology; D016022:Case-Control Studies; D005260:Female; D006349:Heart Valve Diseases / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D013318:Stroke Volume / Q000502:physiology
keywords: aortic valve regurgitation; bicuspid aortic valve; flow; phase-contrast magnetic resonance