Factors that affect mass transport from drug eluting stents into the artery wall

Abstract

Coronary artery disease can be treated by implanting a stent into the blocked region of an artery, thus enabling blood perfusion to distal vessels. Minimally invasive procedures of this nature often result in damage to the arterial tissue culminating in the re-blocking of the vessel. In an effort to alleviate this phenomenon, known as restenosis, drug eluting stents were developed. They are similar in composition to a bare metal stent but encompass a coating with therapeutic agents designed to reduce the overly aggressive healing response that contributes to restenosis. There are many variables that can influence the effectiveness of these therapeutic drugs being transported from the stent coating to and within the artery wall, many of which have been analysed and documented by researchers. However, the physical deformation of the artery substructure due to stent expansion, and its influence on a drugs ability to diffuse evenly within the artery wall have been lacking in published work to date. The paper highlights previous approaches adopted by researchers and proposes the addition of porous artery wall deformation to increase model accuracy.

New approaches in evaluating metallic candidates for bioabsorbable stents

“…Atop this coating, a thick (30 µm) coating of crystalline calcium phosphate was grown by immersion in a supersaturated calcium phosphate solution for 48 hours at 37°C. The resulting layer, as indicated by SEM/EDS, was composed of octacalcium phosphate (OCP), Ca 8 H 2 (PO 4 ) 6 •5H 2 O. The OCPcoated wires were then implanted into the arterial environment for 9 months.…”

Analytical modeling of drug dynamics induced by eluting stents in the coronary multi-layered curved domain

“…1, coronary arteries (the left and the right one) are blood vessels (with an average diameter of the order of 3 − 5 mm) that branch off near the point where the aorta and the left ventricle meet, and they supply oxygen-rich blood to the entire heart muscle [1,2]. Healthy arteries are characterized by a well-defined substructure, comprising of three concentric layers [1][2][3]: the tunica intima, the tunica media, and the tunica adventitia. The tunica intima is the innermost layer, comprising of a single layer of endothelial cells and a subendothelial layer mainly consisting of connective tissue and collagen fibres.…”

“…They combine the mechanical properties of traditional stents with the release into the arterial wall of drugs generally characterized by antithrombotic and anti-proliferative features [3,5]. In particular, a therapeutic drug is loaded within a polymeric film that coats the stent struts, and is delivered in the coronary wall after the stent implantation.…”

“…In particular, a therapeutic drug is loaded within a polymeric film that coats the stent struts, and is delivered in the coronary wall after the stent implantation. As a matter of fact, drug-transport dynamics and thereby DES therapeutic effectiveness are strongly affected by several biomechanical factors, related to the stent geometrical features, to physicochemical properties of drug, coating and tissues, as well as to the tissue histological arrangement [3,5,6].…”

Effect of Diffusivity on the Transport of Drug Eluted from Drug-Eluting Stent

“…A number of studies has been carried out by taking into account the interstitial flow within the porous arterial wall (cf. [17][18][19][20][21][22][23][24]). …”