Reduction in distal emboli with proximal flow control during mechanical thrombectomy: a quantitative in vitro study.

BACKGROUND AND PURPOSE: To evaluate the impact of proximal flow control on efficacy and safety of mechanical thrombectomy in an in vitro middle cerebral artery occlusion. METHODS: Three independent variables, including clot type, device (Merci Retriever, Solitaire FR, and Trevo devices), and use of a balloon guide catheter, were used to ascertain the impact of proximal flow control on the size and number of distal emboli generated during thrombectomy. Secondary end points were the recanalization rate and amount of flow restored. RESULTS: Use of the balloon guide catheter during thrombectomy of the fragile, hard clot significantly reduced the formation of large distal emboli with a diameter >1 mm, regardless of the device used (P<0.01). Applying aspiration via the balloon guide catheter in place of the conventional guide catheter resulted in a significant increase of flow reversal (P<0.0001). Prior to thrombectomy, deployment of the stent-trievers produced immediate flow restoration through the soft and hard clot occlusions, 69.2 ± 27.3 and 45.5 ± 22.8 mL/min, respectively, that was preserved after the balloon inflation because of collateral flow via the posterior communication artery. After deployment but before thrombectomy, no flow was restored when using the Merci Retriever. After thrombectomy, complete flow restoration was achieved in a majority of cases. The Merci Retriever required more thrombectomy attempts to achieve hard clot removal compared with the stent-trievers when the conventional guide catheter was used (1.5 versus 1.1). CONCLUSIONS: The risk of distal embolization was significantly reduced with the use of the balloon guide catheter.