Cardiac arrest

Cardiac arrest, often called sudden cardiac arrest (SCA), is a critical medical condition. It occurs when the heart suddenly and unexpectedly stops beating.

This event stops the circulation of blood throughout the entire body. Because blood carries vital oxygen, the brain and other organs quickly lose their supply. If the brain does not receive blood, a person may lose consciousness. Brain cells can begin to die within just a few minutes of the heart stopping. This can lead to a coma or a persistent vegetative state.

The most common cause of cardiac arrest is an arrhythmia. An arrhythmia is an irregular heart rhythm caused by disrupted electrical activity.

When electrical signals are disorganized, the heart cannot pump blood effectively. This failure of blood flow is known as hemodynamic collapse. Two common types of arrhythmias are ventricular tachycardia and ventricular fibrillation. In ventricular fibrillation, the heart muscle does not contract in a coordinated way. This prevents the heart from generating enough cardiac output to sustain life. Other less common rhythms include pulseless electrical activity and asystole, which is often seen when resuscitation efforts fail.

Many different cardiac issues can lead to these irregular rhythms. One leading cause is coronary artery disease (CAD).

This condition involves the buildup of cholesterol and the formation of atherosclerotic plaques in the arteries. These plaques can block blood and oxygen from reaching the heart muscle. This blockage causes ischemic injury and damages the heart tissue. This damage can disrupt the heart's normal electrical conduction patterns. In the United States, CAD is responsible for 68 percent of sudden cardiac deaths. It is a major factor for older adults but is less common in people under age 40.

Structural heart disease is another significant cause of cardiac arrest. This refers to physical changes in the heart's shape or strength. For example, long-standing high blood pressure can cause left ventricular hypertrophy.

This is a condition where the heart's main pumping chamber, the left ventricle, grows too large. While the muscle grows, it actually becomes less effective at pumping blood. Structural diseases account for 10 percent of sudden cardiac deaths. For people under the age of 30, these structural issues can account for over 30 percent of sudden cardiac arrests. Other examples include cardiomyopathies and myocarditis.

Some people experience cardiac arrest due to inherited arrhythmia syndromes. These are often caused by genetic mutations in ion channels. These channels are specialized proteins that move electrically charged particles across cell membranes. These conditions are sometimes called channelopathies. Examples include long QT syndrome (LQTS), Brugada syndrome, and short QT syndrome. These syndromes can be triggered by environmental factors, such as loud sounds. These genetic causes account for 5 to 10 percent of all sudden cardiac arrests. They often affect younger populations more significantly than structural diseases do.

In the United States, there are approximately 535,000 cardiac arrest incidents every year. This represents about 13 incidents for every 10,000 people. About 61 percent of these events, or 326,000 cases, happen outside of a hospital. The remaining 39 percent, or 209,000 cases, occur within a hospital setting. Cardiac arrest is more common in males and becomes more frequent as people age. Statistics show that black people in the U.S. are twice as likely to die from cardiac arrest as white people. Asian and Hispanic populations are affected less frequently than white populations.

Medical teams work to achieve return of spontaneous circulation (ROSC). This means getting the heart to beat on its own again.

Bystanders can help by performing CPR or using an automated external defibrillator.

Defibrillation uses an electrical shock to help reset the heart's rhythm. After a person survives, doctors use various methods to protect the brain. These include managing blood pressure and using temperature management to improve outcomes. To prevent the event from happening again, doctors may consider an implantable cardioverter-defibrillator.

This device is placed inside the body to monitor and correct dangerous rhythms automatically.