Cardiac ischemia is the term used when blood supply to the heart is decreased, which can happen due to a variety of reasons. Causes can include blockage of the arteries that supply the heart (coronary arteries), and decreased blood volume in the blood vessels (which can occur during serious bleeding). Symptoms vary and include chest pain, sweating, clammy skin, neck or jaw pain, nausea and vomiting, or pain in the right arm or shoulder.
Stable Angina
Stable angina refers to cardiac ischemia that is a result of the oxygen demand of the heart exceeding the blood supply available. One of the most common causes of stable angina is deposition of cholesterol plaques in the arteries (atherosclerosis) that narrow the blood vessels and decrease the amount of blood that can flow inside. The unique symptoms include chest discomfort or pain that lasts less than 15 minutes, is usually brought on by exertion or emotion, and relieved by rest or nitroglycerin. If the pain is not relieved by rest or nitroglycerin, it is not stable angina.
Unstable Angina
In unstable angina, the demand for oxygen by the heart is unchanged; instead, the supply to the heart is decreased. This can lead to a heart attack if not treated promptly, and symptoms include chest pain at rest, new onset chest pain that is worsening and not improving with rest or nitroglycerin, and patients with stable angina that has suddenly changed in character. Causes can include rupture of preexisting cholesterol plaques that block the vessel downstream or hemorrhage.
Prinzmetal's Angina
This is a unique form of cardiac ischemia that is characterized by transient constriction (also known as vasopasm) of the arteries that supply the heart. This results in temporary decrease in blood to the heart, with symptoms of chest pain that occur at rest, and is also associated with disruptions of heart rhythm. This is easily treated with medications that cause dilation of the coronary arteries, such as calcium-channel blocker type drugs.
Myocardial Infarction
Myocardial infarction, also known as heart attack, occurs when heart tissue dies as a result of decreased blood supply. This often begins as unstable angina and progresses if not treated promptly to a clinical heart attack. The symptoms include crushing chest pain, nausea, vomiting, sweating, radiating pain to the jaw and/or left arm, and a sense of impending doom. Diagnosis is made with laboratory tests for heart enzymes and an electrocardiogram reading with corresponding symptoms.
References
- "Step-Up to Medicine, Second Edition;" Agabegi; 2005
- "Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th Edition;" Libby; 2007
