Digital enhancement of stent images in primary and secondary percutaneous coronary revascularisation.

Inadequate stent expansion and apposition during percutaneous coronary intervention increases the risk of subsequent restenosis and thrombosis. In repeat and complex percutaneous interventions, such as treatment of stent restenosis or bifurcation techniques, these aspects present a renewed importance. Intravascular ultrasound (IVUS) constitutes the standard technique to assess stent expansion, but its use in clinical practice is far from being universal. Although most current stent designs are radiolucent, new radiological imaging modalities, specifically tailored to coronary stent imaging, can render images with enough quality to visualise stent sub-expansion. While this approach might be complementary to IVUS in clinical practice, few in vivo studies comparing both techniques are available. In this article we review the principles of digital enhancement of stent images and the available validation studies. Furthermore, we report on a comparison between IVUS and digital enhancement stent images performed after coronary stenting.

Medium with blood-analog mechanical properties for cardiovascular tissue culturing.

Physiological wall shear rates and stresses in vessel culture or tissue engineering are relevant for maintaining endothelial cell (EC) integrity. To this end, the culture medium should have an appropriate viscosity. The viscosity of a standard culture medium was increased using xanthan gum (XG) and compared with literature data on whole blood, resulting in a medium with blood-analog shear-thinning behavior (XG-medium). The measured osmolality of the XG-medium was 285+/-2 mOsm kg(-1), which is within a physiologically acceptable range. The XG-medium was compared to standard medium to verify whether XG alters vascular cell function. First, the effect of XG on the growth of human EC monolayers was determined. In addition, to study whether XG changes drug-induced vasoconstriction or endothelium-dependent vasodilation, different drugs were administered to porcine coronary artery rings in a solution with or without XG, measuring the isometric force developed. XG did not influence EC growth, nor did it change drug-induced vascular tone. Moreover, the ECs aligned in the direction of flow after 24 h of physiological shearing with XG-medium. We conclude that, unlike standard culture media, XG-medium as a blood-analog culture medium has rheological properties suitable for use in vessel culture and tissue engineering to induce physiological wall shear stresses at physiological flow rates.