Segmental arterial mediolysis (SAM), an uncommon arteriopathy putatively caused by norepinephrine released by alpha-1 adrenergic agonists or some Beta-2 agonists capable of
releasing norepinephrine from the peripheral
sympathetic nervous system potentially can present ischemic and organ
injury symptoms caused by sequelae created in its reparative phase in lieu of
catastrophic hemorrhages announced in its injurious phase. The case documents
this presentation—the patient presenting renal
infarcts and ischemic lesions causing abdominal angina, hypertension and
a nephrectomy event developing 10 years after prolonged ritodrine treatment for
premature labor. This agent may have directly caused SAM or sensitized the patient
to agonists causing SAM encountered at a latter date. A variety of lesions
derived from injurious phase arterial injuries characterize reparative phase
SAM. All were encountered in a hilar branch of the resected renal artery. These
included side-by-side sequela aneurysms grossly forming a large fusiform
aneurysm, granulation tissue filling adventitial medial tear spaces in which a
dissecting hematomas developed, medial muscle loss centered to the outer media
repaired with fibrous tissue, arterial stenosis created by reparative intimal
plaques, and arterial thrombo-embolism. These lesions were mirrored in
accompanying radiologic studies. The accompanying renal vein exhibited changes
consistent with repair of the spastic venous angiopathy that often accompanies
abdominal SAM. This angiopathy, putatively induced by Endothelin-1, suggested
that this agent played a role in the genesis of the arterial lesions. Angiographic
resolution of non-treated sequelae occurred in 5 months either spontaneously or
due to treatment with bosentem. Conclusions:
The histologic and angiographic changes demonstrate that the clinical
onset of reparative SAM may be significantly delayed to produce ischemic
lesions, renal infarction and in this case report, medial fibromuscular
dysplasia in the hilar branch of the renal artery.
Cite this paper
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