INTRAARTERIAL INFUSION OF HIGH-CONCENTRATION PAPAVERINE DAMAGES CEREBRAL-ARTERIES IN RATS

PURPOSE: To determine the appropriate concentration of papaverine for therapeutic intraarterial infusion against cerebral vasospasm. METHODS : We investigated histopathologic changes in cerebral arteries and bra in tissue of normal Wistar rats that had received infusions of papaver ine via the carotid artery. Rats were infused with 0.20 mt papaverine (concentration, 0.4% to 4.0%) via the internal carotid artery, Injury to the vascular wall was evaluated by transmission electron microscopy ; pathologic changes in cerebral tissue were studied by light microsco py. RESULTS: Neither brain necrosis nor brain edema was seen under lig ht microscopy at any concentration, At 4.0% papaverine concentration, degeneration of endothelial cells and medial smooth muscle, including vacuole formation, was observed under electron microscopy. At 1.4% con centration, degeneration of endothelial cells was seen. Extravasation of Evans blue dye was noted when drug concentration exceeded 1.4%. At 0.8% concentration, no histopathologic change was noted, CONCLUSION: O n the basis of these results, we recommend a papaverine concentration of 0.8% or less for intraarterial infusion.