title: An in vivo method for measuring turbulence in mechanical prosthesis leakage jets.
abstract: This work introduces a method for the in vivo measurement and analysis of turbulence within the leakage of a mechanical heart valve. Several analysis techniques were applied to ultrasound measurements acquired within the atrium of a pig, and error associated with these techniques was analyzed. The technique chosen applies cyclic averaging to mean and maximum velocity measurements within small, normalized phase windows to calculate Reynolds normal stresses in the direction of the ultrasound beam. Maximum shear stresses are estimated from these normal stresses using an analytical technique. The stresses observed were smaller than those reported from previous in vitro simulations.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Arthus Universitetshospital, Skejby Sygehus, Brendstrupgaardsvej, 8200 Arhus N, Denmark. brandontravis2001@yahoo.com
authors.forename: Brandon R
authors.initials: BR
authors.lastname: Travis
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Christensen
authors.forename: Morten
authors.initials: M
authors.lastname: Smerup
authors.forename: Morten S
authors.initials: MS
authors.lastname: Olsen
authors.forename: J Michael
authors.initials: JM
authors.lastname: Hasenkam
authors.forename: Hans
authors.initials: H
authors.lastname: Nygaard
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology; D003198:Computer Simulation; D004548:Elasticity; D019544:Equipment Failure Analysis / Q000379:methods*; D006350:Heart Valve Prosthesis; D006351:Heart Valves / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000601:surgery; D018056:Hemorheology / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D017078:Laser-Doppler Flowmetry; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics; D010507:Periodicity; D011673:Pulsatile Flow; D013314:Stress, Mechanical; D013552:Swine; D018617:Ultrasonography, Doppler, Pulsed / Q000295:instrumentation / Q000379:methods; D018924:Vascular Capacitance; D014655:Vascular Resistance