In the scheme of invasive operations, the open thoracoabdominal repair is unparalleled. Even some young, healthy patients cannot tolerate the operation, and when it is attempted, mortality associated with the procedure is high.

Obviously, an endovascular approach to accomplish the same repair is vastly preferable and could revolutionize treatment for thoracoabdominal aortic aneurysm (TAAA). In an industry-sponsored clinical trial offered at a handful of centers in the U.S., University of Maryland (UM) Heart and Vascular Center surgeons and the Center for Vascular Research at the UM School of Medicine (UMSOM) are exploring the feasibility of such a solution with the GORE® EXCLUDER® Thoracoabdominal Branch Endoprosthesis (TAMBE). The TAMBE device is used to offer endovascular treatment for all types of TAAAs and pararenal aneurysms. The study will measure the percentage of uncomplicated technical success with the procedure as well as the percentage of participants who do not require significant reintervention for five years.

“If the TAMBE trial goes well, it will significantly change the way we treat thoracoabdominal aortic aneurysms,” says Shahab Toursavadkohi, MD, associate professor of surgery at UMSOM, co-director of the University of Maryland Center for Aortic Disease and the trial’s principal investigator. He and a team comprising of another vascular surgeon (Michael Hall, MD, clinical assistant professor at UMSOM) and two cardiac surgeons (Mehrdad Ghoreishi, MD, assistant professor of surgery at UMSOM, and Siamak Dahi, MD, visiting instructor at UMSOM and cardiac surgery fellow) were the first to use the TAMBE device in a patient in Maryland. They have since used it for others.

The primary arm of the multicenter study will enroll 102 patients, follow participants for five years and has an expected completion date of summer 2026. Even after the last patients are enrolled in the trial, University of Maryland cardiac and vascular surgeons will retain the ability to use the device in patients they deem ideally served by it.

Octopus-like Device Provides Sufficient Number of Perfusion Branches

“The device is complicated and very unique; we have never had a device with this type of design,” Dr. Toursavadkohi says. “It allows the surgeon to perform very morbid and complicated surgery and turn it into something very minimal,” he continues. As a vascular surgeon, he has experience in using the endovascular GORE EXCLUDER stent graft to treat abdominal aortic aneurysms. However, unlike most aortic stent grafts consisting of a single tube or even the AAA EXCLUDER’s double branched tube, the TAMBE device accounts for at least four main branches off the aorta that perfuse the liver, spleen, kidneys and stomach. To Dr. Toursavadkohi, the device “literally looks like an octopus” with each leg corresponding to a major artery.

Before surgery, patients’ aortas are 3-D imaged so the surgeons can make precise measurements of all angles and branches of the aorta. Dr. Toursavadkohi says that, in treating the first patient, he and the other surgeons spent several days analyzing these images and figuring out where all of the parts and stents of the TAMBE device would fit. Then, because such a complex device could not be compressed narrowly enough to fit through the femoral artery, the device had to be inserted, piece by piece, and assembled inside the body to complete the graft network.

In the first patient they treated, the team put in about 20 stents and fit them together inside the aorta. The expandable stents conjoin inside each other, with joints sealed through overlap and the internal pressure caused by a larger gauged stent inside a smaller one. This design precludes the need for surgeons to spend valuable operating time sewing the stents together.

“The modular system … needs to go in piece by piece, and every piece has to be precisely sized for the next one, so quite a bit of planning and sizing goes into this,” says Dr. Toursavadkohi.

For the first patient, he estimates the team spent about three times the amount of actual procedure time in planning their approach: which piece, where, through what access point – groin or upper extremity, at what angle, with which catheter or wire, etc. For hours, the surgeons and OR team practiced the procedure on a pressurized dummy model. Then, on operating day, the surgeons met the patient in the hybrid procedure room and, guided by angiography, executed their plan.

“Ultimately, the finished product is a big beautiful product, which is an aorta with multiple branches coming from every angle,” says Dr. Toursavadkohi. He points out that not a single change was made to the surgeons’ preplanning during the procedure – “an example of good planning” and “a one-hundred percent good outcome.”

Endovascular Approach to TAAA Repair More Tolerable for Patients

The TAMBE device endovascular procedure worked very well for the patient, who underwent a 4-hour operation instead of the typical 6-8 hours for open thoracoabdominal repair. Blood loss with an endovascular approach is minimal, whereas it can be 5L to 10L with an open operation. The patient’s ICU stay was only a couple of days compared to the usual week that patients undergoing the open operation spend there. The patient was also able to begin rehabilitation shortly after surgery and didn’t have the usual 4-6 week wait after a traditional thoracoabdominal procedure. Moreover, the patient had comorbidities that precluded an open approach; the endovascular TAMBE device gave the patient the opportunity to have an aortic aneurysm treatment that, more than likely, will extend the patient’s life.

TAMBE Device Gives Surgeons Another Option for Aortic Emergencies

“This was our first TAMBE, but we’ve been doing complicated branch and fenestrated stent grafts for a long time,” says Dr. Toursavadkohi. He and the UM Center for Aortic Disease team often order custom-made grafts for patients when it becomes clear they will need a repair. This process takes weeks to months. However, for patients who don’t have the luxury of time, the TAMBE device is an off-the-shelf product with several sizes of grafts that can be used in customized configurations to fit more than 9 in 10 patients.

While there will continue to be a role for open repair for thoracoabdominal aortic aneurysms, the vascular and cardiovascular surgeons at the University of Maryland Heart and Vascular Center are pleased to now have an endovascular alternative for patients with aneurysms that would otherwise be untreatable.

To refer a patient with an aortic aneurysm or dissection to the UM Center for Aortic Disease, call 410-328-4771.

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