Week 3: IDE, FDA, and PMA!

I continued to shadow the vascular surgery team in the OR during the third week of the Immersion term. This week, I had the opportunity to observe the endovascular repair of a thoracoabdominal aortic aneurysm (TAAA). TAAAs involve the descending thoracic aorta (above diaphragm), the abdominal aorta (below diaphragm), and multiple branches of the aorta including the superior mesenteric artery (SMA), celiac artery, and the renal arteries. The complexity of these procedures is such that the endograft used to repair the aorta is designed from pre-operational CT images for the patient's unique anatomy. This endograft was designed by Dr. Schneider, and sent to a company for fabrication. The endograft designed for this patient had two fenestrations (holes) for the right/left renal arteries and two branches for the SMA and celiac artery. Fenestrations were chosen for the renal arteries due to the patient's aorta being slightly too narrow for branches. In contrast, the SMA and celiac artery had sufficient room for the branches. The patient also had an iliac aneurysm, requiring the deployment of an endograft in the iliac arteries.

The surgery itself was significantly more complex and lengthy than any of the previous surgeries I have observed. The surgery required approximately 10 hours, and involved the deployment of multiple stents and endografts to repair a very large segment of this person's aorta. Fenestrations require nearly perfect alignment of the endograft with the renal arteries because poor alignment leads to partial occlusion of the renal arteries. Balloon-expandable iCast stents were deployed within each fenestration, while self-expanding viabahn stents were deployed within the each branch. Overall, the procedure was very impressive and integrated many of the strategies I've observed in previous procedures.

This patient is involved in an aortic aneurysm trial led by Dr. Schneider, which is covered by an investigational device exemption (IDE) from the FDA. The study's goal is to assess the feasibility and safety of endovascular repair of TAAA involving the mesenteric and renal arteries in patients at high risk for open surgery using standard or physician-specified branched and fenestrated grafts. As a biomedical engineer interested in medical device design, this aspect of the procedure was particularly interesting to me. Depending on the study outcome, I anticipate the clinical study data generated will be utilized in a pre-market approval (PMA) to the FDA in support of developing this endograft as a class III device.