Carotid stenting with filter protection. Correlation of ACT values with angiographic and histopathologic findings.

Background and Purpose: Filter cerebral protection during carotid stenting has been proposed as a new tool to reduce brain embolism. Angiographic findings (filter patency), pathological analysis of the collected materials inside the filters and coagulation parameters were analyzed to identify potential down sides in the use of these protection devices.
Methods: 29 consecutive endovascular treatments with filter cerebral protection in 27 patients affected by symptomatic internal carotid stenosis>70% were considered. Angiographic findings, activated clotting times and histopathologic specimens were recorded and correlated.
Results: Satisfactory dilatation of the stenosis was always achieved with a complication rate of 3% (1 transient neurological deficit). During the procedure, 9 filters (31%) appeared occluded, with temporary flow impairment. Histopathologic examination demonstrated material inside the filters in 86% of cases but this material was fibrin alone in 38% and plaque debris in 48%. Significant statistical correlation (p=0.009) was found between low activated clotting time and occlusion of the filter.
Conclusion: Distal protection filters can collect plaque fragments occurring during carotid stenting. Significant proportion of the debris found in the filters consisted of thrombotic material. Precise monitoring of heparin anticoagulation is recommended to prevent filter occlusion.