Extension TEVAR and Fenestration of the Dissection Flap Across the Visceral Plate in a Patient with Type B Dissection

The patient was a sixty-one-year-old man with a medical history of coronary artery disease, STEMI treated with a drug-eluting stent in 2014, an abdominal aortic aneurysm, an aortic root aneurysm, and trace aortic insufficiency. In March 2012, the patient suffered a type B aortic dissection with compromise of his superior mesenteric artery, causing mesenteric ischemia. He underwent right common iliac to SMA bypass for treatment. He was followed by vascular surgery since that time.

In May 2022, the patient’s imaging showed aneurysmal degeneration of the distal arch and proximal descending thoracic aneurysm that warranted surgical intervention. A prior bypass graft between the SMA and right common iliac artery appeared to be occluded. He underwent full arch replacement, frozen elephant trunk, bypass of innominate, left common carotid, and left subclavian on August 20, 2022. The antegrade thoracic endovascular aortic repair (TEVAR) was intentionally landed in the false lumen, as the true lumen appeared to be healed closed. A computed tomography angiography in September 2022 showed persistent opacification of the false lumen of the type B dissection. Thereafter, the patient was scheduled for extension TEVAR.

The stent did not have apposition to the wall, so it had to be extended. Celiac was off of the false lumen and SMA was off of the true lumen, which was occluded proximally. Based upon the scan, surgeons felt that the true lumen was occluded halfway through the thorax, so extension intentionally into the false lumen would not change the perfusion. Therefore, the frozen elephant trunk was extended with two stents. An angiogram was performed after demonstrating good apposition distally and the primary goal was achieved.

A completion angiography demonstrated no endoleaks, but the flow into the SMA was sluggish. Given that the SMA was off of the true lumen that was occluded proximally, this delayed filling was most likely from the patient’s distal vasculature. At this time, a repeat IVUS showed that there were dynamic changes with the patient’s visceral blood flow related to changes in the false lumen pressurization, especially as many of these vessels contained dissections into their orifices and as such were dynamically dependent on flow from the false lumen. The combination of the slow filling plus the knowledge that the SMA bypass was no longer open led to the decision to fenestrate the dissection flap in that moment rather than wait to establish better flow into the SMA. The surgeons spent a significant time trying to cross into the true lumen unsuccessfully.

Finally, a Pioneer Plus catheter was used to cross from the false to true lumen in the left common iliac and advanced proximally to where the true lumen narrowed, just below the Thoraflex graft and across the flap into the stented false lumen. Subsequently, a grand slam wire was advanced into the false lumen and felt distally down the aorta. From the left groin, an ensnare catheter was delivered through the false lumen to capture the grand slam wire crossing the septum into the false lumen. Finally, the Pioneer Plus catheter and the ensnare catheter were both pulled back and the septum was sliced by the grand slam wire down to the iliac bifurcation. Repeat angiogram showed improved flow into the SMA. The celiac artery and both renals had good flow as well. At this point, all wires, catheters, and sheaths were removed, and ProGlides were deployed for closure.

Convalescence thereafter was uncomplicated. The patient was discharged on postoperative day six. One month after surgery, the patient was doing well. The patient had had bowel urgency since his type B dissection and reported resolution of his bowel urgency since this most recent surgery. In retrospect, his prior bowel urgency was likely the result of chronic mesenteric ischemia. A CTA demonstrated development of type II endoleak, increase in extension of dissection flap to the proximal left renal, bilateral common femoral arteries, left internal iliac artery, and markedly improved caliber of the true lumen. SMA was perfused nicely.

In conclusion, residual dissections are not infrequently in need of intervention. It is not easy to understand the status of true and false lumen. Dissections are unpredictable; thus, surgeons need to be ready to evaluate and act upon changes in perfusion secondary to the procedure. Lastly, further intraoperative interventions may be required to optimize perfusion.

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