Okay, I'll read this to the class, and it sounds okay on the face of it. And I guess we have to assume that this mechanism, operating with each cardiac cycle (seems a little wierd, but so do lots of things), isn't like the autoregulatory mechanism in the brain, so we don't look for ESP in ICA waveforms.
From: UVM Flownet on behalf of Michael Savage Netscape. Just the Net You Need.
Sent: Tue 3/7/2006 10:15 AM
To: [log in to unmask]
Subject: Re: ESP
The kidney itself continuously regulates distribution of flow within the renal tissue. This process is called autoregulation and is responsible for maintaining intra-renal blood flow over a wide range of systemic perfusion pressures. Selective vasoconstriction or dilatation must occur to maintain renal blood flow at a constant rate. These enable continued glomerular filtration to be maintained across a wide range of systemic blood pressures. The response of maintaining a constant blood flow over a wide range of arterial pressure is one manifestation of the phenomenon of autoregulation. The mechanism behind autoregulation is felt to be via myogenic receptors that regulate AA vasoconstriction. These sense blood pressure changes through stretch receptors and respond accordingly through relaxation or constriction.
So in conclusion the ESP can be explained by vasoconstriction at the beginning of the cardiac cycle causing an increase in distal resistance resulting in decreased velocity (the notch) followed by vasodilation resulting in a continuous diastolic flow in a repeating fashion as it responds to the cardiac cycle..
Other fun facts
ESP disappears with a RA stenosis > 60%
ESP will probably not be seen if the angle of incidence is greater than 30 degrres.
GE Healthcare - Brochure - Renal Artery Stenosis.htm
Don - No extra credit please.
Netscape. Just the Net You Need.
To unsubscribe or search other topics on UVM Flownet link to: