The impact of microcatheter-to-vessel size ratio on distal embolization during mechanical thrombectomy—an in vitro quantitative study

Abstract

Background and purpose

Mechanical thrombectomy (MT) is the gold standard for treating large vessel occlusions. Given the variability in vessel anatomy among patients and the sometimes arbitrary selection of devices by neurointerventionalists, the choice of microcatheter size requires thorough evaluation. We aim to evaluate the impact of device-to-vessel size ratio on periprocedural distal embolization.

Materials and methods

Fragment-prone clot analogs (length = 9.86±0.07 mm) were used to embolize three different vessels (lumen = 2.0, 2.5, 3.5 mm) in a three-dimensional-printed neurovascular model. Three different microcatheter sizes (0.017″, 0.021″, 0.027″) were used to cross the lesion and subsequently, migrated clot fragments were collected in an outflow filter for image analysis. Experiments were conducted both with and without a microguidewire. A total of 180 experiments were performed: 60 for each M1 segment of middle cerebral artery size, including 20 for each microcatheter—10 with J-shaped microguidewire and 10 without.

Results

Across all vessels, the 0.027″ microcatheter caused more distal embolizations compared to 0.017″ (p = 0.04) and 0.021″ (p = 0.01). In the 2 mm M1-MCA, 0.017″ microcatheter reduced emboli compared to 0.021″ (p = 0.062) and 0.027″ (p = 0.017). Procedures in the 2 mm vessel are significantly more prone to embolization compared to larger M1 segments (p < 0.05). Microcatheter-to-vessel ratio ≥0.38 significantly increases risk of distal embolization. The use of microguidewire in the procedures did not have any impact on distal embolization (p = 0.871).

Conclusion

A larger device-to-vessel size ratio induces an increase in distal embolization. Neurointerventionalists should carefully consider vessel anatomy for appropriate microcatheter size selection to minimize the risk of distal embolization.