Intimal hyperplasia following implantation of helical-centreline and straight-centreline stents in common carotid arteries in healthy pigs: influence of intraluminal flow

• Published in: Journal of the Royal Society interface 2013-12, Vol.10 (89), p.20130578-20130578
• Main Authors: Caro, Colin Gerald, Seneviratne, Anusha, Heraty, Kevin B., Monaco, Claudia, Burke, Martin G., Krams, Rob, Chang, Carlos C., Coppola, Gianfilippo, Gilson, Paul
• Format: Article
• Language: English
• Subjects: Animals; Blood Flow Velocity; Blood–wall Oxygen Transport; Carotid Arteries - pathology; Carotid Arteries - surgery; Helical-Centreline Arterial Stent; Hyperplasia - pathology; Intimal Hyperplasia; Models, Cardiovascular; Stents - adverse effects; Sus scrofa; Swirling Intraluminal Blood Flow; Tunica Intima - pathology; Vessel Wall Hypoxia; Wall Shear Stress
• ISSN: 1742-5689; 1742-5662
• DOI: 10.1098/rsif.2013.0578

Intimal hyperplasia (IH) is a leading cause of obstruction of vascular interventions, including arterial stents, bypass grafts and arteriovenous grafts and fistulae. Proposals to account for arterial stent-associated IH include wall damage, low wall shear stress (WSS), disturbed flow and, although not widely recognized, wall hypoxia. The common non-planarity of arterial geometry and flow, led us to develop a bare-metal, nitinol, self-expanding stent with three-dimensional helical-centreline geometry. This was deployed in one common carotid artery of healthy pigs, with a straight-centreline, but otherwise identical (conventional) stent deployed contralaterally. Both stent types deformed the arteries, but the helical-centreline device additionally deformed them helically and caused swirling of intraluminal flow. At sacrifice, one month post stent deployment, histology revealed significantly less IH in the helical-centreline than straight-centreline stented vessels. Medial cross-sectional area was not significantly different in helical-centreline than straight-centreline stented vessels. By contrast, luminal cross-sectional area was significantly larger in helical-centreline than straight-centreline stented vessels. Mechanisms considered to account for those results include enhanced intraluminal WSS and enhanced intraluminal blood–vessel wall mass transport, including of oxygen, in the helical-centreline stented vessels. Consistent with the latter proposal, adventitial microvessel density was lower in the helical-centreline stented than straight-centreline stented vessels.