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New techniques for treating atrial fibrillation

New devices and treatments can help prevent irregular atrial heart rhythms and related risks.

When your heart is pumping well, the four chambers contract and relax in a rhythmic, coordinated manner. However, a malfunction in the heart’s internal electrical system can disrupt the normal beating sequence. As a result, the two upper chambers, the atria, can go into a fast, irregular quiver known as atrial fibrillation, or “afib.”

In some people, episodes of atrial fibrillation cause distressing symptoms such as strong heart palpitations, dizziness, and chest pressure. Others have few overt symptoms but suffer from vague feelings of fatigue and weakness. Either way, untreated atrial fibrillation is a major risk factor for stroke.

Zapping away symptoms

The first avenue of treatment for people with symptomatic afib is medicine to control the heart rate and rhythm. “Medications are easy but not always effective at improving symptoms,” says Dr. Moussa Mansour, an atrial fibrillation specialist at Harvard-affiliated Massachusetts General Hospital.

The next option is a procedure called catheter ablation therapy, in which a thin, flexible tube is inserted into a vein and advanced to the heart. The electrical cells in the heart that are responsible for creating the arrhythmia are destroyed with a zap of radiofrequency heat energy. It’s now the primary treatment for people with symptomatic afib that cannot be controlled with drugs.

Catheter ablation’s popularity has increased rapidly in recent years. “It is the fastest-growing procedure in cardiology,” says Dr. Mansour, partly because of the rise in the number of people with atrial fibrillation. One recent addition to the technology is the incorporation of three-dimensional imaging of the heart made before the procedure together with the real-time echocardiogram and x-ray images the doctor sees while performing the ablation.

Another advance is a novel physiological mapping system called focal impulse and rotor modulation (FIRM). This technology can pinpoint the exact location of the misfiring nerves in the heart wall that are causing the rhythm disturbance. Using this system, the doctor can administer tiny, precise jolts of energy to burn away localized electrical “hot spots” or “rotors.” These problem areas are not addressed with conventional ablation, which focuses only on tissue in the pulmonary vein.

The Watchman LAA Closure Device helps prevent strokes
caused by atrial fibrillation by blocking the opening to the heart’s left atrial appendage.

image
Photo: Courtesy Watchmanâ„¢

Preventing stroke

All people with atrial fibrillation, even those who do not experience symptoms from it, are at risk for a stroke stemming from the arrhythmia. During an episode of afib, blood can pool in a pouch-like extension in the upper left quadrant of the heart called the left atrial appendage (see illustration). Clots that form in the stagnant blood may break loose and travel to the brain, causing a blockage. Even if catheter ablation reduces your afib symptoms from daily to once every five years, you are still at risk of stroke from that episode, says Dr. Mansour.

Stroke prevention is especially important if a person has additional risk factors, such as high blood pressure, diabetes, heart failure, or a previous stroke. “We use warfarin and some of the newer anticoagulant drugs to lower stroke risk,” Dr. Mansour says. “But some people don’t want to take these drugs or can’t because of side effects such as excessive bleeding.”

Newer devices show promise

However, three new medical devices show promise for preventing fibrillation-induced stroke without the use of medications. Both the Watchman LAA Closure Device, recently approved by the FDA, and the Amplatzer Cardiac Plug, currently undergoing clinical trials in the United States, operate on the principle that stroke risk can be minimized by blocking the opening to the left atrial appendage, thereby preventing the collection of blood in this pocket and the formation of clots. The LARIAT Suture Delivery Device, which gained FDA approval in 2009, cinches the opening of the appendage shut with a loop of suture material. Although the three devices employ slightly different designs, all are placed in the heart via catheter and might reduce the need for anticoagulant drugs.

As new catheter-based techniques are being explored, conventional radiofrequency ablation technology continues to be refined as well. Next-generation devices feature catheter tips infused with saline to prevent them from overheating or creating blood clots. Catheters that use lasers or freezing instead of heat to destroy problem tissue are also being tried.

Posted by: Dr.Health

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