Quantitative assessment of device–clot interaction for stent retriever thrombectomy

Abstract

PurposeRapid revascularization in emergent large vessel occlusion with endovascular embolectomy has proven clinical benefit. We sought to measure device–clot interaction as a potential mechanism for efficient embolectomy.MethodsTwo different radiopaque clot models were injected to create a middle cerebral artery occlusion in a patient-specific vascular phantom. A radiopaque stent retriever was deployed within the clot by unsheathing the device or a combination of unsheathing followed by pushing the device (n=8/group). High-resolution cone beam CT was performed immediately after device deployment and repeated after 5 min. An image processing pipeline was created to quantitatively evaluate the volume of clot that integrates with the stent, termed the clot integration factor (CIF).ResultsThe CIF was significantly different for the two deployment variations when the device engaged the hard clot (p=0.041), but not the soft clot (p=0.764). In the hard clot, CIF increased significantly between post-deployment and final imaging datasets when using the pushing technique (p=0.019), but not when using the unsheathing technique (p=0.067). When we investigated the effect of time on CIF in the different clot models disregarding the technique, the CIF was significantly increased in the final dataset relative to the post-deployment dataset in both clot models (p=0.004–0.007).ConclusionsThis study demonstrates in an in vitro system the benefit of pushing the Trevo stent during device delivery in hard clot to enhance integration. Regardless of delivery technique, clot–device integration increased in both clot models by waiting 5 min.

Crossing Y-Solitaire thrombectomy as a rescue treatment for refractory acute occlusions of the middle cerebral artery

“…Ideal interaction for successful thrombectomy is that the retrieval force transmitted to the thrombus by the SR device exceeds the inertial forces created by the friction between the clot and the vessel wall 24. During the thrombectomy, expansion of the SR causes embedding of the thrombus into the inner lumen of the device, which is referred to as integration of the thrombus.…”

“…The integration of the thrombus with the SR device depends on the size, length, and composition of the thrombus as well as the mechanical properties of the SR device. In vitro experiments demonstrated that the amount of thrombus integration was inversely correlated with the fibrin content of the thrombus 24. In addition, higher radial forces for a SR device are needed to penetrate a fibrin-rich thrombus than for a red-blood-rich thrombus 24 25.…”

“…First, in the crossing Y-Solitaire technique, the radial force of the second deployed SR might contribute to expansion of the first stent and thus facilitate thrombus integration 24. To enhance expansion of SRs for better thrombus integration, we used the ‘active pushing technique’ during the deployment of SRs 24 25.…”

Two-year single-center experience with the ‘Baby Trevo’ stent retriever for mechanical thrombectomy in acute ischemic stroke

“…The distal end of the device is softer than that of the Solitaire FR 4×20 mm (deflection force measured to bend the distal tip of the stent retriever to 45°) and allows for an excellent vessel wall conformity and easy placement in tortuous and small caliber vessels. Similar to the other devices of the Trevo family, the large, non-overlapping stent cells permit maximum clot integration, even in smaller intracranial branches 15. In addition, the stent retriever has a hydrophilic coating, which reduces friction during use and is supposed to minimize endothelial damage.…”

Evolution of Stroke Thrombectomy Techniques to Optimize First-Pass Complete Reperfusion

“…With standard deployment of stent-retrievers (i.e., passive unsheathing), the device's inherent radial force should theoretically ensure the compression of the clot against the vessel wall and subsequent clot migration through the stent struts into its lumen, 45,46 but oftentimes, standard deployment often results in insufficient wall apposition and clot integration (►Fig. 3).…”