Creep of Calcium Nodules Through Struts of Paclitaxel-Eluting Stent in Distal Superficial Femoral Artery

A 67-year-old man on hemodialysis, who had been treated with a 6.0 × 80 mm paclitaxel-eluting stent (ELUVIA; Boston Scientific) in the distal superficial femoral artery (SFA) in the previous year (Figure A), presented with recurrent claudication. Angiography (Figure B) showed translucent lesions in the distal-SFA stent, and optical frequency domain imaging (OFDI) showed the lesion as a strongly attenuated protrusion between calcified plates (Figure C). Further, the protrusion extended up between the stent struts, suggesting it had moved from outside the stent through the stent struts (Figure C). Angioscopy showed a cauliflower-like appearance (Figure D). Endovascular catheter biopsy was performed to diagnosis the contents of the protrusion, and it consisted mainly of calcium deposits of irregular shape and size, without atheroma component (i.e., foam cells, cholesterol crystals) (Figure E). We determined this protrusion to be a calcified nodule (CN).

Figure.

(A) Initial angiography shows a translucent protrusion. (B) Angiography performed 1 year later shows in-stent restenosis by a similar protrusion. (C) Optical frequency domain imaging shows the protrusion (asterisks) rising up from between stent struts (yellow arrowheads). (D) In-stent angioscopy shows a cauliflower-like protrusion and in the contralateral area, stent neointimal coverage of grade 0. (E) Pathology of biopsy specimen of the protrusion shows calcium deposits (black asterisks) throughout the specimen. (F) Without the protrusion (a calcium nodule), in-stent angioscopy shows stent neointimal coverage of grade 1.

CN restenosis of a coronary stent is considered to be caused by nodule extension from outside the stent, and our findings suggest a similar mechanism in the peripheral arteries. Angioscopy revealed that the site of the CN had poor neointimal coverage of the stent (stent neointimal coverage grade 0) (Figure D,F).

Lack of healthy endothelial coverage between stent struts may be associated with easy intrusion of a CN. It is also possible for a CN to redevelop from the stent strut.

Conflict of Interest

None.

IRB Information

The Ethics Committee of Toho University granted an exemption from requiring ethics approval.