The excimer laser uses ultraviolet light to dissolve and remove plaque and other matter from blood vessels and arteries, eliminating the risk of additional clots from pieces floating downstream in the vessels
Converging Causes Create A Perfect Storm
Teating coronary artery blockages and peripheral artery disease (PAD) is becoming easier thanks to a new technology known as excimer or "cool" laser ablation. This minimally invasive laser ablation system, which is also currently being used for lasik eye surgery, restores blood flow to the legs and feet of PAD patients and can help prevent amputation in a number of cases. For patients having a heart attack, it also offers a better way of removing clots in coronary arteries.
"This procedure is used most for patients with chronic limb ischemia who have blockage below the knee that causes black toe or a non-healing wound," says Robert E. Foster, M.D., FACC, an interventional cardiologist with Birmingham Heart Clinic, P.C. "We've never had anything good to use for treating blockage below the knee. With this system, we run the laser down one of the three arteries in the foot to open them up. This salvages the limb. We've had great results, and wounds that haven't healed for months will heal in three to four weeks."
Patients who have complete blockages of the femoral artery are also benefiting from cool laser ablation. In the past, these patients required femoral artery bypass surgery. "The problem with bypass surgery is that the grafts don't stay open, so they will probably need the surgery more than once," Foster says. "The patients are already high-risk surgical patients and their risk for a stroke or heart attack increases while recovering from the bypass procedure. Treatment with cool laser ablation is a much lower risk for them."
Foster points out that the cool laser is also effective for clearing clots in coronary arteries in heart attack patients. "If the patient has a large clot, the laser is a good tool to use because it vaporizes the clot, which prevents any broken pieces of plaque from traveling downstream and clogging other vessels," he says. "We clear the clot with the laser and then put in stents if necessary." Foster says drug-eluting stents can re-narrow in about 3 percent of patients. "In the past, we had no good way to clean out the stents when this happened. This laser allows us to remove the scar tissue that forms in the stent."
What makes the excimer laser so effective is its ability to destroy the damaging arterial plaque. The laser produces pulsed bursts of ultraviolet light energy that are capable of ablating or vaporizing plaque and calcium into tiny particles that are easily absorbed into the blood stream. This energy is transmitted along flexible glass fibers encased in catheters which are passed through arteries and veins. The ultraviolet light energy is then focused on the blockages that need to be treated.
Prior to the laser technology, balloon angioplasty was required to push aside blockage from a vessel. The balloon often tore the vessel and injured the artery, which stimulates the artery to re-narrow, Foster says. "With the laser we can clean out the artery without the deep tissue injury. Often we can get by without using a stent when the blockage is below the hips. The femoral artery has a high healing rate so there is no stent for use there that has a re-narrowing rate less than 40 percent."
Because the laser therapy significantly reduces the chance of injuring an affected vessel, the procedure can be used more than once if necessary in most patients. "After we open an artery in a PAD patient, we have a maintenance program where we measure blood pressure in the ankles at one month, three months, six months and one year following the ablation," Foster says. "If we see the pressure is falling, we can go back in and clean the artery again which maintains patency and prevents sudden complete closure due to clot formation."
Foster and his colleagues have performed hundreds of procedures with this new laser technology. As a result, the Spectranetics Corporation – manufacturer of the only excimer laser approved for use in the United States, Europe and Japan in multiple, minimally invasive cardiovascular procedures – recently designated Birmingham Heart Clinic as a Center of Excellence in Excimer Laser Ablation Therapy. In addition, Foster and three other Birmingham Heart Clinic cardiologists – Michael Simpson, M.D., Brian Snoddy, M.D., and James Trimm, M.D. – were recognized as national leaders and a Center of Excellence for Coronary and Peripheral Laser Ablation Therapy.
"Spectranetics selects a group that has embraced the technology, uses it appropriately, and has become a training site. We have trained physicians from all over the country to use the laser," Foster says. "In the field of cardiology, technology is growing so fast. You learn about new devices by reading information and when you're ready to purchase the tool, you go somewhere to learn to use it. Our group practices in an area with high volume and we have developed enough experience and skills to become trainers for this laser technology."
Beginning in February, Birmingham Heart Clinic physicians will conduct official workshops for cardiologists from all over the nation. Training will include lectures on the physics of the laser and actual case studies.
For cleaning blood vessels, Foster thinks laser technology is here to stay. "When you look at the treatments for what we have for complex peripheral disease, there's nothing better than laser ablation out there right now," he says. "If drug-eluting stents are developed for use in the legs, that would better than what he have today, but we would still be putting a foreign body into the patient. If we can avoid using foreign bodies such as stents, that would be even better. We're looking for that magic bullet that will cause plaque regression, but until we have that, we are stuck with fixing clogged arteries and right now this laser technology is the best tool we have."