Influence of Thrombus Composition on Thrombectomy: ADAPT vs. Balloon Guide Catheter and Stent Retriever in a Flow Model

y Purpose A first-pass, direct aspiration technique and stent retrieval with a balloon guide catheter represent advanced thrombectomy techniques that are increasingly being used in the clinical routine. The purpose of this experimental study was to evaluate whether the techniques' effectiveness depended on the clot composition and to visualize the interaction between the devices and the clot. Materials and Methods Erythrocyte-rich (red) and fibrin-rich (white) clots were placed into the M1-segment of the middle cerebral artery in a transparent vascular phantom with physiological architecture. Physiological hemodynamic conditions were maintained with a programmable pump. On the one hand direct aspiration with a 5F aspiration catheter (ADAPT) and on the other hand stent retrieval with a balloon guide catheter (flow arrest/reversal) was performed. The experiments were made under direct visual control to observe the interaction between the devices and the clot. The primary end points were the number of passes/maneuvers and the occurrence of distal emboli and emboli in a new territory (anterior cerebral artery), until full recanalization was achieved. The experiment was filmed with a full high-definition camera identifying emboli. Results Six experiments were conducted for each technique and clot model. Red clots were retrieved by ADAPT with fewer passes and distal emboli, and could usually be aspirated directly at the occlusion site. White clots clogged the tip of the 5F aspiration catheter in every experiment. The catheter had to be pulled back into the long sheath in the cervical internal carotid artery, producing distal emboli. White clots were retrieved by the stent retriever and balloon guide catheter with fewer distal emboli. There was no difference in the number of passes. The stent-thrombus interaction was superficial in both clot models. Successful retrieval was granted by the flow arrest and proximal aspiration/flow reversal. One embolus in a new territory developed when using each technique in white clots. Conclusion This experimental study showed that the efficacy of advanced thrombectomy techniques might depend on clot composition. Identifying the right technique for the right clot might improve the results of thrombectomy. In a clinical setting the thrombus morphology in non-enhanced CT could be used as a marker for patient selection.