Defibrillation The administration of electric shocks to the heart with a defibrillator can reset normal heart rhythm in persons who are experiencing cardiac arrest or whose heart function is endangered because of severe arrhythmia (abnormality of heart rhythm). (more) What Is the Difference Between Cardiac Arrest and Heart Attack? Written by Kara Rogers Kara Rogers is the senior editor of biomedical sciences at Encyclopædia Britannica, where she oversees a range of content from medicine and genetics to microorganisms. She joined Britannica in 2006 and... Kara Rogers Fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Mar. 10, 2026 •History Cardiac arrest is an electrical malfunction in which the heart’s rhythm suddenly fails, and it stops beating without warning. A heart attack (myocardial infarction), by contrast, is a circulation problem—usually caused by a blocked artery that cuts off blood flow to part of the heart muscle. Cardiac arrest leads to collapse within seconds, whereas a heart attack typically causes progressive damage as the deprived heart tissue begins to die. Cardiac arrest and heart attack are...

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