Fans around the world were shocked to learn of the untimely death of pop sensation Michael Jackson on June 25.  While there is no conclusive cause of death known at this time, it is commonly believed the 50-year-old performer died from sudden cardiac arrest, a condition about which many people have little understanding.

Each year, between 200,000 and 300,000 Americans die from sudden cardiac arrest, making it one of the leading causes of death in the country.  Contrary to common knowledge, sudden cardiac arrest is not the same thing as a heart attack.  These two cardiac events are entirely different processes but surviving a heart attack does increase one’s risk for sudden cardiac arrest.

Sudden cardiac arrest describes the end of heart beats after the heart muscle goes into ventricular fibrillation.  Fibrillation is a rapid, quivery, abnormal beating of the heart that is often of erratic rhythm (arrythmia).  During ventricular fibrillation, the heart’s pumping chambers, the ventricles, cannot pump blood adequately.  Within minutes of fibrillation, brain cells begin to die from loss of blood.  Odds of survival drop by 10% for every minute of fibrillation.  It is almost impossible to survive 10 minutes of ventricular defibrillation.

Heart attacks leave scar tissue in the heart muscle.  This scar tissue can interrupt the rhythmic beating of the heart, inducing ventricular defibrillation.

Sometimes ventricular fibrillation can be interrupted by applying a defibrillator to the heart.  Defibrillators emit an electrical impulse that shocks the heart muscle back into a healthier rhythm.  Some defibrillators are external, used in emergency situations by trained medical personnel, but others are implanted within the chest cavities of individuals known to be at high risk for sudden cardiac arrest.

In the absence of a defibrillator, cardiopulmonary resuscitation (CPR) is sometimes helpful.  This procedure is easy to learn but best taught by trained professionals.  The benefit in performing it is that it helps keep the blood circulating, reducing damage to brain cells, until defibrillation can happen.

Sudden cardiac arrest often occurs in individuals who seem otherwise healthy, with no known medical conditions that affect the heart.  In some cases, an individual may have a genetic predisposition to ventricular defibrillation but accidents and surgical procedures can cause erratic heart beat, too.  Some medications affect heart rhythm and the risk for sudden cardiac arrest may be higher when these medications are taken by patients with the genetic disorders associated with ventricular defibrillation.