What is cardiac arrest?

Causes and Symptoms

Many conditions, such as drug overdoses, drowning, poisoning, and electrocution, can result in cardiac arrest, but the major cause is insufficient oxygen supply to the heart
as a result of a heart attack. When a major coronary artery becomes blocked, blood cannot flow to the heart muscle cells to deliver oxygen. Without sufficient oxygen, the heart is unable to pump blood to the rest of the body. Within seconds, the blood flow to the brain is inadequate and the individual loses consciousness and stops breathing. If blood flow is not resumed within several minutes, permanent brain damage will occur, frequently followed by death.

The major symptoms of cardiac arrest are lack of a pulse and lack of normal breathing. Medical personnel can also use an electrocardiogram (ECG or EKG) to identify specific problems with the heart, including too rapid of a heart rate to pump blood, quivering of the heart muscle, the complete absence of electrical activity, or the absence of contractions with normal electrical activity. Any of these cases is a medical emergency and treatment is required.

Treatment and Therapy

Cardiopulmonary resuscitation (CPR)
is the initial treatment for cardiac arrest. The sooner the blood flow to the brain is restored, the better is the prognosis. Breathing into the victim’s mouth and externally compressing the chest over the heart can circulate oxygenated blood throughout the body. However, emergency medical treatment is generally required to get the heart beating on its own. Cardioversion, the use of an external defibrillator to shock the heart, is administered to restore the heart’s normal cardiac rhythm. Additionally, medical personnel will administer specific medications such as atropine, epinephrine, and lidocaine. In some extreme cases, emergency surgery is required.

Perspective and Prospects

One of the best strategies to save the lives of those who suffer cardiac arrest is to decrease the time that it takes to restore blood flow and get the heart beating on its own again.

CPR was first promoted to the general public as a tool to save lives in the 1970s. By teaching many individuals how to respond to this emergency situation, the likelihood of receiving CPR quickly increases. Unfortunately CPR cannot save everyone. In recent years, automatic external defibrillators (AEDs) have been placed in public areas and worksites to improve survival. AEDs can be administered by nonmedical personnel who have been trained how to use them, thus greatly decreasing the time that it takes to restart a normal cardiac rhythm.

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Sherwood, Lauralee. Human Physiology: From Cells to Systems. 8th ed. Pacific Grove, Calif.: Brooks/Cole/Cengage Learning, 2013.

Wood, Debra, and Michael J. Fucci. "Cardiac Arrest." Health Library, Sept. 10, 2012.