June 25, 2009 -- Pop star Michael Jackson has died at age 50 after suffering a cardiac arrest, according to media reports.
Los Angeles TV station KTLA reports that Los Angeles fire officials said they responded to a 911 call at Jackson's home and that Jackson wasn't breathing when they arrived; paramedics performed CPR and rushed him to UCLA Medical Center, although the hospital, due to privacy rules, could not confirm that.
[Editor's Update: Although not denying that Jackson died of cardiac arrest, Los Angeles County Coroner spokesman Craig Harvey, after the initial autopsy on Friday, says the cause of death will be deferred until further toxicology tests can be conducted. He anticipates final results in four to six weeks.]
In a cardiac arrest, the heart stops working properly. A cardiac arrest is not the same as a heart attack, but it can happen because of a heart attack, notes Douglas Zipes, MD, MACC, distinguished professor at Indiana University School of Medicine and past president of the American College of Cardiology.
Zipes explains that "cardiac arrest is a heart rhythm disturbance when the bottom chamber of the heart, the ventricles, beat an at extremely rapid rate -- 4 to 600 times a minute."
Zipes says that heart rhythm "prevents that bottom chamber from effective contraction and pumping blood to the brain and to the rest of the body, and death results if it's not reversed within four or five minutes, generally."
According to Zipes, when that heart rhythm disturbance, which is called ventricular fibrillation, happens, the bottom chambers of the heart are "like a bag of squiggly worms without an effective squeeze, and no blood gets pumped to the rest of the body, and without the necessary oxygen in the blood vessels going to the brain, and so on, the brain then begins to die."
CPR can help keep blood flowing, but it would take an electrical shock to the heart -- either from electrical paddles called defibrillators or from an internal heart device -- to shock the heart back to a normal rhythm.
"Some sort of blood flow has to be initiated, whether it's with CPR or with the shock that terminates the fibrillation and restores an effective contraction," says Zipes.
Zipes notes that in 30% to 50% of cardiac arrests, "that event is the first manifestation of underlying heart disease. So you may not have chest pain, you may not have shortness of breath, you may not have anything" as a warning sign.
Just over a year ago, NBC journalist Tim Russert died after a cardiac arrest. Russert was being treated for his heart disease risk factors; Jackson's previous heart health hasn't been made public.
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