Midterm Results with the Open Chimney Technique during Endovascular Aneurysm Repair

To report the midterm experience with chimney-endovascular aneurysm repair (Ch-EVAR) with the use of open self-expending stents for branch vessel preservation.

From July 2010 to May 2017, 67 patients underwent open Ch-EVAR because their proximal landing zones were adjacent to, or covered, the renal or mesenteric arteries (Zones 7-9), and they were not suitable for standard or fenestrated endovascular aneurysm repair. The proximal landing zone was relocated below the highest renal artery in 46 cases, the superior mesenteric artery in 17 cases, and the celiac artery in 4 cases, using 84 open chimneys (131 stents). A subgroup analysis was performed between an early (2010-2014) and a later (2015-2017) time period. Thirty-two patients were treated during the early period, and 35 were treated during the later period. In the later period, open chimneys were strengthened by a second self-expanding stent.

The primary technical success rate was 89.6%; the early mortality rate was 9.0%; and the median follow-up duration was 13 months (range, 1-76 months). The estimated actuarial survival rate was 85.7% in year 1 and 79.2% in year 2, and the estimated patency rate of open chimneys reached 95.2% at 2 years. Aneurysm sac regression >5 mm and sac stability rates were 39.0% and 57.6%, respectively. Freedom from aneurysm-related reintervention was lower in the later period (log-rank P = .04), while type Ia endoleaks tended to be twice as likely.

Midterm results of open Ch-EVAR show high technical success with acceptable midterm patency and lack of endoleak in appropriately selected patients. The advantages over covered stents are lower-profile delivery systems and maintenance of branch vessel patency in early bifurcations and overlying visceral vessels.