In vitro hemodynamic characteristics of prosthetic heart valves

: The functional characteristics of the prosthetic heart valve are the hemodynamic characteristics when it has been ideally attached; in clinical practice, however, it is seldom that this artificial valve is ideally put in position because of the modality of changeable valve angle in deformed annulus and the narrow aortic root, orientation of the valve, anatomical factors, etc. Thus, we devised an attachment head for the prosthetic valve whose angle can freely be varied in order to evaluate the hemodynamic characteristics of five clinically-available mechanical prosthetic valves and two xenografts in the pulsatile circulation system in the mitral position by changing the angle and orientation of the valve attachment. The prosthetic valves used were St Jude Medical (SJM), Starr-Edwards ball (S-E), monostrut Bjork-Shiley (mB-S), Omniscience (OS), Omnicarbon (OC), Carpentier-Edwards Supra-annular (C-Es) and Carpentier Edwards Pericardial (C-Ep) whose tissue annulus diameter was 27 mm. The experimental instrument similar to that of Umezu et al. was prepared to determine the mean pressure gradient, output and calculated orifice area of each valve. At the same time, a recently-manufactured valve attachment head was employed to measure the output, pressure gradient and orifice area by altering the valve attachment angle and orientation and increasing the number of heart beats from 60 bpm to 160 bpm, and the following results were obtained: With the changeable angle valve, an angle was determined whose end was parallel to the flow path in association with changes in the attachment angle, and the orientation was such that the pressure gradient was reduced and the orifice area was increased.(ABSTRACT TRUNCATED AT 250 WORDS)