Advanced Endovascular Abdominal Aortic Aneurysm Repair: Recent Developments

schmieder_112x127By Frank Schmieder, MD, FACS
Over the past decade, endovascular repair of abdominal aortic aneurysm has become an increasingly viable option for patients who should avoid the risks of open surgery. Open repair of abdominal aortic aneurysm has a perioperative mortality rate of 3 to 4.8 percent, compared with 0.5 to 1.8 percent for endovascular repair, although long-term mortality appears to be similar.1 Some endovascular repairs can now be accomplished with no traditional incisions at all: at Temple, we perform approximately 80 percent of infrarenal aortic aneurysm repairs using a catheter inserted via a needle (percutaneous endovascular repair, PEVAR), with nearly 100 percent technical success. This total percutaneous approach has also been shown to work well for thoracic2 aneurysm repair, although there is a learning curve.

Juxtarenal aneurysm repair is advancing quickly, with complex repairs now possible using a modular endovascular approach (although branch artery occlusion, especially of the renal arteries, remains a concern).

“Chimney” or “snorkel” grafts maintain perfusion to side vessels that would otherwise be occluded by the proximal or distal end of a conventional graft (see Figure 1). However, they also create greater potential for endoleaks, as the main stent no longer adheres completely to the aortic wall. This risk increases when a larger number of snorkel/chimney stents are deployed. There are no available stents created solely for use in snorkel/chimney repairs, and the sharp bend that may be necessary to channel the snorkel stent into a side artery means these stents are prone to kinking or compression, which may block blood flow.

Newer fenestrated or scalloped grafts (with windows positioned at the locations of side branches) allow perfusion to celiac or other arteries while also providing an opening for placement of side stents (see Figure 2). Currently, these fenestrated grafts must be custom designed; however, some manufacturers are working on modular, off-the-shelf models. If successful, this will remove the several-week wait time that currently places too many patients at further risk of aneurysmal rupture.

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Figure 1: “Snorkel” grafting technique permitting placement of a standard thoracoabdominal stent graft and simultaneously allowing blood flow to the renal arteries.
Figure 2: Fenestrated graft with side stents to renal arteries.
Figure 2: Fenestrated graft with side stents to renal arteries.
1 Schanzer, A., and Messina, L. (2012). Two Decades of Endovascular Abdominal Aortic Aneurysm Repair: Enormous Progress With Serious Lessons Learned. J Am Heart Assoc. 1 (3): e000075.
2 Bell, M.T., et al. (2014). Thoracic Endovascular Aortic Repair Using the Percutaneous Technique or Open Exposure: A Comparison of Early Outcomes. Presentation to The International Society for Minimally Invasive Cardiothoracic Surgery Annual Scientific Meeting, May 29, 2014.