What is a Heart Attack?

Are there other causes of heart attack besides blockage?

Sometimes a coronary artery temporarily contracts or goes into spasm. When this happens the artery narrows, and blood flow to part of the heart muscle decreases or stops.

The causes of spasms are unclear. A spasm can occur in normal-appearing blood vessels as well as in vessels partly blocked by atherosclerosis. A severe spasm can cause a heart attack.

Another rare cause of heart attack is spontaneous coronary artery dissection, which is a spontaneous tearing of the coronary artery wall.

How is a heart attack different from cardiac arrest?

People often use these terms to mean the same thing, but they describe different events.

A heart attack is when blood flow to the heart is blocked. It’s a circulation problem.

With sudden cardiac arrest (SCA), the heart malfunctions and suddenly stops beating unexpectedly. Sudden cardiac arrest is an electrical problem.

A heart attack can cause a cardiac arrest. In cardiac arrest (also called sudden cardiac death or SCD), death results when the heart suddenly stops working properly. This is caused by irregular heart rhythms called arrhythmias.

The most common arrhythmia in cardiac arrest is ventricular fibrillation. This is when the heart’s lower chambers suddenly start beating chaotically and don’t pump blood. Death occurs within minutes after the heart stops.

Cardiac arrest may be reversed if CPR (cardiopulmonary resuscitation) is performed and a defibrillator is used within minutes to shock the heart and restore a normal heart rhythm.