Abstract 2941: Wide Variability of Cerebral Blood Volume Response in the Area with Impaired Cerebrovascular Reactivity to Acetazolamide due to Occlusive Carotid Artery Disease
Background and Purpose - Recent studies have suggested that hemodynamic and metabolic responses to reduced cerebral perfusion pressure (CPP) are not so simple in patients with occlusive carotid artery disease. Autoregulatory vasodilation reaches maximal and cerebral blood flow (CBF) starts to fall, when CPP critically falls beyond autoregulatory capacity. Theoretically, cerebral blood volume (CBV) is expressed as maximally elevated in the conditions that cerebrovascular reactivity (CVR) to acetazolamide (ACZ) is impaired. However, there are almost no studies that denote whether CBV is maximally elevated in the area with reduced CBF and CVR to ACZ (Kuroda’s Type 3 ischemia). Therefore, this study was aimed to investigate the CBV response to ACZ in the area with reduced CBF and CVR due to occlusive carotid artery disease.
Methods- This study included totally 24 hemispheres of 20 patients with reduced CBF and CVR on 15O-gas PET due to occlusive carotid artery disease. There were 8 men and 12 women with a mean age of 57.9 years ranging from 33 to 72 years. All of them were admitted to our hospital between 2004 and 2010. In all 20 patients, CBF, CBV, cerebral metabolic rate for oxygen (CMRO2) and oxygen extraction fraction (OEF) were quantitatively measured, using 15O-gas PET. Subsequently, ACZ was intravenously injected to determine the reactivity of CBF and CBV.
Results- Both CBF and CVR were reduced in all 24 hemispheres (Type 3). Of these, OEF was elevated in 7 hemispheres (29%). Compared with normal control (3.4 ± 0.5 mL/100g), baseline CBV were significantly elevated both in elevated OEF group (5.2 ± 1.2 mL/100g) and normal OEF group (4.5 ± 0.9 mL/100g). Intravenous administration of ACZ further increased CBV in 4 of 7 hemispheres with elevated OEF and in all 17 hemispheres with normal OEF. %CBV reactivity was 9.5 ± 12% in elevated OEF group, being significantly lower than 22 ± 13% in normal OEF group (P = 0.04, un-paired t). CBV did not increase in patients with steal phenomenon after ACZ injection in elevated OEF group, but increased in normal OEF group.
Conclusion- These findings strongly suggest that baseline CBV increases, but does not reach maximal in the area with reduced CBF and CVR due to occlusive carotid artery disease, indicating that CBF response to ACZ may imply more complicated mechanisms in the severe ischemic brain.
- © 2012 by American Heart Association, Inc.