Recently, cavitation on the surface of mechanical heart valves has been studied as a cause of fractures occurring in implanted mechanical heart valves. The cause of cavitation in mechanical heart valves was investigated using the 25 mm Medtronic Hall valve and the 23 mm Omnicarbon valve. Closing of these valves in the mitral position was simulated in an electrohydraulic totally artificial heart...

1.0 Introduction 2.0 The 2.1 2.2 2.3 2.4 2.4 Experiment Position Control Velocity Sensors Recording and Analysis Flux Control Rotation Control 3.0 Vibrations of An Annular~Vortex 3.1 An Old Problem 3.2 An Axisymmetric Annular Vortex 3.3 Equations of Motion 3.3.1 Perturbations and Scaling 3.3.2 Complete Equation for the Perturbation Pressure 3.3.3 The Rayliezh Discriminant -3.3.4 Boundary Condit...

The minimum resistance of expiratory Heidbrink-type value has been assessed by determining the pressure decrease across the values at a flow rate of 30 litre min--1. The average resistance of 70 valves currently in clinical use was 318 Pa at that flow rate and about 44% had resistances greater than the limit of 294 Pa previously suggested. The resistances obtained in new valves were either simi...

Early stages of aortic valve disease involve a subtle increase in leaflet stiffness which affects valve performance seen particularly in the opening and closing of the valve. In this study, a pulse duplicator which recreates physiologic flow waveforms was used to evaluate how changes in experimental conditions such as downstream resistance and flow rate affect the opening and closing patterns o...

A flow visualization study was carried out for boiling in a rectangular channel filled with and without metallic random porous media. Four main patterns are observed as intermittent slug-churn flow, churn-annular annular-mist mist regimes. These clearly classified based on the high-speed images of flow. The results pattern map according to mass rate were presented using saturation temperatures ...

High bandwidth, high flow rate electrohydraulic valves typically have two or more stages. Most multi-stage valves are expensive, require meticulously clean fluid, and introduce higher order dynamics. On the other hand, single-stage spool valves are cheaper and more reliable. However, a majority of them are not suitable for high bandwidth, high flow rate applications due to limitations of the el...

BACKGROUND AND AIM OF STUDY Pressure gradients across cardiac valve prostheses have been identified as one of the most important performance measures in valve replacement surgery. Specifically in aortic valves, these gradients influence reduction of left ventricular hypertrophy and are postulated to influence long-term survival. The correct choice of replacement valve is hampered by a lack of u...

BACKGROUND Little is known about the impact of tricuspid annuloplasty (TAP) on annular dynamics. We assessed tricuspid annular dynamics using 3-D transesophageal echocardiography (3D-TEE) before and after TAP with different types of prosthetic ring. METHODS AND RESULTS 3D-TEE of the tricuspid valve was acquired in 30 patients (TAP with rigid ring [RR], n=8; TAP with flexible ring [FR], n=10; ...