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System Gives Hope to Patients with Precancerous Esophageal Condition

ENGINEERING EXCELLENCE

System Gives Hope to Patients with Precancerous Esophageal Condition
Shana Leonard
Radio-frequency electrodes, balloon catheters, and a breakthrough sizing technology enable the Halo360 system to ablate diseased eshophageal tissue associated with a precancerous condition.

Whether from gorging at Thanksgiving dinner or experimenting with spicy food, we’ve all experienced the discomfort of heartburn on occasion. But while many of us pop an antacid and move on, more than 21 million Americans endure the disruptive and painful chronic heartburn associated with gastroesophageal reflux disease (GERD). What’s worse? People burdened by GERD may also suffer from a serious precancerous condition—often without even realizing it.

Barrett’s esophagus develops when acid reflux repeatedly exposes the lower esophagus to stomach acid, causing a cellular conversion to occur. While only about 1% of Barrett’s patients eventually develop esophageal adenocarcinoma, they have a risk of doing so that is 30 to 125 times higher than people without the disorder, according to the National Digestive Diseases Information Clearinghouse. Cancer of the esophagus is not only one of the fastest-growing cancers in the nation, it is also often fatal, owing to ineffective treatment methods and late detection.

But there is hope on the horizon for Barrett’s patients. A Medical Design Excellence Award–winning device purposed to remove diseased esophageal tissue has the potential to prevent individuals with Barrett’s esophagus from developing an often-incurable type of cancer.

“Barrett’s is probably the only precancerous condition that we do not proactively intervene with because we haven’t had a tool to do it,” says Greg Barrett, president and CEO of Bârrx Medical Inc. (Sunnyvale, CA; www.barrx.com), the manufacturer of the system. “There are 3.3 million people who have this disease and they are subjected to a lifetime of surveillance—every year they have to come in and have a scope put down their esophagus and have biopsies taken of this Barrett’s to see if it’s gotten worse.”

Bârrx is hoping that the Halo360 system will change that. Applied in an endoscopic procedure, the system employs a balloon catheter around which a band of radio-frequency (RF) electrodes is wrapped. Along with the endoscope, the catheter is inserted into the esophagus, where the balloon is inflated so that it expands and presses against the walls. When the operator presses down on a foot pedal, a generator connected to the balloon prompts the delivery of short bursts of energy to the affected area. The device enables rapid 360° ablation of the diseased esophageal walls while controlling the depth of penetration so as to avoid damaging deeper, healthier tissue layers. After removal of the balloon, the Barrett’s-tainted cells slough off of the walls and healthy new cells grow in their place. However, Barrett cautions that GERD—the cause of Barrett’s disease—must also be monitored and treated to ensure that Barrett’s esophagus does not reappear.

Bârrx Medical was cofounded and incubated as a virtual company by Stellartech Research Corp. (Sunnyvale, CA; www.stellartec.com), a company specializing in RF technology, along with two physician partners. Stellartech quickly discovered that the design challenges associated with the product would be plentiful. For example, since most techniques tend to remove thick sections of tissue, the firm had to invent an energy-coupling method to the tissue that would enable treatment of very thin layers, according to Jerome Jackson, Stellartech vice president of research and development. The coupling method allowed shallow treatments, as long as they were administered very quickly—a task accomplished by the use of a generator responsible for delivering current in quick, powerful bursts.

Presenting the most ominous design hurdle, however, was the issue of controlled penetration. To treat Barrett’s esophagus, the team needed to be able to remove the thin layer of abnormal cells on the esophageal epithelium. If the technique did not ablate deep enough, the condition would not be effectively treated. But if the system penetrated too deeply, it risked a more serious injury called esophageal stricture.

Stellartech turned to All Flex Inc. (Northfield, MN; www.allflexinc.com) to help develop the RF electrodes that enabled the controlled ablation. “Since we’re trying to very accurately deliver this energy to a specific tissue layer, the electropattern is very important,” says Jackson. “All Flex has the ability to create the electropatterns on a material that we could actually bond to these balloons and know that every electrode that we produce is precisely the same; it’s really the key to consistent and accurate placement of the energy.”

Defining how these electrodes were made so that they could be configured on the outside of a balloon also required some consideration, according to Barrett. Moreover, the fixed size of the electrodes presented problems when it came to patient differentiation. Varying sizes of each patient’s esophagus needed to be taken into account so as to precisely apply the treatment. To do so, the engineers at Stellartech created a breakthrough sizing technology that measures the esophagus before beginning treatment. Physicians insert a balloon catheter and deploy it inside the esophagus. By measuring the amount of air needed to inflate the balloon, the system can calculate the diameter of the esophagus and recommend a treatment catheter size.

It was imperative that the balloons used in the sizing and treatment procedures didn’t overinflate and cause damage to the esophagus. However, the treatment balloon had to be capable of inflating to a sufficient pressure in order to deploy the electrode without stretching or changing shape. For balloons with such tight parameters, Stellartech enlisted the help of Advanced Polymers Inc. (Salem, NH; www.advpoly.com), which specializes in custom balloon manufacturing, as well as custom and thin-walled heat-shrinkable tubing.

“One of the big challenges was making these very large balloons that would actually fit on a very small device and be capable of being folded to a very low profile,” says Mark Saab, president of Advanced Polymers. “And also making that balloon with the proper rated pressures and the right geometry.”

Advanced Polymers worked with Stellartech to develop balloon dimensions, as well as to figure out how to attach the balloon to the catheter and how to accomplish bonding the electrode to the balloon. The balloon had to be able to withstand high pressures and to be folded with the electrode without cracking, splitting, or failing, Saab says. The company also had to heed the need for extremely thin walls. Because the device is inserted into the esophagus, it must be as small as possible despite the many layers of materials necessary for the technology.

Size proved to be a factor in the design of all of the components that were inserted into the body as well. Accurate Injection Molds (Clinton Township, MI; www.aimplastics.com) supplied injection molding of components that had to be consistent and small so that they could interface to the tubing while maintaining tight tolerances, according to Jackson.

“This was not a slap-it-together simple product and six months later it’s out on the marketplace,” Saab notes. “This project was extremely complex.”

Despite the parade of obstacles and plethora of parameters, the companies involved with the Halo360 count the hours laboring over the project as well spent. “We’ve followed some patients now for three years,” says Barrett of Bârrx Medical. “And we have cured 98.3% of all the patients we have treated and the Barrett’s has not come back.”

Copyright ©2007 Medical Product Manufacturing News
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