September 7, 2007

Vascular Surgery on cutting edge of high-tech care

Featured Image

From left, Vascular Surgery’s Charles Ross, M.D., Thomas Naslund, M.D., Jeffery Dattilo, M.D., and Raul Guzman, M.D. (photo by Neil Brake)

Vascular Surgery on cutting edge of high-tech care

The four surgeons who constitute the Vascular Surgery division of the Vanderbilt Heart & Vascular Institute are working to improve the level of patient care they provide by participating in clinical trials and studying the safety and efficacy of the latest high-tech equipment.

• Charles Ross, M.D., assistant professor of Surgery, is participating in a clinical study of a device that uses a tiny rotating blade to shave away plaque from inside leg arteries and remove it from the patient's body. Removing this plaque improves blood flow to the leg and foot, relieving leg pain and preventing amputation.

Ross is comparing the SilverHawk Plaque Excision System to leg artery bypass surgery for patients who are at extremely high risk for limb loss due to a severe form of peripheral artery disease known as critical limb ischemia (CLI). It is caused by plaque, which obstructs arterial flow to the leg and foot to such a degree that patients experience severe pain and tissue ulceration. If left untreated, CLI may progress to gangrene, ultimately requiring amputation.

The study, called PROOF, will randomize 304 patients with CLI either to SilverHawk or traditional leg artery bypass surgery. The primary study goal is amputation-free survival as well as limb salvage, quality of life, re-intervention and the cost efficiency of each procedure. Patients will be followed for five years.

“PROOF is the first study of its kind, comparing plaque excision to leg artery bypass surgery, and Vanderbilt University Hospital is pleased to be a part of the research process,” Ross said.

“It is not uncommon for clinicians who manage severe peripheral arterial disease to be faced with patients who are potential candidates for both traditional bypass or less invasive endovascular options.”

Endovascular techniques, such as plaque removal with Silverhawk are less invasive and offer potential advantages of safety, fewer side effects, and faster recovery than surgical bypass, Ross said. On the other hand, surgical bypass, the traditional mode of therapy for such patients, offers potential benefits of greater long-term durability.

• Raul Guzman, M.D., assistant professor of Surgery, is involved in studies aimed at preventing amputation in patients with diabetes.

In an NIH-funded study to perform these trials, Guzman used CT scans to measure the amount of calcium in leg arteries.

His team has recently determined that calcium build-up in leg arteries can serve as a very sensitive marker of amputation risk in patients with diabetes, and they have found this to be a better predictor of amputation than other currently used measures.

“Having this type of information will allow us to focus our efforts on preventing foot problems in a very high-risk patient population,” Guzman said.

His group is also looking at some of the causes of calcification and potential treatments.

“Our current studies focus on the relationship between arterial calcification and lower extremity amputation. We plan to look more carefully into the factors that affect arterial calcification in individual patients as well as some potential molecular-based therapies to target this process,” he said.

• Jeffery Dattilo, M.D., assistant professor of Surgery, will be studying a novel way of protecting the brain and circulation to the brain during carotid artery stenting.

Conventionally, surgeons have performed an open operation to clean out the plaque within the carotid artery, which supplies the brain with blood. They can use shunts to divert the blood around the plaque while they remove it. Carotid artery stenting gives surgeons and interventionists an alternative to open surgery. The doctor can place a stent in the carotid artery to open the narrowing.

During this procedure the plaque could dislodge and travel to the brain and cause a stroke. Currently, this debris is caught by a very small basket attached to the stent, though some small particles can potentially get past and go to the brain.

The GORE Neuro Protection System is a protection system that has the ability to create blood flow reversal at the treatment site of the carotid artery.

This allows embolic particles released during carotid artery angioplasty and stenting to travel away from the neurovascular circulation through the catheter and be captured in the external filter outside the body.

“It takes advantage of the physiology and hemodynamics of most people,” Dattilo said.

“This is a more natural way of preventing stroke or other problems when we insert stents. It takes advantage of the body's own way of preventing even the smallest particles of the emboli from reaching the brain.”

• Thomas Naslund, M.D., associate professor of Surgery and director of the Division of Vascular Surgery, says he spends 80 percent of his time repairing aneurysms in the abdomen and thorax.

He is studying a new endovascular graft for abdominal aortic aneurysm, which occurs when the blood vessel that supplies blood to the abdomen, pelvis and legs becomes abnormally large or balloons outward. There are two ways to repair these.

In a traditional (open) repair, the surgeon makes large cut in the abdomen. The abnormal vessel is replaced with a graft made of synthetic material. The other approach is called endovascular stent grafting in which a stent graft is sent through a catheter, and permanently placed into the artery.

The graft is held in place by friction or hooks. While this works in most cases, occasionally grafts can migrate or blood can leak around the graft and cause later risks.

Rather than relying on friction or hooks, Naslund is using tiny screws to fix the graft to the artery wall, allowing for active fixation that makes the attachment more robust.

“The problem with old grafts is that they can migrate, or slip down, over a period of time,” Naslund said. “If you have a graft in the abdomen, and it migrates, the aneurysm could leak in from the top and is still subject to rupture.”

Naslund said that while each of the vascular surgeons has his own niche, their areas of expertise often overlap, thus providing opportunities for collaboration within the division. It is this seamless delivery of care that makes the Vascular Surgery division uniquely qualified to repair the most difficult, and delicate, challenges of the circulatory system.

“We have developed a vascular team where everyone pitches in to handle what is needed to care for patients who have vascular disease,” Naslund said.