title: Measurement of volumetric mitral and aortic blood flow based on a new freehand three-dimensional colour flow imaging method. An in vivo validation.
abstract: OBJECTIVE
  To validate a new three-dimensional (3D) colour flow method used to calculate cardiac output (CO) in aortic and mitral blood flow.
  
  
  METHODS
  The transducer was freely tilted transthoracically using a magnetic locating device recording its spatial position. Raw digital ultrasound data were recorded in healthy subjects during 10-20 heartbeats at a high frame rate ranging from 41 to 66 frames/s and analysed off-line with no loss in temporal resolution. Blood flow velocities aligned with the ultrasound beam were integrated across a moving spherical surface to calculate volumetric flow.
  
  
  RESULTS
  The range of agreement between the 3D mitral and 3D aortic method was 0.04+/-1.32 l/min (mean+/-2 standard deviations). The range of agreement between 3D aortic flow and the two-dimensional (2D) pulsed wave Doppler method (2DPW) in the left ventricular outflow tract (LVOT) was 0.7+/-1.7 l/min, while the range of agreement between 3D mitral flow and the 2DPW method was 0.88+/-1.64 l/min.
  
  
  CONCLUSIONS
  The 3D methods agreed well. The 3D volumetric flow overestimated the 2DPW method, as expected, and the range of agreement was wide. The common pitfalls in pulsed wave ultrasound methods to calculate CO were avoided, as the 3D method was angle-independent, no assumptions about the velocity profile were made, and a moving sample surface was applied. The acquisition of data was fast and easy and high temporal resolution was achieved.
authors.affiliation: Department of Cardiology and Lung Medicine, Norwegian University of Science and Technology, N-7006 Trondheim, Norway.
authors.forename: B O
authors.initials: BO
authors.lastname: Haugen
authors.forename: S
authors.initials: S
authors.lastname: Berg
authors.forename: K M
authors.initials: KM
authors.lastname: Brecke
authors.forename: S O
authors.initials: SO
authors.lastname: Samstad
authors.forename: T
authors.initials: T
authors.lastname: Skjaerpe
authors.forename: S A
authors.initials: SA
authors.lastname: Slørdahl
authors.forename: H
authors.initials: H
authors.lastname: Torp
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D002302:Cardiac Output; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation