Poster U11 - Navigating the Complexities of Type II Endoleak Reinterventions for Advancing the Treatment of Abdominal Aortic Aneurysms: A Qualitative Analysis of Expert Opinions

Introduction: Abdominal Aortic Aneurysm (AAA) is a life-threatening condition characterized by the abnormal expansion of the aorta — the primary artery that distributes oxygen-rich blood from the heart throughout the body. In the United States, AAAs are responsible for more than 1.5 million new diagnoses and 30,000 deaths per year, resulting in costs surpassing $9 billion. 80% of AAAs are treated with Endovascular Aneurysm Repair (EVAR), a minimally invasive procedure that involves placing an endograft within the aneurysm sac to shield the arterial walls from direct blood pressure and flow. EVAR is often favored over open surgery for various advantages including shortened hospital stay, decreased blood loss, and quicker associated recovery. However, it is not devoid of flaws. Annually, over a quarter of EVAR procedures fail to prevent blood from reaching the aneurysm as a result of collateral retrograde flow, defined as a type II endoleak. T his complication necessitates rigorous monitoring and often requires additional interventions to prevent aneurysm rupture. On Average, 60% of these interventions are unsuccessful, plagued by challenges such as difficulty in navigating to the leak source, inadequate vessel embolization, or migration of embolic materials leading to severe complications like spinal cord ischemia. To better understand this complex issue, interviews with vascular surgeons and interventional radiologists were conducted, aiming to delineate the benefits and limitations of various intervention strategies and identify the fundamental causes of type II endoleak and the failure of interventions.

Materials and

Methods: To investigate the efficacy and challenges of Type II endoleak interventions, a qualitative study involving in-depth, semi-structured interviews with twenty-five vascular surgeons and interventional radiologists from various medical institutions across the country were conducted. Each participant was selected based on their expertise and experience in managing AAAs through EVAR and addressing complications arising from EVAR. The interviews aimed to explore their perspectives on the advantages and disadvantages of various current intervention techniques and to uncover the underlying causes of type II endoleak, with the goal of providing insight into improved treatment solutions. The interview guide focused on several key areas: (1) Experiences with type II endoleak: "Can you describe a typical case of type II endoleak you have encountered? What were the main challenges?" (2) Intervention Techniques: "What intervention strategies have you used or would you recommend for type II endoleak? What are the pros and cons of these approaches?" (3) Root Causes: "What were the root causes of the failures in interventions for type II endoleak?" (4) Improvement Opportunities: "Based on your experience, what could be improved in current management practices for type II endoleak? What features would you like to see in a new device or method to address type II endoleak?" We then reviewed the transcribed interviews using thematic analysis to identify common themes and divergent views regarding the management of type II endoleak. This approach facilitated a comprehensive understanding of current practices and challenges, as well as the development of potential solutions based on expert opinions.

Results, Conclusions, and Discussions: As of April 2024, twenty-five interviews with vascular surgeons and interventional radiologists across the country have been completed. These discussions shed light on the significant challenges faced during type II endoleak interventions, highlighting the difficulties in accessing the endoleak nidus and the limitations of current embolic agents, emphasizing the need for innovation.

Commonly employed access approaches include transarterial, translumbar, and transcaval routes. Despite the easier endoleak nidus accessibility offered by translumbar or transcaval routes, the transarterial approach remains preferred due to its ability to concurrently target the outflow vessel, patent areas of the sac, and inflow vessel, thereby aiming for a comprehensive treatment in a single procedure. However, this approach requires the catheter to navigate through small and tortuous vascular networks, which increases the risk of intraoperative complications and extends procedural time. The translumbar approach is gaining popularity but still suffers from a high failure rate of 60% to 80%, attributable to the limited angles this approach offers to the endoleak site. Regarding the embolic agents used, participants frequently mentioned embolic liquids such as Onyx (Medtronic) and embolic coils. However, safety concerns were noted with these agents, particularly the risk of post-placement dislodgement and migration. On the efficacy front, the failure of these embolic solutions often stems from the inaccessibility of the endoleak nidus or nidus enlargement around the agent due to continued blood flow. Patient anticoagulation can also complicate the effectiveness of coils by preventing adequate thrombosis. Furthermore, the use of coils can interfere with future surveillance due to the scatter caused by metal during CT angiography, complicating monitoring of the aneurysm sac.

Numerous participants have described type II endoleak as the "Achilles' heel" and the "bane of existence" for EVAR, characterizing the intervention procedures as lengthy, tedious, and complex, often exceeding three hours. There was a prevalent call for improvement, with suggestions focusing on technological advancements that promise precise targeting of the endoleak nidus and effective occlusion of all feeding collateral vessels within one procedure. Moreover, the variability in intervention success rates for type II endoleak underscores the necessity for standardized treatment protocols.

Acknowledgements (Optional):