Ablation Procedure Study

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Gila Z. Reckess

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Minimally Invasive Cure for Heart Rhythm Abnormality Proven Effective

St. Louis, Oct. 14, 2004 — A minimally invasive approach to curing the most

common heart rhythm abnormality, atrial fibrillation, takes half the time of

the traditional surgical procedure but is equally effective, according to

research at Washington University School of Medicine in St. Louis.

Results from the first reported clinical trial testing the procedure appear

in the October issue of The Journal of Thoracic and Cardiovascular Surgery.

“Our findings show that this technique is much easier to perform but works

just as well as the more invasive approach,†says principal investigator Ralph

J. Damiano, M.D., the Shoenberg Professor of Surgery and chief of cardiac

surgery at the School of Medicine, and a cardiac surgeon at -Jewish

Hospital. “This is very good news because it means more surgeons can perform

the

procedure and it will be applicable to virtually all patients with this

irregular rhythm.â€

Atrial fibrillation affects more than two million Americans. Normally,

electric signals trigger the synchronized contraction of muscles in the

heart’s two

upper chambers, the atria. During atrial fibrillation, a chaotic web of

electric impulses spreads throughout the atria, causing the chambers to quiver

rather than contract in unison. The result is a host of painful symptoms and

significantly increased risk of heart attack or stroke. In fact, atrial

fibrillation

accounts for about 15 percent of all strokes in the United States.

Medications can alleviate symptoms in some patients, but they cannot cure the

problem. In 1987, researchers at the School of Medicine led by ,

M.D., developed a surgical cure called the maze procedure to control these

erratic impulses. In this procedure, surgeons make small, strategically placed

incisions in the atria. The slits generate scar tissues that serve as barriers,

trapping abnormal electric signals in a “maze†of barricades. Only one path

remains intact, guiding impulses to their correct destination.

With a success rate of more than 90 percent, the maze procedure

revolutionized the treatment of atrial fibrillation. However, it is technically

difficult and therefore is not performed frequently. Surgeons also must

temporarily

stop the heart and use a heart-lung machine to take over the heart’s role of

circulating blood in order to make the incisions. Not all patients, therefore,

are healthy enough to endure the operation.

Damiano and his colleagues developed an alternative using two electrodes that

pass a current through a section of heart tissue, heating and killing a thin

band of tissue. This bipolar radiofrequency variation of the maze

procedure creates scar tissues that similarly block abnormal impulses

responsible for

atrial fibrillation.

Damiano’s team replaced most of the maze incisions with lesions created

using the new, less invasive approach in 40 consecutive patients treated for

atrial fibrillation at -Jewish Hospital from January 2002 to October 2003.

Overall, the success of the procedure was equivalent to the team’s success

using the traditional maze approach between January 1988 and January 2002.

All patients survived the operation, and about 15 percent needed a pacemaker

after surgery to help maintain a normal heart rhythm. A little over 90 percent

of patients followed for six months still had healthy heart rhythms.

The only notable difference between the patients in this study and their

predecessors who had undergone the traditional surgery was the length of the

operation. Traditional maze procedures took, on average, 93 minutes to

perform,

while procedures that incorporated the new approach took only 54 minutes.

“Shorter operative times are important for patient safety and outcome,†says

Damiano. “If we shorten the procedure, it decreases the time we need to keep

patients on the heart-lung machine. We are working in the laboratory on an

approach that someday will allow us to perform atrial fibrillation surgery on

the

beating heart.â€

###

Gaynor SL, Diodato MD, Prasad SM, Ishii Y, Schuessler RB, MS, Damiano

NR, Bloch JB, Moon MR, Damiano RJ. A prospective, single-center clinical trial

of a modified maze procedure with bipolar radiofrequency ablation. The

Journal of Thoracic and Cardiovascular Surgery, Vol. 128(4), pp. 535-542,

October 2004.

Funding from Atricure, Inc. supported this research.

Washington University School of Medicine’s full-time and volunteer faculty

physicians also are the medical staff of -Jewish and St. Louis Children's

hospitals. The School of Medicine is one of the leading medical research,

teaching and patient care institutions in the nation, currently ranked second in

the nation by U.S. News & World Report. Through its affiliations with

-Jewish and St. Louis Children's hospitals, the School of Medicine is

linked to

BJC HealthCare.