[Opening areas of artificial valves (author's transl)]

The calculation of opening areas of artificial valves by the Gorlin-formula results only in small areas. This is why the converting factors of artificial valves are unknown. In addition, the flow characteristics are different from those of native valves and do not correspond to the conditions necessary for the Gorlin-formula. According to the narrowest flow diameter, however, in all artificial valves the areas can be calculated from volume-time curves and pressure gradients at the moment of maximum flow. In addition, in tilting disc valves the opening area can be estimated from the angle of the opening disc during time of steady flow.