Reader response: Early hemodynamic predictors of good outcome and reperfusion injury after endovascular treatment

Abstract

We read with interest the study by Baracchini et al.1 reporting dynamic blood flow velocity (BFV) changes on transcranial Doppler (TCD) after recanalization by mechanical thrombectomy (MT). In line with our work,2,3 they found abnormal postinterventional BFV to be associated with poor outcome and, specifically, increased BFV indicating subsequent intracerebral bleeding. The main strengths of their study are the availability of (1) neurosonography follow-up, demonstrating increased BFV is mostly a temporary condition with normalization within the first days after MT, and (2) control angiography 24 hours post-thrombectomy. Although these findings point toward hyperperfusion as the most likely pathophysiologic mechanism behind elevated BFV after MT, we are surprised by the mean peak systolic velocity of ∼280 cm/sec immediately post-thrombectomy. Such impressive elevations have not been observed in previous TCD studies a few hours post-recanalization.2–4 Hence, what was the exact time point of the first TCD and was the increased BFV observed in the whole artery segment or rather locally? Further serial TCD studies in combination with postinterventional neuroimaging, including perfusion scans5 and (blood) biomarkers for endothelial/blood-brain-barrier dysfunction, are warranted to better understand the pathophysiology of such findings. This could help individualizing blood pressure management post-thrombectomy, using an easy repeatable bedside tool (i.e., more strict control in hyperperfusion to avoid bleeding vs permissive hypertension in case of dampened BFV to augment collateral perfusion).