Known nationally as a leader in cardiovascular care, Baystate Medical Center was one of only 30 institutions in the U.S. and Europe invited to take part in an important trial seeking Food and Drug Administration (FDA) approval for a new technology to treat aortic disease, a novel device that could benefit a wider group of patients, say the hospital’s vascular surgeons.
Led by Dr. Neal Hadro, interim chief, Vascular Surgery, Baystate Heart & Vascular Program, the hospital’s team successfully used the device, known as Nellix, on five patients with abdominal aortic aneurysms as part of the trial in the summer and fall of 2014. Dr. Hadro and his staff are now sharing the results of the new endograft procedure with the FDA while they continue to monitor the progress of the patients who underwent the procedure.
How it Works
Put simply, the device seals an aneurysm with a conformable polymer-filled bag in order to prevent blood leakage. Other contemporary grafts bridge across a weak spot.
“This long awaited innovation holds great promise for a wider population of patients who can be treated, a more durable result, less radiation exposure, and a safer and faster procedure,” Dr. Hadro said.
Dr. Hadro and fellow vascular surgeon Dr. Marc Norris agreed that Baystate’s high-volume practice, with the modern skills of newly hired physicians, excellent outcomes and state-of-the-art hybrid operating rooms, made the program a natural choice to test out the device. The trial, which involved 180 patients overall, is officially closed, but the vascular team continues to enroll patients in a registry and collect data on the results.
Since the aorta is the major blood vessel that supplies blood to the body, patients who develop an enlarged area in the lower part of the aorta—an abdominal aortic aneurysm—run the risk of it rupturing and causing life-threatening bleeding if it is not treated.
For more than 20 years, minimally invasive endovascular aneurysm repair has served as another option to open surgery, especially for high-risk patients. Nellix is designed as an alternative to endovascular stent grafts.
Before Nellix, getting a successful stent graft involved achieving fixation, which was a challenge. Once inserted into the aorta, the stent didn’t migrate.
“But you also need a seal so the blood doesn’t leak around the attachment points and continue to pressurize the sac and make it expand,” Dr. Hadro said.
In the Nellix procedure, two parallel stents, a combination of metal and a Gore-Tex wrap, are placed in the aorta. Inflatable bags are blown up around the two stents with polymer, which fills the space so it custom fits inside the aorta and the polymer solidifies. In effect, an internal cast is created to seal the aneurysm.
“With this construction, it can’t migrate or leak around it. You’re really not limited by the anatomic restrictions of a traditional graft,” Dr. Hadro said.
Dr. Norris says their hope is that the procedure will decrease an issue that affects approximately 20 percent of their patients who experience persistent flow in the aneurysm sac after the endograft repair, which can lead to further growth of the aneurysm and risk rupture.
A problem with other treatments for abdominal aortic aneurysm is that small branch arteries that come off the aorta can back-bleed into the aneurysm sac and continue to pressurize it in what’s known as a Type 2 endoleak.
“The Nellix graft more effectively seals these endoleaks and will hopefully prevent further aneurysm growth in these 20 percent of patients,” Dr. Norris said. “Over time, this will limit the number of ultrasounds and CT scans that these patients require for more intensive monitoring.”
Treatments for Aortic Dissection
At Baystate, the vascular surgery team members’ knowledge and use of stent graft technology over time has allowed them to expand treatment to areas of aortic pathology, which previously only came in the form of medicine or surgery, such as aortic dissection, says Dr. Norris.
In aortic dissection, the aorta spontaneously develops a small tear in the inner lining, usually due to high blood pressure, or in certain cases of connective tissue disorders. The tear can propagate and cause severe pain and become life-threatening.
“As we’ve added more advanced imaging in our new hybrid operating rooms, along with intravascular ultrasound, we are now able to more effectively treat many of these cases with endovascular stents,” Dr. Norris said. “In our center, vascular and cardiac surgeons work together to treat these problems, which can sometimes be complicated.”
New data suggests that Baystate’s vascular surgeons will likely be placing stent grafts early in those patients. The vascular team’s collaboration with cardiothoracic surgery and newly hired endovascular specialists, and the recent addition of equipment that can be used to perform ultrasound inside the artery, are key foundational elements to developing a successful all-encompassing program.
Fenestrated Stent Graft
While Nellix presents a whole different platform for treating aneurysms, there is another option used at Baystate for appropriate patients. That option involves a fenestrated stent graft, which is used for complicated aortic pathology that cannot be treated by standard “off-the-shelf” grafts.
These custom built grafts have specifically located “windows” to maintain blood flow to branch vessels as the graft is extended above the segment of abdominal aorta with branches to the kidneys and bowel.
This further increases the number of less-invasive treatment options for patients who previously required a major open surgery with a high rate of complications for aneurysm repair.
“Because of our success rates, our volume, and the level of expertise offered by our providers, we have developed relationships with industry leaders and are able to be on the forefront of evaluating and offering the latest technology,” Dr. Hadro said.