Aspects of Cardiovascular Fluid Mechanics Kim H. Parker 15 October 2007

“Fluid dynamicists of the 19 th century were divided into hydraulic engineers who observed what could not be explained and mathematicians who explained things that could not be observed” Sir Cyril Hinshelwood It is better to know that you don’t know something than it is to think that you know something that you don’t.

cardiac loop hypothesis Kilner et al. (2000) Nature linear heart (snail) looped heart (mammal)

Vein Man Vesalius, 1554 anatomy of the arteries

arteries and veins in a twin-twin placenta

pressure and velocity in the aorta

pressure during a ‘missing’ beat

pressure and flow in the veins Wang et al. (2006) Am. J. Physiol. inferior vena cava superior vena cava

microcirculation Gaudio et al. (1993) J. Anat. cast of extrahepatic biliary plexus (x80) A – arteriole V - venule detail of capillary network around a gland (x400)

1-D analysis of pressure and flow in arteries Outline: single vessel: 1.conservation equations 2.method of characteristics 3.wave intensity 4.wave separation 5.determining the wave speed network: 1.reflections 2.wave trapping

Wave intensity in an elderly man

PU – loop measurement of wave speed

reflection coefficient