Hex Induced segmental arterial mediolysis superimposed upon idiopathic pulmonary hypertension; Cross-talk of Serotonin with Norepinephrine?Author(s): Richard E. Slavin
Background: Segmental arterial mediolysis (SAM) is an infrequent arteriopathy initiated by norepinephrine released by the innervating peripheral sympathetic nervous system, that involves the large and medium-sized muscular arteries of the abdomen, retroperitoneum, heart and brain base. It extremely rarely develops in pulmonary arteries. Serotonin (5-HT) is an important vasoconstricting and remodeling agent in the genesis of idiopathic pulmonary hypertension.
Methods and findings: Terror stemming from a history of a hex putatively caused a massive release of catecholamines from the adrenal medulla – the norepinephrine representing another stimulus for pulmonary vasoconstriction. Since a presumed low density of alpha-1 adrenoceptor on the medial muscle of pulmonary arteries exists the cross talk of norepinephrine with 5-HT is theorized to have caused the toxic cytoplasmic calcium overload that transformed the norepinephrine induced vasoconstriction to vasospastic SAM. This was identified by the morphologically distinct features of SAM – vacuolization and apoptosis commencing in the outer media, gap formation and granulation tissue developing at the adventitial medial junction alterations superimposed on the morphologic changes of pulmonary hypertension. Cross talk of these two pressor agents also putatively accounted for the genesis of coronary artery SAM in newborn persistent pulmonary hypertension (NPPH) reported in an infant delivered from a pregnancy depressed mother putatively administered a selective serotonin-reuptake inhibitor.
Conclusion: Cross talk of norepinephrine with 5-HT accounts for the genesis of SAM in idiopathic pulmonary hypertension and in the coronary arteries in NPPH.