Final answer:
Atherosclerosis, the build-up of plaques in artery walls, decreases the radius of arteries which can obstruct blood flow and cause a heart attack when the blood supply to heart muscle is compromised.
Step-by-step explanation:
Causes of Decreased Arterial Radius Leading to Heart Attacks
The radius of an artery can decrease due to atherosclerosis, which is a build-up of plaques in the arterial walls. This condition leads to a hardening and narrowing of the arteries, decreasing the blood flow and the flexibility of these vessels. For instance, even if the vessel's radius is reduced by only 5% (to 0.95 of its original value), the flow rate diminishes significantly to about 81% of its original value. This represents a 19% decrease in flow from a mere 5% reduction in radius. Such a blockage in a coronary artery prevents oxygen from reaching parts of the heart muscle, leading to areas of the heart being starved of oxygen, a scenario referred to as ischemia. If this condition persists, it can result in myocardial infarction or a heart attack. The body's response might be to increase blood pressure to compensate, but this can be dangerous, particularly in vessels that already have weakened walls.
Coronary artery disease, characterized by such blockages, is a leading cause of death worldwide. Symptoms may include chest pain known as angina pectoris; however, some individuals remain asymptomatic. Without proper treatment, coronary artery disease can lead to heart attacks.