OBJECTIVE To determine the relative importance of the different causes of isolated aortic valve stenosis in a surgical series, and to relate these to patient characteristics including the rate of insertion of bypass grafts for coronary artery disease. DESIGN Survey of the clinical and pathological data on patients undergoing aortic valve replacement for isolated stenosis. SETTING Tertiary c...

Oil production optimization is one of the main targets of reservoir management. Smart well technology gives the ability of real time oil production optimization. Although this technology has many advantages; optimum adjustment or sizing of corresponding valves is still an issue to be solved. In this research, optimum port sizing of inflow control devices (ICDs) which are passive control valves ...

Bioprosthetic valve calcification is usually assessed pathologically by gross inspection, radiographic studies, and histologic examination. Quantitation of mineral content by chemical assay has not been reported for failed clinical valves removed from adults. In this study, calcium determination by atomic absorption spectroscopy was done on 52 removed porcine valves after routine pathologic exa...

1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coag...

In an investigation of the influence of glutaraldehyde fixation pressure and subsequent valve constraint on the coaptive characteristics of porcine aortic valves, 14 valves were examined, eight having been fixed at low pressure (congruent to 1 mm Hg) and six at high pressure (80 mm Hg). The coaptive ratios of the left and right coronary leaflets in the low-pressure-fixed valves showed a signifi...

We studied the function of right internal jugular vein valves during cardiac catheterization in 32 patients and external jugular vein valves in vitro from 13 dogs. Patients with normal central venous pressure had competent valves during cough-induced transvalvular pressure gradients of 52.4 ± 8.6 mm Hg. Ten of 15 patients with elevated central venous pressure had either incompetent or absent in...

The deformation range, forces and frequency of the Magnetic Shape Memory Alloys (MSMAs) render them suitable for applications in electro-mechanical transducers, used to control pneumatic valves. A fast-operating electro-mechanical transducers can be designed, whose driving elements should not execute any motion, as they do in valves available to date, and which should get deformed instead. Util...

The presence of valves in the head and neck veins is known since classical anatomical dissections. Previous studies have investigated whether jugular veins show constant valves at their ostium and whether these valves are physiologically competent, but, unluckily, these studies have reported conflicting results. Further, recent observations have raised the question whether the incompetence of j...

Described by many authors, valves refer to the coronary sinus. The best known among them are Thebesius and Vieussen valves. Information about valves in the lumen of the coronary sinus, though, is rarely found in anatomic literature. Frequency of occurrence of valves in the lumen of the coronary sinus and the degree of their formation was chartered in this paper. 150 adult human hearts of both s...

Descriptions of the presence of blood vessels in the valves of human hearts vary. Using routine histological, injection, and clearing techniques, the majority of authors have described vessels in the attached portion of the cusp, but differ on the incidence of this observation and its relation to completely normal histological valve structure. Thus Gross (1921) demonstrated blood vessels in 6 p...