Medical Device Daily
Medtronic's (Minneapolis) recall of its Sprint Fidelis leads has drawn significant attention to the implantable cardioverter defibrillator (ICD) market. When the med-tech giant reported pulling those leads in October because the wires might break inside the body, lawsuits sprouted up like wildflowers in an untamed garden.
Here's something else that became obvious: More technologies are being designed to remove the leads without causing too much harm to the patient.
As the number of cardiac lead implants increases each year, so too does the need to extract a portion of the lead wires. Lead wires that become infected, damaged or blocked must be removed to avoid serious complications and ensure patient safety.
Cook Medical (Bloomington, Indiana) is introducing Evolution, a mechanical dilator sheath, a small device that visually resembles a carpenter's drill gun. The device has a threaded barrel distal tip design, a rotating sheath and boasts not having to use an electrical energy supply.
"The device has one proximal turn per trigger squeeze and will rotate and bore through tissue with its tip that's blunted and tapered to a point," Barry Norlander, global marketing manager for Cook, told Medical Device Daily. "Usually physicians start near the shoulder area to remove the leads."
The device received 510(k) clearance in 2006 and was introduced to the U.S. market this past August. It received CE-mark approval last year as well.
Evolution is actually a throwback device — harkening back to the 1980s, when most removal of implantable leads was done by mechanical sheaths before electric or power sheaths became the sheaths of choice. The name reflects a change not only in design but in philosophy of lead removal as well.
"It's a back-to-the-future approach," Norlander said. "We started out with basic mechanical sheathes to powered sheaths to laser, now back to mechanical. Each step was a huge jump forward to the next. But the problem we saw with mechanical sheaths the first time was the awkwardness and physicality of completing the procedure with these tools. It was pretty rigorous to do these procedures with a mechanical sheath. You really could get a workout."
The issue dealt with the design of the tool.
"These leads become pseudo-fixed — scar tissue becomes tenacious and pulling very firmly is a recipe for disaster," he said.
Most electronic sheaths are bulky, costly and because of the design can often cause unintended damage to nearby tissue.
Cook cited several differences between Evolution and laser sheaths.
- Evolution sheaths are from one-third to one-half the cost of laser sheaths.
- Laser extraction requires a 600-pound, stand-alone unit to interface and energize the SLS laser sheaths. Each SLS laser sheath must be calibrated before use. Evolution does not require any additional capital equipment. It also does not require an annual maintenance contract or biomedical inspection that is mandated by laser sheaths. No electricity is needed. No on-site laser officer is required.
- Evolution has been designed to require less operator finesse and is more intuitive to use than laser-powered systems. The device's mechanical trigger allows the operator to better feel progress along the lead and through the lesion thus maximizing physician control.
"Laser sheaths won't successfully negotiate through calcified tissue that often occurs near the leads," he said. "They are great devices but they have a forward depth-of-cut. Oftentimes during these procedures, you're going to have to make sharp turns while removing the leads. That's just not practical when you have a device with a forward depth-of-cut. The chances for complications increase dramatically."
Cook's device comes at a time when ICD leads are under fire and heavy scrutiny. St. Jude Medical (St. Paul, Minnesota) was the latest company to feel the "kick in the shins" — as one expert called it at the time — to the ICD market because of Medtronic's recall. Rumors and speculation ran wild that the company's Riata leads would be the next devices for recall.
Norlander said that leads came under scrutiny like this about 12 years ago, when a now-defunct med-tech company, Teletronics, recalled its Acquifix lead. A wire in the device broke in some patients, causing massive injuries and complications, and in some cases death.
"We think our timing is good," Norlander said. "Our approach is to make sure physicians have the tools they need to successfully complete these procedures."