Cardiac arrest, also known as cardiopulmonary arrest or circulatory arrest, is a sudden stop in effective blood circulation due to failure of the heart to contract effectively or at all. Medical personnel may refer to an unexpected cardiac arrest as a sudden cardiac arrest (SCA).
A cardiac arrest is different from (but may be caused by) a heart attack, where blood flow to the muscle of the heart is impaired. It is different from congestive heart failure, where circulation is substandard, but the heart is still pumping sufficient blood to sustain life.
Arrested blood circulation prevents delivery of oxygen and glucose to the body. Lack of oxygen and glucose to the brain causes loss of consciousness, which then results in abnormal or absent breathing. Brain injury is likely to happen if cardiac arrest goes untreated for more than five minutes. For the best chance of survival and neurological recovery, immediate and decisive treatment is imperative.
Cardiac arrest is a medical emergency that, in certain situations, is potentially reversible if treated early. Unexpected cardiac arrest can lead to death within minutes: this is called sudden cardiac death (SCD). The treatment for cardiac arrest is immediate defibrillation if a "shockable" rhythm is present, while cardiopulmonary resuscitation (CPR) is used to provide circulatory support and/or to induce a "shockable" rhythm.
What is cardiac arrest?
Cardiac arrest is the abrupt loss of heart function in a person who may or may not have diagnosed heart disease. The time and mode of death are unexpected. It occurs instantly or shortly after symptoms appear.
Each year, more than 420,000 emergency medical services-assessed out-of-hospital cardiac arrests occur in the United States.
Is a heart attack the same as cardiac arrest?
No. The term "heart attack" is often mistakenly used to describe cardiac arrest. While a heart attack may cause cardiac arrest and sudden death, the terms don't mean the same thing. Heart attacks are caused by a blockage that stops blood flow to the heart. A heart attack (or myocardial infarction) refers to death of heart muscle tissue due to the loss of blood supply, not necessarily resulting in the death of the heart attack victim.
Cardiac arrest is caused when the heart's electrical system malfunctions. In cardiac arrest death results when the heart suddenly stops working properly. This may be caused by abnormal, or irregular, heart rhythms (called arrhythmias).
A 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 to shock the heart and restore a normal heart rhythm within a few minutes.