Dr. Gerhard Muelheims, a cardiac electrophysiologist who joined Spokane Cardiology PS last month, soon will begin performing here an emerging catheter-based procedure for treating sufferers of atrial fibrillation, a potentially dangerous form of irregular heartbeat.


Because its still being perfected, the procedure, called atrial fibrillation ablation, can be performed only on a small percentage of people who suffer from the condition. The procedures success rate currently is around 70 percent.


Atrial fibrillation ablation is less invasive than a surgical procedure that sometimes is conducted to treat the condition, and is more effective than prescription medicines used to alleviate the patients symptoms, Muelheims says. He currently is screening patients who are potential candidates for the procedure, and he expects to perform soon at least two to three ablations a month.


Atrial fibrillation is a common heart-rhythm disturbance that occurs when some of the electrical impulses in the heart begin to fire rapidly. Electrical impulses act as a pacemaker for a normally functioning heart, but the rapid firing causes the hearts upper chambers to fibrillate, or quiver. That quivering causes the hearts lower chambers to beat more rapidly than usual.


Atrial fibrillation suffererspredominantly elderly peoplesometimes dont show any symptoms of the ailment, but most become fatigued or light-headed, Muelheims says. In some cases, the condition is debilitating, he says, and it can cause strokes and blood clots in the heart.


Conventional treatments include prescription medicines, such as anti-coagulants that thin the blood to prevent clots, and anti-arrhythmic drugs that correct a patients heart rate. Implanted pacemakers also are used to control heart rate for some atrial fibrillation sufferers, he says.


Those remedies, however, address the conditions effects, but dont stop fibrillation from occurring, Muelheims says.


Atrial fibrillation ablation is designed to keep fibrillation from occurring. Typically, Muelheims says, the rapid firing of electrical impulses that causes atrial fibrillation originates in one or more of the four pulmonary veins that lead into the right atrium, or upper right chamber, of the heart. To cut off those impulses, the ablation procedure uses a heart catheter to identify in which veins the rapid firing is occurring and to burn some of the nerves in those veins so that the impulses never reach the right atrium. Such a catheter includes a heating element at its tip that burns nerve endings at between 55 degrees and 60 degrees Celsius, or 130 to 140 degrees Fahrenheit.


Three heart cathetersone inserted through each femoral artery and one through the right jugular veinare used during the procedure, which typically takes between four and six hours to complete and requires an overnight stay in the hospital, Muelheims says.


The ablation procedures effect is similar to that of a surgical procedure used to treat atrial fibrillation thats called the Maze procedure. Spokane cardiovascular surgeon Dr. William Coleman began performing that operation about a year ago.


Briefly, the Maze procedure involves making multiple incisions into the upper chambers of the heart, then stitching them back up. The maze-like incisions block the irregular electrical impulses.


Maze requires a longer hospital stay than the ablation procedure, since it involves a cardiopulmonary bypass, which involves opening up a patients chest and hooking him or her to a heart-lung machine.


Procedures limitations


Dr. Timothy Lessmeier, an eletrophys-iologist with Heart Clinics Northwest PS, says that of the six electrophysiologists who practice in Spokane, Muelheims is the only one who will be performing atrial fibrillation ablations in the near future.


Lessmeier says the patient population thats eligible for the ablation procedure is small, and at 70 percent, the success rate of the procedure is relatively low. He has sent eligible candidates to other cities for the procedure in the past, but he isnt seeking training in the procedure himself yet.


From a conservative standpoint, Im waiting for the technique to get better, Lessmeier says.


Muelheims says the best candidates for the procedure are patients with structurally normal hearts who have whats called paroxysmal atrial fibrillation, an early stage of atrial fibrillation during which quivering of the heart comes and goes. Patients who have more advanced stages of atrial fibrillation, either persistent or permanent fibrillation, arent good candidates for the procedure.


Heres why, Muelheims says. During early-stage atrial fibrillation, the rapid firing of electrical impulses typically doesnt leave the pulmonary veins that lead into the right atrium. As the condition progresses, the rapid firing spreads to the right atrium.


While the catheter procedure effectively can stop the electrical impulses in the veins, impulses in the atrium itself are difficult to locate with current catheter technology and cant be treated with the ablation procedure.


Muelheims says, however, that catheter technology will improve in coming years so that more of the ablation procedures will be successful and more patients will be eligible for the procedure.


I believe the success rate will increase to 85 or 90 percent in the next five years, Muelheims says.


Some risk is involved in the procedure. A small percentage of patients who undergo the proceduremaybe 1 percent, Muelheims sayswill develop pulmonary-vein stenosis, or narrowing of those veins. To minimize the chances of that happening, Muelheims says he tries to burn nerve endings only in the problem veins, rather than all four of them.