Phd in ANGIO-CARDIO-THORACIC PATHOPHYSIOLOGY AND IMAGING

Thesis title: THE TECHNIQUE OF “CHIMNEY NELLIX” FOR THE ENDOVASCULAR TRATMENT OF COMPLEX ABDOMINAL AORTIC ANEURISMS

OBJECTIVE The objective of this study has been to evaluate the feasibility and clinical outcomes and of the Nellix System in conjunction with parallel grafts (Ch-EVAS) for the endovascular repair of juxta-renal, para-renal and supra-renal abdominal aortic aneurysms (AAA). Definition of the pararenal pathologic processes included pararenal or juxtarenal degenerative aneurysms, aneurysms with large (>4mm in diameter) ectopic/accessory renal arteries or inferior mesenteric artery, type IA endoleaks after conventional EVAR and para-anastomotic aneurysms after open repair of AAA. METHODS Forty-three patients were included in this multicenter study. All patients were subjected to pre-operative Angio Tc and reconstructions were made for correct planning. The patients were included in a follow-up protocol that provided for ultrasound checks at discharge and after 3-6-12-24 months. Each center has associated a level II investigation such as computed contrast tomography (CTA) or contrast Magnetic Resonance (RMA). RESULTS The mean age of included 43 patients was 77.9 years and 95.3 % (n 41) of them were male in gender. Thirteen patients had a pararenal aneurysm, 7 were type IV aneurysms, 1 supra-anastomotic pseudoaneurysm and the remaining cases were reinterventions of post EVAR complications, mainly type A endoleaks. All patients were divided into two groups: Group A (48.8% patients suffering from abdominal aortic aneurysms; group B (52.2%) patients with complication after EVAR, in particular I A type endoleaks. Five patients (11.6 %) underwent CHEVAS in emergency. Immediate technical success in both groups was 100%. The chimney technique was performed on a single visceral vessel for 15 (34.9%) patients, on 2 visceral vessels in 21(48.8%) and on three visceral vessels in 7 cases (16.3%); balloon expandable stents were used for targeted chimney vessels, as they allow a more controlled positioning avoiding migration of the same. Some centers suggest the percutaneous technique through specific devices for the femoral accesses, this technique was used for 30 (69.8%) and greatly reduced surgical times. All patients underwent Angio CT or ECD follow up. During the follow-up, no migration of the Nellix endoprosthesis occurred , there was 5 cases (11.6%) of gutters with persistent type A endoleaks which required surgical conversion in 2 cases and secondary intervention using Onyx glue in 1(2.3%). Three patients (6.9%) had the occlusion of a renal artery stent while in two cases (4.6%) there was the occlusion of a Nellix stent that required fibrinolytic therapy. Fifteen (34.8%) patients had a 2-year follow up without complications, 9 of them were Group A and 6 of them were Group B. Four patients (9,3%) experimented a partial or total occlusion of a visceral stent. Twelve (27.9%) patients died for causes unrelated to ChEVAS. The procedure-related mortality was 4.6%: one patient died on the Ist post operative day and another patient died of aneurismal rupture due to a persistent endoleak I type A. CONCLUSIONS Ch-EVAS can be used successfully for the treatment of challenging AAAs involving side branches showing a high patency rate of the chimney stents and a lower risk for gutter endoleaks due to the polymer filling of the space around the stents thus reducing the need of reintervention. Our clinical results of this therapy have been promising in a challenging group of patients with complex AAA anatomy and suggest that ChEVAS and other parallel graft techniques provide an immediate off-the-shelf solution that is safe, effective, and durable in the midterm. Outcomes over extended follow-up will determine the application of this novel technique and longer term follow-up and data from the international registry such as the ChEVAS ONE IDE study are required to determine the widespread applicability and durability of this technique and to better define which patients and aneurysm morphology can be treated effectively.