Around The Bend
New clinical trial at MUSC treats complex aortic aneurysms
By Carin Moonin
The aorta is as thick as a garden hose. Over time or with pathologies such as atherosclerosis, parts of the aorta can deteriorate, creating an aneurysm—a bubble or weak spot in the hose.
When the aorta is straight, it maintains steady, even blood flow. But, it can develop bends or kinks, which makes treating aortic aneurysms difficult.
Many aortic aneurysms, especially in the abdominal area, are repaired through endovascular aneurysm repair (EVAR) instead of traditional surgery. During the procedure, a stent graft is inserted into the aneurysm through the groin to the femoral artery. This helps prevent the aneurysm from rupturing by providing an alternate channel for blood flow.
“When we use aortic stents to treat aneurysms, it has to be a nice, long, straight segment of aorta for the stent to work best,” explained Ravikumar Veeraswamy, M.D., vascular surgeon at MUSC. “The blood goes through the stent and doesn’t hit the aneurysm below it.”
But some patients don’t have a straight enough stretch of aorta for this treatment. When a typical stent is placed into a bent aorta, it can’t push up against the walls of the aorta to form a seal, so it leaks. Vascular surgeons can fix this by stapling the area to secure or change the stent’s location, but then they have to ensure it isn’t adversely affecting other areas, such as the kidneys.
“There needs to be a balance,” explained Veeraswamy. “The stent has to be strong enough to stay sealed and stay in place but flexible enough to bend.”
Bending over backwards
As part of the GORE® EXCLUDER® Conformable AAA Endoprosthesis study, MUSC will assess the safety and effectiveness of this particular stent in treating abdominal aortic aneurysms below the kidney in patients with challenging anatomy. MUSC is one of 56 centers involved in this clinical trial.
This study evaluates two types of patients who have angled aortic anatomies: those whose aorta is angled at 0 to 60 degrees and those with an aortic angle of 61 to 90 degrees. The stent is made of a combination of Gore’s proprietary ePTFE graft material as well as nickel titanium, also known as Nitino. It includes angulation control, which gives the vascular surgeon the ability to bend the device to a patient’s unique anatomy.
The procedure is performed similarly to EVAR, with a stent graft through the groin and femoral artery, and typically takes about two hours even though patients remain in the hospital overnight for observation. Veeraswamy says preliminary results show quick procedure and recovery times in participants.
“It simplifies a complex anatomy, which is a great advantage to patients,” he added. “They appreciate a fairly straightforward procedure versus having a complex and longer stay.”
Because MUSC provides tertiary care for all of South Carolina, many patients come to the Heart & Vascular Center for exceptionally challenging aortic concerns. The division as a whole cares for a wide range of vascular conditions, including diseases of the carotid and peripheral arteries as well as vascular surgery. And according to Veeraswamy, patient volumes have increased with double-digit rates of growth over the past few years.
“We are seeing more and more patients with complex problems,” he said. “And we work internally and externally with industry partners to help us meet those needs. It’s important to have clinical trials like these, because they allow us to treat complicated problems in a more effective manner.”
The division is currently carrying out additional clinical trials. They include trials for a drug-eluting stent, which would slowly release medication and treat peripheral artery disease; a stem cell trial to help grow new arteries and help with blood flow to legs; and a carotid artery disease clinical trial to understand which patients can be managed medically versus surgically.
“We are always trying to stay at the cutting edge of new technology and leveraging existing technology in very creative ways,” he said. “We’re trying to give the people of South Carolina the best care available anywhere in the country; they don’t need to travel out of the state to get state-of-the-art care.”