What can cause angina pectoris?

Angina pectoris is primarily caused by a deficient blood supply to the myocardium, or heart muscle. This condition typically arises due to the narrowing of the coronary arteries, often resulting from atherosclerosis or other heart diseases that limit the amount of oxygen-rich blood that can reach the heart. When the heart muscle does not receive adequate oxygen, it can lead to chest pain or discomfort, which is experienced as angina.

Increased physical activity, while it is a common trigger for angina, does not itself cause the condition; rather, it can exacerbate the already existing deficiency of blood supply during moments of increased demand. Meanwhile, excessive oxygen in the blood is not associated with angina and would not contribute to the development of this condition. Coronary bypass surgery is a treatment primarily aimed at improving blood flow to the heart rather than a direct cause of angina. Therefore, the correct reasoning points to a deficiency in blood supply as the fundamental cause of angina pectoris.