Asystole is when the electrical system that keeps your heart beating stops.

It is sometimes referred to as a flatline because on an electrocardiogram, the activity of the heart is depicted as a steady flat line, rather than the wavy line associated with a beating heart.

Asystole is the most severe of the four heart rhythm problems that can lead to cardiac arrest. When the heart stops beating, it can cause a drop in blood flow to the brain and other parts of the body, which can be fatal.

The electrical activity that controls the beating of your heart starts at the top of your heart in the sinoatrial (SA) node — the heart’s natural pacemaker. Under normal circumstances, the sinus node generates an electrical stimulus around 60 to 100 times per minute.

The SA node sends an electrical impulse through a special pathway that allows each cell to send the charge to the next cell. The impulse goes down through the heart and causes the two atria to contract.

The two ventricles of the heart contract, which allows blood to be pumped to your lungs and the rest of your body.

The whole process starts over again after the SA node sends another signal.

Asystole can occur from events that lead to cardiac arrest or that significantly disrupt your heart’s electrical system. During cardiac arrest, your heart isn’t pumping, your blood isn’t circulating, and you’re not breathing. This state is known as clinical death.

Your brain cells can survive for a short time without blood or oxygen. Your brain cells will die after that. Your brain will be unable to function again because of the disease. This state is called brain death.

There are a number of common causes of asystole.

Heart-related causes

The electrical system of your heart is vulnerable to interference and damage as it is durable. Asystole can be caused by a number of heart problems.

Some of the most common causes of heart disease.

  • Heart attack: A heart attack is more of a “heart plumbing” problem than an electrical issue. This is because a heart attack is usually the result of a blockage in an artery that supplies blood to the heart muscle. But heart tissue damage caused by a heart attack can involve the electrical pathways within the heart. It’s not unusual for an arrhythmia to result from a heart attack.
  • Ventricular fibrillation (VFib): VFib is an arrhythmia in which the ventricles quiver instead of contracting fully to pump blood out to the body. Research suggests that a prolonged episode of VFib is one of the most common causes of asystole.
  • Ventricular tachycardia: Ventricular tachycardia is an arrhythmia that occurs when the ventricles beat too fast to allow the heart to efficiently pump oxygenated blood throughout the body. Like VFib, ventricular tachycardia can become so serious that it leads to a complete stop in the heart’s electrical activity.
  • Atrial fibrillation (AFib): When the heart is in AFib, the atria quiver instead of contracting and relaxing in rhythm with the ventricles. A 2020 study suggests that AFib may be a risk factor for heart attack, an established cause of asystole. In addition, AFib can lead to other complications, including ventricular tachycardia.
  • Congenital heart disease: Some heart conditions are present at birth. Congenital heart defects significantly increase the risk of cardiac arrest, according to a 2018 study. Most children born with some type of congenital heart disease live long, healthy lives. However, their heart health and risk of cardiac arrest and heart attack must be monitored throughout their lives.

CPR is considered the primary method of immediately treating a person in asystole.

Asystole is a non-shockable rhythm, unlike VFib or ventricular tachycardia, which can be treated by shocking a person. Effective cardiopulmonary resuscitation may convert asystole into a shockable rhythm.

A 2020 analysis of more than 67,000 cases of cardiac arrest treatment suggests that when a nonshockable rhythm such as asystole is converted into VFib or ventricular tachycardia, the odds of surviving significantly increase.

The key is for the conversion to happen as soon as possible after a person goes into cardiac arrest.

The key to managing asystole is to try to determine if the cause is fixed. If high levels of potassium cause asystole, it could possibly be reversed and lead to a shockable rhythm.

“If the cause is identified as a blood clot in the lungs, it’s an example. In this instance, administering a fast-acting clot-busting medication could help break up the clot and restore the heart’s rhythm.”

One other treatment that may help revive a heart in asystole is the administering of medications known as vasopressors. These drugs, which include epinephrine, can help increase blood flow to the heart, brain, and throughout the body.

The person may be administered with epinephrine while receiving cardiopulmonary help.

Any form of cardiac arrest carries a high risk of death. About 70% to 90% of people who experience cardiac arrest outside a hospital die before reaching the hospital, according to the Centers for Disease Control and Prevention (CDC).

But asystole is an especially dangerous condition. The American Medical Resource Institute reports that less than 2% of people who experience asystole outside a hospital setting survive, even if trained paramedics or other healthcare professionals intervene.

Asystole is a condition when your heart stops pumping and there are no electrical impulses. It is also known as a flatline because of the straight, flat line depicted on an electrocardiogram.

Asystole can occur from a variety of causes.

Asystole is the most serious type of cardiac arrest. The survival rates are low, but starting vigorous cardiopulmonary resuscitation and injecting the drug epinephrine may improve them.