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Sudden cardiac arrest is death resulting from an abrupt loss of heart function.
The victim may or may not have diagnosed heart disease. The time and mode of death are unexpected. It occurs within minutes after symptoms appear. The most common underlying reason for patients to die suddenly from cardiac arrest is coronary heart disease (fatty buildups in the arteries that supply blood to the heart muscle).
About 310,000 people a year die of coronary heart disease without being hospitalized or admitted to an emergency room. That's about half of all deaths from CHD-about 850 Americans each day. Most of these are sudden deaths caused by cardiac arrest.
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When the heart is beating correctly, an electrical and chemical impulse is sent from the top of the heart to the bottom. The impulse travels the same path every time. Cardiac arrest, or cardiopulmonary arrest, occurs when the heart stops beating for any reason. One reason can be the failure of the electrical system in the heart to conduct impulses along the correct path. Random impulses firing all over the heart will cause it to shiver uselessly, not producing a pulse.
When the defibrillator shocks the heart it causes the heart to stop momentarily. While the heart pauses, the small piece of tissue responsible for the next impulse (the sinus node or sinoatrial node) should fire off the next heart beat. |
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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. This is called bradycardia.
In 90 percent of adult victims of sudden cardiac death, two or more major coronary arteries are narrowed by fatty buildups. Scarring from a prior heart attack is found in two-thirds of victims. When sudden death occurs in young adults, other heart abnormalities are more likely causes. Adrenaline released during intense 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 - as well as illegal drug abuse - can lead to abnormal heart rhythms that cause sudden death.
The term "massive heart attack" is often wrongly used in the media to describe sudden death. The term "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 the terms aren't synonymous. |
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Early defibrillation means having immediate access to a properly working automated external defibrillator (AED). This allows trained lay rescuers to give a potentially lifesaving electrical shock to the victim's heart during a cardiac arrest.
Early defibrillation is often called the critical link in the chain of survival, because it's the only way to successfully treat most sudden cardiac arrests. When cardiac arrest occurs, the heart starts to beat chaotically (fibrillation) and can't pump blood efficiently. Time is critical. If a normal heart rhythm isn't restored in minutes, the person will die. In fact, for every minute without defibrillation, the odds of survival drop 7-10 percent. A sudden cardiac arrest victim who isn't defibrillated within 8-10 minutes has virtually no chance of survival.
Emergency Medical Services providers have traditionally performed defibrillation, but quick EMS response isn't always available. Even the best EMS systems are delayed by heavy traffic, secured buildings and gated communities. Large building complexes and high-rises also pose problems. In some communities and facilities, EMS personnel or traditional first responders with AEDs can't reach sudden cardiac arrest victims within the necessary four minutes after a collapse. For these situations, the American Heart Association advocates establishing public access defibrillation (PAD) programs. This helps ensure that the people most likely to arrive first at a medical emergency are equipped to help. These people include firefighters, law enforcement and security officers, industrial facility personnel and retirement community workers, among others. |
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| When a heart stops beating, early intervention can often get it going again and save
a life. Together with City of Ottawa Paramedics, trained citizens can and have
improved survival rates for those suffering from sudden cardiac arrest. The four links
shown in the illustration below, referred to as the "Chain of Survival", are critical to
ensuring the survival of an individual who experiences cardiac arrest. |
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