Innovative Stent-Grafts Safe, Feasible for High-Risk Complex Aortic Aneurysms

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In patients with complex aortic aneurysms, the use of chimney or periscope grafting is feasible and safe while maintaining blood flow to the renovisceral arteries, according to a study published in the October 2013 issue of the Journal of Endovascular Therapy. At 2-year follow-up, most of the aneurysms decreased in diameter.

Chimney grafting refers to deploying covered stents in the renal artery to rescue an inadvertently covered renal artery orifice during aortic stent-grafting, while the periscope graft technique is similar but in a reverse fashion to extend the distal stent-graft landing zone.

Researchers led by Felice Pecoraro, MD, of the University of Palermo (Palermo, Italy), looked at 77 consecutive high-risk patients with either pararenal aortic (71.4%), thoracoabdominal (20.8%), or arch to visceral artery aneurysms (7.8%) who were treated with aortic stent-graft implantation from June 2002 to August 2012. All procedures required chimney and/or periscope grafts planned in advance and not used as bailout. Follow-up consisting of CTA, lab testing, and clinical examination was performed at 6 weeks, 3, 6, and 12 months, and annually thereafter.

Aneurysm Shrinkage with Stent-Grafts

Technical success was achieved in all but 1 patient (99%). Overall, 111 chimney grafts and 58 periscope grafts treated 169 target vessels (121 renal arteries, 30 superior mesenteric arteries, 17 celiac trunks, and 1 inferior mesenteric artery). Of the 228 devices used, 213 were Viabahn stent-grafts (WL Gore & Associates, Flagstaff, AZ) and 15 were BMS (Wallstent, Boston Scientific, Natick, MA).

The mean aneurysm diameter was 70 ± 23 mm and a mean of 3 stent-grafts were used in each patient. Mean procedure time was 248 ± 104 minutes with a mean radiation dose area product of 45,494 ± 29,022 mGy*cm². Patients stayed in the ICU for a mean of 2.2 days and in the hospital for a mean of 14 days.

Perioperative major complications included renal hematoma (n = 3) and a psoas hematoma due to an iliac rupture (n = 1). After implantation, 19 patients had primary type 1 endoleaks, with 14 having type II and 1 having a type III leak.

After 25 months of follow-up, mean aortic aneurysm diameter decreased by 13.3% to 61.1 mm. Aneurysm diameter increased in 4 patients (5.2%), but 1 had a type Ia endoleak. Only 3 of the type I/III leaks remained at 2 years, and no secondary or recurrent endoleaks were seen.

During follow-up there was no difference in renal function, and 9 patients died of unrelated causes. Additional endovascular maneuvers were required for stent-graft-related complications in 16.8% of patients. There were 4 occluded grafts (98% target vessel patency), all within 30 days.

New Treatment Options for High-Risk Patients

Chimney and periscope grafts “are an alternative way of treating these complex aneurysms and allow the use of off-the-shelf devices to treat emergency cases, patients unfit for thoracoabdominal open surgery, or patients who are not suitable for branched or fenestrated stent-grafts due to anatomical restrictions,” Dr. Pecoraro and colleagues write.

In addition, they list specific advantages for these grafts over the branched graft techniques:

• The optimal branch design can be chosen specifically for each aortic branch based on the target vessel, the remote access vessel, and the aortic anatomy, minimizing procedural delay
• Navigation and/or manipulations are greatly simplified as the wires, catheters, and parallel stent-grafts do not have to be directed through the aortic stent-graft
• Secondary stent-graft dislocation out of the aortic branch is minimized, as the grafts are fixed in between the aortic wall and the aortic stent-graft

Although the results “suggest that [chimney and periscope grafts] are a durable way of revascularizing renovisceral aortic branches involved in aneurysmal disease, the overall experience with [these grafts] is limited, and long-term follow-up is needed to document the durability of these techniques,” the authors conclude.

Attention to Detail Essential

In an accompanying editorial, Ralf R. Kolvenbach, MD, PhD, of Augusta Hospital (Duesseldorf, Germany), writes that “meticulous attention to detail is key to success” with these techniques, including selective angiography, pressure measurements, and potentially relining parallel grafts with stents when control angiography shows evidence of kinking.

Another reason for the study’s success is the use of dual antiplatelet therapy in all patients, Dr. Kolvenbach says.

“The technique described by [the authors] is ideal for ruptured aneurysms, even though a more aggressive approach toward sealing of gutters should be chosen to avoid continued bleeding from the sac or type II leaks in these emergency cases,” he writes, adding that a remarkably high number of patients were treated under local anesthesia, “which can only be accomplished with experience and a highly standardized technique.”

In a telephone interview with TCTMD, Barry T. Katzen, MD, of Baptist Cardiac and Vascular Institute (Miami, FL), said his institution primarily performs these procedures with local anesthesia, but general anesthesia might be needed in cases where more precise positioning is required to control the patient’s breathing.

Further Evaluation Warranted

The study provides the longest follow-up to date on these stent-grafts, according to Dr. Katzen. “In terms of both protecting these patients from rupture and the freedom from secondary events [the findings] are pretty good. . . . These techniques can be somewhat durable over time.”

According to Dr. Kolvenback, the early concern over deterioration of the fabric of either the aortic stent-graft or the chimney graft should no longer be an issue given the results, which also “[justify] wider use and evaluation of this technique.”

Going forward, Dr. Katzen said he would like to see chimney and periscope grafts studied in more specific groups of patients. The current cohort is “a mix of a lot of different types of pathologies, so it’s a little hard to draw conclusions about whether it’s better for one application than another,” he observed.

Study Details

The majority (80.5%) of patients were men, the mean age was 73 years, and more than half (62%) presented with multiple comorbidities.

Five commercially available stent-grafts were used:

• Excluder and TAG (WL Gore and Associates)
• Evita (Jotec, Hechingen, Germany)
• Talent (Medtronic Vascular, Santa Rosa, CA)
• Zenith (Cook Inc, Bloomington, IN)

 

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Sources:
1. Lachat M, Veith FJ, Pfammatter T, et al. Chimney and periscope grafts observed over 2 years after their use to revascularize 169 renovisceral branches in 77 patients with complex aortic aneurysms. J Endovasc Ther. 2013;20:597-605.

2. Kolvenbach RR. Chimneys are smoking hot: Midterm results of the chimney technique in the repair of pararenal and throracoabdominal aneurysms [editorial]. J Endovasc Ther. 2013;20:606-608.

 

 

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