Remarkable Device Saves Patients from Cardiac Arrest

January 13, 2009

You may not hear about sudden cardiac arrest as often as you hear about heart attacks, but it is one of our nation’s leading killers. Cardiologist Bapineedu Gondi, MD, treats many patients who are at risk for sudden cardiac arrest, and explains what it is, its causes and how a remarkable medical device can make the difference between life and death.

What Is Sudden Cardiac Arrest?

As Dr. Gondi described it, “Sudden cardiac arrest occurs when the heart muscle goes out of rhythm, shaking or quivering instead of contracting rhythmically. When this happens, the heart is not pumping blood to the body and brain. It is the equivalent of the heart stopping. Death will occur within minutes if pumping is not restored.” Sudden cardiac arrest is an electrical problem in the heart and is different from a heart attack, which occurs when one or more of the heart’s arteries becomes blocked.

What Causes It?

“Sudden cardiac arrest is brought on most of the time by weakness of the heart muscle,” said Dr. Gondi.  Weakness can be caused by many things, including damage from a previous heart attack, heart failure, an infection in the heart, longstanding high blood pressure or congenital heart disease. When the heart muscle is weak and pumps inefficiently, with an ejection fraction of less than 35 percent, the risk that it will go out of rhythm rises dramatically.”

What Does Ejection Fraction Mean?

Dr. Gondi explained, “Each time your heart contracts, it ejects blood from its pumping chambers, or ventricles. The ejection fraction measures the capacity at which your heart is pumping. A normal ejection fraction ranges from 50 to 65 percent, which means that with each beat, your heart is pumping out 50 to 65 percent of the blood in the left ventricle. An ejection fraction below 50 percent indicates that the heart has been damaged or that there is some problem with the valves or muscle.”

How Does the Implantable Cardiac Defibrillator Work?

The defibrillator is a small electronic device that is implanted under the skin in the chest, with tiny wires seeded into the heart. The procedure does not require open heart surgery or a lengthy hospital stay. According to Dr. Gondi, “An ICD is a combination pacemaker and defibrillator. The device works as a pacemaker that detects when your heart is out of rhythm and sends electrical signals to regulate your heart rate. If the heart does not respond, then it works as a defibrillator to shock the heart back into rhythm. It also records and stores when it has responded to an irregular beat so your doctor can review your history.”

How Do You Know If You Are at Risk?

“People may not realize they have a weak heart,” said Dr. Gondi. “One way to be sure is to have a simple ultrasound test of the heart called an echocardiogram to determine your ejection fraction.”