Background Over the past decade mechanical thrombectomy has become the clinical standard of care for stroke from large vessel occlusions. The most recent studies have shown rates of modified thrombolysis in cerebral infarction 2b/3 of over 70%. Although larger clots are successfully retrieved the effect of microembolic showers that occur during the procedure is not fully investigated. Here we seek to quantify the risk of distal infarct from such embolic showers in a preclinical model.

Methods Ex vivo rat clots were made using a standard protocol and were then macerated into micro-emboli (< 300 um). Emboli were filter separated into 3 different sizes: 8–40um, 40–80um, 100–250um. Before injection each category of emboli was measured for size and concentration to allow for dilution to a procedure relevant density compared to a stentriever thrombectomy.¹ Twenty rats were randomly assigned to one of 4 different groups (n = 5/group): control, small, medium, and large emboli. Other than the size of the emboli all animals underwent the same procedure, catheterization of the ICA distal to the pterygopalatine artery and 1 ml of calibrated emboli (total emboli: 21,000 for small, 90 for medium, and 3 for large) were injected. High field MRI was acquired including susceptibility and diffusion tensor imaging (DTI, figure 1) at 90 min post injection. From the DTI the size and number of infarcts were measured and the average size per infarct was calculated.

Results All animals survived emboli injections and were successfully imaged in the 7T MRI. In both the medium and large emboli groups all animals had a detectable infarct, while only 60% of the small emboli group animals had an infarct. For both the medium and large emboli groups the total infarct size was 9.1 mm³ and 109.7 mm³ which is significantly larger than the control group (p = 0.002 and p < 0.001, respectively). Due to two animals in the small emboli group not having a detectable infarct the small emboli group infarct size of 2.50 mm³ was not significantly larger than the control (p = 0.06); however, if the average of each discrete infarct is compared, they are significantly bigger than the control group (p < 0.001).

Conclusion Independent of emboli size, there was a significantly higher number and size of infarcts compared to the control group. Although the smallest emboli (8–40um) did not always produce an infarct they did in 60% of animals. ¹J Neurointerv Surg. 2017 Feb;9(2):183–187

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Abstract P-003 Figure 1

Representative Apparent Diffusion Coefficient (ADC) maps calculate from diffusion tensor images (DTI) of infarcts (arrow) caused by: A) small emboli (8–40um), B) middle size emboli (40–80um), and C) large emboli (100–250um)

Disclosures R. King: 1; C; SNIS. C. Raskett: None. M. Gounis: None. V. Anagnostakou: None.