June 17, 2025
Mayo Clinic vascular surgeons are modifying endografts to make endovascular aneurysm repair (EVAR) possible for thoracoabdominal aortic aneurysms (TAAAs) requiring timely treatment. Standardized tube and fenestrated endografts cannot accommodate the varied anatomy of the thoracoabdominal aorta, and the planning and manufacturing of custom-made stents can take several weeks or months. EVAR performed with physician-modified endografts (PMEG) provides a less invasive option for patients needing urgent or complex aneurysm repair or both.
"Repairs within the thoracoabdominal aorta are challenging due to anatomic variability of aortic and visceral branches," says Young M. Erben, M.D., a vascular surgeon at Mayo Clinic in Jacksonville, Florida. "Our vascular surgery team decided that the next frontier is finding a way to treat patients with thoracoabdominal aneurysms without open surgical repair. That's where physician-modified endografts come into play."
Limitations of off-the-shelf fenestrated stent-grafts
Complex aortic aneurysms, such as those that develop in the thoracoabdominal space, are traditionally repaired using open surgery. EVAR offers reduced operative time, length of hospital stay, morbidity and mortality compared with open surgical repair. However, TAAAs require a stent that perfectly aligns with critical arteries.
Currently, the only fenestrated device approved by the U.S. Food and Drug Administration (FDA) has significant anatomical constraints. It is designed with a maximum of two fenestrations and a scallop and is indicated for patients with short-necked abdominal aortic aneurysms. "Since there is no standardized, FDA-approved device available to treat aneurysms located in the thoracoabdominal aorta, our team of three vascular surgeons plans for the location of the patient's vessels and modifies a standard endograft to fit their anatomy," says Dr. Erben.
Addressing the complexities associated with PMEG for thoracoabdominal aortic aneurysms
Modifying an endograft requires meticulous planning, but only after ensuring that PMEG is indicated. The vascular team considers the complexity of the aneurysm and the patient's age, anatomy and health.
If PMEG is a good option, Dr. Erben says that achieving optimal patient outcomes with PMEG requires:
- Close collaboration with other specialists.
- Meticulous planning.
- Advanced imaging before, during and after EVAR.
- Comprehensive postoperative support.
Close collaboration with other specialists
The vascular surgeons at Mayo Clinic work as a team to modify and place the endograft. The modification process and procedure require surgical expertise and an understanding of all aspects of complex aortic aneurysms.
Vascular surgeons also have access to a team of specialists, including:
- Anesthesiologists trained to manage high-risk cardiothoracic operations.
- Cardiac surgeons, whose expertise is critical when the aneurysm involves the ascending aorta or requires a staged operation.
- Genetics experts, if the patient has congenital aortopathy or early-onset aneurysm that suggests a hereditary condition.
- ICU team, since repairs using a modified endograft require recovery protocols that differ from those for standard endograft repair.
- Radiologists who perform the advanced imaging necessary for PMEG.
Meticulous planning
Dr. Erben and her surgical colleagues work together on every PMEG. They examine a 3D reconstruction, precisely measure how the vessels come up from the midline and oversize the graft by 20% to ensure a snug fit that minimizes gutter.
"The anatomical assessment of the aneurysm is key so that when you open the endograft inside the vessel, it's going to line up with the fenestrations in that specific patient," says Dr. Erben.
Advanced imaging before and during EVAR
Advanced imaging of the aorta is critical during the planning stage. CT angiography (CTA) gated for vessel imaging reduces motion and improves image quality. The surgeons use those images to take precise measurements that guide the endograft modification. They also rely on advanced imaging during the procedure.
"Intraoperatively, we mount the 3D reconstruction on live fluoroscopy, so we can precisely calculate where the vessels are," says Dr. Erben. The real-time visualization of anatomical structures during the procedure helps with guidance and accuracy. "This technique helps to reduce radiation exposure and decrease the amount of contrast needed to find those vessels."
Comprehensive postoperative support
Postoperative care following a TAAA repair with a modified endograft differs from care after a standard endograft repair. Patients receiving a PMEG require intensive care and close monitoring to ensure blood circulates to the lower extremities. Some patients undergoing PMEG may need a spinal drain and require specialized postoperative care.
"You need to have the necessary support to perform these operations," says Dr. Erben. "EVAR is less invasive than open surgical repair, but PMEG for thoracoabdominal aortic aneurysms is still a complex and high-risk procedure."
Endovascular repair also requires yearly surveillance with CT scans to ensure that the stent-graft is in place and that no endoleaks occur.
"Proper surveillance is critical," says Dr. Erben. "The care we provide patients with complex aortic aneurysms does not end when we finish the repair."
For more information
Refer a patient to Mayo Clinic.