Coronary artery spasm is a temporary, sudden contraction in one location in the muscles in the wall of an artery in the heart. The spasm slows or stops blood flow through the artery and starves the heart of oxygen-rich blood.

The spasm may occur in arteries that appear normal or it may take place in arteries that have turned hard due to plaque build up (atherosclerosis).

Coronary artery spasm is a cause of inadequate oxygen levels (ischemia) of the heart. It affects approximately 4 out of 100,000 people, and affects approximately 2% of patients with angina.

Spasm may be "silent" -- without symptoms -- or it may result in persons with stable angina or unstable angina. It is usually appears as variant angina, a type of chest pain that is thought to be due to endothelial dysfunction, a condition in which the coronary artery may appear normal, but does not function normally.

Prolonged spasm may even cause a heart attack.

Coronary artery spasm may occur without cause, or it may be triggered by:

• Alcohol withdrawal
• Emotional stress
• Exposure to cold
• Medications that cause narrowing of the blood vessels (vasoconstriction)

Cocaine use and cigarette smoking can cause severe spasm of the arteries while also causing the heart to work harder. In many people, coronary artery spasm may occur without any other heart risk factors( such as smoking, diabetes, high blood pressure, and high cholesterol).

The main symptom is type of chest pain called angina, which can be felt under the chest bone and is described as:

• Constricting
• Crushing
• Pressure
• Squeezing
• Tightness

It is usually severe. The pain may spread to the neck, jaw, shoulder, or arm.

The pain:

• Often occurs at rest
• May occur at the same time each day, usually between midnight and 8:00 AM.
• Lasts from 5 to 30 minutes

The person may lose consciousness.

Tests to diagnose coronary artery spasm may include:

• Coronary angiography
• ECG

The goal of treatment is to control chest pain and to prevent heart attack. The pain is relieved by a medicine called nitroglycerin.

Other medications may be prescribed to relieve chest pain. Calcium channel blockers may be needed long term.

Medications may also include beta-blockers. However, in some cases of variant angina, beta-blockers may be harmful (especially if used along with cocaine).

Coronary artery spasm is a chronic condition. However, treatment usually helps control symptoms.

The disorder may be a sign that you have a high risk for heart attacks or potentially deadly irregular heart rhythms (arrhythmias). The outlook is generally good if you follow your doctor's treatment recommendations and avoid certain triggers.

• Abnormal heart rhythms
• Heart attacks

Immediately call your local emergency number (such as 911) or go to the hospital emergency room if you have a history of angina and the crushing or squeezing chest pain is not relieved by nitroglycerin. The pain may be due to a heart attack. Rest and nitroglycerin do not completely relieve the pain of a heart attack.

A heart attack is a medical emergency. If you have symptoms of a heart attack, seek immediate medical help.

Prevention involves avoiding triggers and taking measures to reduce your risk of atherosclerosis. This may a low-fat diet and increased exercise.

If you have this condition, you should avoid exposure to cold, cocaine use, cigarette smoking, and high stress situations, which can trigger a spasm.

Cannon CP, Braunwald E. Unstable angina and non-ST elevation myocardial infarction. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Libby: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Saunders; 2007:chap 53.