[In vitro studies for the echocardiographic evaluation of pathologic movement of the björk-shiley valve in mitral position in the presence of loose sutures (author's transl)].

A Björk-Shiley disc valve was sutured into a plastic syringe with 4 threads. With the piston of the syringe it was possible to close and open the disc in a waterbath. The syringe was rotated along the long axis stepwise, in a 45 degrees-fashion up to 360 degrees. In each position an echocardiographic registration was performed. The best registration was achieved, if the axis around which the disc is pivoting was positioned at a 90G-angle to the echo-beam, and if there was a maximum excursion of the disc towards the transducer. The threads were cutt off, one after the other, so that an additional movement of the valve ring could be registered. Depending on the position of the loose thread, the movement of the ring added to, or substracted itself from the disc movement. A "hump", which is considered typical for paravalvular regurgitation, could be registered, if the loose thread was in the posterior part of the ring. If the threads were lossened up in the lateral sides of the ring, there was only a slightly abnormal disc movement inspite of a considerable ring movement, since the disc moved parallel to the transducer. The technic allows an analysis of many pathological mechanisms of the disc movement, and it can explain some of the difficulties which occur during in-vivo registrations of the Björk-Shiley disc valve.