A phonocardiographic method is described for measuring the time taken by the ball of a Starr-Edwards prosthesis to move to the apex of the cage at the onset of left ventricular ejection, and from this its acceleration can be derived. The acceleration is conspicuously increased in post-ectopic beats and in exercise, but is unaffected by posture and tachycardia induced by atropine or ventricular ...

Abstract When the oil supply is not adequate to maintain ideal lubrication, angular contact ball bearing will enter into starved lubrication regime resulting in potential performance degradation and consequently severe failures. To study effects of on bearing, this paper first proposes a multi-degree-of-freedom (DOF) tribo-dynamic model by introducing five-DOF inner ring, six-DOF balls, cage. T...

Abstract Concept of patient prosthesis mismatch came into existence from 1978 onward when Rahimtoola first defined it as “mismatch can be considered to present the effective prosthetic valve area, after insertion patient, is less than that a normal human valve.” Patient produces higher expected pressure gradient through normally functioning valve. Since ball caged mechanical in descending aorta...

A nonlinear dynamic model for an unconventional, commercially available electrohydraulic flow control servovalve is presented. The valve is a two-stage valve and differs from the conventional servovalve in that it does not require a feedback wire and ball, and the boost stage uses two spools, instead of a single spool, to meter flow into and out of the valve separately. Consequently, the valve ...

Left atrial thrombus in the presence of diseased mitral valve and atrial fibrillation is a well known entity. But it is very rare to occur in the presence of normal mitral valve apparatus. We report the case of a 36 year old female who presented with left atrial ball valve thrombus and normal mitral valve apparatus and underwent surgery. This patient with gangrene of right lower limb came for c...

The long term performance characteristics of the 2400 and 1260 series of StarrEdwards aortic prostheses were investigated by a follow up study of clinical outcome of 327 patients discharged from hospital with isolated aortic valve replacement. Follow up lasted for up to 10 years and was based on 1616 patient-years. The 2400 series cloth covered tracked valve was implanted in 182 patients from 1...

The spring-driven ball-type check valve is one of the most important components of hydraulic systems: it controls the position of the ball and prevents backward flow. To simplify the structure, the spring must be eliminated, and to accomplish this, the flow pattern and the behavior of the check ball in L-shaped pipe must be determined. In this paper, we present a full-scale model of a check bal...