Natural History and Management Outcomes of Segmental Arterial Mediolysis

Abstract

Segmental arterial mediolysis (SAM) is a poorly understood, nonatherosclerotic, noninflammatory disease resulting from degeneration of the arterial media. Patients may present with aneurysm, dissection, stenosis, or bleeding from visceral or renal arteries. Indications for intervention have been poorly characterized. A retrospective review of all patients with a diagnosis of SAM was undertaken at a single institution in multiple geographic locations. Patients were identified using established criteria for the diagnosis of SAM (Table), which excluded those diagnosed with fibromuscular dysplasia. Basic demographics, presenting symptoms, diagnostic evaluation, and outcomes were reviewed. Between 2004 and 2014, there were 116 patients diagnosed with SAM; 78 (67%) were male, with a mean age of 52.5 years (range, 23-90 years). There were 76 (65.5%) patients who presented with abdominal pain, 21 (18.1%) with flank pain, 18 (15.5%) with back pain, and 11 (9.5%) with hematuria; 16 (13.8%) patients had acute hypertension and 7 (6.0%) had hypotension. Thirteen (11.2%) patients presented with abdominal pain >30 days in duration. Twelve (10.3%) patients were asymptomatic. Imaging revealed dissection in 96 (82.8%) patients, aneurysm in 49 (42.2%), stenosis in 24 (20.7%), occlusion/thrombosis in 18 (15.5%), pseudoaneurysm in 12 (10.3%), hemorrhage in 9 (7.8%), and arteriovenous fistula in 1 (0.9%). Disease location was renal in 57 (49.1%) patients, celiac in 51 (44.0%), superior mesenteric in 48 (41.4%), hepatic in 23 (19.8%), splenic in 18 (15.5%), inferior mesenteric in 3 (2.6%), and pancreatic in 3 (2.6%). Forty-five (38.8%) patients demonstrated evidence of end-organ ischemia. Twenty-three (19.8%) patients underwent intervention, including 11 endovascular and 8 open interventions. Four patients underwent both open and endovascular interventions. Thirteen (86.7%) endovascular procedures involved embolization. Seven (58.3%) patients with open intervention underwent bypass grafting, two (16.7%) ligation, and two (16.7%) thrombectomy. One (8.3%) patient underwent thrombectomy with patch angioplasty. Indications included large aneurysm in 12 patients (41.4%), end-organ ischemia in 9 (31.0%), hemorrhage in 6 (20.7%), and chronic pain in 2 (6.7%). There was one perioperative death. Presence of dissection was associated with successful medical management (P = .0007). Statistically significant variables associated with need for intervention included pseudoaneurysm (P = .002) and hemorrhage (P = .0003). There were 109 (94%) patients who underwent serial imaging, with mean follow-up of 37.2 months (range, 0-197.2 months). Nine (8.3%) patients had progression of radiologic findings and 17 (15.6%) had new findings seen in a different artery. Presentation of patients with acute abdominal pain was the only statistically significant variable associated with new findings on subsequent imaging (P = .03). SAM remains an uncommon yet important disease process that may require intervention. Therefore, it is important that the vascular surgery community be aware of this disease. Patients with SAM presenting with dissection are more likely to avoid invasive intervention. Those presenting with pseudoaneurysm and hemorrhage are more likely to fail to respond to medical management, and intervention should be considered. Serial imaging is imperative to identify disease progression, especially in those patients who present with acute abdominal pain.TableCriteria for diagnosis of segmental arterial mediolysis (SAM)ClinicalExclusion of congenital predispositions for dissection (eg, Ehlers-Danlos, Loeys-Dietz, and Marfan syndromes)Exclusion of collagen vascular disease, arteritis, or fibromuscular dysplasiaAcute presentation: abdominal, flank, or back pain; hematuria, hypertension, hypotension, strokeChronic presentation: abdominal pain, hypertension, hematuriaMay also be asymptomaticRadiographicDissection, fusiform aneurysm, occlusion, beaded appearance, wall thickening of the visceral or renal arteries, organ infarctionNo contiguous aortic dissection or atherosclerosisSerologicAbsence of inflammatory markers (eg, antinuclear antibody, antineutrophil cytoplasmic antibody, complement) Open table in a new tab