Magnetically guided catheter zaps atrial fibrillation

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"Based on our experience with remote navigation and ablation technology, a new era in interventional electrophysiology is beginning as magnetic, very soft catheters can be navigated in the heart more precisely and safely than manual catheters without risk of major complications, even in less experienced centers," said Carlo Pappone, M.D., Ph.D. from the Department of Electrophysiology, San Raffaele University Hospital in Milan, Italy.

Atrial fibrillation is an abnormal heart rhythm in which the upper chambers of the heart flutter, and do not pump blood normally. If the condition cannot be managed with medications, some patients are treated with radio frequency ablation. The technique uses a high energy pulse to destroy a small area of heart muscle cells, in order to prevent them from conducting nerve signals that trigger fibrillation.

Typically the radio frequency pulse is emitted by from the tip of a catheter threaded through blood vessels into the heart until it is positioned next to the target area. Conventional catheters are somewhat stiff, so they can be pushed and pulled through blood vessels, and their tips can be curled and pointed by an operator standing by the patient. The device tested in this trial uses a very soft, limp tip that has a magnet on the end. Rather than manually pointing the catheter tip, the operator of this device uses a computer to control a magnetic field that robotically moves the catheter tip. The principle is the same as a compass needle pointing to magnetic north; allowing this device to steer the magnetic catheter in three dimensions to a target visualized on 3-D scans of the patient's heart.

"Catheter ablation for atrial fibrillation is now an important treatment for this common disorder, but the current strategy of manual catheter manipulation is highly operator-dependent, with a long and variable learning curve and a great potential for both inefficacy and complications in inexperienced hands. Robotic navigation may increase the ability of inexperienced operators to perform this procedure easily and safely, as it is most dependent on a well-trained team rather than on a single operator," Dr. Pappone said.

Since catheter procedures of this type require frequent use of X-rays to track the location of the target and the catheter tip, another advantage of remote navigation is that the operator can work from a shielded control room, rather than having to stand next to the patient for several hours while wearing protective lead aprons.

This first trial of the robotic magnetic navigation system in patients with atrial fibrillation involved 40 participants whose conditions were not adequately controlled by medication. After encountering some difficulties in the first three patients, the researchers said the remaining procedures went smoothly. In all, the catheter tip was successfully guided by magnetic navigation to the target and radio frequency ablation was applied in 38 of the 40 study participants. There were no reported complications during the procedures.

"Based on our results, we believe that incorporation of remote navigation and ablation in the electrophysiology laboratory may represent a true revolution regardless of age and experience of the operators leading to a seismic change in electrophysiologic paradigms for many laboratories worldwide. People always have had a love/hate relationship with robots, but this psychological barrier must be overcome. After performing more than 10,000 procedures with manually deflectable catheters, I have become enthusiastic for this emerging field," Dr. Pappone said.

E. Kevin Heist, M.D., Ph.D. from Massachusetts General Hospital in Boston, who was not connected with this study, said even though catheter ablation is more successful than medical treatment for atrial fibrillation, the conventional procedure can be long and difficult.

"Catheter ablation as currently practiced with hand held, manually deflected catheters is a long procedure, typically 3 to 5 hours, has a long learning curve, and has a significant risk of procedural complications and of recurrent atrial fibrillation after the procedure. Robotic catheter navigation with a magnet-tipped catheter directed by large, computer directed magnets can provide more precise catheter control as compared to manual catheter manipulation. This has the potential, as yet unproven, to shorten the procedure, reduce the length of the learning curve, and perhaps to improve the outcomes of the procedure and reduce complications," Dr. Heist said.

Dr. Heist said future trials will be needed to directly compare robotic navigation to conventional manually operated catheters in regard to procedural safety and efficacy.

Mitchell N. Faddis M.D., Ph.D. from the Washington University School of Medicine in St. Louis, Missouri, who was not involved with this study, helped develop the remote magnetic navigation system the researchers used.

"The work of Pappone et al. is extremely exciting to me as the culmination of this work, and to the cardiology community in general as a potential important technical advance in the treatment of atrial fibrillation," Dr. Faddis said.

Dr. Faddis said this new system should be easier to master, as well as being more precise, than conventional catheter ablation.

"Because of computer control, the efficiency of the procedure may improve. By the end of the 40 patient cohort of Pappone et al., procedures were routinely performed in less than an hour. This will likely have an important impact on the complication rate for the procedure which is likely affected by procedure duration," he said.

American College of Cardiology