Device-Specific Issues With EVAR: Cook

Introduction

Since the advent of endovascular abdominal aortic aneurysm repair (EVAR) for abdominal aortic aneurysms (AAA), the rate of technical proficiency has reached impressive levels, with modern reports reaching 99%–100% of endografts successfully placed during initial treatment. However, despite technical success and exceedingly low perioperative mortality, the need for reintervention continues to be the crux of EVAR and is most often related to endograft-specific complications. Although complications may be universal to all devices, a significant proportion of devices are being used outside their instructions for use (IFU) guidelines, leading to concern for device-specific complications when used in this manner. Being aware of and knowing how to mitigate or to prevent these complications will help provide better outcomes for patients undergoing EVAR.

Although patient selection is often critical in achieving good outcomes, procedural/device-related issues can occur. Technical complications directly associated with endograft placement during EVAR include: device delivery and deployment issues; access-related complications; lack of fixation or poor sealing of the graft leading to endoleak or aneurysm expansion; stent fractures, graft material breakdown, or component separations. Despite these issues, EVAR has become the standard of care for the surgical treatment of AAA, and multiple devices share these common limitations.

Zenith endografts (Cook Medical Inc., Bloomington, Indiana), one of the most implanted endografts in the United States today, consist of a woven polyester and stainless steel main body. It is a modular, long-bodied, three-piece, self-expanding system with an active suprarenal fixation. It comes with an integrated sheath for delivery and its push-pull method of deployment allows accurate repositioning until the top cap is released. It is approved for 15-mm infrarenal necks and ≤60 degree angulation. Because it is one of the earliest and most used endografts, there is a relatively abundant amount of data on outcomes with use of this device. Here we review the complications that may arise with EVAR results associated with the use of Cook’s Zenith endografts for the treatment of AAA.

Endoleak

Early results using the Zenith AAA endovascular graft, reported in 2004 by Greenberg and colleagues , demonstrated a safe and effective treatment for AAA in both groups of patients, either deemed too high risk for open repair or those considered safe for open repair. Despite technical success being near 99% or higher for both groups, the rate of endoleak in the perioperative period was upward of 17%, the majority of perioperative endoleak being type II. On follow-up, the endoleak rate diminished to 7.4% and 5.4% at 12- and 24-months, respectively. No patient had persistent Type I or III endoleak by 24 months. This was counter-balanced by the standard risk group (for open repair) undergoing more secondary interventions, most of which were for endoleaks. Follow-up to this in 2008 for the same group concluded the long-term durability of the graft to be acceptable in both groups. However, the rate of endoleak continued to be of concern. The rate of late endoleak development (first appearing 6 months after repair and surveillance) was reported between 12% and 14%, most of which were Type II. While generally considered benign, 80% of the endoleaks attributed to causing aneurysm sac enlargement were Type II. Moreover, the majority of secondary interventions were a result of these Type II endoleaks during the study period. Notably, in either group, no Type I or III endoleak was identified at the 5-year follow-up period.

Most recently, Verzini and colleagues have reported the 14-year outcomes of patients treated with Zenith endograft for AAA in Italy. They treated 610 patients over a longer than 10-year period. Overall endoleak of any type at any time was 22.9%, 74% of which were Type II endoleaks. Endoleak of any type was attributed to 9 of the 11 conversions to open repair and 56 of the 80 patients requiring reintervention. While endoleak contributed to a large proportion of the reinterventions for these grafts, the results compare favorably in comparison with other reports, both remote and recent.