OBJECTIVE The aims of this study were to compare opening and closing angles of normally functioning mechanical aortic valves measured on dual-source computed tomography (CT) with the manufacturers' values and to compare CT-measured opening angles according to valve function. MATERIALS AND METHODS A total of 140 patients with 10 different types of mechanical aortic valves, who underwent dual-s...

In this review, the anatomy and structure of the aortic valve and its prostheses are comprehensively discussed. Cardiac anatomy and function, human heart valves and their prostheses are also extensively discussed. The current status of prosthetic heart valves along with the next generation of these devices is broadly deliberated. Ather promising options such astranscatheter technologies (percut...

A 59-year-old male who had undergone aortic and mitral valve replacement with Starr-Edwards ball valves 27 years ago was admitted to our hospital for hemolytic anemia and heart failure. Echocardiography revealed prosthetic valve failure with a high-pressure gradient and small effective orifice area. The Starr-Edwards ball valves were successfully replaced with bileaflet mechanical valves. The e...

QUESTION What are the major concerns during pregnancy for women with prosthetic heart valves? ANSWER There are 2 types of prosthetic heart valves, bioprosthetic and mechanical. Although successful pregnancies are possible for women with prosthetic heart valves, there are potential complications-some of which can be fatal-for both types of valves. Therefore, preconception counseling and assess...

The study was performed on 110 great saphenous veins in human foetuses of both sexes aged 9 to 37 weeks. The earliest well-shaped valves were observed in foetuses aged 13 weeks. In these foetuses the number of valves varies from 2 to 7. Consecutive microscopic sections revealed that the developing valves at their origin present thickening of the endothelium which is continuous into the cusps of...

The increasing environmental awareness of the last decades has led to a huge tightening restrictions on vehicle pollutant and carbon dioxide emissions. Friction dissipation plays strategic role as its reduction necessarily leads decrease in CO2 Valve timing system is responsible for significant part overall friction losses provides relatively wide margin improvement. This regulates intake exhau...

The primary task of the electronic pressure (E/P) valves is to control the pressure continuously in different industrial automation processes. Their use in pneumatic drives allows regulating pressures in both cylinder chambers and so it is possible to achieve a direct force controlled actuator. Additionally to the force control, position control of the pneumatic actuator using E/P valves has be...

Introduction: The neural substrates of temporal processing are not still fully known. The majority of interval timing studies have dealt with this subject in the context of “Explicit timing” (computing the time intervals explicitly). The hypothesis “Implicit timing” (implicitly using temporal processing to improve function) has also proposed. This lesion study addressed explicit and implicit ti...

Results of long-term follow-up of an early cohort of patients receiving aortic valve homografts for aortic stenosis and aortic insufficiency are presented. All patients were operated upon by a single surgeon from 1966 to 1971. Eighty-three patients underwent insertion of 85 homograft aortic valves. Homografts were sterilized with either betapropiolactone (39 valves) or gamma irradiation (41 val...

Echocardiographic studies have confirmed that normal splitting of the first heart sound is a result of mitral valve closure preceding tricuspid valve closure. This fits in with contraction of the left ventricle before the right, but the width of splitting is usually greater than would be expected from the known ventricular asynchrony. The importance of atrial systole, which initiates closure of...