Observation of the embolus protection filter for Carotid Artery Stenting.

BACKGROUND Carotid artery stenting in patients with high surgical risk is considered as an effective alternative to carotid endarterectomy. Because the occurrence of distal embolization with CAS is still a major concern, an embolus protection device is usually used during the procedure. We developed a technique for observation of embolus protection filter and evaluated the debris or thrombus microscopically, and the pathologic findings were compared with preoperative imaging studies. METHODS After completing CAS, the filter membrane was stained with HE solution and removed from filter strut. Mounting onto a glass slide, the filter was evaluated under a microscope. Plaque debris and appearance of filter membrane were evaluated, and the covered area was measured. The pathologic findings were compared with preoperative imaging studies. RESULTS Microscopic observation of the slide revealed atheromatous debris as well as thrombotic material to the filter membrane. Hematoxylin-eosin stain facilitates the characterization of the debris composition, namely, thrombotic debris, calcified debris, organized debris, fibrous debris, and lipid-rich debris. The subtypes of debris were consistent with preoperative imaging studies. Thus, in cases of intraprocedural flow impairment, more than 50% of the filter area was covered with debris or thrombotic material. CONCLUSION Carotid plaque debris captured during carotid stenting with protection filter can be visualized with HE stain on the glass side. This simple method allows us to better understand the plaque debris and appearance of embolus protection filter.