Understanding What Happens During Cardiac Arrest: Arrythmias and How They Affect Other Body Organs

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What Is a Cardiac Arrest?

A cardiac arrest is when the heart stops beating. When this happens, the normal blood flow ceases to be pumped through the body. If the heart stops for more than just a few minutes, it is highly unlikely that the patient can be resuscitated because the lack of blood flow in the body deprives the brain and other vital organs of oxygen.A lack of oxygen to internal organs like the brain can cause life threatening consequences such as loss of consciousness, respiratory failure or brain damage.

A cardiac arrest is quite different than that of a heart attack, since a heart attack involves impairment of the blood flow from blockages within the heart muscle.

What happens during cardiac arrest makes the situation a life threatening emergency and critical medical care is needed immediately because time is of the utmost importance. Survival and successful recovery is dependent on immediate and prompt medical intervention.

Causes of Cardiac Arrest

Sudden cardiac arrest is usually the result of electrical disturbances within the heart causing it to stop abruptly. The heart’s electric system relies on a special collection of cells known as the sinus node located in the upper right atrium of the heart. The sinus node normally causes a steady flow of electrical impulses that determines your heart rate and is a necessary component that regulatates the pumping of the blood through the heart muscle to the rest of the body. Arrhythmias are heart rhythm abnormalities that are the direct result of a misfiring of the heart’s electric system.

Arrhythmias happen when there are disruptions within the sinus node causing interruption of the electrical impulses such as an irregular rhythm. Many arrhythmias can be diagnosed and controlled with proper medical treatment. Some arrhythmias, however, can be life threatening and can suddenly cause cessation of the heart muscle.

Ventricular fibrillation is a rapid erratic arrhythmia that causes the hearts ventricles to quiver instead of efficiently pumping blood through the heart muscle. Irregular rhythms within a healthy heart are commonly associated with external causes such as illegal drug use, electrical shock or sudden trauma to the heart.

When cardiac arrest happens suddenly in children, it is often the direct result of a congenital heart condition. A congenital heart condition means there was a heart defect or condition that has been present since birth which may or may not have gone undetected. Even if the defect has been corrected the heart will always be at a higher risk for arrythmias and possible sudden cardiac arrest than that of a healthy heart.

A heart attack can also trigger arrhythmias such as ventricular fibrillation which can result in sudden cardiac arrest. It can also leave scar tissue within the heart causing abnormalities in the heart’s electrical system and its firing.

Sudden cardiac arrest can also occur in anyone suffering from coronary artery disease. The blockages within a heart caused by coronary artery disease can in some instances make it difficult for the electrical impulses within the heart to remain steady.

Cardiomyopathy is a term referring to enlargement of the heart muscle. Cardiomyopathy refers to the heart’s muscle walls thickening and stretching causing abnormal tissue damage and enlargement. Enlargement and damage to the heart muscle can thereby result in life threatening heart arrhythmias. Narrowing and leaking of the valves of the heart can also lead to damage of the heart muscle. When the hearts chambers become damaged or weakened there is a risk of life threatening arrhythmias which can result in cardiac arrest.


Cardiopulmonary resuscitation is the common medical treatment for cardiac arrest, as well as defibrillation. Defibrillation is only possible, however, if certain types of cardiac rhythms are present. If a shockable rhythm after cardiopulmonary resuscitation and other cardiac responsive medical intervention is not present, a physician will pronounce the person dead.


American Heart Association: Cardiac Arrest

Sudden Cardiac Arrest, Information and Facts Mayo Clinic