Angina is a type of chest pain or discomfort that occurs when the heart muscle does not receive enough oxygen-rich blood. It is a common symptom of coronary artery disease, which is a condition in which the coronary arteries that supply blood to the heart muscle become narrow or blocked due to the buildup of fatty deposits (atheroma) on the inner walls of the arteries.
There are several types of angina, including:
- Stable angina: This is the most common type of angina and occurs when the heart muscle does not receive enough oxygen-rich blood during physical activity or emotional stress. The symptoms of stable angina are usually predictable and can be relieved by rest or medication.
- Unstable angina: This is a more serious form of angina that occurs suddenly and unpredictably, even at rest, and lasts longer than stable angina. Unstable angina is a sign that the coronary arteries are becoming increasingly blocked and may be at risk of rupturing, leading to a heart attack.
- Variant angina: This is a rare form of angina that occurs at night, often during sleep, and is caused by spasms of the coronary arteries. Variant angina can be life-threatening and requires prompt medical attention.
Angina usually feels like a pressure or squeezing sensation in the chest, but it can also cause pain or discomfort in the arms, neck, jaw, shoulder, or back. The severity and duration of angina can vary, and it may be triggered by physical exertion, emotional stress, cold weather, or heavy meals.
Stable Angina
The pathophysiology of stable angina is related to the buildup of fatty deposits (atheroma) in the coronary arteries that supply blood to the heart muscle. These deposits can partially or completely block the arteries, reducing the amount of oxygen-rich blood that reaches the heart muscle.
During physical activity or emotional stress, the heart muscle needs more oxygen-rich blood to meet its increased energy demands. If the coronary arteries are partially blocked, the heart may not receive enough oxygen-rich blood to meet these increased demands, leading to angina. The symptoms of angina are caused by the temporary shortage of oxygen in the heart muscle and typically resolve when the heart’s demand for oxygen decreases, such as when a person rests or takes medication.
In stable angina, the coronary arteries are usually not completely blocked, and the angina is usually relieved by rest or medication. However, over time, the fatty deposits in the coronary arteries can continue to build up, increasing the risk of heart attack and other complications of coronary artery disease. Effective treatment for stable angina is aimed at reducing the risk of progression to more serious forms of coronary artery disease, such as unstable angina or heart attack.
Unstable Angina
The pathophysiology of unstable angina is similar to that of stable angina, but with a more pronounced and rapidly progressive blockage of the coronary arteries. Unstable angina occurs when a buildup of fatty deposits (atheroma) in the coronary arteries causes the formation of a blood clot or the rupture of the atheroma, leading to a sudden and severe reduction in blood flow to the heart muscle.
In unstable angina, the coronary arteries are typically partially blocked, and the symptoms of angina are more severe and occur more frequently. Unlike stable angina, the symptoms of unstable angina are not always relieved by rest or medication and can last for hours or even days. The risk of heart attack is higher in people with unstable angina because the blockage in the coronary arteries is unstable and at risk of rupturing.
Unstable angina is considered a medical emergency, and prompt medical attention is required to reduce the risk of heart attack and other complications of coronary artery disease. Treatment for unstable angina may include medications to dissolve blood clots, open up the coronary arteries and improve blood flow to the heart muscle, as well as lifestyle changes and other therapies to reduce the risk of future heart attacks and other complications of coronary artery disease.
Variant Angina (Prinzmetal)
The pathophysiology of variant angina is related to spasms of the coronary arteries, which can reduce or completely block the blood flow to the heart muscle. In variant angina, the spasms are often triggered by rest or occur at night and are not related to physical activity or emotional stress. The spasms cause the coronary arteries to narrow, reducing the amount of oxygen-rich blood that reaches the heart muscle and leading to angina.
The exact cause of variant angina is not well understood, but it is thought to be related to changes in the walls of the coronary arteries, including the development of abnormal smooth muscle cells and an increased production of certain chemicals that cause the blood vessels to constrict. Other factors that may contribute to the development of variant angina include hormonal imbalances, medications, and underlying medical conditions such as vasospastic angina, cocaine use and various forms of autoimmune disease.
Variant angina is considered a medical emergency and prompt medical attention is required to reduce the risk of heart attack and other complications of coronary artery disease. Treatment for variant angina may include medications to improve blood flow to the heart muscle, relieve spasms of the coronary arteries and reduce the risk of future heart attacks and other complications of coronary artery disease. In some cases, interventional procedures such as coronary angioplasty or coronary artery bypass surgery may be necessary to improve blood flow to the heart muscle and reduce the risk of heart attack and other complications of coronary artery disease.