Effect of Intracarotid Papaverine on Human Cerebral Blood Flow and Vascular Resistance During Acute Hemispheric Arterial Hypotension

Abstract

Summary:

This study assessed the feasibility of augmenting cerebral blood flow (CBF) and decreasing hemispheric cerebrovascular resistance (CVR) by intracarotid papaverine during acute cerebral hypotension. Awake patients (n = 10) undergoing transfemoral balloon occlusion of an internal carotid artery (ICA) with nitroprusside (SNP)-induced systemic hypotension (10% reduction of mean arterial pressure) were studied. We measured mean femoral artery pressure (MAP), mean distal ICA pressure (P ica), and CBF (intracarotid 133Xe) at two time points: before and after intracarotid papaverine infusion (1 or 7 mg/min). Two patients became symptomatic immediately after ICA occlusion and were excluded. One patient developed a focal seizure during papaverine infusion. In another, the occlusion balloon deflated prematurely. Of the remaining six patients, two of the three patients who received high-dose papaverine (7 mg/min) developed transient obtundation. The remaining three patients, who received low-dose papaverine (1 mg/min), did not develop any neurologic symptoms. There was a trend for intracarotid papaverine to increase hemispheric CBF by 36% (33 ± 10 versus 45 ± 22 ml · 100 g−1 · min−1, P = .084, n = 6); papaverine decreased CVR from 1.3 ± 0.4 to 1.0 ± 0.3 mm Hg · ml−1 · 100 g−1 · min−1 (P = .049). There was no significant change in heart rate, MAP, or P ica during experimental protocol. Manipulation of CVR by intracarotid papaverine during acute hemispheric arterial hypotension appears to be feasible. Further studies are needed to establish safety and efficacy.