Medical Device Daily

A medical procedure for clearing arterial blockages in the leg – too often resulting in amputations – can save limbs and save lives, according to Craig Walker, MD, of the Cardiovascular Institute of the South (Houma, Louisiana).

Walker, a cardiologist who performs in excess of 500 cases a year with the CLIRpath laser from Spectranetics (Colorado Springs, Colorado), told Medical Device Daily that the excimer laser catheter system “represents a means by which we can help to avoid a lot of amputations.”

Doctors “often jump too quickly to amputation rather than exploring medical advances that can prevent limb loss,” in diabetic or obese patients with severe peripheral arterial disease, he said. Yet even at the “very best centers there is a 5% to 8% chance of dying if you cut the leg off below the knee.” Walker described amputation as “more morbid and more mortal” than procedures such as revascularization, as well as more expensive with “huge societal costs.”

The CLIRpath (Cool Laser Revascularization for Peripheral Artery Therapy) “cool” laser produces a pulsed burst of ultraviolet light energy that is transmitted along flexible glass fibers encased in catheters, which vaporizes arterial blockages, restores blood flow and promotes wound healing.

Walker said the percutaneous procedure, which does not involve anesthesia or a lengthy hospital stay, “cleans out the artery” and “makes a channel” to restore blood flow to the limb. The laser vaporizes the build up of plaque inside the vessel that had been choking off the blood supply, he explained. “It takes these solid materials and converts them into gaseous form. This gaseous form is made up of very small molecules which are much smaller than a red blood cell, and therefore are simply washed right out and removed by the liver.”

As founder, president and chief medical officer of the Cardiovascular Institute of the South, Walker has long been a supporter of Spectranetics' laser technology and in December 2004 was asked to join the company's board of directors.

“I probably do more cases of this [CLIRpath procedure] than anyone in the world,” he said, adding: “I use every technology that's out there; CLIRpath is not the only peripheral technology.” Surgical interventions are another alternative, he said. “But in limb salvage, especially in people who have intrapopliteal disease, I use it in the majority of those cases as I feel it's got the most data showing that we can save limbs.”

CLIRpath was first cleared by the FDA in April 2004 (Medical Device Daily, May 3, 2004) to cross refractory total occlusions in the leg arteries, based largely on data from Spectranetics' LACI (Laser Angioplasty for Critical limb Ischemia) trial. LACI evaluated the effectiveness of excimer laser angioplasty in critical limb ischemia patients with complex blockages in their legs. The primary endpoint of the trial, limb salvage among surviving patients at six months following the initial laser treatment, was 93%.

The most recent addition to Spectranetics' CLIRpath line of excimer laser catheters is the 2.5 Turbo, which ranges in diameter from 0.9 mm to 2.5 mm. The CLIRpath 2.5 Turbo Catheter was FDA-cleared in August 2005 (MDD, Aug. 25, 2005) to treat total occlusions in the superficial femoral artery (SFA).

The Turbo features several design enhancements, including an increased number of fibers creating 30% more energy and 60% faster penetration rate to more efficiently ablate larger lumens in the SFA and popliteal arteries. According to Walker, this means that “energy is transmitted better. We can make it fire more rapidly per second, which allows it to more effectively ablate the tissue. That has huge implications in terms of the ability to cross calcified lesions, which are notoriously the hardest thing we have to treat in vascular disease.”

A second enhancement is a “continuous on” lasing train as compared to the “10 second on, five second off” lasing train of the 2.5 catheter, which the company said enables shorter procedure times and reduces radiation exposure. “Now when we turn it on, it stays on until we take our foot off the switch, and that gives us control,” Walker said of his experience with the new probe.

The third feature unique to the Turbo is a hydrophilic coating to allow for smoother advancement through tight lesions and an easier transition over the aortic bifurcation, “which means there is less drag on the catheter,” Walker said.

Another device in Spectranetics' pipeline is the CLIRpath Turbo-Booster. The Turbo-Booster allows for controlled deflection of the tip of the laser catheter, enabling a larger channel to be created as compared with that created by the laser catheter alone.

Spectranetics said it hopes to obtain FDA clearance for the device in 2007. The company is in the process of initiating the CELLO study using the Turbo-Booster system in the U.S. This single-arm study will take place in 10 to 15 centers, and will enroll about 100 patients.

Walker spoke of his recent experience with the Turbo-Booster in Germany. “Using the 2 mm probe, we were able to open up a channel in the superficial femoral artery which by intravascular ultrasound measured 5 mm in diameter,” he said. “That is very important because in the past the laser probe could really only core a channel out roughly the same size as the laser probe. The biggest one is 2.5 mm, therefore we weren't able to make nearly as big of a channel as we can now make.”

Walker also performed a live case demonstration using the Turbo-Booster during last month's EuroPCR gathering in Paris (MDD, May 22, 2006). “We had a very spectacular outcome that caused a lot of people to be interested in this tool,” he said of the new system's ability to “quickly and easily” recanalize in-stent restenosis lesions.

More than 300 hospitals across the U.S. are now offering the CLIRpath procedure as an alternative to amputation. “More and more hospitals are getting lasers, and more and more physicians have developed an interest, especially given the recent results that have been shown in live case demonstrations,” Walker said.

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