[Maximum flow velocity in the normally functioning Björk-Shiley mitral prosthesis].

The heart valve prosthesis, even with normal function produce a functional obstruction to the blood flow increasing its maximal velocity. With pulsed wave Doppler technique we measured the maximal velocity in 12 patients with normally functioning Bjork-Shiley mitral prosthesis, (group I), comparing the results with those obtained in 12 healthy persons (group II). The maximal velocity of group I was significantly higher than that of group II (p less than 0.001) and higher than the values so far reported in the literature. In 5 patients of group I the maximal velocity was above 2.6 m/sec, which is the upper limit that our Doppler unit is able to register. We conclude that the maximal velocity of blood flow through some Bjork-Shiley mitral valves with normal function may be higher than those reported in the literature. Therefore the pulsed wave Doppler technique has limited application in the evaluation of transprothetic flow.