What happens to the heart during cardiac arrest

Apr 13, 2017 Cedars-Sinai Staff

We've all heard the terms and each one signifies a health crisis involving the heart. But heart attack, cardiac arrest, and heart failure aren't the same thing. They're three different problems with radically different causes and treatments.

Heart Attack

During a heart attack, blood flow to the heart is blocked, often by a blood clot or a buildup of plaque in the arteries.

Since the heart muscle needs oxygen to survive, when blood flow is blocked, the muscle begins to die. This is why heart attack sufferers need to be rushed into surgery to resolve the obstruction and restore blood flow.

Symptoms may start slowly and persist for hours, days, or weeks before the heart attack. The heart continues to beat, but because of the blockage, it is not receiving all the oxygen-rich blood it requires.

Not everyone has the same symptoms. About ⅔ of people have chest pain or shortness of breath, or they feel tired days or weeks before the heart attack.

During a heart attack, you may feel pain in the middle of the chest that can spread to the back, jaw, or arms. Or you may feel pain in these places and not in your chest. Sometimes people feel pain in their stomach and mistake the heart attack for indigestion.

Other symptoms include faintness, sudden sweating, nausea, shortness of breath, heavy pounding of the heart, abnormal heart rhythms, loss of consciousness, restlessness, anxiety, and bluish lips, hands, or feet.

If you believe someone is experiencing the symptoms of a heart attack, call 911 immediately.

Learn more about the symptoms of heart attack (AKA myocardial infarction).

Cardiac Arrest

In cardiac arrest, the heart stops beating and needs to be restarted.

While a heart attack is a circulation problem, cardiac arrest is an electrical problem triggered by a disruption of the heart's rhythm. Most heart attacks do not lead to cardiac arrest. However, when cardiac arrest happens, a heart attack is a common cause.

In many cases, cardiac arrest is a temporary condition experienced during a medical emergency. It is not necessarily preceded by heart disease, but many patients experience warning symptoms up to a month before cardiac arrest.

While a heart attack is a circulation problem, cardiac arrest is an electrical problem triggered by a disruption of the heart's rhythm.

Because cardiac arrest stops the heart from beating, the brain, lungs, and other organs do not get the blood and oxygen they need. Cardiac arrest can lead to death within minutes if not treated.

Symptoms of cardiac arrest include dizziness, loss of consciousness, and shortness of breath. Within seconds of cardiac arrest, a person will become unresponsive and have trouble breathing.

Call 911 immediately if you think someone has gone into cardiac arrest.

Using CPR and an automated external defibrillator (AED) can improve the survival rate over CPR alone by 23%. CPR is intended to pump the heart to get blood flowing and circulating to organs. The AED sends an electric shock to the heart in an attempt to restore its normal rhythm.

It's important to use these tools correctly. The American Red Cross and the American Heart Association have extensive programs on learning how to perform CPR and use an AED.

Heart Failure

Heart failure occurs when the heart muscle fails to pump as much blood as the body needs. It is usually a long-term, chronic condition, but it may come on suddenly.

In people with heart failure, the heart doesn’t pump normally, causing the hormone and nervous systems to compensate for the lack of blood. The body may raise blood pressure, making the heart beat faster and causing it to hold on to salt and water. If this retained fluid builds up, the condition is called congestive heart failure.

In the early stages of congestive heart failure, there may be no symptoms. When symptoms do develop, they may include weight gain, nausea, and others not normally associated with the heart.

Other symptoms include:

• Dry, hacking cough, especially when lying down
• Confusion, sleepiness and disorientation in older people
• Dizziness, fainting, fatigue or weakness
• Fluid buildup, usually in the legs, ankles and feet
• Increased urination at night
• Nausea, abdominal swelling, tenderness or pain that may result from fluid in the body and backup of blood in the liver
• Rapid breathing
• Bluish skin
• Feelings of anxiety, restlessness and suffocation
• Shortness of breath and lung congestion
• Wheezing and spasms in the airway, similar to asthma

Heart failure is usually the result of another disease, most commonly coronary artery disease. Other causes include different forms of heart disease, a blood clot in the lungs, problems with the thyroid gland, heart valve disorders, kidney failure, and untreated or out-of-control blood pressure.

This condition can affect people of any age, especially if they were born with a heart defect. It most often affects older people whose hearts may be weakened by age-related conditions.

Heart failure may also cause arrhythmia that can lead to cardiac arrest.

Read more on the common symptoms and causes of heart failure.