| Summary: | 碩士 === 淡江大學 === 水資源及環境工程學系 === 86 === A series of tests were performed on the currently used St. Jude
Medical (SJM), CarboMedics (CM), Edwards Tekna modified
DuroMedics (DM) and Sorin Bicarbon (SB) bileaflet artificial
heart valves. Flow velocity was measured with a laser Doppler
Anemometer in order to compare the four valves by their
influence towards various retrograde flow fields and as revealed
in relative documents, their relation with blood element damage.
All experiments were performed with a pulse duplicator
simulating the left side of the human circularity system under
the following condition: a cardiac out put of 5 L/min, a
constant heart rate of 70 beats/min, and pressure wave forms
within the physiological range. The measurement points were
primarily located at the gaps between the closed leaflets during
diastole, between the leaflets and housing ring, and the hinges.
Results show that the peak values of reverse velocity of all
four valves during diastole are concentrated at the center of
the gap between the leaflets Meanwhile, the peak reverse
velocity and peak Reynolds shear stress own simultaneously. The
average peak reverse velocities of SB, Dm, SJM, and CM are U =
-0.50 m/sec, -0.47 m/sec, -0.45 m/sec, and -0.25 m/sec,
respectively. SB has the highest peak Reynolds normal and shear
stress values, which are 1950 dynes/cm2 and 800 dynes/cm2,
followed by DM, SJM, and CM. The peak Reynolds shear stress
values of all four valves range from 300 to 800 dynes/cm2, which
exceeds the threshold of platelet damage.
|
|---|
