Abstract WP128: Blood Sampling Oxygen Extraction Fraction As Predictors Of Hyperperfusion Phenomenon Following Carotid Artery Stenting

Backgrounds and Purpose: Hyperperfusion syndrome following carotid artery stenting (CAS) may occur in patients suffering from stage 2 hemodynamic failure, where oxygen extraction fraction is elevated. The purpose of our retrospective study was to investigate whether or not blood sampling OEF has some relation to hyperperfusion phenomenon (HP) following CAS. Materials and Methods: Included for analysis were patients (1) who were admitted to our institution from 2010 to 2012, (2) who underwent elective CAS and (3) who underwent blood sampling for OEF calculation and single-photon emission computed tomography (SPECT) before and immediately after CAS. Oxygen extraction fraction (OEF) was calculated from arteriovenous oxygen difference as follows: OEF = (Ca02-Cv02) / Ca02 where Ca02 is arterial oxygen content and CvO2 is the jugular vein oxygen content. Cerebral blood flow (CBF) was measured in bilateral middle cerebral artery (MCA) territory and in the affected side cerebellar hemisphere by SPECT. Asymmetry index (AI) was defined as CBF in the affected side / CBF in the unaffected side, and MCA-to-cerebellar activity ratio as the CBF in the affected side / the CBF in the ipsilateral cerebellar hemisphere. HP was defined as 10% or more of increase in MCA-to-cerebellar activity ratio following CAS. Results: During the study period, 90 patients matched our criteria for retrospective analysis and 21 patients presented post-CAS HP. Procedures were successful in every case. There was no relation of pre-CAS OEF to asymmetry index and MCA-to-cerebellar activity ratio. There was no relation of post-CAS OEF to asymmetry index, but post-CAS OEF had relation to MCA-to-cerebellar activity ratio (r=0.26, p Conclusion: Elevation of blood sampling OEF immediately after CAS is related to post-CAS HP.