Engineers model blood flow

A computer simulation that shows how branches and bends in blood vessels disturb smooth-flowing blood and contribute to heart disease has been built by researchers at the University of California, Davis. Eventually, it could be possible to use such models to predict the risk of some types of heart disease.

Every minute at rest the heart pumps out about five litres, or more than a gallon, of blood. The swirls and eddies of that blood could help determine where fatty plaques build up, damaging blood vessels and eventually leading to heart disease.

Mechanical engineers Abdul Barakat and Harry Dwyer, mathematician Angela Cheer and postdoctoral researchers Nader Shahcheraghi and Thomas Rutaganira built the model by studying CAT scans of the aorta, the major vessel carrying blood from the heart.

The aorta rises out of the heart and then bends over, taking blood to the abdomen and the legs. Three major arteries branch off the top of the bend, taking blood to the upper body, head and heart itself.

The model shows how disturbed flows form in places such as the inside wall of curves and around branch points. Disturbed flows could play a role in the early stages of atherosclerosis, when fatty plaques form on the blood vessel walls, Barakat said. Oscillating flows, where the blood swooshes back and forth, seem to cause the most damage, Barakat said. The computer models can predict where this effect is likely to happen under different conditions.

Aorta shape varies slightly between individuals and could be an inherited risk factor for heart disease, Barakat said.

Eventually, it could be possible to image a patient’s aorta by CAT scan, put that image into a computer model and see how it performs under different conditions, allowing doctors to assess the risk of atherosclerotic disease due to disturbed flows, Barakat said.

Details of the model have been published in the August issue of the Journal of Biomechanical Engineering.