Final answer:
Angina pectoris commonly occurs when the coronary arteries are partially blocked by plaque, leading to reduced blood flow and oxygen starvation (ischemia) to the heart muscle. Stable angina is exercise-induced and improves with rest or nitroglycerin, while unstable angina, which requires urgent medical attention, can happen at rest and may precede a heart attack.
Step-by-step explanation:
Angina pectoris most commonly occurs when heart muscle cells do not receive adequate blood flow, leading to a starved condition of oxygen, known as ischemia. This typically happens due to the partial blockage of the coronary arteries by the buildup of plaque. The heart muscle, requiring oxygen to function properly, induces chest pain or pressure as a signal of this deficiency.
There are two major classifications of angina: stable angina and unstable angina. Stable angina is usually triggered by exertion and is alleviated by rest or medication like nitroglycerin. On the other hand, unstable angina is more serious and can occur even at rest, lasting longer and possibly indicating an impending heart attack.
Coronary artery disease, the underlying condition often responsible for angina, involves the build-up of plaque in the coronary arteries, leading to a restriction in blood flow and hence ischemia. Treatment focuses on symptom relief and slowing the progression of atherosclerosis to prevent serious complications like myocardial infarction (heart attack).