Biomechanics Research Today is a free monthly online journal that collates and summarizes the latest research about Biomechanics, including details on mechanics of living organisms, movement, locomotion, prosthetic limbs. | ||||||||
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Diversion of blood flow from noncompliant to compliant vasculature in awake dogs: mechanical impact on right atrial pressure.Zidon TM, Sheriff DD Department of Exercise Science, University of Iowa, Iowa City, IA 52242, USA. The distribution of cardiac output between compliant vasculature (e.g., splanchnic organs and skin) and noncompliant vasculature (e.g., skeletal muscle) is proposed to constitute an important determinant of the amount of blood available to the heart (central blood volume and pressure). The aim here was to directly test the hypothesis that diversion of blood flow from a relatively noncompliant vasculature (muscle) to compliant vasculature (splanchnic organs and skin) acts to reduce right atrial pressure. The approach was to inflate an occluder cuff on the terminal aorta for 30 s in one of two modes of ventricular pacing in five awake dogs with atrioventricular block and autonomic blockade. In one trial, cardiac output was maintained constant, meaning cuff inflation caused a portion of terminal aortic flow (a noncompliant circulation) to be diverted to the splanchnic and skin circulations (compliant circulations). In the other trial, arterial pressure was maintained constant, meaning blood flow to these other regions did not change. The response of right atrial pressure (corrected for differences in arterial pressure between the two trials) fit our hypothesis, being lower when blood flow was diverted to compliant regions. We conclude that a small (4% of cardiac output) diversion of blood flow from a noncompliant region to a compliant region reduces right atrial pressure by 0.7 mmHg. Published 23 December 2005 in Am J Physiol Heart Circ Physiol, 290(1): H217-23.
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