Underwent emergency CEA *No temporal windows to measure the MCAV by TCD *Stenosis caused by nonatherosclerotic diseases *Refusal to sign the ethical information consent form.
Preoperation: The MCAV (V [sub]pre ) and BP [sub]pre were registered 10 min before anesthetic admitted.
For the TCD measure and registration, a pulsed Doppler transducer gated at a focal depth of 45-60 mm was placed over the temporal bone to insonate the main stem of the ipsilateral MCA; the TCD transducer was fixed with a head frame, and the peak systolic MCAV was recorded continuously.
According to previous publications, we also chose 2 as the cut-off value for VR (which means a 100% increase of MCAV compared with the preoperative value).
They used a postoperative mean MCAV increase of ≥100% as the cut-off value.