BACKGROUND AND PURPOSE: Intracranial hemorrhage due to hyperperfusion syndrome is a severe carotid artery stent placement complication of extremely high-grade stenosis, causing hemodynamic insufficiency. To prevent hyperperfusion syndrome, we attempted intentional residual stent stenosis and implemented "gentle" carotid artery stent placement, defined as carotid artery stent placement using a closed-cell stent coupled with slight balloon predilation, without balloon postdilation. Gradual stent expansion was expected. We investigated the incidence of hyperperfusion syndrome and long-term outcomes after gentle carotid artery stent placement.
MATERIALS AND METHODS:We included patients who underwent carotid artery stent placement for extremely high-grade stenosis from January 2015 to March 2019. We defined extremely high-grade stenosis as carotid stenosis with conventional angiographic "slow flow" and a reduced MCA signal intensity on MRA. A reduced MCA signal intensity was defined as MCA with a relative signal intensity of ,0.9 in the ipsilateral compared with the contralateral MCA. We evaluated the stent diameter, CBF on SPECT, hyperperfusion syndrome, and intracranial hemorrhage. We defined hyperperfusion syndrome as a triad of ipsilateral headache, seizure, and hemiparesis.RESULTS: Twenty-eight of the 191 patients met our inclusion criteria. After carotid artery stent placement, their median minimal stent diameter was 2.9 mm, which expanded to 3.9 mm at 4 months. Neither cerebral hyperperfusion syndrome nor intracranial hemorrhage occurred.
CONCLUSIONS:The gentle carotid artery stent placement strategy for intentional residual stent stenosis may prevent hyperperfusion syndrome in high-risk patients. Stents spontaneously dilated in 4 months.ABBREVIATIONS: AI ¼ asymmetric index; AVDO 2 ¼ arteriovenous difference of oxygen; CAS ¼ carotid artery stent placement; HI ¼ hemodynamic insufficiency; ex-HS ¼ extremely high-grade carotid artery stenosis; HPP ¼ hyperperfusion phenomenon; HPS ¼ hyperperfusion syndrome; ICH ¼ intracerebral hemorrhage; MLD ¼ minimal luminal diameter; OEF ¼ oxygen extraction fraction; PSV ¼ peak systolic velocity; rCBF ¼ regional CBF; SI ¼ signal intensity