Cardiac Arrest
Definition
Cardiac arrest refers to the loss of heart function. In many cases, it is an expected outcome to a serious illness. Cardiac arrest often results in death.
-
Sudden cardiac arrest
refers to the heart unexpectedly stopping activity due to a potentially reversible cause. Brain death occurs within a few minutes if the situation is not reversed.
- Sudden cardiac arrest may be caused by many different conditions. It does not necessarily mean that the person has had a heart attack.
- Sudden cardiac death refers to an unexpected, heart-related death within 1 hour from the start of symptoms.
Electrical System of the Heart
Causes
Causes of cardiac arrest include:
- Ventricular fibrillation —a rapid, irregular heart rhythm preventing any circulation of blood (most common cause of sudden cardiac arrest)
- Ventricular tachycardia —a rapid but regular heart rhythm that, if sustained, may turn into ventricular fibrillation
- Dramatic slowing of heart rate due to failure of its pacemaker or severe heart block (interference with electrical conduction)
- Respiratory arrest
- Choking or drowning
- Electrocution
- Hypothermia
- Sudden loss of blood pressure
- Unknown causes
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.
Risk factors for cardiac arrest include:
- Coronary artery disease
- Heart attack
- Cardiomyopathy
- Enlarged heart
- Congenital heart disease
- Improperly functioning heart valves
- Conditions affecting the heart's electrical system
- Severe metabolic imbalances
- Adverse drug effects, such as from drugs to treat abnormal heart rhythms
- Lung conditions
- Trauma to the chest
- Extensive blood loss
- Excessive overexertion in people with heart disorders
- Use of illicit substances (eg, cocaine)
Symptoms
Symptoms include:
- Loss of consciousness
- No breathing
- No pulse
Prior to cardiac arrest, some patients report the following symptoms or warning signs in the weeks before the event:
- Chest pain
- Weakness
- Pounding in the chest
- Feeling faint
Diagnosis
The first person to respond to a cardiac arrest should check if the person is responsive. Shake the shoulders and ask, "Are you OK?"
- If there is no response, call 911.
- If there are other people around and you can perform CPR (cardiopulmonary resuscitation), send someone to call 911 and turn your attention to the victim.
- Check if the person is breathing. Tilt the head back to open the airway. Put your cheek near the person's mouth and nose. Look, listen, and feel for air movement. If no air movement is detected, CPR should be started.
Treatment
Prompt treatment improves the chance of survival. The four steps in the cardiac chain of survival are:
Call 911
Immediately call for emergency medical support. Call 911 as soon as you notice cardiac warning signs or suspect a cardiac arrest has occurred.
Start CPR
CPR helps keep blood and oxygen flowing to the heart and brain until other treatment can be given. The heart and brain are very susceptible to low oxygen levels. Permanent damage can occur, even with successful resuscitation.
During CPR, the rescuer positions the head to open the airway, breathes air into the patient, and compresses the patient's chest. In 2008, the American Heart Association began recommending a simplified version of CPR. There is no rescue breathing in this version. This version was created to encourage previously reluctant by-standers to help.
Defibrillation
Once on the scene, emergency medical technicians or paramedics will assess the heart rhythm and determine whether the rhythm warrants defibrillation (eg, ventricular fibrillation or tachycardia). Defibrillation sends an electrical shock through the chest. The surge of electricity aims to stop the ineffective, irregular heart rhythm. This may allow the heart to resume a more normal electrical pattern. Automated external defibrillators check the heart rhythm before instructing the rescuer to give the shock.
Advanced Medical Care
Paramedics at the scene and doctors at the hospital provide essential medical care and intensive monitoring. They will give drugs, insert a tube to maintain an open airway, and manage emergency care. Epinephrine is often given early to make the heart more receptive to electrical impulses and improve blood flow to the heart and brain. The patient will receive oxygen. Even if an effective heart rhythm is restored, low oxygen levels may cause serious complications, including damage to the heart, brain, and other vital organs. The emergency medical personnel may perform an electrocardiogram (ECG, EKG)—a test that records the heart's activity by measuring electrical currents through the heart muscle.
Doctors will attempt to find and correct the underlying cause of the cardiac arrest. At the hospital, the doctor will ask about symptoms prior to the collapse and the patient's medical and drug history.
If the patient survives, the doctor will:
- Assess the electrocardiogram.
- Perform a physical exam.
- Confirm a cardiac arrest has occurred.
- Look for the cause.
- Evaluate the effects of pre-hospital care.
- Order additional blood and diagnostic tests to help determine the cause of the arrest.
A telemetry machine will continually monitor the heart's electrical activity.
Prevention
Become aware of heart disease warning signs and promptly seek treatment for any that develop. If you do not have a heart condition, follow the rules of primary prevention of heart disease. If you have a heart condition or may be at high risk for one, ask your doctor about how to reduce your risk of sudden cardiac arrest. You might be a right candidate for certain medications that prevent heart arrhythmias or implantation of an implantable cardioverter defibrillator (ICD) device.
Also, if you are known to be at high risk, you may consider purchasing an automatic external defibrillator (AED) for home use. Discuss it with your doctor.
Resources:
American Heart Association
Sudden Cardiac Arrest Association
Canadian Resources:
Canadian Cardiovascular Society
Canadian Family Physician
References:
Braunwald E, Zipes DP, Libby P, et al. Heart Disease: A Textbook of Cardiovascular Medicine. 6th ed. Philadelphia, PA: WB Saunders Company; 2001.
Conn HR, Rakel RE, Bope ET. Conn's Current Therapy 2001. 53rd ed. Philadelphia, PA: WB Saunders Company; 2001.
Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Part 3: adult basic life support. The American Heart Association in collaboration with the International Liaison Committee on Resuscitation. Circulation. 2000;102(supple 8):I22-59.
Rea TD, Eisenberg MS, Becker LJ, Murray JA, Hearne T. Temporal trends in sudden cardiac arrest: a 25-year emergency medical services perspective. Circulation. 2003;107:2780-2785.
Rosen P, Barkin R, Danzl DF, et al. Emergency Medicine: Concepts and Clinical Practice. 4th ed. St. Louis, MO: Mosby-Year Book Inc; 1998.
Stevenson LW, Desai AS. Selecting patients for discussion of the ICD as primary prevention for sudden death in heart failure. J Card Fail. 2006;12:407-412.
Sudden cardiac arrest. Heart Rhythm Society website. Available at: http://www.hrsonline.org/PatientInfo/HeartRhythmDiso...rs/SCA/index.cfm. Accessed July 13, 2009.
Last reviewed August 2010 by Craig Clark, DO, FACC, FAHA, FASE
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.