FIG 1.

Histologic processing of cross-section of MT catheter. A, Macrophotograph of the Sofia catheter, showing the catheter is cut into pieces in coronary plane (arrows), with removal of metal scaffold for further histology processing (orange arrow) (asterisk: lumen side). B, Macrophotograph of catheter piece in image A mixed with clot analog tissue (asterisk: lumen side). C, Macrophotograph showing the catheter piece mixed with clot tissue embedded in paraffin after tissue processing; catheter piece remains in the coronal orientation (asterisk: lumen side). D, Low-magnification microphotograph of H&E-stained catheter piece from image C (blue cross: the surrounding clot; yellow asterisk: the lumen/inner side of catheter; red arrows: outer layer surface-coating material that is next to the surrounding clot tissue). E, Reverse image of image D, showing each layer of the catheter, in relation to the lumen and outside surrounding clot tissue (yellow star: lumen side; blue cross: surrounding clot tissue). F–I, High magnification of microphotograph taken from the red rectangular area in image E, showing each layer of the catheter materials from the outer layer surface (red arrows), middle layer (blue arrows and green arrows) to the inner liner layer (black arrow) (H&E, original magnification ×400; yellow star: the lumen side of catheter; blue cross: the surrounding clot analog tissue). J–L, Microphotographs taken with oil lens, showing the surface-coating material (red arrows), its subsequent layer (blue arrows), and deeper layer (green arrow). The surface-coating material appears to be light gray, gray-pink, or lightly stained; attenuated or loose in texture; and with varied shape, same as the type II foreign material found in the patient clot tissue (Fig 6). The layer that is immediately underneath the coating layer appears to be homogeneous in texture, light pink, or pale in color (blue arrows). It is similar to the type IV foreign material observed in the patient clot tissue (Fig 8) (H&E, oil lens ×100).