A new procedure to remove plaque from the lower extremities enables patients with peripheral vascular disease (PVD) to walk pain-free. This same procedure allows scientists to evaluate the biologic profile of plaque, a fatty substance that stems or blocks normal blood flow.
University of Nebraska Medical Center surgeons are using a new plaque excision system called SilverHawk as part of a multi-center clinical trial to study the effect of drug therapy on artherosclerotic plaque. UNMC is among a select group of institutions in the U.S. and Canada, and the only one in this region, participating in the trial, known as LEAP (Lower Extremity Atherosclerotic Plaque Excision).
SilverHawk involves a wire catheter inserted into a tiny puncture in the groin, along which a kind of roto-rooter device, with a rotating blade the size of a grain of rice, is traversed. The blade cores or shaves plaque from arteries and collects it in a nose cone for extraction. Removal of the plaque restores normal blood flow.
An estimated 12 million Americans suffer from PVD, whose symptoms include pain, numbness, tingling or weakness in the leg. The pain can be so severe it prevents patients from walking even short distances. If left untreated, it can lead to amputation. Smoking and diabetes are the main risk factors for PVD.
UNMC vascular surgeons, Matt Longo, M.D., and Jason Johanning, M.D., were among the first surgeons in Nebraska to use the new procedure and are leading UNMC’s efforts with it in the trial, which began last May. SilverHawk represents “a huge advancement” in the treatment of PVD, Dr. Longo said, “as it allows us to treat long segment blockages and very small blood vessels” that older techniques did not.
Dr. Longo said this new way of attacking plaque avoids the longer recovery and greater complications associated with angioplasty, stents and bypass surgery. “The benefits for patients are many. Usually they go home in 12 to 18 hours and are up and moving about, doing their normal, every day life activities, within a day. There’s very little pain, lower risk and less stress on the body,” he said.
The experience of Plattsmouth, Neb. resident Frank Schmid, who had plaque removed from his right leg last fall with the procedure, is typical. Before surgery the 87-year-old retired farmer had severe “burning” in his foot and leg that limited his movement. He was diagnosed with PVD. Matters got worse when he suffered cuts to his foot and ankle in an accident that required stitches. When the poor blood flow in his leg slowed healing, the possibility of amputation was discussed.
Since his plaque excision Schmid’s foot and leg have healed and he’s getting around better than he has in a long time. He said, “My leg and foot feel a lot better. I don’t have any trouble anymore.” Tests indicate excellent blood flow.
To be eligible for the trial patients must have atherosclerotic disease in both legs and cannot be on any of the study drugs administered in the trial. Patients have plaque removed from both legs, with a six-week interval between each procedure. After the first excision patients are either put on one of three study drugs or a placebo. Excised plaque is sent to a lab for comparative analysis. The medications used in the study represent three classes of drugs: statins, ARB (angiotensin-receptor blocker)/ACE inhibitors and TZDs (thiazolidinedione hypoglycemic agents).
Dr. Longo said all three classes of drugs have “shown promise of affecting plaque” and “can help provide a platform off which we can base a new drug.”
“Essentially the study is looking to see what changes these medications make within the plaque itself,” he said. “The study also is trying to identify specific biomarkers within the plaque that can be targeted with new medications down the road.”
Dr. Longo said the new procedure extracts plaque in such a way as to allow a more thorough analysis of it.
“We haven’t had a way to harvest plaque up until this point in time where we take it out fresh and can look at it and send it to a lab dedicated to analyzing it,” he said. “This will hopefully not only provide new medications to treat plaque but give us insight into why plaques form and how we can get rid of them with medications as opposed to treating them with surgical procedures.”
The three-pronged trial aims to have 900 patients participate nationwide.
“Based off this initial clinical trial, there should be anywhere from seven to 10 more studies where we continue to focus down on the areas that we think we can really affect plaque stabilization or regression,” Dr. Longo said.
SilverHawk is now undergoing European trials for use in coronary athereosclerotic disease. Beyond this technique, advances in stents may offer promise for impacting PVD. Dr. Longo said there are ongoing trials in Europe with drug-eluting stents. These stents are coated with drugs that once released into the blood stream can prevent plaque from reforming. He said biodegradable stents may be another area of investigation.
UNMC is the only public health science center in the state. Its educational programs are responsible for training more health professionals practicing in Nebraska than any other institution. Through its commitment to education, research, patient care and outreach, UNMC has established itself as one of the country’s leading centers in cancer, transplantation biology, bioterrorism preparedness, neurodegenerative diseases, cardiovascular diseases, genetics, biomedical technology, ophthalmology and arthritis. UNMC’s research funding from external sources is now nearly $80 million annually and has resulted in the creation of more than 2,600 highly skilled jobs in the state. UNMC’s physician practice group, UNMC Physicians, includes more than 460 physicians in 50 specialties and subspecialties. They practice primarily in The Nebraska Medical Center, UNMC’s teaching hospital. For more information, go to UNMC’s Web site at www.unmc.edu.