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Cardiac Resynchronization Therapy – Keeping Your Heart in Perfect Rhythm

Steven Peterson, M.D.

According to the American Heart Association, approximately five million Americans have heart failure and each year more than 500,000 new cases are diagnosed. Although there are many reasons for heart failure, all people with heart failure have one thing in common: their hearts do not pump like it should, so blood does not circulate properly.

In a healthy heart, both ventricles (lower part of the heart) pump or beat in a coordinated fashion at the same time, similar to making a fist by closing all fingers at the same time. But for those with heart failure, the ventricles do not pump in a coordinated fashion, rather it is like making a fist by closing one finger at a time. For those with heart failure, the electrical impulses of the heart need assistance so the ventricles can pump in a coordinated or synchronized fashion.

Every year, hundreds of thousands of people have pacemaker or resynchronization devices implanted to help treat irregular heart rhythms. Without these devices, they would be at a higher risk for sudden cardiac death, which kills more people each year than AIDS, breast cancer and lung cancer combined.

Cardiac Resynchronization Therapy

Cardiac Resynchronization Therapy (CRT) uses a device implanted under the skin near the heart to help restore proper coordination so the heart pumps more efficiently. A CRT device does not cure heart failure. But many people who receive a CRT device experience relief from their symptoms and increased energy.

Patients who are good candidates for a CRT device are those with moderate to severe heart failure; a weakened or enlarged heart; or an electrical problem that causes uncoordinated pumping of the heart.

There are two kinds of CRT devices:

• CRT-Pacemaker (CRT-P) is a special pacemaker that is used to treat slow heart rhythms by delivering low-energy electrical impulses to the ventricles to help them contract at the same time. The same impulses can also speed up the heart if it is pumping too slow. If the heart rate is regular but too fast, low-energy electrical impulses help return the heart to its normal rhythm. Most people do not feel these therapies.

• CRT-Defibrillator (CRT-D) is very similar to CRT-P used to treat slow heart rhythms and synchronize pumping. However, the CRT-D can also treats dangerously fast heart rhythms (arrhythmias) that can lead to sudden cardiac arrest. If the device senses heartbeats that are dangerously fast, it delivers a fairly strong shock to the heart to stop the abnormal rhythm. Without this life-saving device, the dangerously rapid rhythm could lead to sudden cardiac death in just minutes.

How does a CRT device work?

A CRT device has two parts – a pulse generator and leads – that deliver low-energy electrical impulses to the heart:

• The pulse generator is about the size of a hotel-size bar of soap. The device is implanted just under the skin near the left collar bone and contains computerized parts that run on a battery. The device treats your heart by sending very small amounts of electrical energy to the heart through the leads or wires. Patients usually can't feel the treatment.
• The leads are thin, insulated wires that carry electrical signals back and forth between the device and the heart. The leads can sense the heartbeats and deliver therapy to help both sides of the heart contract at the same time. Usually three leads are implanted in the heart: one in the top right chamber (atrium) and two that come into contact with the two bottom chambers or ventricles.

Over the year, advances in medical technology have made the surgery to implant a CRT device much simpler, taking only a few hours. After surgery, patients may stay in the hospital one to two days to make sure the device is programmed properly for the patients’ normal heart rhythm. Full recovery from the surgery can take from several days or weeks to a few months depending on the individual.

On average, a CRT device lasts four to six years. Regular check-ups will ensure the device is working properly. Once the battery levels drop to a certain level a new CRT device will have to be implanted.

Steven Peterson, M.D., cardiothoracic and vascular surgeon, has performed more than 4,000 open heart surgery procedures. He is the medical director of Cardiovascular Surgery at Flagstaff Medical Center.