The observed properties of valves in collecting lymphatic vessels include transmural pressure-dependent bias to the open state and hysteresis. The bias may reduce resistance to flow when the vessel is functioning as a conduit. However, lymphatic pumping implies a streamwise increase in mean pressure across each valve, suggesting that the bias is then potentially unhelpful. Lymph pumping by a mo...

the prospect of surgery can be frightening and more extensive surgery is included more anxious . knowledge of how to surgery reduces anxiety. hence,our goals are as follows :   what conditions can cause heart surgery? the majority of adults who should be considered for cardiac surgery , suffer from the disease of the heart valves or coronary artery disease or both.also, a few of them have conge...

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 ...

Aortic valve stenosis (AS) is an active disease process akin to atherosclerosis, with chronic inflammation, lipid accumulation, extracellular matrix remodeling, fibrosis, and extensive calcification of the valves being characteristic features of the disease. The detailed mechanisms and pathogenesis of AS are still incompletely understood, however, and pharmacological treatments targeted toward ...

OBJECTIVE Allografts are the valve of choice for fertile women, patients with infective endocarditis and those with small aortic roots. However, the supply of valves is problematic and widespread usage is restricted by limited availability. Allograft valves are available from cadaveric donors and from the explanted hearts of transplant recipients. Potentially, hearts from these patients could b...

Several prostheses are available to replace degenerative diseased aortic valves with unique advantages and disadvantages. Bioprotheses show excellent hemodynamic behavior and low risk of thromboembolic complications, but are limited by tissue deterioration. Mechanical heart valves have extended durability, but permanent anticoagulation is mandatory. Tissue engineering created a new generation h...

Rheumatic involvement of all four heart valves is uncommon and its association with congenital heart disease is very rare. Tetralogy of Fallot is a frequent cyanotic congenital heart disease with a survival beyond middle age. Background of this case report described the rheumatic involvement of all four heart valves (quadrivalvar rheumatic cardiopathy) with stenotic lesions of semilunar valves ...

INTRODUCTION The cause of ascending aortic dilatation occurring in patients with congenitally bicuspid aortic valves was investigated. METHODS Flow patterns through human aortic roots with congenitally bicuspid aortic valves as well as through porcine constricted aortas were studied in a left heart simulator. Vibration was recorded as a measure of turbulence in the post-stenotic segment. Hist...

A new procedure for deriving nonlinear mathematical modeling for a specific class of aerospace hydro - mechanical control valves is presented. The effects of friction on the dynamic behavior of these types of valves along with the experimental verifictions are also given. The modeling approach is based on the combination of the following three tasks: decomposition of the valve into simple speci...