Sudden cardiac arrest
Sudden cardiac arrest
Sudden cardiac arrest is the sudden, unexpected loss of heart function, breathing and consciousness. Sudden cardiac arrest usually results from an electrical disturbance in your heart that disrupts its pumping action, stopping blood flow to the rest of your body.
Sudden cardiac arrest is different from a heart attack, which occurs when blood flow to a portion of the heart is blocked. However, a heart attack can sometimes trigger an electrical disturbance that leads to sudden cardiac arrest.
Sudden cardiac arrest is a medical emergency. If not treated immediately, it causes sudden cardiac death. With fast, appropriate medical care, survival is possible. Administering cardiopulmonary resuscitation (CPR) — or even just rapid compressions to the chest — can improve the chances of survival until emergency personnel arrive.
Sudden cardiac arrest symptoms are sudden and drastic:
Sometimes, other signs and symptoms precede sudden cardiac arrest. These may include fatigue, fainting, blackouts, dizziness, chest pain, shortness of breath, weakness, palpitations or vomiting. But sudden cardiac arrest often occurs with no warning.
When to see a doctor
When the heart stops, the lack of oxygenated blood can cause brain damage in only a few minutes. Death or permanent brain damage can occur within four to six minutes. Time is critical when you're helping an unconscious person who isn't breathing. Take immediate action:
Portable automated external defibrillators (AEDs) are available in an increasing number of places, including airports, casinos and shopping malls. You can also purchase them for your home. AEDs come with built-in instructions for their use. They're programmed to allow a shock only when appropriate.
The immediate cause of sudden cardiac arrest is usually an abnormality in your heart rhythm (arrhythmia), the result of a malfunction in your heart's electrical system.
Unlike other muscles in your body, which rely on nerve connections to receive the electrical stimulation they need to function, your heart has its own electrical stimulator — a specialized group of cells called the sinus node, located in the upper right chamber (right atrium) of your heart. The sinus node generates electrical impulses that flow in an orderly manner through your heart to synchronize heart rate and coordinate the pumping of blood from your heart to the rest of your body.
If something goes wrong with the sinus node or the flow of electric impulses through your heart, an arrhythmia can result, causing your heart to beat too fast, too slow or in an irregular fashion. Often, these interruptions in rhythm are momentary and harmless. But some types of arrhythmia can be serious and lead to a sudden stop in heart function (sudden cardiac arrest).
The most common cause of cardiac arrest is an arrhythmia called ventricular fibrillation — when rapid, erratic electrical impulses cause your ventricles to quiver uselessly instead of pumping blood.
Most of the time, cardiac-arrest-inducing arrhythmias don't occur on their own. In a person with a normal, healthy heart, a lasting irregular heart rhythm isn't likely to develop without an outside trigger, such as an electrical shock, the use of illegal drugs, or trauma to the chest at just the wrong time of the heart's cycle (commotio cordis).
Heart conditions that can lead to sudden cardiac arrest
Chambers and the valves of the heart
A normal heart has two upper and two lower chambers. The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood ...
Because sudden cardiac arrest is so often linked with coronary artery disease, the same factors that put you at risk of coronary artery disease may also put you at risk of sudden cardiac arrest. These include:
Other factors that may increase your risk of sudden cardiac arrest include:
When sudden cardiac arrest occurs, your brain is the first part of your body to suffer because, unlike other organs, it doesn't have a reserve of oxygen-rich blood. It's completely dependent on an uninterrupted supply of blood. Reduced blood flow to your brain causes unconsciousness.
If your heart rhythm doesn't rapidly return to its normal rhythm, brain damage occurs and death results. If sudden cardiac arrest lasts more than 10 minutes, survival is rare. Survivors of cardiac arrest may show signs of brain damage.
Tests and diagnosis
If you experience an episode of sudden cardiac arrest without warning and survive, your doctor will want to investigate what caused the cardiac arrest. Identifying the underlying problem may help prevent future episodes of cardiac arrest.
Tests your doctor may recommend include:
Treatments and drugs
Sudden cardiac arrest requires immediate action for survival.
If you don't know CPR but someone collapses unconscious near you, call 911 or emergency medical help. Then, if the person isn't breathing normally, immediately begin pushing hard and fast on the person's chest — about 100 compressions per minute, allowing the chest to fully rise between compressions. Do this until an automated external defibrillator (AED) becomes available or emergency personnel arrive.
To perform CPR:
The shock may be administered by emergency personnel or by a trained citizen if a public-use defibrillator, the device used to administer the shock, is available. If you're not trained to use an AED, a 911 or emergency medical help operator may be able to guide you in its use. Trained staff members at many public places are able to provide and use an AED.
Defibrillators are available in a small, portable form and come with built-in automated instructions to ensure proper use. They're programmed to recognize ventricular fibrillation and send a shock only when it's appropriate. These portable defibrillators are available in an increasing number of public places, including airports, shopping malls, casinos, health clubs, and community and senior citizen centers.
At the emergency room
The prognosis after sudden cardiac arrest varies. Some people may be in a coma for days, weeks or indefinitely. Others may recover only partial function. After you recover, your doctor will discuss with you or your family what additional tests you may need to determine the cause of the cardiac arrest. Your doctor will also discuss preventive treatment options with you, to reduce your risk of another cardiac arrest.
Treatments may include:
There's no sure way to know your risk of sudden cardiac arrest, so reducing your risk is the best strategy. Steps to take include regular checkups, screening for heart disease, and living a heart-healthy lifestyle with the following approaches:
If you know you have heart disease or conditions that make you more vulnerable to an unhealthy heart, your doctor may recommend that you take appropriate steps to improve your health, such as taking medications for high cholesterol or carefully managing diabetes.
In some people with a known high risk of sudden cardiac arrest — such as those with a heart condition — doctors may recommend anti-arrhythmic drugs or an implantable cardioverter-defibrillator (ICD) as primary prevention.
If you have a high risk of sudden cardiac arrest, you may also wish to consider purchasing an automated external defibrillator (AED) for home use. Before purchasing one, discuss the decision with your doctor; the devices can be expensive and aren't always covered by health insurance.
If you live with someone who is vulnerable to sudden cardiac arrest, it's important that you be trained in CPR. The American Red Cross and other organizations offer courses in CPR and defibrillator use to the public. Being trained will help not only your loved one but also those in your community. The more people who know how to respond to a cardiac emergency, the more the survival rate for sudden cardiac arrest can be improved.
Last Updated: 2010-11-12
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