SurfingDoctor

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Oct 20, 2005
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Having a wonderful time on Omicron Persei 8
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Attending Physician
How does an AV Fistula cause tachycardia?
AV fistulas steal blood from the systemic circulation (due to a lower vascular resistance) that can participate in tissue gas exchange. Essentially the stroke volume that delivers oxygen to the tissue is lower (though the actual cardiac stroke volume is higher or unchanged). By the fact that cardiac output is the product of heart rate and stroke volume, if one's stroke volume is down, the heart rate must increase to maintain the same cardiac output and tissue oxygen delivery. This is carried out by changes in sympathetic tone.
 
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