Sudden Cardiac Arrest Overview
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 compressions to the chest can improve the chances of survival until emergency personnel arrive.
What are the causes of Sudden Cardiac Arrest?
Sudden death is most often caused by heart disease. When blood vessels narrow, the heart muscle can become irritated because of lack of blood supply. In heart attack (acute myocardial infarction), a blood vessel becomes completely blocked by a blood clot, and there is enough irritability of the muscle to cause ventricular fibrillation. In fact, the reason many people with chest pain are admitted to the hospital is to monitor their heart rate and rhythm for signs that might lead to ventricular fibrillation. Sudden death may also be the first sign or symptom of heart disease.
Congestive heart failure and heart valve problems, like aortic stenosis (narrowing of the aortic valve) also increase the risk of sudden cardiac arrest.
Cardiomyopathy is a broad category of heart disease where the heart muscle does not contract properly for whatever reason. Often it is ischemic, where part of the heart muscle doesn’t get an adequate blood supply for a prolonged period of time and no longer can efficiently pump blood. People whose ejection fractions (the amount of blood pumped out of the heart with each heart beat) is less than 30% are at greater risk for sudden death (a normal ejection fraction is above 50%). In some people, cardiomyopathy may develop in the absence of ischemic heart disease.
Inflammation of the heart muscle, known as myocarditis (myo=muscle + card=heart + itis= inflammation), can also cause rhythm disturbances. Diseases like sarcoidosis, amyloidosis, and infections can cause inflammation of the heart muscle.
Is sudden Cardiac Arrest the same as a heart attack?
No. A heart attack (or a myocardial infarction) occurs when part of the heart’s blood supply is reduced or blocked, causing the heart muscle to become injured or die. It has been described as a “plumbing problem” in the heart. The heart attack victim is awake and may complain about one or more of the signs and symptoms of heart attack. In contrast, the SCA victim is not awake and needs immediate help. More…
While a heart attack can lead to SCA, there are many other causes, including:
- Thickening of the heart muscle (e.g., Hypertrophic Cardiomyopathy, Arrhythmogenic Right Ventricular Dysplasia)
- Heart rhythm disorders (e.g., Brugada syndrome, long QT syndrome, Wolff Parkinson White syndrome)
- Heart valve disorders (e.g., Mitral Valve Prolapse).
Other causes of SCA among people who do not have heart disease include recreational drug use, electrocution, and commotio cordis, a disruption in the heart rhythm due to a sudden blow to the chest.
When SCA occurs, the heart stops beating in an effective, organized manner. As a result, blood is no longer pumped throughout the body. The person suddenly passes out and appears lifeless, except for abnormal “gasping,” which may last for several minutes. Occasionally, SCA victims experience 10-20 seconds of seizure activity (shaking of the arms and legs) at the onset of the event, as the brain stops receiving blood and oxygen from the heart.
What to do if Sudden Cardiac Arrest
Cardiac arrest is reversible in most victims if it’s treated within a few minutes. First, call 9-1-1 for emergency medical services. Then get an automated external defibrillator if one is available and use it as soon as it arrives. Begin CPR immediately and continue until professional emergency medical services arrive. If two people are available to help, one should begin CPR immediately while the other calls 9-1-1 and finds an AED.
What are the symptoms of Sudden Cardiac Arrest?
Some people may experience a racing heartbeat or they may feel dizzy, alerting them that a potentially dangerous heart rhythm problem has started. In over half of the cases, however, sudden cardiac arrest occurs without prior symptoms.
What about Sudden Cardiac Arrest in the young?
In younger people, sudden death is a rare event, but since it often involves people involved in athletics, cases are often reported in the press. The most common cause is hypertrophic cardiomyopathy (hypertrophy=to grow abnormally large + cardio=heart + myopathy = diseased muscle). This disease is often hereditary, and the walls of the ventricle are larger than they should be. This makes the pumping chamber of the heart smaller, and the heart has to work harder to pump blood out of the heart. As well, the thickened muscle narrows the space for the blood to flow through the aortic valve and to the rest of the body. During exercise, this decreased blood flow can irritate the heart muscle itself and cause ventricular fibrillation, collapse, and sudden death.
Anomalous coronary arteries can also cause sudden death in the young. The heart is a muscle itself, and like any muscle, it needs blood supply to provide oxygen for it to work. Normally, the coronary arteries lie on the surface of the heart. Anomalous arteries dive into the heart muscle itself and may be occluded when the heart muscle that surrounds the abnormally placed artery squeezes aggressively, as with exercise, shutting off blood supply to part of the heart. This irritates the electrical system and can cause ventricular fibrillation and sudden death.
How common is Sudden Cardiac Arrest?
Each year, 326,200 people in the U.S. experience EMS-assessed out-of-hospital non-traumatic SCA, and nine out of 10 victims die. This is roughly equivalent to the number of people who die from Alzheimers’ disease, assault with firearms, breast cancer, cervical cancer, colorectal cancer, diabetes, HIV, house fires, motor vehicle accidents, prostate cancer and suicides combined. In fact, the incidence of sudden cardiac death is nearly 10 times higher than the incidence of death from breast cancer.
Can Sudden Cardiac Arrest be prevented?
If you have any of the risk factors listed above, it is important to speak with your doctor about how to reduce your risk.
Keeping regular follow-up appointments with your doctor, making certain lifestyle changes, taking medications as prescribed and having interventional procedures or surgery (as recommended) are ways you can reduce your risk.
How Is Sudden Cardiac Arrest Treated?
Sudden cardiac arrest (SCA) is an emergency. A person having SCA needs to be treated with a defibrillator right away. This device sends an electric shock to the heart. The electric shock can restore a normal rhythm to a heart that’s stopped beating.
To work well, defibrillation must be done within minutes of SCA. With every minute that passes, the chances of surviving SCA drop rapidly.
Police, emergency medical technicians, and other first responders usually are trained and equipped to use a defibrillator. Call 9–1–1 right away if someone has signs or symptoms of SCA. The sooner you call for help, the sooner lifesaving treatment can begin.
Automated External Defibrillators
Automated external defibrillators (AEDs) are special defibrillators that untrained bystanders can use. These portable devices often are found in public places, such as shopping malls, golf courses, businesses, airports, airplanes, casinos, convention centers, hotels, sports venues, and schools.
AEDs are programmed to give an electric shock if they detect a dangerous arrhythmia, such as ventricular fibrillation. This prevents giving a shock to someone who may have fainted but isn’t having SCA.
You should give cardiopulmonary resuscitation (CPR) to a person having SCA until defibrillation can be done.
People who are at risk for SCA may want to consider having an AED at home. Currently, one AED, the Phillips HeartStart Home Defibrillator, is sold over-the-counter for home use.
A 2008 study by the National Heart, Lung, and Blood Institute and the National Institutes of Health found that AEDs in the home are safe and effective. However, the benefits of home-use AEDs are still debated.
Some people feel that placing these devices in homes will save many lives because many SCAs occur at home.
Others note that no evidence supports the idea that home-use AEDs save more lives. These people fear that people who have AEDs in their homes will delay calling for help during an emergency. They’re also concerned that people who have home-use AEDs will not properly maintain the devices or forget where they are.
When considering a home-use AED, talk with your doctor. He or she can help you decide whether having an AED in your home will benefit you.
Treatment in a Hospital
If you survive SCA, you’ll likely be admitted to a hospital for ongoing care and treatment. In the hospital, your medical team will closely watch your heart. They may give you medicines to try to reduce the risk of another SCA.
While in the hospital, your medical team will try to find out what caused your SCA. If you’re diagnosed with coronary heart disease, you may have percutaneous coronary intervention or coronary artery bypass grafting. These procedures help restore blood flow through narrowed or blocked coronary arteries.
Often, people who have SCA get a device called an implantable cardioverter defibrillator (ICD). This small device is surgically placed under the skin in your chest or abdomen. An ICD uses electric pulses or shocks to help control dangerous arrhythmias.