Segmental arterial mediolysis, reparative phase: An analysis and case report showing conversion to fibromuscular dysplasia with renal infarction


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.

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Slavin, R. , Gonzalez, J. , Machin, J. , Robles, A. , Regojo, R. and Diez, M. (2014) Segmental arterial mediolysis, reparative phase: An analysis and case report showing conversion to fibromuscular dysplasia with renal infarction. World Journal of Cardiovascular Diseases, 4, 50-60. doi: 10.4236/wjcd.2014.42009.

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The authors declare no conflicts of interest.


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