Reduction in arterial wall strain with aggressive lipid-lowering therapy in patients with carotid artery disease

Background: Inflammation and biomechanical factors have been associated with the development of vulnerable atherosclerotic plaques. Lipid-lowering therapy has been shown to be effective in stabilizing them by reducing plaque inflammation. Its effect on arterial wall strain, however, remains unknown. The aim of the present study was to investigate the role of high- and low-dose lipid-lowering therapy using an HMG-CoA reductase inhibitor, atorvastatin, on arterial wall strain. Methods and Results: Forty patients with carotid stenosis >40% were successfully followed up during the Atorvastatin Therapy: Effects on Reduction Of Macrophage Activity (ATHEROMA; ISRCTN64894118) Trial. All patients had plaque inflammation as shown by intraplaque accumulation of ultrasmall super paramagnetic particles of iron oxide on magnetic resonance imaging at baseline. Structural analysis was performed and change of strain was compared between high- and low-dose statin at 0 and 12 weeks. There was no significant difference in strain between the 2 groups at baseline (P=0.6). At 12 weeks, the maximum strain was significantly lower in the 80-mg group than in the 10-mg group (0.085±0.033 vs. 0.169±0.084; P=0.001). A significant reduction (26%) of maximum strain was observed in the 80-mg group at 12 weeks (0.018±0.02; P=0.01). Conclusions: Aggressive lipid-lowering therapy is associated with a significant reduction in arterial wall strain. The reduction in biomechanical strain may be associated with reductions in plaque inflammatory burden.

N-3 polyunsaturated fatty acids and inflammation in the arterial wall

Atherosclerosis, leading to cardiovascular disease, is a chronic condition involving a strong inflammatory component. There is evidence that the n-3 polyunsaturated fatty acids (PUFA) present in oily fish and fish oils protect against cardiovascular disease. While these fatty acids have well-recognised effects on plasma triacylglycerol concentrations, it is likely that they exert beneficial effects through other mechanisms in addition. A large body of evidence suggests that the n-3 PUFA have anti-inflammatory properties, some of which may be manifested in the arterial wall, either directly or indirectly, to modulate the progression of atherosclerosis. This review critically evaluates the evidence for the anti-inflammatory effects of the n-3 PUFA in cells and on pathways which have a direct influence on atherogenesis in the arterial wall.

Angiographic geometric changes of the lumen arterial wall after bioresorbable vascular scaffolds and metallic platform stents at 1-year follow-up

The aim of this study was to compare the angiographic changes in coronary geometry of the bioresorbable vascular scaffolds (BVS) and metallic platform stent (MPS) between baseline and follow-up.

Energy harvesting through arterial wall deformation: design considerations for a magneto-hydrodynamic generator

As the complexity of active medical implants increases, the task of embedding a life-long power supply at the time of implantation becomes more challenging. A periodic renewal of the energy source is often required. Human energy harvesting is, therefore, seen as a possible remedy. In this paper, we present a novel idea to harvest energy from the pressure-driven deformation of an artery by the principle of magneto-hydrodynamics. The generator relies on a highly electrically conductive fluid accelerated perpendicularly to a magnetic field by means of an efficient lever arm mechanism. An artery with 10 mm inner diameter is chosen as a potential implantation site and its ability to drive the generator is established. Three analytical models are proposed to investigate the relevant design parameters and to determine the existence of an optimal configuration. The predicted output power reaches 65 μW according to the first two models and 135 μW according to the third model. It is found that the generator, designed as a circular structure encompassing the artery, should not exceed a total volume of 3 cm3.

Energy harvesting through arterial wall deformation: A FEM approach to fluid–structure interactions and magneto-hydrodynamics

Engineers are confronted with the energy demand of active medical implants in patients with increasing life expectancy. Scavenging energy from the patient’s body is envisioned as an alternative to conventional power sources. Joining in this effort towards human-powered implants, we propose an innovative concept that combines the deformation of an artery resulting from the arterial pressure pulse with a transduction mechanism based on magneto-hydrodynamics. To overcome certain limitations of a preliminary analytical study on this topic, we demonstrate here a more accurate model of our generator by implementing a three-dimensional multiphysics finite element method (FEM) simulation combining solid mechanics, fluid mechanics, electric and magnetic fields as well as the corresponding couplings. This simulation is used to optimize the generator with respect to several design parameters. A first validation is obtained by comparing the results of the FEM simulation with those of the analytical approach adopted in our previous study. With an expected overall conversion efficiency of 20% and an average output power of 30 μW, our generator outperforms previous devices based on arterial wall deformation by more than two orders of magnitude. Most importantly, our generator provides sufficient power to supply a cardiac pacemaker.

Multimodal 3 tesla MRI confirms intact arterial wall in acute stroke patients after stent-retriever thrombectomy

BACKGROUND AND PURPOSE The aim of this prospective study was to assess vascular integrity after stent-retriever thrombectomy. METHODS Dissection, contrast medium extravasation, and vasospasm were evaluated in 23 patients after thrombectomy with biplane or 3D-digital subtraction angiography and 3-Tesla vessel wall MRI. RESULTS Vasospasm was detected angiographically in 10 patients, necessitating intra-arterial nimodipine in 2 of them. Contrast extravasation, intramural hemorrhage, or iatrogenic dissection were not detected on multimodal MRI in any patient even after Y-double stent-retriever technique. CONCLUSIONS Our findings suggest that clinically relevant vessel wall injuries occur rarely after stent-retriever thrombectomy.

Separation of the arterial wall from blood contact using hydrogel barriers reduces intimal thickening after balloon injury in the rat: The roles of medial and luminal factors in arterial healing

The objective of this study was to clarify the relative roles of medial versus luminal factors in the induction of thickening of the arterial intima after balloon angioplasty injury. Platelet-derived growth factor (PDGF) and thrombin, both associated with thrombosis, and basic fibroblast growth factor (bFGF), stored in the arterial wall, have been implicated in this process. To unequivocally isolate the media from luminally derived factors, we used a 20-μm thick hydrogel barrier that adhered firmly to the arterial wall to block thrombus deposition after balloon-induced injury of the carotid artery of the rat. Thrombosis, bFGF mobilization, medial repopulation, and intimal thickening were measured. Blockade of postinjury arterial contact with blood prevented thrombosis and dramatically inhibited both intimal thickening and endogenous bFGF mobilization. By blocking blood contact on the two time scales of thrombosis and of intimal thickening, and by using local protein release to probe, by reconstitution, the individual roles of PDGF-BB and thrombin, we were able to conclude that a luminally derived factor other than PDGF or thrombin is required for the initiation of cellular events leading to intimal thickening after balloon injury in the rat. We further conclude that a luminally derived factor is required for mobilization of medial bFGF.

Urinary albumin levels in the normal range determine arterial wall thickness in adults with Type 2 diabetes: a FIELD substudy

Aim Cardiovascular disease (CVD) rates are substantially higher among patients with Type 2 diabetes than in the general population. The objective of this study was to identify the determinants of carotid intima media thickness (IMT) in patients with Type 2 diabetes. Methods We measured the thickness of the intima media layer of the carotid artery, a strong predictor of the risk of future vascular events, in 397 Type 2 diabetic patients drawn from the Fenofibrate Intervention and Event Lowering in Diabetes study, prior to treatment allocation. Results The mean IMT was 0.78 mm [interquartile range (IQR) 0.23 mm], and the maximum IMT was 1.17 mm (IQR 0.36 mm). By multivariate analysis, age, sex, duration of diabetes, triglycerides, and total cholesterol were independently correlated with IMT, as was urine albumin-creatinine ratio (ACR) (P < 0.001). The effect of ACR on IMT was further examined by tertile. Clinically significant differences in IMT were associated with ACR > 0.65 mg/mmol, approximately one-fifth the standard clinical threshold for microalbuminuria (P < 0.01). Long-term diabetes, independent of other parameters, was associated with a 50% increase in age-related thickening. Conclusions IMT in people with Type 2 diabetes is independently and continuously related to urine albumin levels and to the duration of diabetes. These results support previous data linking urine albumin measurements within the normal range with increased ischaemic cardiac mortality in the setting of Type 2 diabetes, and strongly suggest that urine albumin levels within this range should trigger a formal evaluation for CVD.

Stress analysis on human arterial plaques by fluid structure interactions - Multi-case study

Atherosclerotic plaque rupture has been extensively considered as the leading cause of death in the world. It is believed that high stress within plaque can be an important factor which can trigger the rupture of the plaque. High resolution multi-spectral magnetic resonance imaging (MRI) has allowed the plaque components (arterial wall, lipids, and fibrous cap) to be visualized in vivo [1]. The patient specific finite element model can be generated from the image data to perform stress analysis and provide critical information on understanding plaque rupture mechanisms [2]. The present work is to apply the procedure to a total of 14 patients (S1 ∼ S14), to study the stress distributions on carotid artery plaque reconstructed from multi-spectral magnetic resonance images, and the possible relationships between stress and plaque burdens.