Angina

Angina pectoris is chest pain due to ischemia (a lack of blood and hence oxygen supply) of the heart muscle, generally due to obstruction or spasm of the coronary arteries (the heart's blood vessels). Coronary artery disease, the main cause of angina, is due to atherosclerosis of the cardiac arteries. The term derives from the Greek ankhon ("strangling") and the Latin pectus ("chest"), and can therefore be translated as "a strangling feeling in the chest".

Worsening ("crescendo") angina attacks, sudden-onset angina at rest, and angina lasting more than 15 minutes are symptoms of unstable angina (usually grouped with similar conditions as the acute coronary syndrome). As these may herald myocardial infarction (a heart attack), they require urgent medical attention and are generally treated as a presumed heart attack.

Symptoms
Most patients with angina complain of chest discomfort rather than actual pain, the discomfort is usually described as a pressure, heaviness, squeezing, burning, or choking sensation. Anginal pain may be localized primarily in the epigastrium (upper central abdomen), back, neck, jaw, or shoulders. Typical locations for radiation of pain are arms, shoulders, and neck. Angina typically is precipitated by exertion or emotional stress, and exacerbated by having a full stomach or cold temperatures. Pain may be accompanied by sweating and nausea in some cases. It usually lasts for about 1 to 5 minutes, and is relieved by rest or specific anti-angina medication. Chest pain lasting only a few seconds is normally not angina.

Some experience "autonomic symptoms" (related to increased activity of the autonomic nervous system) such as nausea, vomiting and pallor.

Major risk factors for angina include family history of premature heart disease, cigarette smoking, diabetes, high cholesterol, and high blood pressure.

A variant form of angina (Prinzmetal's angina) occurs in patients with normal coronary arteries or insignificant atherosclerosis. It is thought to be caused by spasms of the artery. It occurs more in younger women.

Diagnosis
In patients with occasional angina who are not having chest pain, an electrocardiogram (ECG) is typically normal, unless there have been other cardiac problems in the past. During pain, depression or elevation of the ST segment may be observed. To elicit these changes, an exercise ECG test ("treadmill test") may be performed, during which the patient exercises to the point that the pain occurs; if the ECG changes are documented, the test is considered diagnostic for angina. Other alternatives include a thallium scintigram (in patients that cannot exert enough for the purposes of the treadmill tests, e.g., due to asthma or arthritis).

In patients in whom noninvasive testing is diagnostic, a coronary angiogram is typically performed to identify the nature of the coronary lesion, and whether this would be a candidate for angioplasty, coronary artery bypass graft (CABG) or other treatments.

Pathophysiology
Increases in heart rate result in increased oxygen demand by the heart. The heart has a limited ability to increase its oxygen intake during episodes of increased demand. Therefore, an increase in oxygen demand by the heart (eg, during exercise) has to be met by a proportional increase in blood flow to the heart.

Myocardial ischemia can result from:
 * 1) a reduction of blood flow to the heart caused by the stenosis or spasm of the heart's arteries
 * 2) resistance of the blood vessels
 * 3) reduced oxygen-carrying capacity of the blood.

Atherosclerosis is the most common cause of stenosis (narrowing of the blood vessels) of the heart's arteries and, hence, angina pectoris. Some people with chest pain have normal or minimal narrowing of heart arteries; in these patients, vasospasm is a more likely cause for the pain, sometimes in the context of Prinzmetal angina and syndrome X.

Myocardial ischemia also can be the result of factors affecting blood composition, such as reduced oxygen-carrying capacity of blood, as seen with severe anemia (low number of red blood cells), or long-term smoking.

Epidemiology
Roughly 6.3 million Americans are estimated to experience angina. Angina is more often the presenting symptom of coronary artery disease in women than in men. The prevalence of angina rises with an increase in age. Similar figures apply in the remainder of the Western world. All forms of coronary heart disease are much less-common in the Third World, as its risk factors are much more-common in Western and Westernized countries; it could therefore be termed a disease of affluence. The increase of smoking, obesity and other risk factors has already led to an increase in angina and related diseases in countries such as China.

Treatment
The main goals of treatment in angina pectoris are relief of symptoms, slowing progression of the disease, and reduction of future events, especially heart attacks. An aspirin (75 mg to 100 mg) per day has been shown to be beneficial for all patients with stable angina that have no problems with its use. Beta-blockers and nitroglycerin medication are used for symptomatic relief of angina and prevention of ischemic events, and calcium channel blockers (such as nifedipine). Isosorbide mononitrate and nicorandil are vasodilators commonly used in chronic stable angina.

Identifying and treating risk factors of coronary heart disease is a priority in patients with angina. This means testing for elevated cholesterol, diabetes, hypertension (high blood pressure), stopping smoking and losing weight.