Impact of advanced glycation end products (AGEs) signaling in coronary artery disease

Coronary artery disease remains the leading cause of mortality in adult diabetic population with however, a high predominance also in non-diabetic subjects. In search of common molecular mechanisms and metabolic by-products with potential pathogenic role, increased advanced glycation end products (AGEs) present a critical biomarker for CAD development in both cases. Interaction of AGEs with their transmembrane cell receptor, RAGE in endothelial and smooth muscle cells as well as in platelets, activates intracellular signaling that leads to endothelial injury, modulation of vascular smooth muscle cell function and altered platelet activity. Furthermore, tissue accumulation of AGEs affects current treatment approaches being involved in stent restenosis. The present review provides an update of AGE-induced molecular mechanisms involved in CAD pathophysiology while it discusses emerging therapeutic interventions targeting AGE reduction and AGE-RAGE signaling with beneficial clinical outcome.     

缺血性中风患者脑血管支架植入最佳时机的分析

目的:探讨缺血性中风患者脑血管支架植入的最佳时机。方法:选取我院收治的缺血性脑血管疾病患者90例,依据发病时间分为三组并进行脑血管支架植入术。对比三组患者治疗前后脑血管血流速度、认知功能评分及血管内皮细胞生长因子(VEGE)、碱性成纤维细胞生长因子(b FGF)、神经生长因子(NGF)的含量变化。结果:1三组患者手术后的脑血管血流速度与手术前相比明显改善,差异有统计学意义(P0.05),但三组之间比较无明显差异(P0.05);2三组患者手术后的认知功能均较手术前有所改善,与A组和C组比较,B组认知功能评分明显升高,差异有统计学意义(P0.05),而A组和C组比较无明显差异(P0.05);3三组患者手术后的血清VEGE、b FGF、NGF含量均较手术前升高,且B组明显高于A组和C组,差异有统计学意义(P0.05),而A组和C组间比较无明显差异(P0.05)。结论:脑血管支架植入时机与缺血性中风患者的临床疗效及预后可能有一定相关性,发病后1个月为脑血管支架植入最佳时机。     

Numerical evaluation of RF-induced heating for various esophageal stent designs under MRI 1.5 Tesla system

This paper presents a numerical investigation of radio frequency (RF)-induced heating for various esophageal stent designs under magnetic resonance imaging (MRI). The length, patterns and insulation layer as well as the radius of the wire are comprehensively evaluated. It is shown that different stent designs can alter the induced current distributions on the stent and consequently its corresponding heating. Detailed discussions on these factors on RF heating are presented.     

The effect of ureteric stents on urine flow: Reflux

If the ureter becomes blocked, the resultant increased pressure may be relieved by inserting a double-J stent (a polymer tube, usually punctuated with holes). A major clinical problem associated with stent use is reflux (retrograde flow of urine from the bladder to the kidney), which may result in infections, scarring, and even renal failure. We develop a mathematical model, treating the ureter as an elastic tube and the stent as a permeable rigid tube within it. We investigate how the number of holes in the stent wall affects the total amount of reflux that occurs when bladder pressure rises, by considering the limits of a highly-permeable stent, and an impermeable stent. We find that, in the scenarios we consider, the highly-permeable stent gives rise to less total reflux than the impermeable one.Revised version: 8 August 2003     

Numerical investigations of the haemodynamic changes associated with stent malapposition in an idealised coronary artery

The deployment of a coronary stent near complex lesions can sometimes lead to incomplete stent apposition (ISA), an undesirable side effect of coronary stent implantation. Three-dimensional computational fluid dynamics (CFD) calculations are performed on simplified stent models (with either square or circular cross-section struts) inside an idealised coronary artery to analyse the effect of different levels of ISA to the change in haemodynamics inside the artery. The clinical significance of ISA is reported using haemodynamic metrics like wall shear stress (WSS) and wall shear stress gradient (WSSG). A coronary stent with square cross-sectional strut shows different levels of reverse flow for malapposition distance (MD) between 0 mm and 0.12 mm. Chaotic blood flow is usually observed at late diastole and early systole for MD=0 mm and 0.12 mm but are suppressed for MD=0.06 mm. The struts with circular cross section delay the flow chaotic process as compared to square cross-sectional struts at the same MD and also reduce the level of fluctuations found in the flow field. However, further increase in MD can lead to chaotic flow not only at late diastole and early systole, but it also leads to chaotic flow at the end of systole. In all cases, WSS increases above the threshold value (0.5 Pa) as MD increases due to the diminishing reverse flow near the artery wall. Increasing MD also results in an elevated WSSG as flow becomes more chaotic, except for square struts at MD=0.06 mm.     

Hemodynamics in coronary arteries with overlapping stents

Coronary artery stenosis is commonly treated by stent placement via percutaneous intervention, at times requiring multiple stents that may overlap. Stent overlap is associated with increased risk of adverse clinical outcome. While changes in local blood flow are suspected to play a role therein, hemodynamics in arteries with overlapping stents remain poorly understood. In this study we analyzed six cases of partially overlapping stents, placed ex vivo in porcine left coronary arteries and compared them to five cases with two non-overlapping stents. The stented vessel geometries were obtained by micro-computed tomography of corrosion casts. Flow and shear stress distribution were calculated using computational fluid dynamics. We observed a significant increase in the relative area exposed to low wall shear stress (WSS<0.5 Pa) in the overlapping stent segments compared both to areas without overlap in the same samples, as well as to non-overlapping stents. We further observed that the configuration of the overlapping stent struts relative to each other influenced the size of the low WSS area: positioning of the struts in the same axial location led to larger areas of low WSS compared to alternating struts. Our results indicate that the overlap geometry is by itself sufficient to cause unfavorable flow conditions that may worsen clinical outcome. While stent overlap cannot always be avoided, improved deployment strategies or stent designs could reduce the low WSS burden.     

Ultra-thin strut cobalt chromium bare metal stent usage in a complex real-world setting. (SOLSTICE registry)

AimTo report clinical follow-up at 6 months after implantation of the ultra-thin strut cobalt chromium SolarFlex stent in a real-world setting.ConclusionsThe SOLSTICE registry showed that in a complex real-world setting the SolarFlex bare metal stent, with ultra-thin struts and customised scaffolding, provided low clinical MACE and TLR rates. These results provide support for the use of the latest generation bare metal stent in contemporary European practice.