Cardiac arrest, or cardiac death, describes the immediate, unexpected and sudden loss of heart function. It can occur in people with or without a previously diagnosed heart condition. Response time is critical, with the death of all other brain and bodily functions occurring in just four to six minutes following cardiac death.
The chances of survival are reduced by seven to ten percent for every minute that passes without defibrillation, which is the process of sending an electric shock to the heart to restore a normal heartbeat and reverse cardiac arrest. After ten minutes, survival is unlikely, as approximately 95 percent of cardiac arrest victims die before reaching the hospital.
Automated external defibrillators (AEDs), which are portable units that can be mounted in public areas to be employed on the scene of a cardiac arrest or kept in the home in case of this type of emergency, are becoming more common. When used promptly and properly, these defibrillators, along with the administration of cardiopulmonary resuscitation (CPR), can revive victims, restore circulation quickly and reduce the chance of brain damage.
Cardiac arrest is not the same as having a heart attack, though it can occur during recovery from a heart attack by causing an unstable heart rhythm.
When to Call an Ambulance
Call 911 if you see the warning signs of cardiac arrest (loss of consciousness, loss of pulse and blood pressure, cessation of normal breathing) and begin CPR immediately until help arrives. CPR will keep blood and oxygen flowing to the heart and brain until defibrillation can be administered.
Heartbeat rhythm is controlled by the internal electrical system. When that electrical system is disrupted, it causes an abnormal heart rhythm that can cause the heart to beat too fast, too slow or to stop beating altogether.
The warning signs and symptoms of cardiac arrest occur almost instantaneously, with little warning. They are drastic and usually include:
- Loss of consciousness.
- No pulse.
- No blood pressure.
- No breathing.
Coronary heart disease is the most common cause of cardiac arrest. The rapid, irregular or chaotic heart rate associated with arrhythmia can cause the heart to suddenly stop beating, as well. In some cases, the heart rate slows (bradycardia) to the point of stopping. Other heart disease-related causes include:
- Valvular heart disease.
- Congenital heart disease (Learn more about Center for Inherited Heart Diseases).
- Electrophysiological abnormalities.
Respiratory arrest, drowning, choking, electrocution, the use of illicit drugs and trauma can also cause a cardiac arrest.
Occasionally, cardiac arrest occurs without any known causes.
There is no way to know your risk of cardiac arrest, but you can take measures to reduce your risk of heart disease. Leading a heart-healthy lifestyle, along with regular heart disease screenings, is an important part of prevention.
For those with a heart condition, managing weight, cholesterol and diabetes is highly important to maintaining good health and reducing risk.
If you live with someone who is diagnosed with a heart condition, you should be trained in CPR and you may want to purchase an automatic external defibrillator (AED) for home emergency response. This option should be discussed with your physician. Such preparation can be valuable to your loved ones, as well as the broader community by increasing the number of people who are prepared to respond to a cardiac emergency when they occur in public.
If you survive a cardiac arrest, you are likely to undergo testing to determine the cause. It is otherwise difficult to predict who may experience a cardiac arrest, particularly for persons who appear healthy.
Those tests may include:
- Physical exam. Your physician will review patient history.
- Blood tests. Cardiac enzymes, electrolytes and hormones may be measured, as well as a test for prescription and non-prescription drugs that may induce arrhythmia, or irregular heartbeat.
- Exercise tests. Blood pressure, heart rate and changes to breathing rate can be measured during exercise and at rest.
- Electrocardiogram. An ECG or EKG records the electrical activity of the heart and shows abnormal rhythms (arrhythmias or dysrhythmias).
- Ambulatory cardiac monitoring. A Holter monitor may be used for 24 hours. Other monitors may be worn in excess of two weeks.
- Echocardiogram. An “echo” uses ultrasound waves to produce a moving picture of the heart and heart valves.
- Nuclear scan. Usually performed during a stress test this type of scan studies blood flow through your bloodstream.
- Chest X-ray. An X-ray will help assess lung condition.
- A coronary angiogram. The coronary angiogram, a series of X-rays of the coronary arteries, is considered to be the most accurate way to measure the severity of coronary disease. During an angiogram, a thin, long, flexible tube called a catheter is threaded into an artery in the forearm or groin, and then moved through the circulatory system into one of the two major coronary arteries. Dye is then injected to show the flow inside the coronary arteries and to identify any areas of narrowing or blockage.
- Electrophysiological test. This test is designed to locate the point of origination for a heart arrhythmia and is usually performed after you have been diagnosed with a specific underlying cause.
Cardiac arrest must be treated immediately with CPR and defibrillation. Upon arrival to the scene, emergency personnel will work to stabilize your condition to transport you to the emergency room where medical staff will treat you for possible heart attack or electrolyte imbalances. Medications may also be given to stabilize your heart rhythm.
After your recovery, you are likely to begin a preventative treatment program that may include:
- Medications, such as anti-arrhythmics.
- An implantable cardioverter-defibrillator (ICD), which is a battery-powered unit implanted near your left collarbone with electrodes that run through veins to your heart. The ICD monitors and stabilizes your heart rhythm.
- Angioplasty, formally called percutaneous transluminal coronary angioplasty (PTCA). This procedure opens up narrowed arteries. Using local anesthesia, the doctor will insert a catheter (a long, narrow tube) with a deflated balloon at its tip into the narrowed part of the artery. Then the balloon is inflated, compressing the plaque and enlarging the inner diameter of the blood vessel so blood can flow more easily.
- Coronary bypass surgery, which may be performed in more serious cases to improve blood flow to the heart. A mammary artery or a vein taken from the leg is grafted onto the damaged coronary artery to circumvent a narrowed or blocked portion.
- Catheter ablation, if the doctor can pinpoint specific areas of the heart causing the abnormal rhythm. This outpatient procedure can destroy these areas using radio wave energy, removing damaged heart tissue. This can often be performed during an electrophysiological study.
In severe cases where heart tissue has proven to be badly damaged, some people may be eligible for heart transplant surgery.