Sudden cardiac arrest

Diagnosis

Sudden cardiac arrest happens suddenly and requires emergency medical care at a hospital. If the heart is quickly restored, survival is possible. When you are stable, health care providers at the hospital run tests to determine the cause.

Tests

Tests are done to help determine how well the heart pumps blood and to look for diseases that affect the heart.

Tests for sudden cardiac arrest often include:

• Blood tests. Certain heart proteins slowly leak into the blood after heart damage from a heart attack. Blood tests can be done to check for these proteins. Other blood tests are done to check levels of potassium, magnesium, hormones and other body chemicals that affect the heart's ability to work.
• Electrocardiogram (ECG or EKG). This quick and painless test checks the electrical activity of the heart. Sensors, called electrodes, are attached to the chest and sometimes the arms and legs. An ECG can tell how fast or how slowly the heart is beating. The test can show changes in the heartbeat that increase the risk of sudden death.
• Echocardiogram. Sound waves create images of the heart in motion. This test can show how blood flows through the heart and heart valves. It can show heart valve problems and heart muscle damage.
• Ejection fraction. This test is done during an echocardiogram. It's a measurement of the percentage of blood leaving the heart each time it squeezes. A typical ejection fraction is 50% to 70%. An ejection fraction of less than 40% increases the risk of sudden cardiac arrest.
• Chest X-ray. This test shows the size and shape of the heart and lungs. It might also show whether you have heart failure.
• Nuclear scan. This test is usually done with a stress test. It helps see blood flow problems to the heart. Tiny amounts of radioactive material, called a tracer, are given by IV. Special cameras can see the radioactive material as it flows through the heart and lungs.

• Cardiac catheterization. This test helps health care providers see blockages in the heart arteries. A long, thin flexible tube called a catheter is inserted in a blood vessel, usually in the groin or wrist, and guided to the heart. Dye flows through the catheter to arteries in the heart. The dye helps the arteries show up more clearly on X-ray images and video.

  A treatment called balloon angioplasty can be done during this test to treat a blockage. If a blockage is found, the health care provider may treat place a tube called a stent to hold the artery open.

Treatment

Treatment for sudden cardiac death includes:

• CPR. Immediate CPR is needed to treat sudden cardiac arrest and prevent death.
• Resetting the heart rhythm. This is called defibrillation. You can do this by using an automated external defibrillator, called an AED, if one is available. They are found in many public places.
• Medicines to treat irregular heartbeats and to manage symptoms.
• Heart procedure or surgery to place heart devices or to treat a blockage.

At the emergency room, health care providers run tests to check for the cause, such as a possible heart attack, heart failure or changes in electrolyte levels. Treatments depend on the causes.

Medications

Medicines may be used to help restore the heart rhythm. These medicines are called anti-arrhythmic drugs.

Other medicines that might be used to treat causes of sudden cardiac death or lower the risk of it include:

• Beta blockers.
• Angiotensin-converting enzyme (ACE) inhibitors.
• Calcium channel blockers.

Surgery or other procedures

Surgeries and other treatments may be needed to correct a heart rhythm problem, open a blockage, or place a device to help the heart work better. They may include:

• Implantable cardioverter-defibrillator (ICD). An ICD is a battery-powered unit that's implanted under the skin near the collarbone — similar to a pacemaker. The ICD continuously monitors the heart rhythm. If the device finds an irregular heartbeat, it sends out shocks to reset the heart's rhythm. It can stop a potentially life-threatening change in the heartbeat.

• Coronary angioplasty. Also called percutaneous coronary intervention, this treatment opens blocked or clogged heart arteries. It can be done at the same time as a coronary catheterization, a test that doctors do to find narrowed arteries to the heart.

  The health care provider inserts a thin, flexible tube into a blood vessel, usually in the groin, and moves it to the area of the blockage. A tiny balloon on the tip of the tube is widened. This opens the artery and improves blood flow to the heart.

  A metal mesh tube called a stent may be passed through the tube. The stent stays in the artery and helps keep it open.

• Coronary artery bypass surgery. Also called coronary artery bypass grafting or CABG, this surgery creates a new pathway for blood to flow around a blocked artery to the heart. This restores blood flow to the heart.
• Radiofrequency catheter ablation. This treatment is done to block a faulty heart signaling pathway. A problem with heart signaling can cause an irregular heartbeat. One or more flexible tubes called catheters are threaded through the blood vessels to inside the heart. Heat, called radiofrequency energy, on the end of the catheter is used to create small scars in the heart. This blocks the irregular heart signals.
• Corrective heart surgery. Surgery may be done to correct heart problems present at birth, heart valve disease or diseased heart muscle.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Lifestyle and home remedies

Preventing sudden cardiac arrest starts with keeping the heart and blood vessels in good shape. To live a heart-healthy lifestyle:

• Don't smoke.
• Achieve and maintain a healthy weight.
• If you drink alcohol, do so in moderation — no more than one drink a day for women and men older than 65 and no more than two drinks a day for younger men.
• Eat a heart-healthy diet.
• Get regular exercise.
• Manage stress.

Training

If you live with someone who is at risk of sudden cardiac arrest, it's important that you be trained in CPR. The American Red Cross and other organizations offer courses in CPR and defibrillator use.

Being trained will help not only your loved one, but your training might help others. The more people know how to respond to a heart emergency, the greater the survival rate for sudden cardiac arrest is likely to be.