Pediatric Cardiologist Dr. John Clark stood over a patient who was under anesthetic for a heart catheterization procedure at Akron Children’s Hospital. He pointed to a red image shaped like a caterpillar on the wide screen. That’s the ablation catheter inside her heart. He will use the catheter tip to destroy an abnormal electrical pathway causing a heart rhythm disorder.
The images in front of him come from 3-D mapping technology. Dr. Clark, director of the Pediatric Arrhythmia Center, has been using 3-D mapping instead of X-ray imaging since 2005. He said 3-D mapping should be more widely used around the nation to reduce exposure to radiation emitted from fluoroscopy – the X-ray technology widely used to see moving images of the heart.
Dr. Clark cited a recent study showing that radiation exposure from medical imaging in the United States jumped 6 times between 1980 and 2006.
The long-term risks of too much radiation for a young girl, such as many of his patient, are cancer in her and genetic defects in her children.
“We need to find ways to not overuse radiation and to cut back where we can.”
Akron Children’s is committed to minimizing medical radiation exposure to children. The hospital supports a national campaign called Image Gently, which aims to reduce exposure to children. The young are more susceptible to radiation than adults, and they have a longer time span to develop complications from excess exposure.
3-D imaging is now the recommended standard for pediatric heart ablation procedures. Fluoroscopy remains the standard for adults, “but 3-D mapping is beginning to filter into the adult world,” Dr. Clark said.
“We really pushed the envelope to eliminate radiation exposure to patients undergoing these procedures,” Dr. Clark said. “The movement has been slow to take foot. When I started doing ablation without radiation in 2005, not a lot of people thought it could be done. But the risks of radiation for U.S. citizens will push it forward.”
The technology works by using electrodes placed on the chest, back and armpits to create electrical fields that are converted to moving images. “It’s like GPS for the body,” Dr. Clark said.
Next to heart images, the wide screen above the patient displays EKG waves where Dr. Clark sees the electrical abnormality he will fix with catheter ablation.
The problem with the young girl is the electrical impulse is moving too quickly across a wire from her heart’s pacemaker – the sinus node – in the upper chamber down to the lower, pumping chamber. The disorder, called supraventricular tachycardia, causes rapid heartbeat.
Dr. Clark’s job is to destroy the problem wire so that the electrical impulse will instead travel through a normal wire. He does it by delivering extreme cold or heat, depending on the location of the abnormal pathway.
In this case, he had to guide the catheter through the septum, which divides the two upper chambers, to reach the wire. After ablating the area at a temperature of about 160 degrees, he saw the results on the EKG.
“Two signals were kissing each other. Now you see space between them. That’s the goal.”
Dr. Clark said it’s important to note that 3-D mapping not only protects children from radiation, it also protects staff.
The girl undergoing the ablation procedure would go home the next day without so much as a Band-Aid, and with a much improved quality of life.
“These kids have racing hearts and often have to go to the ER to make it stop,” he said. “It’s very destructive. You never know when it’s going to happen or how long it’s going to last. If you go on vacation, you have to know every ER between here and Hilton Head.”
Now that her procedure is finished, she and her family no longer have to worry about that.