Study Supports Chimney Stent Grafts to Treat Complex Aortic Aneurysms

October 16, 2013—In the International Society of Endovascular Specialists' Journal of Endovascular Therapy, Mario Lachat, MD, et al published midterm results showing a high success rate using the chimney stent graft technique and its periscope variation to treat patients with complex aortic aneurysms (2013;20:597–605).

According to the publication's press release, open repair can be risky for patients with pararenal or thoracoabdominal aneurysms. This alternative technique offers emergency treatment and another option for patients unsuitable for open surgery or branched/fenestrated stent grafts.

The chimney graft technique preserves blood flow to side branches of the aorta by deploying a stent or covered stent parallel to the main aortic stent graft. It extends upwards, like a chimney, while the periscope variation of this technique is downward facing. The chimney graft method uses commercially available stent devices rather than custom-made branched ones, allowing immediate use in emergency situations.

As summarized in the Journal of Endovascular Therapy, the investigators conducted the study to evaluate the performance of chimney and/or periscope grafts (CPGs) in the endovascular treatment of pararenal or thoracoabdominal aneurysms using off-the-shelf devices.

Between February 2002 and August 2012, 77 consecutive patients (62 men; mean age, 73 ± 9 years) experiencing pararenal aortic (n = 55), thoracoabdominal (n = 16), or arch-to-visceral-artery aneurysms (n = 6) were treated with aortic stent graft implantation requiring CPGs to maintain side branch perfusion. CPGs were planned in advance and were not used as bailout.

A standardized follow-up protocol, including CT angiography, laboratory testing, and clinical examination, was performed at 6 weeks; at 3, 6, and 12 months; and annually thereafter.

The investigators reported that technical success was achieved in 76 patients (99%); one branch stent graft became dislocated from a renal artery, which could not be re-accessed. Overall, 169 target vessels (121 renal arteries, 30 superior mesenteric arteries, 17 celiac trunks, and one inferior mesenteric artery) were addressed, with the chimney graft configuration in 111 and the periscope graft configuration in 58. In total, 228 devices were used for the CPGs: 213 Viabahn stent grafts (Gore & Associates, Flagstaff, AZ) and 15 bare metal stents.

Over a mean 25 ± 16 months (range, 1–121), nine patients died of unrelated causes. Nearly all (95%) of the patients demonstrated a decreased or stable aneurysm size on imaging; there was a mean 13% shrinkage in aneurysm diameter. Twenty patients had primary type I/III endoleaks at discharge; in follow-up, only three of these were still present (no secondary or recurrent endoleaks were noted). Additional endovascular maneuvers were required for CPG-related complications in 13 patients from intervention throughout follow-up. Overall, four CPGs occluded (98% target vessel patency); no stent graft migration was observed. Renal function remained stable in all patients.

The investigators stated that in this series, the use of CPGs has proven to be a feasible, safe, and effective way to treat thoracoabdominal and pararenal aneurysms with maintenance of blood flow to the renovisceral arteries. Approximately all of the aneurysms showed no increase in diameter over a > 2-year mean follow-up, which supports the midterm adequacy of the CPG technique as a method to effectively revascularize branch vessels with few endoleaks or branch occlusions, concluded the investigators in the Journal of Endovascular Therapy.

In an accompanying commentary, Ralf R. Kolvenbach, MD, emphasized that the length of the chimney grafts can present a challenge and that meticulous attention to detail is key to the success of this technique (2013;20:606–608). Dr. Kolvenbach noted the chimney grafts are proving to last over time, allaying initial concerns of deterioration and type III leaks. The commentary concluded that that the results so far prove the technique to be safe and effective and justify its wider use.