A Medical Device Daily

Calcified plaque buildup has often been a difficult road block for physicians trying to remove blocked vessels in those patients suffering from peripheral arterial disease (PAD).

The problem is longstanding — and twofold in nature: first, how to use an atherectomy system strong enough to cut through the stone-like blockage, dubbed by some physicians as a “brick wall”; next how to keep surrounding tissue safe during the process.

The first needs aggressive, treatment, the second requires finesse, difficult procedures to combine in one system.

But Cardiovascular Systems (Minneapolis) touts its recently FDA-cleared Diamondback 360° Orbital Atherectomy System as able to do both. The company said the device can safely remove the plaque blockages that affect a high percentage of the 12 million people that suffer from PAD in the U.S., without damaging delicate adjacent tissue.

The clearance was largely based on the results of a clinical trial, called OASIS, involving 124 patients, that demonstrated dramatic plaque reduction in leg arteries with lasting results.

The company said the trial — its enrollment completed at the beginning of the year (Medical Device Daily, Jan. 25, 2007) — exceeded the FDA’s Objective Performance Criteria on multiple key measurable endpoints including the amount of plaque, reduced the percentage of patients that didn’t require repeat procedures and demonstrated the overall safety/efficacy of the device.

“The Diamondback treats patients that have no other options,” Carla Dahl, senior marketing manager of Cardiovascular Systems told Medical Device Daily. “What we found is that physicians were turning away patients because some of the plaque blockages were calcified.”

The company says the system doesn’t require a distal embolization protection device — often used in similar devices in this category to capture the calcified material and prevent downstream damage — since the particles are chipped down to a size about 75% smaller than red blood cells.

The device is shaped like a very exotic pen, with additional instrumentation including a touch-screen interface and an easily maneuverable, lightweight IV pole .

Dahl said the device differs from existing atherectomy technologies because of its ability to “sand away” the calcified plaque using an orbiting motion.

“The safety feature is a tiny diamond-coated crown that uses the principles of centrifugal force to rapidly spin or “orbit” at high speeds and sand away plaque,” Dahl said. “It’s the motion that preserves the tissue. We’ve had close to 80 cases with no [complications] thus far.”

Besides Cardiovascular Systems, several other companies are developing technologies to clear plaque, both soft and hard, from the vasculature.

“Up until now, we have not had an effective tool for treating heavy calcified vessels ...[the Diamondback 360] is a significant breakthrough for treating PAD,” said Tom Davis MD, of the Detroit Medical Center (Detroit, Michigan). “The Diamond Back 360 allows me the ability to offer my patients almost instantaneous improvement in restoring mobility and or healing wounds.”

Davis was one of the first doctors to use the technology which was made available for commercialization a mere 48 hours after the FDA gave the green-light clearance for the device. The company said that dozens of patients were then treated within the first couple of weeks of the device’s release.

Nearly a year ago, the FDA ordered the company to expand its clinical study centers from 10 to 20 sites, a probable indication of the agency’s early confidence in the device (MDD, Sept. 20, 2006). The trial was conducted under an FDA-approved investigational device exemption.

To date PAD has been extremely problematic if left untreated.

If not treated, PAD can result in arteries hardening and narrowing to create a condition called atherosclerosis-reducing blood flow to the legs and feet. If allowed to progress, PAD can possibly lead to Critical Limb Ischemia (CLI) and may result in non-healing wounds and eventual amputation.

According to a report by the Sage group, fewer then 20% of patients are diagnosed with the disease, despite the availability of treatments. Those patients diagnosed are often not treated aggressively enough, thus explaining the high mortality rates.

Underlying this statistic is an estimated $35 billion in unrealized annual U.S. sales in providing treatments for PAD.