Type:
Educational Exhibit
Keywords:
Dissection, Aneurysms, Diagnostic procedure, Computer Applications-3D, MR-Angiography, CT-Angiography, CT, Contrast agents, Arteries / Aorta, Abdomen, Ischaemia / Infarction
Authors:
A. Fuentealba1, D. Ramirez2, N. Rossel1, P. Almarza1, A. Pizarro1, M. CASTRO1, D. I. Herquinigo1; 1Santiago/CL, 2Santiago, METROPOLITANA/CL
DOI:
10.1594/ecr2018/C-3145
Background
Segmental arterial mediolysis (SAM) is an uncommon vasculopathy of unknown etiology,
not inflammatory or atherosclerotic.
SAM can presents as an aneurysm rupture with life threating abdominal,
retroperitoneal or intracraneal hemorrhage,
resulting in end organ ischemia.
Common symptoms include abdominal pain,
shock,
or neurologic symptoms. It develops most commonly in middle and old age people with no gender preponderance.
Segmental arterial mediolysis commonly affects the large branches of the aorta,
such as celiac trunk,
superior mesenteric artery (SMA),
inferior and renal arteries.
Intracraneal arteries can also be involved.
Also multiple vessels can be affected through the body in different time frames.
Multiple parts of a simple artery may be affected causing the "segmental" and skip patterns.
The pathology of SAM appears to be a dynamic process consisting in two phases:
- The initial injurious phase
- The reparative phase
Mediolysis involves varying sized vacuolar degenerations and lysis within the smooth muscle in the outer media of the arterial wall,
leading to tear and separation of the outer medial muscle from the adventitia layer.
This process may involve only a part of the arterial circumference or its enterity,
showing segmental distribution and leaving normal arterial segments between.
The blood between the gaps loosen the arterial wall and render it more susceptible to dissection and aneurysm, stenosis,
occlusion and aneurysm formation. Any of these vascular lesions can concurrently develop in a patient.