title: Dynamics of Björk-Shiley Convexo-Concave mitral valves in sheep.
abstract: The outlet strut of Björk-Shiley (BSCC) Convexo-Concave heart valves has fractured in some implanted valves resulting in disc escape and emergency reoperation or death. The closing dynamics of BSCC heart valves was studied in situ to determine the forces acting on the outlet strut during valve closure. BSCC valves with strain gages attached to the outlet strut were implanted in the mitral position in sheep. Impact forces were measured under various circumstances including anesthetized, sedentary, and exercise conditions. Left ventricular (LV) pressures were recorded simultaneously via catheter-tip pressure transducers. Impact forces increased with the 1/3 power of left ventricular pressure rise and the square root of LV pressure at valve closure. Good agreement between the in vivo measurements and theoretical models was observed. Based on this study, it is concluded that sheep provides a good in situ model for the testing of mechanical mitral valves.
authors.affiliation: Shiley Heart Valve Research Center, Irvine, California 92714, USA.
authors.forename: S
authors.initials: S
authors.lastname: Schreck
authors.forename: R
authors.initials: R
authors.lastname: Inderbitzen
authors.forename: H
authors.initials: H
authors.lastname: Chin
authors.forename: D W
authors.initials: DW
authors.lastname: Wieting
authors.forename: M
authors.initials: M
authors.lastname: Smilor
authors.forename: E
authors.initials: E
authors.lastname: Breznock
authors.forename: D
authors.initials: D
authors.lastname: Pendray
mesh_terms: D000768:Anesthesia, General; D000818:Animals; D001696:Biomechanical Phenomena; D006328:Cardiac Catheterization / Q000295:instrumentation; D004195:Disease Models, Animal; D004562:Electrocardiography; D006339:Heart Rate; D006350:Heart Valve Prosthesis; D008943:Mitral Valve; D008955:Models, Cardiovascular; D005082:Physical Exertion; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012146:Rest; D012756:Sheep; D013314:Stress, Mechanical; D013599:Systole; D014160:Transducers, Pressure; D016277:Ventricular Function, Left; D017725:Ventricular Pressure