[The evaluation of pressure gradients of various aortic valve prostheses by Doppler ultrasound and influence of pressure gradients to left ventricular function].
Although the pressure gradients of heart valve prostheses has been discussed over the years, currently available valve prostheses are still not sufficient and may leave pressure gradients following aortic valve replacement. The selection of valve prosthesis and its size is still controversial. This study is aimed to measure the pressure gradients of 64 aortic valve prostheses noninvasively by means of doppler ultrasound and determine which size and what kind of valve prosthesis is suitable for aortic valve replacement. 1. Pressure gradients and LV function were serially assessed pre- and post operatively. Left ventricular mass index regressed to a normal range and the response to exercise test is quite satisfactory in the patients whose pressure gradients were less than 25 mmHg. In the cases that showed pressure gradients more than 25 mmHg, however, left ventricular hypertrophy significantly remained even 5 years after aortic valve replacement and the response to exercise was not good enough. From these results, it is concluded that the upper limit of acceptable pressure gradients is 25 mmHg in aortic valve prosthesis. 2. The pressure gradients of St. Jude Medical (SJM) valve (11 cases), Björk-Shiley (B-S) valve (7 cases), Lillehei-Kaster (L-K) valve (13 cases) and Omniscience (O-S) valve (33 cases) was evaluated to compare the hemodynamic characteristics in the long term follow-up periods. In SJM and B-S, a correlation between valve area index (geometrical valve orifice area/body surface area) and pressure gradients was significant. The valve area index more than 1.4 cm2/m2 in SJM or more than 1.7 cm2/m2 in B-S should be selected. Whereas for L-K and O-S, a correlation between valve area index and pressure gradients was not significant and it is suggested that his is due to suboptimal disc opening angle (L-K; 54 degree on the average, O-S; 46 degree on the average). For this reason, the use of these prostheses is not recommended for choice in the aortic position.
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D000328:Adult; D001021:Aortic Valve / Q000503:physiopathology*; D001794:Blood Pressure; D005069:Evaluation Studies as Topic; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000503:physiopathology*; D006350:Heart Valve Prosthesis; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D014463:Ultrasonography