Histopathology of Embolic Debris Captured During Transcatheter Aortic Valve Replacement
Background—Recent Transcatheter Aortic Valve Replacement (TAVR) studies have raised concerns about adverse cerebrovascular events. The etiopathology of the embolized material is currently unknown.
Methods and Results—A total of 40 patients underwent TAVR with the use of a dual filter-based embolic protection device (Montage™ Dual Filter System, Claret Medical, Inc. Santa Rosa, CA, USA). Macroscopic material liberated during the TAVR procedure was captured in the device filter baskets in 30 (75%) patients and sent for histopathological analysis. The captured material varied in size from 0,15mm to 4,0mm. Amorphous calcified material (size 0.55 mm - 1.8 mm) was identified in five patients (17%). In eight patients (27%), the captured material (size 0.25mm - 4.0mm) contained valve tissue composed of loose connective tissue (collagen and elastic fibers) with focal areas of myxoid stroma, with or without coverage by endothelial cells and intermixed with fibrin. In another 13 (43%) patients collagenous tissue, which may represent elements of vessel wall and/or valve like structures were identified. In nine patients (30%) thrombotic material was intermixed with neutrophils (size 0.15 mm - 2.0 mm). Overall, thrombotic material was found in 52% of patients and tissue fragments compatible with aortic valve leaflet or aortic wall origin in 52% (21/40) of patients.
Conclusions—Embolic debris travelling to the brain was captured in 75% of TAVR procedures where a filter-based embolic protection device was used. The debris consisted of fibrin, or amorphous calcium and connective tissue derived most likely from either the native aortic valve leaflets or aortic wall.
- Received January 2, 2013.
- Revision received April 11, 2013.
- Accepted April 26, 2013.