The present invention relates to an artificial cardiac valve.
Numerous artificial cardiac valves employing flap valve devices of the ball, disc or flap type in the form of a hemi-disc, already exist.
This is the case, for example, of the valves described in Patent Applications EP 0 176 337 (CARBOMEDICS INC.), EP 0 023 797 (HEMEX INC.), EP 0 039 217 (MITRAL MEDICAL INTERNATIONAL, INC. and EP 0 050 971 (HEMEX INC.).
Furthermore, GB 2 084 299 (HEMEX INC.) describes a cardiac valve comprising an annular element and a flap pivotally lodged inside said element as well as linking elements adapted to cooperate with guiding and restraining means provided on the internal lateral wall of the annular element.
These documents describe in particular valves of the type comprising a flap with single pivoting disc. The disc in question pivots by means of hinges in the form of protuberances disposed on the inner wall of the body of the valve and which, due to their configurations and arrangements, are capable of provoking phenomena of thrombosis.
Furthermore, these valves are in a position of complete opening only when the flap has pivoted through a certain angle which is always less than 90.degree. about an axis of rotation which merges with its diameter. In fact, the limited angle of 90.degree. does not allow passive closure of the valve. Consequently, in the position of opening, half of the disc constituting the flap is engaged in the aorta, which may raise problems of flow and/or space requirements.
Moreover, it is observed that these valves tend to oscillate due to the great distance between the axis of rotation and the most remote end of the flap.