Natural History and Management Outcomes of Segmental Arterial Mediolysis
Kate X. Peng1, Victor J. Davila1, William M. Stone1, Fadi E. Shamoun1, Sailendra G. Naidu1, Robert D McBane2, Samuel R. Money1
1Mayo Clinic Arizona, Phoenix, AZ;2Mayo Clinic Rochester, Rochester, MN
Introduction
Segmental arterial mediolysis (SAM) is a poorly understood, non-atherosclerotic, non-inflammatory 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.
Methods
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 1), which excluded those diagnosed with fibromuscular dysplasia. Basic demographics, presenting symptoms, diagnostic evaluation, and outcomes were reviewed.
Results
One hundred sixteen patients were diagnosed with SAM between 2004-2014. Seventy-eight (67%) were male with a mean age of 52.5 years (range 23-90). Seventy-six (65.5%) patients presented with abdominal pain, 21 (18.1%) flank pain, 18 (15.5%) back pain, and 11 (9.5%) hematuria. Sixteen (13.8%) patients had acute hypertension and 7 (6.0%) hypotension. Thirteen (11.2%) patients presented with abdominal pain greater than 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, 2 (16.7%) ligation, and 2 (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=0.0007). Statistically significant variables associated with need for intervention included pseudoaneurysm (p=0.002) and hemorrhage (p=0.0003).
One hundred nine (94%) patients underwent serial imaging with mean follow up of 37.2 months (range=0–197.2). Nine (8.3%) patients had progression of radiologic findings and 17 (15.6%) had new findings seen in a different artery. Patients presenting with acute abdominal pain was the only statistically significant variable associated with new findings on subsequent imaging (p=0.03).
Conclusions
SAM remains an uncommon yet important disease process which 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 avoid invasive intervention. Those presenting with pseudoaneurysm and hemorrhage are more likely to fail medical management and intervention should be considered. Serial imaging is imperative to identify disease progression, especially in those patients that present with acute abdominal pain. 
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