What is cardiac arrest?
Cardiac arrest is the abrupt loss of heart function in a person who may or may not have been diagnosed with heart disease. It can come on suddenly, or in the wake of other symptoms. Cardiac arrest is often fatal, if appropriate steps aren’t taken immediately.
Each year in the United States, more than 350,000 cardiac arrests occur outside of a hospital setting.
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, the two 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. Heart attack can be understood as a “circulation” problem. A heart attack is quite serious, sometimes fatal.
By contrast, cardiac arrest is caused when the heart’s electrical system malfunctions. The heart stops beating properly. Hence the name: The heart’s pumping function is “arrested,” or stopped.
In cardiac arrest, death can result quickly if proper steps aren’t taken immediately. 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.
Cardiac arrest may be caused by irregular heart rhythms, called arrhythmias. A common arrhythmia associated with cardiac arrest is ventricular fibrillation. Ventricular fibrillation means that the heart’s lower chambers suddenly start beating chaotically and don’t pump blood.
Causes of Cardiac Arrest
Cardiac arrest may be caused by almost any known heart condition.
Most cardiac arrests occur when a diseased heart’s electrical system malfunctions. This malfunction causes an abnormal heart rhythm such as ventricular tachycardia or ventricular fibrillation. Some cardiac arrests are also caused by extreme slowing of the heart’s rhythm (bradycardia).
Irregular heartbeats such as these that can cause cardiac arrest should be considered life-threatening arrhythmias.
Other causes of cardiac arrest include:
Scarring of the heart tissue Such scarring may be the result of a prior heart attack or another cause. A heart that’s scarred or enlarged from any cause is prone to develop life-threatening ventricular arrhythmias. The first six months after a heart attack represents a particularly high-risk period for sudden cardiac arrest in patients with atherosclerotic heart disease.
A thickened heart muscle (cardiomyopathy) Damage to the heart muscle can be the result of high blood pressure, heart valve disease or other causes. A diseased heart muscle can make you more prone to sudden cardiac arrest, especially if you also have heart failure. Learn more about cardiomyopathy.
Heart medications Under certain conditions, various heart medications can set the stage for arrhythmias that cause sudden cardiac arrest. (As odd as it may sound, antiarrhythmic drugs used to treat arrhythmias can sometimes produce ventricular arrhythmias even at normally prescribed doses. This is called a “proarrhythmic” effect.) Significant changes in blood levels of potassium and magnesium (from using diuretics, for example) also can cause life-threatening arrhythmias and cardiac arrest.
Electrical abnormalities Certain electrical abnormalities such as Wolff-Parkinson-White syndrome and Long QT syndrome may cause sudden cardiac arrest in children and young people.
Blood vessel abnormalities In rare cases, congenital blood vessel abnormalities, particularly in the coronary arteries and aorta, may cause cardiac arrest. Adrenaline released during intense physical activity often acts as a trigger for sudden cardiac arrest when these abnormalities are present.
Recreational drug use Use of certain recreational drugs can cause sudden cardiac arrest, even in otherwise healthy people.
Emergency Treatment of Cardiac Arrest
Cardiac arrest can strike without warning
Do you suspect that someone is experiencing cardiac arrest? Here are the signs:
Sudden loss of responsiveness The person doesn’t respond, even if you tap him or her hard on the shoulders, or ask loudly if he or she is OK. The person doesn’t move, speak, blink or otherwise react.
No normal breathing The person isn’t breathing or is only gasping for air.
What to do
If you have tried and failed to get the person to respond, and you think the person may be suffering cardiac arrest, here’s what to do:
Yell for help Tell someone nearby to call 911 or your emergency response number. Ask that person or another bystander to bring you an AED (automated external defibrillator), if there’s one on hand. Tell them to hurry – time is of the essence.If you’re alone with an adult who has these signs of cardiac arrest, call 911 and get an AED (if one is available).
Check breathing If the person isn’t breathing or is only gasping, administer CPR.
Give CPR: Push hard and fast Push down at least two inches at a rate of 100 to 120 pushes a minute in the center of the chest, allowing the chest to come back up to its normal position after each push.
Use an AED Use the automated external defibrillator as soon as it arrives. Turn it on and follow the prompts.
Keep pushing Continue administering CPR until the person starts to breathe or move, or until someone with more advanced training takes over, such as an EMS team member.