Success & Less Risk in Treating Kids with Heart Rhythm Problems

A University of Michigan Cardiovascular Center team today is reporting high levels of success, and lowered risk and radiation dose, from a new approach to treating children with rapid heartbeats and other heart rhythm conditions.

In a presentation at the American Heart Association's Scientific Sessions meeting, members of the Michigan Congenital Heart Center will present new data from a study of a treatment called RF catheter ablation in children using a three-dimensional computer assisted navigation system.

They show that by adding the 3-D navigation system to a conventional X-ray based method to visualize electrophysiological catheters inside the heart, they were able to successfully treat 99.1 percent of 113 patients included in the study.

While the procedural success rate was very high, the most significant finding was that the patients who were treated using the 3-D computer navigation system were spared almost half the radiation dose received by 108 comparable patients treated immediately before the new system was available.

"The goal of reducing radiation dose is especially important in children, because of the risk it can pose to their health and fertility later in life," says Peter Fischbach, M.D., M.A.., senior author of the new study. "Radiation exposure is very different for children and adults due to their small body mass as well as their longer life expectancy, which allows for a greater likelihood of the radiation to cause adverse effects. This system allows us to see multiple catheters in real time and guide their movements in three dimensions. We can record electrical activity in specific locations to help plan and deliver RF treatment."

RF (radiofrequency) catheter ablation treatment uses electrical current transmitted at very high frequencies through a tiny thin probe called a catheter that is steered through the blood vessels and into the heart. The electricity is passed through the tip of the catheter, cauterizing a small piece of muscle on the inside of a child's heart. Prior to delivering the electrical energy, doctors test the targeted area to determine if it is critical for supporting abnormal electrical activity in the heart that leads to fast heart rates, also known as tachycardia. Both the X-ray and 3-D systems allow doctors to see exactly where the catheter is positioned during testing and treatment.

The data are being presented by Mohamed Al-Ahdab, M.D., a former member of the U-M team now at Children's Hospital in Boston. Fischbach, an assistant professor at the U-M Medical School, directs the pediatric electrophysiology laboratory at C.S. Mott Children's Hospital, where children with abnormal heart rhythms are treated.

The research study involved a mapping system known as LocaLisa, which uses a law of physics known as Ohm's law to localize a catheter in 3-dimensional space and tell doctors where in the heart thier catheters are located. The catheters are inserted into the child's body through a small incision in the leg, and threaded up into the heart through the blood vessels.