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Investigating Novel Endografts for Complex Aortic Disease

In This Article

  • Massachusetts General Hospital vascular and cardiac specialists are collaborating on an early feasibility trial for a novel dual-branch arch endograft to treat aortic arch pathology
  • A physician-sponsored IDE trial is also investigating fenestrated and branched endografts customized to each patient's anatomy
  • Using custom-made endografts, Mass General has successfully treated over 100 thoracoabdominal aortic aneurysm and aortic dissection patients with excellent outcomes
  • Lead investigator Matthew Eagleton, MD, in conjunction with 10 other academic medical centers with similar IDE trials, has helped form the United States Aortic Research Consortium to advance and improve endovascular therapies

Massachusetts General Hospital specialists are investigating novel endografts to treat complex aortic disease. "We have endovascular alternatives to conventional open surgery that are only available at 10 locations in the U.S.," says Matthew Eagleton, MD, chief of Vascular and Endovascular Surgery and co-director of the Fireman Vascular Center at Mass General. "We can provide patients with phenomenal outcomes in a less invasive way."

Dr. Eagleton's research pursuits include evaluating a novel arch branch device, a customized fenestrated and branched endograft, an FDA-approved abdominal aortic stent-graft system, and an investigational three-branch endograft. These less invasive procedures have the potential to reduce recovery times and improve patient outcomes.

Early Feasibility Study Examines Novel Arch Branch Device

Investigators in Mass General's multidisciplinary Thoracic Aortic Center are involved in an early feasibility trial to treat aortic arch dissections and aortic arch aneurysms with a new arch branch device that has two branches so surgeons can preserve blood flow to both the innominate and carotid arteries.

This is the first commercially available dual-branch device to enter clinical trials in the U.S. and Mass General is one of four sites involved in the early feasibility trial. "The arch branch device is exciting," says Dr. Eagleton. "If you do a single branch, then you must do a debranching operation, where you reroute blood flow to the carotid arteries and the left subclavian artery. With the dual branch, you only have to do that to one blood vessel, making it potentially less invasive."

The trial has been paused until fall 2020 to further refine the protocol and outcomes measures, based on the initial experience.

"We are looking at ways of putting in and deploying the grafts to help reduce the risk of stroke and perform procedures more safely," says Dr. Eagleton. "There have been strokes at a few sites, but the incidence has not been alarming. They are hoping to reopen the trial using different protocols and evaluations to better understand why these strokes occur and if they occur for different reasons than in conventional open surgery."

The Division of Vascular and Endovascular Surgery is working in partnership on these cases with the Cardiac Surgery team within the Corrigan Minehan Heart Center, led by co-investigator Arminder Jassar, MBBS.

"We have a lot to learn from our cardiac surgery colleagues. And they have a lot to learn from us," says Dr. Eagleton. "Each unique perspective and area of expertise makes procedures safer and helps broaden our program."

IDE Trial of Customized Fenestrated and Branched Endografts

Dr. Eagleton is conducting a physician-sponsored, investigational device exemption (IDE) trial studying custom endografts to treat aortic arch and thoracoabdominal aortic aneurysms. He brought the technology and trial to Mass General nearly two years ago. Since then, the team has treated over 100 patients with thoracoabdominal aortic aneurysms and aortic dissections that developed aneurysmal degeneration of the dissection.

"When we started doing these procedures over a decade ago, we reserved the procedures for patients who were considered unhealthy for open surgery. This was their only option," Dr. Eagleton says. "But the outcomes have been so good that the trial is open to all patients who have the disease, provided they meet certain anatomic requirements."

As part of the trial, investigators use CAT scans to help design stent-grafts with attached branches or fenestrations.

"Endovascularly, we align the fenestrations with either the vessels that come off the aortic arch or are in the visceral segment, including the superior mesenteric, celiac and renal arteries," says Dr. Eagleton.

Investigators have altered how device designs are manufactured, changed the stents used to make connections between the aortic endograft and target vessel, improved durability, decreased the profile size and examined ways to reduce spinal cord ischemia. As a result, the devices are easier to use and outcomes have significantly improved:

  • Spinal cord ischemia rates are down to less than 5% from 10%–15% originally observed with these procedures over a decade ago
  • In contrast to open surgery, most patients with significant renal dysfunction no longer require postoperative dialysis because the patency of the branches between the intestines and kidneys has significantly improved
  • Mortality rates are typically less than 3% for thoracoabdominal aortic aneurysm surgery, a severalfold improvement over national outcomes for open surgery

"Patients are returning to work, home and normal activities in a much shorter period of time," says Dr. Eagleton. "The operations are also less morbid than conventional surgery, which requires a large incision through the chest and belly. It's still major surgery, but our approach is less invasive."

Due to anatomic restrictions, Dr. Eagleton says that about 20% of patients still require conventional surgery to fix their aneurysms. The customized endografts also cannot be utilized in most acute situations or in patients with very large aneurysms because they take two months to manufacture.

Clinical Lessons Learned and Challenges

Dr. Eagleton notes that endovascular aneurysm repair (EVAR) has become the gold standard for infrarenal abdominal aortic aneurysm in the U.S., which is the result of over two decades of investigation and research. "It's taken that long to get commercially available devices, see improvements in them and broadly apply them to people with this disease."

While this evolution has led to the widespread availability of these less invasive procedures, clinicians still need to better identify the best candidates and situations to prevent failure and reintervention. Dr. Eagleton believes fenestrated and branched device development will follow a similar trajectory, predicting that "we will continue to see improvements in the devices and our application of the technology."

And to investigate these endovascular technologies with more rigor, Dr. Eagleton has helped form the United States Aortic Research Consortium with 10 other sites around the country. These facilities all have similar IDE trials underway. Consortium members pool and compare data to improve outcomes as well as endograft performance and design.

"By working together as a group, we can have a more robust database and provide information back to clinicians, patients and industry about how we can do things better," he says.

Dr. Eagleton foresees that the commercialization of these devices will be a challenge due to their level of customization. "They can't make a custom device for every patient that needs an operation. So we're looking at ways of improving our non-custom devices, so outcomes can more closely mirror those of custom-designed endografts."

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