Simulation models exercise, age effects on plaque formation in arteries

Plaque formation in the arteries that supply blood to the head and neck is a serious medical problem that can lead to strokes and heart attacks. In Fluid Physics, Chinese engineers use fluid dynamics simulations to study the effect of exercise at various ages on plaque formation.

It’s been known for years that exercise and age affect plaque formation through a process known as atherosclerosis. What has not been fully understood, however, is how the geometric features of the arteries to affect plaque formation, although a dilated region in the internal carotid branch, the sinus, appears to be a vulnerable site.

“It is commonly accepted that disturbed flow induces atherosclerosis,” said author Xiaolei Yang.

To study this, the authors considered two arterial geometries, one with a bulging outer artery and one without, and modeled the effect of exercise and age on blood flow through the two model arteries.

Two main arteries that carry blood to the head and neck, known as the carotid arteries, branch off from a single large artery near the thyroid gland. One branch, the internal carotid artery, or ICA, carries blood inside the skull to the brain, while the external carotid artery it stays outside the skull and carries blood to the neck, face, and scalp.

Just above the bifurcation, the ICA bulges outward, forming a region known as the sinus that is sensitive to changes in blood pressure and helps regulate blood flow and heart rate.

“Our work investigated the patterns of perturbation blood flow in two different model carotids, one with geometric high-risk factors and the other without,” said co-author Xinyi He.

She explained high-risk factor’s they include high flare and low proximal curvature in the breast. Flare is defined as the ratio between the maximum cross section in the sinus bulb and its minimum value, while the proximal curvature measures how much the artery curves above the point of bifurcation.

To model the exercise, the authors digitized blood flow measurements of individuals in three different age groups: 32-34, 54-55 and 62-63. These digitized flows were used as input for their computational model.

“In general, the effects of exercise are different for different people. In particular, we show that exercise decreases reverse flow volume for the low-risk 62-63 age group.” carotid, which is probably related to the shortening of the systolic time interval,” Yang said.

He said this suggests that assessing the effect of exercise on atherosclerosis requires consideration of specific patient geometries and ages.

“For the current findings to be useful, the analysis must be combined with physiological and chemical processes occurring at the cellular level,” Yang said, indicating that this would be the subject of the group’s future work.