Why does a patient with atherosclerotic heart disease experience chest pain during exertion?

A patient with atherosclerotic heart disease experiences chest pain during exertion primarily because the lumen of the artery is narrowed and cannot accommodate the increased blood flow that occurs during physical activity. Atherosclerosis is characterized by the buildup of plaques within the arterial walls, which reduces the diameter of the arteries over time. When a patient exerts themselves, the demand for oxygen increases in the heart muscle, and if the arteries are narrowed, they may not be able to supply enough blood to meet this increased demand. This mismatch between oxygen supply and demand leads to the sensation of chest pain, also known as angina.

While other factors such as spasms of coronary arteries or tissue necrosis may also contribute to chest pain in different contexts, during exertion specifically, the immediate issue is the limited ability of narrowed arteries to facilitate adequate blood flow. This is why narrowing of the artery lumen is the most pertinent reason for the chest pain experienced by these patients during physical activity.