Surgeons announce advance in atrial fibrillation surgery

Heart surgeons at Washington University School of Medicine in St. Louis report that by adding a simple 10-20 second step to an operative procedure they achieved a significant improvement in the outcome for the surgical treatment of atrial fibrillation (AF).

Reporting in the April issue of the Journal of Thoracic and Cardiovascular Surgery, the surgeons describe an enhancement to the Cox-Maze procedure, a surgical procedure that redirects wayward electrical impulses causing AF by creating precisely placed scars, or ablations, in the heart muscle. The Cox-Maze procedure is highly effective, offering the best long-term cure rate for persistent atrial fibrillation.

The surgeons added one ablation to the series of ablations typically made during the Cox-Maze procedure and that short step improved how well patients did after surgery. As a result, they recommend using this extra ablation in all patients undergoing the procedure.

"The single additional ablation creates what we call a box lesion," explains Ralph J. Damiano Jr., M.D., the John Shoenberg Professor of Surgery at the School of Medicine. "The box lesion surrounds and electrically isolates the pulmonary veins and the posterior left atrial wall from the rest of the left atrium. Our study shows excellent success when using the box lesion, and we recommend it for any patient with long-standing atrial fibrillation."

AF is the most common irregular heart rhythm and affects more than 2 million people in the United States. During atrial fibrillation, the upper chambers (atria) of the heart beat rapidly and quiver instead of contracting, drastically reducing the amount of blood they pump. AF can cause fatigue, shortness of breath, exercise intolerance, heart palpitations and stroke.

The area of the heart near the pulmonary veins is a common source of the irregular electrical impulses that can cause AF. Without the box lesion, in some patients this area could still support electrical signals that disrupt the regular contractions of the heart's upper chambers.

Led by Damiano, also chief of cardiac surgery at the School of Medicine and a cardiac surgeon at Barnes-Jewish Hospital, the Washington University surgeons revolutionized AF treatment in 2002 by helping develop a radiofrequency clamp that creates the ablation lines needed to reroute electrical impulses in the heart. The clamp directs radiofrequency energy into the heart muscle and creates a full-thickness scar.

The radiofrequency clamp procedure is quicker and easier than the original "cut and sew" Cox-Maze procedure, which was developed by James Cox, M.D., at Washington University in 1987. The original procedure relied on a complex series of 10 incisions in the heart muscle, creating a "maze" to channel errant electrical impulses where they should go. In the newer version, called Cox-Maze IV, most of these incisions were replaced by radiofrequency ablations, reducing the operation from an average of 90 minutes to about 30 minutes.

The current study involved two groups of patients with AF. One group underwent radiofrequency ablation-assisted Cox-Maze IV procedures without a box lesion and the other with a box lesion. The box lesion group had a 48 percent lower occurrence of atrial flutter and fibrillation in the first weeks after surgery. These patients also had shorter hospital stays (nine days on average) than patients who had the standard Cox-Maze IV procedure (average stay of 11 days).

Three months after surgery, 95 percent of patients who had the box lesion had no signs of AF, while only 85 percent of the patients who had the standard Cox-Maze IV procedure were free from AF. By six and 12 months postsurgery, all of the patients in the box lesion group were free from AF compared to 90 percent of the other group, although that difference was not statistically significant.

"We also saw that the use of antiarrhythmic drugs was lower after three and six months in those who received a box lesion," Damiano says. "These drugs can have serious side effects, and if patients can stop using them they often feel better. Overall, the use of the box lesion set was associated with shorter hospitalization, fewer medications and reduced recurrence of atrial fibrillation. We were very pleased with these results."

Compared to those without atrial fibrillation, people with the disorder are five times more likely to suffer from stroke and have up to a two-fold higher risk of death. For some patients, medications can control the abnormal heart rhythms and the risk of clotting associated with atrial fibrillation, but unlike the Cox-Maze procedure, the drugs usually do not cure the disorder.

Source: Washington University School of Medicine

Related stories:

6-month follow-up diagnostic mammograms recommended for women with probably benign lesions
Radiologists can, with confidence, recommend a six-month follow-up diagnostic mammogram rather than an immediate biopsy for patients with “probably benign” breast lesions, a new study emphasizes.
Drug-releasing stent shows promise for improving outcomes in patients with coronary artery disease
For patients who underwent angioplasty to open narrowed coronary arteries, the use of stents releasing the drug everolimus reduced the rate of renarrowing of the arteries and significantly reduced the risk of major cardiac events, compared to the widely-used paclitaxel-releasing stents, according to a study in the April 23/30 issue of JAMA.
New 'seed' therapy helps pinpoint breast tumors with more accuracy
Physicians at UT Southwestern Medical Center are the first in Texas to use a new technique in which a small radioactive pellet, or “seed”, is implanted into a mass or suspicious lesion in the breast to pinpoint its exact location for surgical removal.
Light-based probe 'sees' early cancers in first tests on human tissue
In its first laboratory tests on human tissue, a light-based probe built by researchers at Duke University's Pratt School of Engineering almost instantly detected the earliest signs of cancer in cells that line internal organs.
New medical technique punches holes in cells, could treat tumors
A large animal study has shown that certain microsecond electrical pulses can punch nanoscale holes in the membranes of target cells without harming tissue scaffolding, including that in the blood vessels - a potential breakthrough in minimally invasive surgical treatments of tumors.
Improved imaging for identifying breast cancer in overweight women
Increasing the ability to identify sentinel nodes—the very first lymph nodes that trap cancer cells draining away from a breast lesion site—has a major impact in the treatment and outcome of breast cancer patients, possibly eliminating the need for unnecessary and painful surgery. Researchers found that using SPECT/CT imaging aids in sentinel node identification—especially for overweight or obese women, according to a report in the February issue of the Journal of Nuclear Medicine.
'Smart bomb' nanoparticle strategy impacts metastasis
A new treatment strategy using molecular "smart bombs" to target metastasis with anti-cancer drugs leads to good results using significantly lower doses of toxic chemotherapy, with less collateral damage to surrounding tissue, according to a collaborative team of researchers at the University of California, San Diego.
Disruption of blood sugar levels after heart surgery is common
A study reveals today that inadequate blood sugar control in patients having heart surgery is associated with a four fold increase in post-surgery death and major complications - and that the blood sugar disturbances occur in patients with and without diabetes.

News discussion:

Medicine & Health news