title: The role of epicardial echocardiography in the measurement of transvalvular flow velocities during aortic valve replacement.
abstract: OBJECTIVE
  The purpose of this study was to compare transvalvular flow velocities obtained by transesophageal echocardiography and epicardial echocardiography (EE) during aortic valve replacement (AVR).
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Patients undergoing AVR for aortic stenosis.
  
  
  METHODS
  After institutional review board approval, 17 patients undergoing AVR consented. Deep transgastric (deep TG LAX) and transgastric long-axis (TG LAX) views and epicardial aortic valve long-axis views (S8 probe) were obtained on a SONOS 5500 (Phillips Medical Systems, Bothell, WA) before and after AVR. Transvalvular flow velocity and velocity time integral (VTI) were recorded via each technique. Measurements were made offline by 2 independent reviewers. Agreement between measurements made by different views was evaluated by using Bland-Altman analysis.
  
  
  RESULTS
  The epicardial probe was well tolerated. Quality images were obtained in all patients with TEE and 30 of 34 studies via epicardial scanning. The mean bias for peak velocities derived through EE and deep TG LAX was 96.3 cm/s (95% confidence interval [CI], 51.1-141.4) before AVR and 58 cm/s (95% CI, 32.4-83.7) after AVR. The mean bias for peak velocities between EE and TG LAX was 70 cm/s (95% CI, 31.1-108.9) before and 84.7 cm/s (95% CI, 55.6-113.7) after AVR. Similar results were obtained for VTI.
  
  
  CONCLUSIONS
  Peak transaortic valve velocities and VTI measured with epicardial echocardiography are higher in comparison to measurements via TEE in patients undergoing AVR. The precise role of epicardial echocardiography in the comprehensive echocardiographic examination of patients undergoing aortic valve replacement needs further evaluation.
authors.affiliation: Department of Anesthesia and Perioperative Medicine, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada. Ravi.Taneja@lhsc.on.ca
authors.forename: Ravi
authors.initials: R
authors.lastname: Taneja
authors.forename: Bert
authors.initials: B
authors.lastname: Quaghebeur
authors.forename: Larry W
authors.initials: LW
authors.lastname: Stitt
authors.forename: Mackenzie A
authors.initials: MA
authors.lastname: Quantz
authors.forename: Lin R
authors.initials: LR
authors.lastname: Guo
authors.forename: Bob
authors.initials: B
authors.lastname: Kiaii
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Bainbridge
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000601:surgery*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D001783:Blood Flow Velocity / Q000502:physiology; D017548:Echocardiography, Transesophageal / Q000379:methods*; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D010496:Pericardium / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies