Complications

**Endoleaks** are classified into five types based on their source and mechanism [@svs2018]. Type I (proximal or distal attachment site) and Type III (fabric tear or component separation) endoleaks represent device failure with ongoing pressurization of the aneurysm sac and require urgent reintervention [@svs2018]. Type II endoleaks (from branch vessels such as lumbar or inferior mesenteric arteries) are common (15–25% of cases) [@evar2019] and typically managed with observation unless associated with sac growth >5 mm, in which case selective embolization may be indicated [@aburahma2019]. Type IV (graft porosity) endoleaks usually resolve spontaneously. Type V endoleaks, or endotension, describe persistent sac expansion without identifiable leak on imaging and may warrant conversion to open repair.

**Migration and limb occlusion** occur when inadequate fixation or progressive neck dilation allows device movement or when limb stenosis/kinking develops. Risk factors include short necks, severe angulation, large initial neck diameter, and lack of proximal fixation (suprarenal vs infrarenal devices). Management includes extension cuffs, relining with aortic extenders, or limb thrombectomy with adjunctive femorofemoral bypass when endovascular salvage is not feasible.

**Branch vessel occlusion** after fenestrated or branched endovascular aneurysm repair (EVAR) represents a serious complication requiring prompt recognition and intervention. Renal or mesenteric artery occlusion may present with acute kidney injury, flank pain, or abdominal symptoms. Salvage techniques include catheter-directed thrombolysis, mechanical thrombectomy, angioplasty with stenting, or open revascularization depending on the timing and extent of occlusion.

**Spinal cord ischemia (SCI)** remains the most feared complication of thoracoabdominal aortic repair, with incidence ranging from 3–15% depending on extent of coverage [@esc2014]. Prevention strategies include preoperative risk stratification, selective cerebrospinal fluid (CSF) drainage (maintain CSF pressure <10 mmHg), maintenance of mean arterial pressure >80–90 mmHg, correction of anemia (hemoglobin >10 g/dL), and revascularization of the left subclavian artery and hypogastric arteries when appropriate [@rutherford2018-rutherford].[@esvs2025]. Treatment involves immediate optimization of spinal cord perfusion through the same principles. For detailed [[TAAA]] management, see [[Thoracic and Complex Aortic Disease|Chapter 6]].

**Colonic ischemia** after aortoiliac repair results from interruption of mesenteric collateral flow, particularly when inferior mesenteric and hypogastric arteries are sacrificed simultaneously. Recognition requires high clinical suspicion with symptoms of left-sided abdominal pain, bloody diarrhea, or peritoneal signs. Early colonoscopy aids diagnosis; management ranges from supportive care for mucosal ischemia to emergent laparotomy and resection for transmural infarction.

**Access complications** include arterial dissection, occlusion, bleeding, and pseudoaneurysm formation. Prevention strategies include careful pre-procedural imaging, appropriate sheath sizing, ultrasound-guided access, and consideration of conduit placement in hostile groins. **Acute kidney injury (AKI)** occurs in 10–30% of complex aortic procedures [@oderich2017] due to contrast nephropathy, atheroembolism, or renal ischemia. Prevention includes optimization of hydration status, minimization of contrast volume, use of iso-osmolar contrast agents, and selective renal artery protection during complex repairs.