Valve Systems Heart valve disease is a condition in which one or more of the valves situated between the chambers of the heart of a patient can malfunction and fail. Valvular heart disease in adults is a major cause of morbidity and mortality. The Yehonatan Medical heart valve system is designed to reduce the incidence and magnitude of valve-related thrombosis and especially reduce the incidence and/or magnitude of risk in valve implantation procedures, even in repeat procedures. This improved modular mechanical valve encompasses the following features: 1. The valve is comprised of a material that: reduces electrostatic forces between red blood cells and platelets; is shock absorbing; and controls blood flow through the valve. Each of these features reduces valve related thrombosis and provides an ideally safe and effective replacement for the human heart mitral valve. 2. The valve has an improved leaflet shape that improves the general blood flow as compared to currently available heart valves. 3. The valve structure promotes non-linear and linear blood flow through different parts of the device; 4. The modular design allows for interlocking of a replaceable valve structure within a ring which is permanently implanted within the subject, such that the valve structure can be removed and replaced, with less tissue trauma, risk and time needed for subsequent implantation/replacement procedures. Each individual feature alone can reduce valve related thrombosis and the need for anti-coagulant medication dramatically, as well as surgical risk associated with the implantation procedure, per se and the combination of any number of these features provides for a superior mechanical valve.