Differences in vasodilatory capacity and changes in cerebral blood flow induced by acetazolamide in patients with cerebrovascular disease.

UNLABELLED: To investigate changes in cerebral blood flow (CBF) and blood volume induced by acetazolamide (ACZ) in patients with a variable autoregulatory status responding to reduced perfusion pressure, PET measurements of hemodynamic parameters were performed on patients with cerebrovascular disease, and the relationships between the parameters were evaluated. METHODS: Sixteen patients with unilateral major cerebral arterial occlusive disease underwent PET studies with (15)O-gas and the steady-state method to obtain hemodynamic parameters in the brain. All patients and 8 healthy volunteers underwent H(2)(15)O PET at baseline and 10 min after ACZ injection to calculate the CBF and arterial-to-capillary blood volume (V(0)) based on a 2-compartment model. RESULTS: The regional CBF (rCBF) and V(0) increased significantly after ACZ administration in volunteers and in the hemisphere contralateral to the ischemic side in patients. However, in a subgroup of patients with disease who showed a significant reduction in the rCBF increase in the ipsilateral hemisphere, the ACZ challenge caused a decrease in the rCBF even though the V(0) showed a significant increase. The reduction in the rCBF increase was associated with an asymmetric increase in oxygen extraction fraction (OEF) but not with an absolute OEF increase. CONCLUSION: The increases in rCBF and V(0) induced by ACZ administration, as well as absolute OEF value in the baseline condition, did not necessarily parallel each other in the ipsilateral hemispheres of patients. Thus, the increase in rCBF after ACZ challenge may not represent vasodilatory capacity in patients with cerebrovascular disease, especially in the regions with a reduced rCBF response.