|Sudden cardiac arrest is sometimes called sudden cardiac death.
What Is Sudden Cardiac Arrest?
Sudden cardiac arrest (SCA) is where the heart suddenly out of the blue stops beating. When this happens blood is no longer pumped to the brain and other vital organs of the body. The person collapses, loses consciousness and stops breathing. SCA usually results in death within 3 to 5 minutes unless it is treated. Given this small window of opportunity only about 5 percent of victims survive. SCA accounts for 325,000 deaths a year in America making it one of the leading causes of death in the country (heart disease statistics).
What Causes It?
The heart has an internal electrical system that controls how often the heart beats. There are a few different things that can go wrong with the electrical system to cause abnormal beating patterns; these abnormalities are known as arrhythmias. While some arrhythmias are harmless, others are fatal. Arrhythmias can cause the heart to beat too slowly, too fast or to stop altogether. SCA occurs when the heart develops an arrhythmia that causes it to stop beating. The most common arrhythmia which causes SCA is called ventricular fibrillation. So what interferes with the electrical system enough to cause ventricular fibrillation and SCA?
Heart Attacks: During a heart attack blood is restricted to certain parts of the heart muscle. If blood flow is not restored the muscle begins to die and is replaced permanently with scar tissue (see heart attack causes). The scar tissue can damage the heart's electrical system enough to result in SCA.
Electric Shock: Hundreds of people die every year from electric shock in the workplace; the most common cause of death is SCA.
Drug Overdose: In people who do not have heart disease, recreational drug use is usually the cause of SCA.
Physical Exertion: Sometimes younger victims of SCA have underlying blood vessel abnormalities, particularly in the arteries supplying the heart. Adrenaline released during intense athletic or physical activity can act as a trigger for SCA. This is the most common cause of sudden cardiac death in professional athletes.
Cardiomyopathy: A thickened heart muscle (from any cause but typically caused by persistent high blood pressure or heart valve disease). Anyone with cardiomyopathy or congestive heart failure is more prone to SCA.
Loss Of Blood: Associated with trauma, such as a bad car accident. Severe loss of blood (known as hypovolemic shock) can cause SCA.
Choking: A blockage in the throat can cause respiratory arrest where you are no longer able to breathe. It usually coincides with SCA.
Anaphylactic Shock: An extremely severe type of allergic reaction, such as to peanuts, can prompt SCA.
Inherited Disorders: Certain inherited disorders can cause electrical abnormalities in young people such as Wolff-Parkinson-White syndrome and long QT syndrome.
Other Causes: Drowning and hypothermia.
Is Sudden Cardiac Arrest The Same As A Heart Attack?
No, although a heart attack can lead to SCA. During a heart attack, the heart continues to beat but blood flow to it is blocked. This causes typical heart attack symptoms (image) such as chest pain and shortness of breath. With SCA the heart stops beating and the victim will immediately collapse unconscious. A heart attack patient usually remains conscious and can continue communicating.
What Are The Warning Signs?
SCA strikes out of the blue without warning. The warning signs are:
• Person collapses unconscious.
• Loss of responsiveness (no response to tapping on shoulders and does nothing if asked if they are OK).
• Stops breathing.
• No pulse.
How Is It Treated?
Most people who have SCA will die within a few minutes. Their only hope is rapid treatment with an automated external defibrillator (AED - image), a device which sends an electric shock through the chest to try and restore the heart's natural rhythm. People at high risk for SCA may even purchase a home defibrillator for such instances. AED devices are being installed in public places across America and Europe including shopping malls, airports, airplanes, hotels, sport venues and schools. Trained personal are usually on hand, but most devices are designed for use by bystanders. AEDs automatically read the person's need for electric shock, so the bystander does not need to worry about giving treatment where it is not necessary. If someone collapses with what you suspect is SCA, then look for the following sign to indicate an AED is nearby:
The Chain Of Survival
The American Heart Association recommends the following immediate treatment for SCA victims, which they term a 'chain of survival':
• Early recognition that a cardiac emergency exists, dial 911 for emergency medical services.
• Start CPR (cardiopulmonary resuscitation) until an AED device is available. This allows the brain to receive some oxygen.
• Start defibrillation as soon as the device arrives.
• Advanced life support care by healthcare providers.
When is CPR necessary?
How is hands only CPR performed?
Womens health questions for a variety of heart topics.
What Is The Prognosis After SCA?
While 95 percent of people will die before reaching hospital, 5 percent do survive. In hospital doctors will try to discover the cause of the SCA. If CHD is found to be the cause then coronary bypass surgery (image) or coronary angioplasty (image) may be scheduled. This will restore blood flow through the arteries. Often patients who survive SCA are given a device called an implantable cardioverter defibrillator (ICD). This emits electric shocks and impulses to help control future dangerous arrhythmias.
Survivors of SCA can face a variety of complex medical issues known as Post-Cardiac Arrest Syndrome (PCAS). This can include brain injury and heart dysfunctions. Most of these conditions can be monitored and treated by the patient's healthcare team.
Who Is Most At Risk?
The risk of SCA increases with age and it is also higher in people with heart disease. Men are 2 to 3 times more likely to have SCA than women. Other risk factors include:
Silent Heart Attacks: People who have silent heart attacks (where symptoms are not obvious and go undiagnosed) are at risk. The risk of SCA is much higher within the first 6 months of a heart attack. It is worth reading about your heart attack risk factors and advice on heart attack prevention.
Silent CHD: People with silent (no signs) coronary heart disease (CHD) are at increased risk. However 80 percent of SCA victims showed previous signs of CHD.
Genetics: If there is a history of SCA in the family or you have an inherited disorder which makes you prone.
Heart Disorders: If you have a history of arrhythmias or heart failure.
Drug Abuse: If you have a history of drug or alcohol abuse.
How Is It Diagnosed?
As SCA happens without warning it is only diagnosed after the event (usually by autopsy). However, if you are high risk for SCA your doctor will refer you to a specialist in the heart's electrical system called a cardiac electrophysiologist. You will undergo heart disease testing including possibly an electrocardiogram, echocardiogram and exercise stress test. An electrophysiology study may be performed which uses heart catheterization to record how your heart's electrical system responds to certain drugs and electrical stimulation. This helps the consultant locate where the heart's electrical system is damaged. You may also receive a blood test to check for levels of magnesium and potassium, chemicals which play an important role in the heart's electrical signaling.