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M Swanepoel
08-03-1998, 11:52 PM
Hello Biofluid-dynamicists and Cardiologists,

I am writing an aortic flow computer model for some S African
cardiologists. I have found most of the information I require (thanks
to biomch-l!), but I still lack sufficient knowledge about the aortic
(semi-lunar) valve to make the model work properly. Please note that
I am interested in the natural valve, not valve replacements/ prostheses.

Does anyone have a measurement of the mean pressure difference over
the aortic valve leaflets which is required to open them? The only info
I can find indicates that the valve opens in response to a tiny
pressure difference (but how big?), that flow then opens it rapidly
(how rapidly?) to its full diameter, that it imposes "almost no" pressure loss on
the flow in this fully open position, (what is "almost no"
quantitatively?), and that it "snaps" closed from a fully open position
at the end of the ejection phase.

Is the aortic valve aperture restricted by inward flexure of the aortic
walls, due to the pressure reduction associated with the accelerated flow
through the valve (venturi effect)? Is significant disturbance of flow
through the aortic valve actually advantageous, in order to allow more
blood to pass into the coronary arteries? (Does the aortic valve play a
role in disturbing the momentum of the bloodflow in order to allow
more blood to pass sideways into the coronary arteries?) Is a plot of
the aortic valve aperture versus the phase of the heartbeat
(i.e.preferably non-dimensionalised), and mean aortic flow velocity
available?

All original info will be respected, and the source/s acknowledged in
the computer programme.

Thank you,

Mark W Swanepoel
School of Mechanical Engineering
University of the Witwatersrand
Tel: 0927 11 716 2578/2558
Fax: 0927 11 339 7997

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