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Sudden Cardiac Arrest Causes

Medical Author: Benjamin C. Wedro, MD, FAAEM, FACEP
Medical Editors: Melissa Conrad Stöppler, MD

On June 25, 2009, paramedics were called to the home of Michael Jackson responding to calls that he wasn't breathing. They found him in cardiac arrest and started CPR. He was transported to UCLA medical center were numerous attempts to restart his heart failed and he was pronounced dead.

Every day, calls come into the 911 emergency dispatch centers across the country with frantic voices crying for help. A person can't be wakened, breathing has stopped, and a pulse can't be felt. Cardiac arrest, the failure of the heart's electrical conducting system to generate a heart beat, 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.

Sudden Cardiac Arrest Causes

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

  • The electrical irritability may be 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.

  • The same irritability may be caused by hyperkalemia, abnormally high potassium levels in the blood stream.

  • Abnormal heart rhythms may be 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 blood stream.

  • 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.

But sudden death and cardiac arrest aren't supposed to happen to young people, and the definition of young has gradually become older. Modern medicine tries to cheat death by attempting to restore the heart's beat, but sometimes death cannot be denied.

Electricity is what kills and electricity is what saves. If sudden death is 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 the stars are aligned and bystanders, paramedics, doctors, and nurses did the right thing at the right time.

Nobody said that cheating death was easy.


Last Editorial Review: 6/26/2009






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