TED GRIGGS

Diamondback 360 Orbital Atherectomy System - handle

A new device that can pulverize the calcified plaque in arteries offers new hope to those suffering from peripheral arterial disease, and an Arkansas physician is playing a pivotal role in demonstrating the new technology.

One of the Diamondback 360 Orbital Atherectomy System’s major advantages is its ability to handle severely calcified plaque, which occurs in the majority of PAD cases, said Dr. Bruce E. Murphy, interventional cardiologist at Arkansas Heart Hospital in Little Rock.

Murphy, the first physician in Arkansas to offer the new treatment, said until now he has used a laser on blood vessels in the legs and a plaque scraper called the Silverhawk, but neither approach is very useful with the tough, hardened plaque.

“The Diamondback does appear to have overcome that obstacle in that we can, in fact, ablate large vessels, through a tiny burr, that are severely calcified,” Murphy said. The procedure results in a nice-sized lumen, or opening, that better fits the size of the artery.

The new device is also a major leap forward over some older technology called rotational atherectomy, Murphy said. That technology, used widely in the early and mid-1990s for calcified lesions, fell into disuse because of safety issues, the device’s complexity and the fact that it offered little benefit over stents, Murphy said.

The dramatic difference the Diamondback provides is that the diamond-coated burrs, or crowns, that sand away the plaque rotate elliptically, Murphy said. The faster the burrs rotate, the bigger the ellipse becomes.

“One of our constraints in working in leg arteries is the size of the device that we use,” Murphy said. “For instance, the artery in the thigh is 5 mm, 6 mm, or 7 mm in size. Well, to put a device that size in the leg would require you to put a hole in the leg … about the size of your thumb.”

The beauty of the Diamondback is that it is tiny, Murphy said. But as it spins faster and faster, it creates a bigger and bigger hole.

And the pieces of plaque that result are smaller than a red blood cell so they pass through a person’s circulatory system without creating any congestion, Murphy said.

Another advantage of the Diamondback is that no stents are required, Murphy said. At present, there are no approved and durable stents that can be used in the legs on a regular basis.

However, Murphy said it’s still too early to know if the Diamondback is a better solution than stents. Each person’s case is different, and it’s not as if there’s an ideal stent for each situation, he said.

“Peripheral vascular disease is a silent disease. Most people that have it don’t know they have it,” Murphy said. “By the time we get to them, identify it and start to treat it, it’s almost in its terminal stages. And that’s why something that can deal with severe calcification is so important.”

More than 12 million people in the United States suffer from PAD, a life-threatening condition where fatty material builds up on the inside of the arteries that carry blood from the heart to the arms and legs. The build-up causes the blood vessels to harden and narrow.

The resulting reduction in blood flow to the legs and feet can cause debilitating pain and can even lead to critical limb ischemia, which may force doctors to amputate the leg. It is estimated that less than 2 million people are actually diagnosed with PAD each year, and less than 700,000 are treated.

The U.S. Food and Drug Administration cleared the Diamondback for use in late September, following a clinical trial involving 124 patients.

Murphy said using the Diamondback doesn’t take that long, an hour or so. He performed a handful of procedures in the first two weeks after obtaining the equipment. Each procedure involved clearing blockages above and below the knee.
The procedures aren’t considered surgery, he said. They are performed through a puncture wound in the skin, so no incision or stitches are required. But all of that doesn’t equate to a care-free procedure.

“When you’ve got something that’s spinning around 200,000 times a minute in someone’s body, it can be intensive,” Murphy said.

Murphy said the procedures are expensive, roughly twice the cost of a laser catheter.

“When we use it we have strong indications for its use,” Murphy said.

He said he does not know if the cost of the Diamondback procedures will fall as the equipment’s use becomes more common.

Still the start-up cost is not that much when compared to other medical devices, Murphy said. For instance, the laser he uses cost $200,000, and each of its catheters is $1,700 per catheter.

The Diamondback costs around $10,000 for the console and $3,500 for each catheter, he said.



December 2007