General Health Topic - Information on Sudden Cardiac Arrest (SCA)

Hello Everyone,

On my last post I was talking about Automated External Defibrillators (AED). I received an email asking about how the AED works for heart attacks.

Sudden Cardiac Arrest (SCA) is very different from a Heart Attack. They are not the same thing! SCA results from an abrupt loss of heart function. The victim may or may not have diagnosed heart disease. The most common underlying reason for patients to die suddenly from cardiac arrest is coronary heart disease.

SCA is also known as Sudden Cardiac Death because when SCA occurs, the odds of survival are low. Time and mode of death are unexpected and it occurs within minutes after symptoms appear. The American Heart Association estimates about 325,000 people per year die from SCA without being taken to an emergency room or hospitalized. One of the most devastating aspects of sudden cardiac arrest is that it often strikes active, healthy individuals that seem healthy.

The causes of SCA are usually some underlying heart disease. All known heart diseases can lead to cardiac arrest and sudden cardiac death. Most of the cardiac arrests that lead to sudden death occur when the electrical impulses in the diseased heart become rapid (ventricular tachycardia) or chaotic (ventricular fibrillation) or both. This irregular heart rhythm (arrhythmia) causes the heart to suddenly stop beating. Some cardiac arrests are due to extreme slowing of the heart (bradycardia).

In the majority of adults that have a SCA, two or more major coronary arteries are partially or completely blocked by fatty buildups. Scarring from a prior heart attack is also found in two-thirds of victims. When sudden death occurs in young adults, other heart abnormalities are more likely causes. Adrenaline released during physical or athletic activity often acts as a trigger for sudden death when these abnormalities are present. Under certain conditions, various heart medications and other drugs can lead to abnormal heart rhythms that cause sudden death.

SCA is very different from a heart attack. Heart Attack refers to death of heart muscle tissue due to the loss of blood supply, not necessarily resulting in a cardiac arrest or the death of the heart attack victim. A heart attack may cause cardiac arrest and sudden cardiac death, but they are not the same thing.

Think of a heart attack as a problem with the heart's plumbing system. SCA is caused by a problem with the heart's electrical system. That is why an AED is effective in treating a patient with SCA but not a heart attack.

Brain death starts to occur in just four to six minutes after someone experiences cardiac arrest. Cardiac arrest may be reversible in some victims if it is treated within a few minutes with an electric shock to the heart to restore a normal heartbeat with defibrillation. According to the American Heart Association, a victim's chances of survival are reduced by 7 to 10 percent with every minute that passes without CPR and defibrillation. CPR can double or triple a cardiac arrest victim's chances of survival. Few attempts at resuscitation succeed after 10 minutes. If someone becomes unconscious, call 9-1-1 immediately. They may be suffering from sudden cardiac arrest.

In my next post, I will cover some recommendations that can be taken to try to prevent SCA, who is at risk for SCA and if you are are at risk, how can you manage that risk.

If you have any other questions, do not hesitate to email me or post a comment.

Thanks,

Dr. Paul