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Segmental arterial mediolysis-an iatrogenic vascular disorder induced by ractopamine.
MedLine Citation:
PMID:  22036070     Owner:  NLM     Status:  Publisher    
BACKGROUND: Segmental arterial mediolysis, an uncommon arterial disorder most often occurring in the splanchnic muscular arteries of the abdomen, is a cause of catastrophic hemorrhages. Its histology and initial clinical presentations suggested that it represented a localized norepinephrine-induced vasospastic response to perturbations in vascular tone and blood volume distribution caused by coexisting vasoconstrictor conditions. However, later presentations were at odds with some aspects of this hypothesis. METHODS: Nine greyhound dogs were administered a single dose of ractopamine. Two dogs developing persistent conduction abnormalities with biochemical evidence of heart injury were euthanized and necropsied-one 4 days and the other 17 days after dosage This report is based on findings and comparisons of the canine abdominal and coronary arteries to segmental arterial mediolysis. RESULTS: Lesions having features of early-injurious-stage segmental arterial mediolysis were identified in the canine arteries 4 days postractopamine, and arteries examined after 17 days showed alterations typically occurring in reparative-stage segmental arterial mediolysis. It is suspected that ractopamine, a Beta-2 adrenergic agonist, created segmental arterial mediolysis by neuromodulating the peripheral sympathetic nervous system to release norepinephrine from varicosities of efferent nerves serving splanchnic arteries that stimulate alpha-1 receptors to induce injury at the adventitial medial junction and medial muscle apoptosis. CONCLUSION: This finding and other cited examples suggest that segmental arterial mediolysis may be a disorder principally caused by iatrogenic or accidental exposure to alpha-1 adrenergic receptor agonists or Beta-2 agonists able to release norepinephrine from the peripheral nervous system.
Richard E Slavin; Micheal J Yaeger
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-10-27
Journal Detail:
Title:  Cardiovascular pathology : the official journal of the Society for Cardiovascular Pathology     Volume:  -     ISSN:  1879-1336     ISO Abbreviation:  -     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-10-31     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9212060     Medline TA:  Cardiovasc Pathol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Elsevier Inc. All rights reserved.
Cascade Pathology Group, Legacy Emanuel Hospital and Health Center, Portland, OR.
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