The effects of the valve opening and opening height are very crucial in internal combustion engine. The optimum setup for the opening cam high and timing of camshafts in engines will improve fuel economy and exhaust gas emission. This improvement can be obtained from intake (inlet) valve timing and also from exhaust (outlet) valve timing. The challenging technique is to set up the engine to the...

The nature and relative proportions of acid mucopolysacharides (AMPS) in mitral valves of normal individuals and individuals with rheumatic valvular disease were compared. The total AMPS content of valves from rheumatic patients under 21 years of age is significantly higher than that from older rheumatic patients and higher than that from age-matched normal controls. The major AMPS components o...

The heart of Bathynomus doederleini gives rise to an anterior median artery (AMA), one pair of anterior lateral arteries (ALAs) and five pairs of lateral arteries (LAs). Cardioarterial valves are located at the junctions between the heart and arteries, each composed of a pair of muscular flaps. All valves of the AMA and the ALAs receive valve excitatory (constrictor) nerves (VEs). The valves of...

OBJECTIVE To establish whether there is more psychological distress among recipients of Björk-Shiley convexo-concave (BScc) valves than among recipients of other valves not known to fracture. DESIGN Cross sectional study. PATIENTS 137 patients who received either a BScc valve or a Sorin Biomedical spherical valve during a randomised trial between 1982 and 1983 at St Antonius Hospital, Nieuw...

BACKGROUND To evaluate normal regurgitant characteristics of St. Jude (SJ) and Medtronic-Hall (MH) mitral valves, four sizes (25-31 mm) of each were studied in a pulsatile flow model. METHODS AND RESULTS Regurgitant flow was measured by flowmeter at left ventricular pressures of 80, 130, and 180 mm Hg. Peak regurgitant flow rates ranged from 6.2 to 12.7 cm3/sec in SJ valves and from 7.9 to 17...

BACKGROUND An estimated 275,000 patients undergo heart valve replacement each year. However, existing solutions for valve replacement are complicated by the morbidity associated with lifelong anticoagulation of mechanical valves and the limited durability of bioprostheses. Recent advances in tissue engineering and our understanding of stem cell biology may provide a lifelong solution to these p...

BACKGROUND The type of cardiac valve replacement associated with the lowest health risks for young women who may undergo pregnancies is unknown. We investigated which valve type was associated with greatest patient and valve survival and the effect of pregnancy on valve loss. METHODS AND RESULTS In this retrospective study, all women 12 to 35 years old who underwent valve replacements between...

OBJECTIVES This study aimed to clarify the clinical anatomy of the pulmonary root. BACKGROUND Many descriptions of valvular anatomy have focused on the annulus, leading to varied interpretations of abnormal valves. METHODS Twenty-two heart specimens with isolated pulmonary valvular stenosis were examined to analyze the gross structure of the pulmonary root. For comparison, we examined a nor...

BACKGROUND The life span of human aortic valve allografts is finite, and many fail because of cusp rupture or calcification. Subcellular changes occurring in aortic valves in response to transplantation include the uptake of calcium. This study uses a heterotropic rat aortic valve transplant model to determine whether the calcium channel blockers diltiazem and verapamil might attenuate leaflet ...

OBJECTIVES This biochemical study compared the extracellular matrix of normal mitral valves and myxomatous mitral valves with either unileaflet prolapse (ULP) or bileaflet prolapse (BLP). BACKGROUND Myxomatous mitral valves are weaker and more extensible than normal valves, and myxomatous chordae are more mechanically compromised than leaflets. Despite histological evidence that glycosaminogl...