Test procedure for artificial mitral valves.

The flow curve of a valve-tester has a great influence on the performance of a valve. Usually the flow curve of the aorta is used. However, the mitral valve flow curve differs greatly from the flow curve of the aortic valve. It varies with the pulse rate and is further changed in patients with certain heart diseases. To investigate the different mitral flow conditions, ultrasonic flow curves from patients with a mechanical artificial mitral valve were analyzed. The curves show that a mitral valve prosthesis has not only to work under physiological flow conditions, but also in pathologically deviant flows. According to these results three different characteristic flow curves were selected and used to test several valves with a computer controlled valve-tester. The mean diastolic pressure difference and the whole closing behavior were influenced by the flow curve; and the differences in energy losses were particularly great. This indicates, that the flow curve must be adjusted appropriately.