Fundamental mechanics of aortic heart valve closure.
Stresses in a prosthetic heart valve at closure are determined by its geometrical and structural characteristics, by the mechanical support environment, and by the momentum of the valve leaflets or occluder and of the blood at the instant of closure. The mass of blood to be arrested is significantly greater than that of the leaflets or occluder, and is therefore likely to dominate the closure impulse. The kinetic energy of the blood must be transduced into potential energy in the structural components (valve leaflets, aortic root and aorta). This paper presents a methodology for computation and parameterisation of the blood momentum associated with a valve in the aortic position. It is suggested that the influence of physiological parameters, such as systolic waveform and systemic impedance, on the closure characteristics can be investigated based on the fluid dynamic implications. Detailed results are presented for a single leaflet mechanical valve (Bjork-Shiley 60 degrees Convexo-Concave). It is demonstrated that a simple analytical method can yield results that might be adequate for the purposes of valve design.
Medical Physics Department, University of Sheffield, Royal Hallamshire Hospital, I Floor, Glossop Rd, Sheffield S10 2JF, UK. d.r.hose@sheffield.ac.uk
David Rodney
DR
Hose
Andrew James
AJ
Narracott
Justin M T
JM
Penrose
David
D
Baguley
Ian P
IP
Jones
Patricia V
PV
Lawford
D001011:Aorta / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000295:instrumentation / Q000379:methods; D001783:Blood Flow Velocity / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006350:Heart Valve Prosthesis; D006801:Humans; D008955:Models, Cardiovascular; D013314:Stress, Mechanical