Comparative Study of Vasodilatation After Intra-arterial Nicardipine or Dantrolene Infusion in Animal Model of Cerebral Vasospasm.

Abstract

Intra-arterial (IA) infusion of calcium channel blockers (CCBs) has been widely applied in treating medically refractory vasospasm; however, surprisingly little is known regarding their vasodilatory duration. This study was undertaken to compare attributes of nicardipine and dantrolene, focusing on efficacy and capacity for sustained vasodilation. In New Zealand white rabbits (N = 22), vasospasm was individually provoked through experimentally induced subarachnoid hemorrhage and confirmed via conventional angiography, grouping animals by IA-infused drug (nicardipine vs. dantrolene). Controls received normal saline. After chemoangioplasty, follow-up angiography was performed at intervals of 1-3 h for 6 h to compare vasospastic and dilated (i.e., treated) arterial diameters. Drug efficacy, duration of action, and changes in mean arterial pressure (relative to baseline) were analyzed by group. Compared with controls, effective vasodilation was evident in both nicardipine and dantrolene test groups after IA infusion. Vasodilatory effects of nicardipine peaked at 1 h, returning to former vasospastic states at 3 h. In dantrolene recipients, vasodilation endured longer, lasting >6 h. Only the nicardipine group showed asignificant 3‑h period of lowered blood pressure. Unlike the vasodilatory action of aCCB, sustained for < 3 h after IA infusion, the effect of dantrolene endured for > 6 h. This outcome suggests that IA dantrolene infused alone or together with aconventional CCB infusion may be anew means of prolonging vasodilatory effect. Further research is needed to assess durations of IA-infused vasodilatory drug based on perfusion status.