Differential Peri-Strut Vascular Healing After Stent Deployment in Swine Subclavian and Carotid Arteries

Vascular healing after stent implantation is influenced by local biomechanical and anatomical environments. Swine carotid and subclavian arteries are commonly used in preclinical vascular device studies; however, regional differences in peri-strut healing responses between these vascular territories remain incompletely defined. This study compared histopathological vascular healing after stent implantation in swine carotid and subclavian arteries.

Self-expanding stents were implanted in both carotid and subclavian arteries in the same domestic swine according to the instructions for use. Animals survived for either 3 or 28 days before necropsy (n=6/time point). Stented vessels were perfusion-fixed, embedded in plastic, and stained with hematoxylin and eosin and Movat's pentachrome stain. Histopathological evaluation included injury, inflammation, fibrin, thrombus, endothelialization, neointimal maturity, fibrosis, and hemorrhage. Histomorphometry included percent stenosis, neointimal thickness, and area.

Stent-to-artery ratios were comparable between carotid and subclavian arteries. At 28 days, subclavian arteries demonstrated significantly greater persistent peri-strut fibrin deposition and intramural hemorrhage than carotid arteries (fibrin: 1.67 ± 0.72 vs. 0.03 ± 0.18, p<0.05; hemorrhage: 1.53 ± 1.06 vs. 0.03 ± 0.18, p<0.05). Percent area stenosis was also greater in subclavian arteries (28.77 ± 18.35% vs. 14.94 ± 5.25%, p<0.05). No significant regional differences were observed at 3 days.

Subclavian arteries demonstrated peri-strut delayed vascular healing characterized by persistent fibrin deposition, hemorrhage, and increased neointimal formation compared with carotid arteries despite similar stent deployment conditions. Mechanical stress associated with forelimb movement may contribute to delayed healing and subsequent neointimal formation in the subclavian artery.