Cardiac Arrest

A cardiac arrest, sometimes called sudden cardiac death, is when the heart suddenly stops beating. This abrupt loss of heart function cuts off blood flow to the brain and other organs. A cardiac arrest is triggered by an electrical malfunction in the heart that causes an irregular heartbeat (arrhythmia).

A cardiac arrest isn't the same as a heart attack, when blood flow to a part of the heart is blocked. But, a heart attack can trigger a cardiac arrest.

A cardiac arrest is an emergency. When the heart stops, the lack of blood can cause death or permanent brain damage within minutes. But survival is possible with fast, appropriate medical care. Cardiopulmonary resuscitation (CPR), using a defibrillator — or even just giving compressions to the chest — can increase the chances of survival until healthcare professionals can take over.

Symptoms

Signs of sudden cardiac arrest are intense and drastic, and can often occur without any warning. They include:

Sudden collapse
No pulse
No breathing
Loss of consciousness

Sometimes other signs and symptoms occur before sudden cardiac arrest. These might include:

Chest discomfort
Shortness of breath
Palpitations (rapid, fluttering heartbeat)
Weakness

Causes

A number of factors can cause sudden cardiac arrest. The most common are ventricular and tachycardia.

Ventricular Fibrillation (VF) and Tachycardia (VT): Ventricular fibrillation (V-fib) is a dangerous type of arrhythmia, or irregular heartbeat. It affects the heart's ventricles. The heart has four chambers, and the two lower chambers are the ventricles. In ventricular fibrillation, these chambers quiver out of control or fibrillate, rather than beating normally.

This prohibits the heart from pumping blood, causing collapse and cardiac arrest. VF is more likely to occur as a result of a heart attack, long QT syndrome, Brugada syndrome, and electrolyte imbalance with reduced levels of potassium and magnesium in your blood. This type of arrhythmia is a life-threatening medical emergency.

Ventricular tachycardia is similar in a sense that the rhythm in the lower chambers of the heart is too fast to allow the heart to fill and pump blood to your brain and your body. VT is more organized, typically driven by a short circuit in the heart. These short circuits are frequently the result of having had a heart attack and having an island of scar tissue with channels that conduct electricity around and within the scar.

While this type of arrhythmia is also life-threatening, some patients may present with the slower short circuit and so called ‘walk-in’ VT typically symptomatic for shortness of breath, chest pain, fatigue and palpitations.

Risk Factors

Various heart conditions and health factors can increase your risk of cardiac arrest, such as:

Coronary Heart Disease (CAD): This type of heart disease begins in the coronary arteries. With CAD, the arteries become clogged with cholesterol and other deposits, reducing blood flow to the heart.
Cardiomyopathy (abnormal heart function): Cardiomyopathy is a progressive disease of the heart muscle (myocardium). Generally speaking, the heart muscle weakens and is unable to pump blood to the rest of the body in an efficient manner.
Valvular heart disease: Valvular heart disease is when any valve in the heart has damage or is diseased.
Congenital Heart Disease (heart defect present at birth): When a child or adolescent has a cardiac arrest, it can be due to congenital heart disease. Adults who've had corrective surgery for a congenital heart defect are also at a higher risk for cardiac arrest.
Heart Rhythm Abnormalities: Problems with your heart’s electrical system can increase your risk of sudden cardiac death.

Other risk factors for cardiac arrest include:

High blood pressure
Obesity
Smoking
Sedentary lifestyle
High cholesterol
Family history of heart disease
History of a previous heart attack
Age over 45 for men, or over 55 for women
Male gender
Using illegal drugs, such as cocaine or amphetamines
Low potassium or magnesium

When to see a doctor

Seek emergency medical help if you experience any of these signs and symptoms:

Chest pain or discomfort
Palpitations (rapid or irregular heartbeats)
Unexplained wheezing
Shortness of breath
Fainting or near fainting
Lightheadedness or dizziness

Prevention

You can reduce your risk of cardiac arrest by doing the following:

Getting regular check ups
Being screened for heart disease
Quitting smoking
Losing weight if overweight
Exercising regularly
Following a heart-healthy diet
Managing diabetes
Managing other health conditions