title: Postsurgical hemodynamics of the aortic valve bypass operation evaluated with phase contrast magnetic resonance.
abstract: OBJECTIVE
  To characterize the postsurgical hemodynamics in aortic valve bypass (AVB) patients, and to determine the relationship between presurgical native aortic valve pressure gradient and postsurgical hemodynamics.
  
  
  METHODS
  Twenty patients scheduled for AVB surgery underwent presurgical transthoracic Doppler echocardiography to assess the degree of aortic stenosis and postsurgical cardiac magnetic resonance imaging (MRI) to acquire phase contrast magnetic resonance (PCMR) flow values along the ascending and descending aorta, and in the conduit. Net flow values were calculated from the PCMR images and compared to presurgical aortic valve pressure gradient measurements.
  
  
  RESULTS
  PCMR showed that: 1) The blood flow split between the aorta and the conduit was 35%:65% of cardiac output and 2) 60% of patients had net retrograde blood flow in the superior thoracic aorta over the cardiac cycle. Patients with presurgical pressure gradient (ΔP) > 45 mmHg had significantly less blood flow out of the native aorta than patients with ΔP < 45 mmHg, and had significantly more retrograde flow in the superior thoracic aorta postsurgery.
  
  
  CONCLUSIONS
  In patients undergoing AVB, presurgical aortic valve pressure gradient is associated with the volume of blood flow out the aorta and the direction of blood flow in the superior thoracic aorta after conduit addition as measured by PCMR.
authors.affiliation: Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA.
authors.forename: Adrian
authors.initials: A
authors.lastname: Lam
authors.forename: Stephanie
authors.initials: S
authors.lastname: Clement-Guinaudeau
authors.forename: Muralidhar
authors.initials: M
authors.lastname: Padala
authors.forename: Robert L
authors.initials: RL
authors.lastname: Eisner
authors.forename: Vinod
authors.initials: V
authors.lastname: Thourani
authors.forename: David
authors.initials: D
authors.lastname: Vadnais
authors.forename: Stuart
authors.initials: S
authors.lastname: Hurst
authors.forename: Robert A
authors.initials: RA
authors.lastname: Guyton
authors.forename: John N
authors.initials: JN
authors.lastname: Oshinksi
mesh_terms: D000368:Aged; D001011:Aorta / Q000503:physiopathology* / Q000601:surgery; D001024:Aortic Valve Stenosis / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D001783:Blood Flow Velocity; D013504:Cardiovascular Surgical Procedures / Q000379:methods*; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011182:Postoperative Care / Q000379:methods; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: aortic; bypass; conduit; stenosis