Direct detection and measurement of wall shear stress using a filamentous bio-nanoparticle

The wall shear stress (WSS) that a moving fluid exerts on a surface affects many processes including those relating to vascular function. WSS plays an important role in normal physiology (e.g. angiogenesis) and affects the microvasculature's primary function of molecular transport. Points of fluctuating WSS show abnormalities in a number of diseases; however, there is no established technique for measuring WSS directly in physiological systems. All current methods rely on estimates obtained from measured velocity gradients in bulk flow data. In this work, we report a nanosensor that can directly measure WSS in microfluidic chambers with sub-micron spatial resolution by using a specific type of virus, the bacteriophage M13, which has been fluorescently labeled and anchored to a surface. It is demonstrated that the nanosensor can be calibrated and adapted for biological tissue, revealing WSS in micro-domains of cells that cannot be calculated accurately from bulk flow measurements. This method lends itself to a platform applicable to many applications in biology and microfluidics

Focus on the research utility of intravascular ultrasound - comparison with other invasive modalities

Intravascular ultrasound (IVUS) is an invasive modality which provides cross-sectional images of a coronary artery. In these images both the lumen and outer vessel wall can be identified and accurate estimations of their dimensions and of the plaque burden can be obtained. In addition, further processing of the IVUS backscatter signal helps in the characterization of the type of the plaque and thus it has been used to study the natural history of the atherosclerotic evolution. On the other hand its indigenous limitations do not allow IVUS to assess accurately stent struts coverage, existence of thrombus or exact site of plaque rupture and to identify some of the features associated with increased plaque vulnerability. In order this information to be obtained, other modalities such as optical coherence tomography, angioscopy, near infrared spectroscopy and intravascular magnetic resonance imaging have either been utilized or are under evaluation. The aim of this review article is to present the current utilities of IVUS in research and to discuss its advantages and disadvantages over the other imaging techniques

Computational Simulations of Provisional Stenting of a Diseased Coronary Artery Bifurcation Model

Although stenting of non-branched arterial segments has acceptable clinical outcomes, in-stent restenosis (ISR) and stent thrombosis remain clinically significant issues for vascular bifurcations (15-28% restenosis). Local fluid and solid stresses appear to play an important role in restenosis and thrombosis. The combined role of wall shear stress (WSS) and circumferential wall stresses (CWS) is unclear in the case of stenting at vascular bifurcations. Using numerical simulations, we computed the fluid shear, solid stresses and the stress ratio at the the bifurcation region. Stenting of main vessel increased the maximum CWS in the the side branch (SB), resulting in a nearly two-fold increase of stress ratio in the SB compared to the MB (5.1 × 10(5) vs. 9.2 × 10(5)). The existence of plaque decreased WSS and increased CWS near the carina, increasing the stress ratio at the SB. The changes of stress ratio were highly consistent with clinical data on bifurcation stenting. Fluid dynamics and solids mechanics should be considered in planning of stenting for a specific bifurcation, as their combined biomechanical effect may play an important role in stent restenosis and thrombosis

Cholesterol embolization syndrome following thrombolysis during acute myocardial infarction

BACKGROUND: Cholesterol embolization syndrome (CES) is the result of atherosclerotic plaque erosion and subsequent dislodgement of cholesterol crystals from the core of the plaque to the peripheral arteries. The source of emboli is usually located in the aorta, whereas the most commonly affected organs are the skin and the kidneys. CASE REPORT: The case of a 69-year-old male with cyanotic painful discoloration of his toes following thrombolysis for acute myocardial infarction 1 month previously is presented. Both transesophageal echocardiography and magnetic resonance aortography showed a diffuse ulcerated atherosclerotic plaque in the course of descending thoracic aorta, while a skin biopsy of the cyanotic toes revealed cholesterol crystals in the lumen of the small diameter arteries. CONCLUSION: Cholesterol embolizations from the aorta are difficult to treat and may end in renal failure. Since treatment options are limited without proven efficacy, increased awareness by the clinicians is needed

Pheochromocytoma crisis presenting with cardiogenic shock

Pheochromocytoma is a catecholamine-secreting tumor of the adrenal glands whose typical presentation includes the triad of headache, palpitations, and diaphoresis. Pheochromocytoma crisis is an urgent medical condition whose diagnosis and management constitute a challenge for physicians. We present the case of a 55-year-old man who developed cardiogenic shock in the setting of a pheochromocytoma crisis. After stabilizing blood pressure with combined administration of α- and β-blockers, the tumor was surgically removed. Our diagnostic and therapeutic challenges are discussed

Non-diabetic hyperglycaemia correlates with angiographic coronary artery disease prevalence and severity

AIM: The role of glycaemia as a coronary artery disease (CAD) risk factor is controversial, and the optimal glucose level is still a matter of debate. For this reason, we assessed the prevalence and severity of angiographic CAD across hyperglycaemia categories and in relation to haemoglobin A(1c) (HbA(1c)) levels. METHODS: We studied 273 consecutive patients without prior revascularization undergoing coronary angiography for suspected ischaemic pain. CAD severity was assessed using three angiographic scores: the Gensini's score; extent score; and arbitrary index. Patients were grouped, according to 2003 American Diabetes Association criteria, into those with normal fasting glucose (NFG), impaired fasting glucose (IFG) and diabetes mellitus (DM). RESULTS: CAD prevalence was 2.5-fold higher in both the IFG and DM groups compared with the NFG group. Deterioration of glycaemic profile was a multivariate predictor of angiographic CAD severity (extent score: P=0.027; arbitrary index: P=0.007). HbA(1c) levels were significantly higher among CAD patients (P=0.016) and in those with two or more diseased vessels (P=0.023) compared with the non-CAD group. HbA(1c) levels remained predictive of CAD prevalence even after adjusting for conventional risk factors, including DM (adjusted OR: 1.853; 95% CI: 1.269-2.704). CONCLUSION: Non-diabetic hyperglycaemia, assessed either categorically by fasting glucose categories or continuously by HbA(1c) levels, correlates with the poorest angiographic outcomes

Oxidized Low-density Lipoproteins and Lipopolysaccharides Augment Carotid Artery Plaque Vulnerability in Hypercholesterolemic Microswine

Atherosclerosis is a chronic inflammatory disease and hypercholesterolemia is a risk factor. This study aims to compare the potency of lipopolysaccharide (LPS) and oxidized low-density lipoproteins (oxLDL) to induce plaque formation and increase plaque vulnerability in the carotid artery of hypercholesterolemic Yucatan microswine. Atherosclerotic lesions at the common carotid artery junction and ascending pharyngeal artery were induced in hypercholesterolemic Yucatan microswine at 5-6 months of age with balloon angioplasty. LPS or oxLDL were administered intraluminally at the site of injury after occluding the arterial flow temporarily. Pre-intervention ultrasound (US), angiography, and optical coherence tomography (OCT) were done at baseline and just before euthanasia to assess post-op parameters. The images from the US, OCT, and angiography in the LPS and the oxLDL-treated group showed increased plaque formation with features suggestive of unstable plaque, including necrotic core, thin fibrous caps, and a signal poor region more with oxLDL compared to LPS. Histomorphology of the carotid artery tissue near the injury corroborated the presence of severe lesions in both LPS and oxLDL-treated pigs but more in the oxLDL group. Vascular smooth muscle and endothelial cells treated with LPS and oxLDL showed increased folds changes in mRNA transcripts of the biomarkers of inflammation and plaque vulnerability compared to untreated cells. Collectively, the results suggest that angioplasty-mediated intimal injury of the carotid arteries in atherosclerotic swine with local administration of LPS or ox-LDL induces vulnerable plaques compared to angioplasty alone and oxLDL is relatively more potent than LPS in inducing vulnerable plaque