Evaluating endothelial function of the common carotid artery: an in vivo human model

Background and aims: Flow mediated dilation (FMD) of peripheral conduit arteries is a well-established tool. to evaluate endothelial function. The aims of this study are to apply the FMD model to cerebral circulation by using acetazolamide (ACZ)-induced intracranial vasodilation as a stimulus to increase common carotid artery (CCA) diameter in response to a Local increase of blood flow velocity (BFV). Methods and results: In 15 healthy subjects, CCA end-diastolic diameter and BFV, middle cerebral artery (MCA) BFV and mean arterial blood pressure (MBP) were measured at basal conditions, after an intravenous bolus of 1 g ACZ, and after placebo (saline) sublingual administration at the 15th and 20th minute. In a separate session, the same parameters were evaluated after placebo (saline) infusion instead of ACZ and after 10 mu g/m(2) bs and 300 mu g of glyceryl trinitrate (GTN), administered sublingually, at the 15th and 20th minute, respectively. After ACZ bolus, there was a 35% maximal MCA mean BFV increment (14th minute), together with a 22% increase of mean CCA end-diastolic BFV and a CCA diameter increment of 3.9% at the 3rd minute (p = 0.024). There were no MBP significant variations up to the 15th minute (p = 0.35). After GTN administration, there was a significant increment in CCA diameter (p < 0.00001). Conclusions: ACZ causes a detectable CCA dilation in healthy individuals concomitantly with an increase in BFV. Upon demonstration that this phenomenon is endothelium dependent, this experimental model might become a valuable tool. to assess endothelial function in the carotid artery.