A novel endovenous scaffold for the treatment of chronic venous obstruction in a porcine model: Histological and ultrastructural assessment

Abstract

Objective To investigate the biological effects of a novel endovenous scaffold in a porcine model. Methods Petalo is a compliant venous scaffold implanted into the internal jugular veins of 12 healthy pigs. The pigs were sacrificed at one, two, three, and six months, respectively. Microscopic investigations were performed at two blinded laboratories. Results Neo-intima formation progressively covering up the stent metallic bars was observed. The inflammatory response of the venous wall showed a peak after three months by the implant, followed by marked reduction after six months. The device induced a significant ( p < 0.01) increase of the thickness respect to the control regions, but was comparable in sections obtained after three and six months. Conclusions The implant of Petalo compliant venous scaffold in the venous wall of this porcine model is characterized by neointima formation and by an inflammatory reaction which tends to decrease after six months. Our data point against the induction of smooth muscle cells proliferation and migration as confirmed by electronic transmission microscopy analyses.

What are the ideal characteristics of a venous stent?

“…Dedicated venous stents were not available until very recently. 4,9,27,[33][34][35][36]40 The preclinical study about a new scaffold, denominated Petalo CVS, has been shown that it could have the ideal characteristics of a venous stent, but it is necessary a first in man study to affirm it. 9…”

“…Alternatively, if the stent has an anchor point, that permits a passive anchoring, the radial force required to avoid migration will be lower and the risk of myointimal hyperplasia and restenosis will decrease too. 1,2,4,11,22,35,38,40,41 Undersized stent and residual stenoses at the inflow or outflow segments can induce significant complications, such as chronic occlusion or persistence of symptoms. 1,3,42 The ideal venous stent has not instent restenosis.…”

“…In the cervical region, the venous stent's fracture could be induced by the large movements of the head and the strong muscles. 16,22,38,40,46,47 Another characteristic of the venous stent is flexibility. Ideally, the scaffold should adapt its shape to the vein, not vice versa.…”

“…4,27,34 There is a preclinical study about a new venous scaffold implanted in the porcine internal jugular vein (IJV), that is a compliant nitinol stent, denominated Petalo CVS (Figure 1). 40 This scaffold has a particular shape, that permits to anchor the vein wall only at the extremities. Its radial force is enough to avoid migration, but it does not cause myointimal hyperplasia.…”

“…So the inflammatory response to the placement of the stent is highest after three months and then decreases over time. 9,40 After three months a neo-intimal tissue covered up the stent's extremities, while the central part was surrounded after six month (Figure 2). 9,40…”