Sudden Cardiac Arrest Causes

Reviewed on 4/6/2022

What Is Sudden Cardiac Arrest? Why Does Sudden Cardiac Arrest Happen?

Cardiac arrest is the failure of the heart's electrical conducting system to generate a heartbeat. Cardiac arrest marks the end of life. No matter what the cause, death happens when the heart stops beating.

The heart is an electrical pump. The mechanical pumping action that circulates blood requires an organized electrical system to get the heart muscle to squeeze. There are many reasons for the electrical activity to fail, and it's almost always due to irritable heart muscle cells that, in effect, cause a short circuit.

What Causes Sudden Cardiac Arrest?

Examples of some of the causes of sudden cardiac arrest include the following:

  • Electrical irritability may arise due to a heart attack (myocardial infarction), in which a blood vessel in the heart is blocked and prevents oxygen-rich blood from getting to heart cells. This can cause a fatal heart rhythm called ventricular fibrillation characterized by electrical activity that is so chaotic, that the heart just jiggles and does not beat effectively to pump blood.
  • Hyperkalemia refers to abnormally high potassium levels in the bloodstream.
  • A complication of accidental poisoning or drug overdoses, in which the drug is directly toxic to the heart or else potentially blocks oxygen from getting into the bloodstream
  • Carbon monoxide and cyanide attach tightly to red blood cells, preventing them from accessing oxygen. Not only does the smoke of a house fire contain carbon monoxide, but the chemicals in drapes, rugs, and furniture release cyanide.
  • Drugs such as cocaine and methamphetamine act like adrenaline in the body and can put the heart's electrical system into a deadly overdrive.
  • Downer drugs (depressant drugs that diminish the function of the central nervous system), such as narcotics [for example pain medication such as meperidine (Demerol)] and alcohol, can depress brain function and it "forgets" to tell the body breathe, which is detrimental to the heart.
  • Sudden cardiac arrest occurs in young athletes with previously undetected heart valve problems.
  • It occurs in SIDS (sudden infant death syndrome).
  • Sudden cardiac arrest can occur in people at the end of a long, healthy life when they die quietly in their sleep.

What Are Signs and Symptoms of a Sudden Cardiac Arrest?

Signs and symptoms of sudden cardiac arrest include

  • sudden collapse,
  • absence of pulse, and
  • absence of breathing.

Preventing Death in Cases of Sudden Cardiac Arrest

Efforts to revive a person in sudden cardiac arrest involve attempts to restore the heart's beat, but sometimes death cannot be prevented.

Since sudden death can be caused by ventricular fibrillation, then using a defibrillator is the only way to potentially fix the problem. CPR temporarily circulates blood until the defibrillator is used, but whether it's a bystander with an AED (automated external defibrillator) or a paramedic with more sophisticated machinery, the ability to save a life depends upon the ability to shock the heart into establishing a normal electrical rhythm.

Time is the adversary when trying to cheat death. Every minute without a heartbeat means that the organs in the body (including the brain) aren't getting any oxygen-carrying blood. Cells are being killed every second during oxygen deprivation, and if a heartbeat isn't restored within a few minutes, the heart may be saved, but the brain functions may be lost. Yet, everyday people are returned to life because of quick thinking by family members or passersby who have taken CPR courses or know where to find an AED. Most often it is just luck.

Cardiac arrest equals death, and the vast majority of individuals who suffer a sudden cardiac arrest remain dead, even if bystanders, paramedics, doctors, and nurses did the right thing at the right time.


Heart Disease: Causes of a Heart Attack See Slideshow

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Reviewed on 4/6/2022
Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care


"Overview of sudden cardiac arrest and sudden cardiac death"