Measurement of arterial part of vascular volume ( V0) for the evaluation of hemodynamic changes in cerebrovascular disease

Abstract

Evaluation of critical hemodynamic deficiency is important for the treatment of patients with cerebrovascular disease (CVD). To investigate the hemodynamic status in the impaired cerebral circulation, changes in regional cerebral blood flow (rCBF) and blood volume induced by acetazolamide (ACZ) were measured in CVD. Twenty-five patients with unilateral major cerebral arterial occlusive disease underwent H 2 15O-PET scans at baseline and 10 min after ACZ injection to calculate rCBF and arterial-to-capillary blood volume ( V 0), as well as scans with the 15O gas steady-state method to evaluate cerebral hemodynamics. A new parameter of rCBF/ V 0 ratio, which was expected to disclose the arterial part of the perfusion pressure, was also compared. The rCBF and V 0 increased significantly after ACZ administration in the contralateral hemisphere of the patients. However, a subgroup of patients (group A) showed a significant reduction of rCBF increase in the ipsilateral hemisphere after the ACZ injection, although V 0 increased significantly. A parameter defined by the rCBF/ V 0 ratio decreased significantly in the ipsilateral hemisphere of group A after ACZ administration, whereas the ratio showed no change in the contralateral hemisphere or in the other subgroup (group B). The increase in rCBF after the ACZ challenge may not represent the vasodilatory capacity in patients with CVD, especially in the regions with a reduced rCBF response. The changes in the rCBF/ V 0 ratio after the ACZ challenge may represent an alteration in the arterial part of the cerebral perfusion pressure (CPP) that is expected to indicate a critical hemodynamic status in patients with CVD who have a reduced rCBF response.