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Vessel Diameter (vessel + diameter)
Kinds of Vessel Diameter Selected AbstractsCerebral Thrombosis And Microcirculation Of The Rat During The Oestrous Cycle And After OvariectomyCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1-2 2002H Ono SUMMARY 1. The effects of oestrogen on thrombogenesis and the cerebral microcirculation of the female rat were studied during the oestrous cycle and after ovariectomy. 2. Serum levels of oestradiol (E2) and plasma concentrations of nitric oxide (NO) metabolites were significantly greater at pro-oestrus than at dioestrus. Blood vessel diameter, mean red cell velocity, wall shear rate and blood flow at pro-oestrus were significantly higher than at dioestrus. Thrombotic tendency, assessed using a He,Ne laser-induced thrombosis model, was significantly decreased at pro-oestrus compared with dioestrus. 3. The long-term deprivation of oestrogen by ovariectomy significantly depressed serum levels of E2 and plasma concentrations of NO metabolites. Thrombotic tendency was significantly increased 4 weeks after ovariectomy. Vessel diameter, mean red cell velocity, wall shear rate and blood flow in pial arterioles were significantly reduced after ovariectomy. 4. Exogenous administration of oestrogen (17,-oestradiol) after surgery reversed the increased thrombotic tendency mediated by ovariectomy. 5. These results strongly indicate that oestrogen mediates beneficial effects on the cerebral microcirculation and moderates cerebral thrombotic mechanisms in the female rat. [source] Changes in hepatic venous morphology with cirrhosis on MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2009Yang Zhang MD Abstract Purpose To identify changes in vascular morphology on magnetic resonance imaging (MRI) in patients with cirrhosis and to compare these findings to liver donors. Materials and Methods Patients undergoing liver transplantation with biopsy-proven cirrhosis (n = 74) and liver donor candidates (n = 85) underwent dynamic gadolinium-enhanced 3D MR at 1.5T. Vessel diameters were measured independently by three radiologists and features of cirrhosis were identified and correlated with cirrhosis. Results Hepatic veins were smaller in patients with cirrhosis (4.9, 4.5, and 5.0 mm for right, middle, and left vs. 9.9, 7.6, and 8.9 mm in donors, P , 0.001) and were negatively correlated with cirrhosis (P < 0.001). Right hepatic vein (RHV) <5 mm diagnosed cirrhosis with 59% sensitivity and 99% specificity; the sensitivity and specificity were 88% and 85% for RHV <7 mm. Main portal vein was minimally larger in cirrhosis, 14 versus 12 mm (P < 0.001) in donors. Right portal veins were smaller in cirrhotic patients, 6.5 and 6.2 mm compared to 8.4 and 7.6 mm (P , 0.001), respectively, in donors. Conclusion Vascular features of cirrhosis include small hepatic veins, minimally enlarged main portal vein, and small intrahepatic portal veins; these features may facilitate identification of cirrhosis. J. Magn. Reson. Imaging 2009;29:1085,1092. © 2009 Wiley-Liss, Inc. [source] 2325: Dynamic retinal vessel analysis , how different parameters create the whole pictureACTA OPHTHALMOLOGICA, Issue 2010I LANZL Purpose Dynamic vessel analysis is usually associated with the observation of the reaction of retinal vessels to a defined stimulus. The data which is generated this way may be further analysed with respect to the dynamic unstimulated and stimulated vessel behaviour. Assessment of different parameters may highlight different aspects of the underlying disease. Methods Vessel diameters of retinal vessel segments were assessed by Dynamic Vessel Analyzer (DVA) in healthy volunteers of different age groups and patients with diabetes, glaucoma and systemic hypertension. Mathematical analysis of unstimulated vessels was used to describe vessel wall characteristics. Methods of signal analysis including Fourier Transformation, spectral filtration, auto- and cross correlation were applied to evaluate characteristic oscillations and pulse wave propagation along the vessel. Results Characteristic different vessel behaviour and vessel wall conformation are obtained by dynamic quantitative evaluations from the unstimulated vessels in physiologic aging and disease. Conclusion Dynamic vessel analysis includes information which may lead to further understanding of the vascular status and underlying disease pathology. It is also feasible to assess pulse wave velocities in retinal arterioles und thus clinically characterize the elasticity of the upstream vasculature in health and disease. [source] Long-Pulsed Dye Laser Treatment for Facial Telangiectasias and Erythema: Evaluation of a Single Purpuric Pass versus Multiple Subpurpuric PassesDERMATOLOGIC SURGERY, Issue 8 2005Shilesh Iyer MD Background and Objective. Subpurpuric treatments with the pulsed dye laser can be effective for treatment of vascular lesions, although less so than when purpuric fluences are used. Increased efficacy may be achieved by performing multiple passes at the time of treatment. We performed a split-face bilateral paired comparison of multiple low-fluence subpurpuric passes compared with a single high-fluence purpuric pass in the treatment of facial telangiectasias. Materials and Methods. Nine patients were included in the study. One cheek was chosen to be treated with four passes of a nonpurpuric fluence, and the contralateral cheek was treated with a single purpuric pass. Reductions in vessel density, diameter, arborization, and background erythema were evaluated 3 weeks after treatment. Results. We found a 43.4% reduction in surface area covered by telangiectasias on the cheek treated with a single purpuric pass compared with 35.9% on the cheek treated with four subpurpuric passes. The purpuric fluences produced greater reduction in vessel diameter and arborization, whereas the subpurpuric protocol was more effective in reducing background erythema. Purpuric fluences were also noted to produce more significant edema and transient hyperpigmentation in one patient. Conclusion. The multipass subpurpuric approach to treatment with the pulsed dye laser is both cosmetically acceptable and effective, although purpuric treatments may be required to effectively eliminate larger-caliber, more highly networked vessels. [source] Post-challenge glucose predicts coronary atherosclerotic progression in non-diabetic, post-menopausal women,DIABETIC MEDICINE, Issue 10 2007P. B. Mellen Abstract Aims, We sought to determine whether fasting or post-challenge glucose were associated with progression of coronary atherosclerosis in non-diabetic women. Methods, We performed a post-hoc analysis of 132 non-diabetic women who underwent 75-g oral glucose tolerance testing. The primary outcome of interest was progression of atherosclerosis determined by baseline and follow-up coronary angiography, a mean of 3.1 ± 0.9 years apart. We analysed the association of change in minimal vessel diameter (,MD) by quartile of fasting and post-challenge glucose using mixed models that included adjustment for age, systolic blood pressure, total : high-density lipoprotein cholesterol ratio, current smoking, lipid-lowering and anti-hypertensive medication use and other covariates. Results, At baseline, participants had a mean age of 65.7 ± 6.7 years and a mean body mass index of 27.9 ± 8.5 kg/m2. Although there were no significant differences in atherosclerotic progression by fasting glucose category (P for trend across quartiles = 0.99), there was a significant inverse association between post-challenge glucose and ,MD (in mm) (Q1 : 0.01 ± 0.03; Q2 : 0.08 ± 0.03; Q3 : 0.13 ± 0.03; Q4 : 0.11 ± 0.03; P for trend = 0.02). Conclusions, In post-menopausal women without diabetes, post-challenge glucose predicts angiographic disease progression. These findings suggest that even modest post-challenge hyperglycaemia influences the pathogenesis of atherosclerotic progression. [source] Interspecific relationships among growth, mortality and xylem traits of woody species from New ZealandFUNCTIONAL ECOLOGY, Issue 2 2010Sabrina E. Russo Summary 1.,Wood density is considered a key functional trait influencing the growth and survival of woody plants and has been shown to be related to a slow,fast rate-of-living continuum. Wood density is, however, an emergent trait arising from several vascular properties of wood, including the diameter and frequency of xylem conduits. 2.,We aimed to test the hypotheses that there is a set of inter-related trade-offs linked to the different functions of wood, that these trade-offs have direct consequences for tree growth and survival and that these trade-offs underlie the observed correlations between wood density and demographic rates. We evaluated the covariation between xylem anatomical traits among woody species of New Zealand and whether that covariation had the potential to constrain variation in wood density and demographic rates. 3.,Several xylem traits were strongly correlated with each other, but wood density was not correlated with any of them. We also found no significant relationships between wood density and growth or mortality rate. Instead, growth was strongly related to xylem traits associated with hydraulic capacity (conduit diameter and a conductivity index) and to maximum height, whereas mortality rate was strongly correlated only with maximum height. The diameter and frequency of conduits exhibited a significant negative relationship, suggesting a trade-off, which restricted variation in wood density and growth rate, but not mortality rate. 4.,Our results suggest, for woody species in New Zealand, that growth rate is more closely linked to xylem traits determining hydraulic conductance, rather than wood density. We also found no evidence that denser woods conferred higher survival, or that risk of cavitation caused by wide conduits increased mortality. 5.,In summary, we found little support for the idea that wood density is a good proxy for position along a fast,slow rate-of-living continuum. Instead, the strong, negative relationship between vessel diameter and frequency may constrain the realized diversity of demographic niches of tree species in New Zealand. Trade-offs in function therefore have the potential to shape functional diversity and ecology of forest communities by linking selection on structure and function to population-level dynamics. [source] Effect Of Height On Tree Hydraulic Conductance Incompletely Compensated By Xylem TaperingFUNCTIONAL ECOLOGY, Issue 2 2005S. ZAEHLE Summary 1The hydraulic limitation theory proposes that the decline of forest productivity with age is a consequence of the loss of whole-plant and leaf-specific hydraulic conductance with tree height caused by increased friction. Recent theoretical analyses have suggested that tapering (the broadening of xylem vessel diameter from terminal branches to the base of the stem) could compensate completely for the effect of tree height on hydraulic conductance, and thus on tree growth. 2The data available for testing this hypothesis are limited, but they do not support the implication that whole-tree and leaf-specific hydraulic conductance are generally independent of tree height. Tapering cannot exclude hydraulic limitation as the principle mechanism for the observed decline in growth. 3Reduction of the leaf-to-sapwood area ratio, decreased leaf water potential, loss of leaf-cell turgor, or osmotic adjustments in taller trees could reduce the effect of increased plant hydraulic resistance on stomatal conductance with height. However, these mechanisms operate with diminishing returns, as they infer increased costs to the tree that will ultimately limit tree growth. To understand the decline in forest growth, the effects of these acclimation mechanisms on carbon uptake and allocation should be considered. [source] The Impact of Diabetes Mellitus on Two-Year Mortality Following Contemporary Percutaneous Coronary Intervention: Implications for Revascularization PracticeJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2009M. ANDRON M.D., M.R.C.P. Objective:To assess the impact of diabetes on 2-year mortality in current PCI practice. Background:In patients with coronary artery disease undergoing revascularization, diabetes mellitus is associated with higher mortality. Methods:A retrospective analysis was done of all patients undergoing PCI at our tertiary center between January 2000 and December 2004. There were 6,160 PCI procedures performed in 5,759 patients who received at least one stent. Of these patients, 801 (13.9%) were diabetic and 4,958 (86.1%) were nondiabetic. The primary outcome measure of the study was all-cause mortality. All patients were followed up for a period of 2 years. Multivariate logistic regression analysis was used to test for a potential independent association between diabetic status and follow-up mortality. Results:Before adjustment, a trend toward higher mortality was observed in diabetic patients compared to non-diabetics at 1 year (3.2% vs 2.4%) and 2 years (5.1% vs 3.8%), P = 0.12. Independent predictors for mortality were increasing age, renal dysfunction, peripheral vascular disease, NYHA class >2, urgent PCI, treating left main stem lesions, vessel diameter , 2.5 mm, and 3-vessel disease. The use of drug-eluting stent was associated with a reduction in mortality. Diabetes was found to have no independent impact on mortality following PCI (odds ratio = 1.08; 95% confidence intervals = 0.73,1.60; P = 0.71). Conclusion:The presence of diabetes was not an independent predictor of mortality following PCI. A diabetic patient that does not require insulin treatment and has no evidence of macro- or microvascular diabetic disease could enjoy a PCI outcome similar to nondiabetic subjects. [source] Flow-Reversal Device for Cerebral Protection During Carotid Artery Stenting,Acute and Long-Term ResultsJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 1 2006KASJA RABE M.D. Objective: Several types of cerebral (embolic) protection devices have been used in patients undergoing carotid stenting. This study assessed results achieved with a flow-reversal system. Method: Carotid stenting was performed in 56 patients (mean age, 68 ± 9 years). The mean percentage of stenosis was 77%± 10%. During the procedure, cerebral protection was achieved by means of balloon occlusion of the common and external carotid artery with use of a Parodi Anti-Emboli System. The patients' neurologic status was assessed during the intervention; at discharge; 1, 6, and 12 months after the procedure; and yearly thereafter. Results: The procedure was technically successful in all cases. One patient had a minor stroke 6 hours after the intervention. No major strokes, deaths, or myocardial infarctions occurred. During long-term follow-up (to 40 months), 2 patients died of a secondary complication after intracerebral bleeding and stroke and 1 died as a result of ventricular fibrillation. Restenosis did not exceed 50% of vessel diameter in any patient. Conclusions: The acute results indicate that proximal occlusion and flow reversal for cerebral protection during carotid stenting is a safe and effective method. The low restenosis and complication rate during long-term follow-up is in accordance with other series of carotid angioplasty and shows that the occlusion balloons do not cause any long-term side effects. [source] Femur window,a new approach to microcirculation of living bone in situJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2005N. Hansen-Algenstaedt Abstract Background: The processes of osteogenesis, bone remodelling, fracture repair and metastasis to bone are determined by complex sequential interactions involving cellular and microcirculatory parameters. Consequently studies targeting the analysis of microcirculatory parameters on such processes should mostly respect these complex conditions. However these conditions could not yet be achieved in vitro and therefore techniques that allow a long-term observation of functional and structural parameters of microcirculation in bone in vivo at a high spatial resolution are needed to monitor dynamic events, such as fracture healing, bone remodelling and tumor metastasis. Methods: We developed a bone chamber implant (femur window) for long-term intravital microscopy of pre-existing bone and its microcirculation at an orthotopic site in mice preserving the mechanical properties of bone. After bone chamber implantation vascular density, vessel diameter, vessel perfusion, vascular permeability and leukocyte-endothelial interactions (LEIs) in femoral bone tissue of c57-black mice (n = 11) were measured quantitatively over 12 days using intravital fluorescence microscopy. Furthermore a model for bone defect healing and bone metastasis in the femur window was tested. Results: Microvascular permeability and LEIs showed initially high values after chamber implantation followed by a significant decrease to a steady state at day 6 and 12, whereas structural parameters remained unaltered. Bone defect healing and tumor growth was observed over 12 and 90 days respectively. Conclusion: The new femur window design allows a long-term analysis of structural and functional properties of bone and its microcirculation quantitatively at a high spatial resolution. Altered functional parameters of microcirculation after surgical procedures and their time dependent return to a steady state underline the necessity of long-term observations to achieve unaltered microcirculatory parameters. Dissection of the complex interactions between bone and microcirculation enables us to evaluate physiological and pathological processes of bone and may give new insights especially in dynamic events e.g. fracture healing, bone remodeling and tumor metastasis. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Effects of 5-HT2A receptor antagonist on blood flow in chronically compressed nerve rootsJOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 4 2004Miho Sekiguchi Abstract Neurogenic intermittent claudication (NIC) can be caused by compression of the cauda equina by spinal stenosis and is a major clinical problem. A reduction of blood flow is an important mechanism for inducing NIC and may be caused by a vasoconstrictive effect mediated by the serotonin 5-HT2A receptor in chronic cauda equina compression lesions. This study assessed the effects of the 5-HT2A receptor antagonist on nerve vasculature in chronically compressed nerve roots. A plastic balloon was placed under the lamina of L7 and inflated to 10 mmHg and left for 1 week in several cauda equina compression models. All experimental animals received an acute administration of serotonin. One group received sarpogrelate hydrochloride (5-HT2A receptor antagonist: 5-HTRA) before administration of serotonin, and another group was administered 5-HTRA after administration of serotonin. Diameters and blood flow in the vasculature of S2 or S3 nerve roots were measured after injection of serotonin. In animals without compression of the cauda equina (sham), blood vessels contracted and the blood flow was reduced after administration of serotonin. In sham and compression animals receiving both serotonin and 5-HTRA, blood vessel diameter was not reduced and was significantly larger than that in the compression group receiving only serotonin (p < 0.05). Likewise, the blood flow was not reduced in sham and compression animals receiving serotonin and 5-HTRA and was significantly greater in the compression group treated only with serotonin. 5-HTRA inhibited vasoconstriction and the reduction of blood flow in chronically compressed nerve roots challenged with serotonin. This fact suggests that 5-HTRA might be effective at improving blood flow in chronically compressed nerve roots in patients with spinal canal stenosis and changes in circulation levels of serotonin. [source] Functional traits of woody plants: correspondence of species rankings between field adults and laboratory-grown seedlings?JOURNAL OF VEGETATION SCIENCE, Issue 3 2003J.H.C. Cornelissen Castroviejo et al. (1986,2000); Stace (1991) Abstract. Research into interspecific variation in functional traits is important for our understanding of trade-offs in plant design and function, for plant functional type classifications and for understanding ecosystem responses to shifts in species composition. Interspecific rankings of functional traits are a function of, among other factors, ontogenetic or allometric development and environmental effects on phenotypes. For woody plants, which attain large size and long lives, these factors might have strong effects on interspecific trait rankings. This paper is the first to test and compare the correspondence of interspecific rankings between laboratory grown seedlings and field grown adult plants for a wide range of functional leaf and stem traits. It employs data for 90 diverse woody and semiwoody species in a temperate British and a (sub)Mediterranean Spanish flora, all collected according to a strict protocol. For 12 out of 14 leaf and stem traits we found significant correlations between the species ranking in laboratory seedlings and field adults. For leaf size and maximum stem vessel diameter > 50 % of variation in field adults was explained by that in laboratory seedlings. Two important determinants of plant and ecosystem functioning, specific leaf area and leaf N content, had only 27 to 36 and 17 to 31 % of variation, respectively, in field adults explained by laboratory seedlings, owing to subsets of species with particular ecologies deviating from the general trend. In contrast, interspecific rankings for the same traits were strongly correlated between populations of field adults on different geological substrata. Extrapolation of interspecific trait rankings from laboratory seedlings to adult plants in the field, or vice versa, should be done with great caution. [source] Improvement of port wine stain laser therapy by skin preheating prior to cryogen spray cooling: A numerical simulationLASERS IN SURGERY AND MEDICINE, Issue 2 2006Wangcun Jia PhD Abstract Background and Objectives Although cryogen spray cooling (CSC) in conjunction with laser therapy has become the clinical standard for treatment of port wine stain (PWS) birthmarks, the current approach does not produce complete lesion blanching in the vast majority of patients. The objectives of this study are to: (1) experimentally determine the dynamic CSC heat flux when a skin phantom is preheated, and (2) numerically study the feasibility of using skin preheating prior to CSC to improve PWS laser therapeutic outcome. Study Design/Materials and Methods A fast-response thin-foil thermocouple was used to measure the surface temperature and thus heat flux of an epoxy skin phantom during CSC. Using the heat flux as a boundary condition, PWS laser therapy was simulated with finite element heat diffusion and Monte Carlo light distribution models. Epidermal and PWS blood vessel thermal damage were calculated with an Arrhenius-type kinetic model. Results Experimental results show that the skin phantom surface can be cooled to a similar minimum temperature regardless of the initial temperature. Numerical simulation indicates that upon laser irradiation, the epidermal temperature increase is virtually unaffected by preheating, while higher PWS blood vessel temperatures can be achieved. Based on the damage criterion we assumed, the depth and maximum diameter of PWS vessels that can be destroyed irreversibly with skin preheating are greater than those without. Conclusions Skin preheating prior to CSC can maintain epidermal cooling while increasing PWS blood vessel temperature before laser irradiation. Numerical models have been developed to show that patients may benefit from the skin preheating approach, depending on PWS vessel diameter and depth. Lasers Surg. Med. 38:155,162, 2006. © 2006 Wiley-Liss, Inc. [source] Intravascular low-power laser irradiation after coronary stenting: Long-term follow-upLASERS IN SURGERY AND MEDICINE, Issue 3 2001Ivan K. De Scheerder MD Abstract Background and Objective A high restenosis rate remains a limiting factor for percutaneous transluminal coronary angioplasty and stenting. The objective of this study was to evaluate the effect of intravascular red laser therapy (IRLT) on restenosis after stenting procedures in de novo lesions. Study Design/Materials and Methods A total of 68 consecutive patients were treated with IRLT in conjunction with coronary stenting procedures. Mean lesion length was 16.5,±,2.4,mm. Reference vessel diameter (RVD) and pre-minimal lumen diameter (MLD) were 2.90,±,0.15,mm and 1.12,±,0.26,mm, respectively. Results After treatment, MLD was 2.76,±,0.32 mm with no procedural complications or in-hospital adverse events. Angiographic follow-up (n,=,61) revealed restenosis in nine patients (14.7%) with rate by artery size of >,3 mm (n,=,21) 0%; 2.5,3.0 mm (n,=,28) 14.2%; and <,2.5 mm (n,=,12) 41.6%. Conclusion Intravascular red light therapy is safe, feasible, and reduces expected restenosis rate after coronary stenting. Lasers Surg. Med. 28:212,215, 2001. © 2001 Wiley-Liss, Inc. [source] Inhibition of Canonical Wnt Signaling Increases Microvascular Hemorrhaging and Venular Remodeling in Adult RatsMICROCIRCULATION, Issue 5 2010JASON T. GLAW Microcirculation (2010) 17, 348,357. doi: 10.1111/j.1549-8719.2010.00036.x Abstract Objective:, The canonical Wnt signaling pathway, heavily studied in development and cancer, has recently been implicated in microvascular growth with the use of developmental and in vitro models. To date, however, no study exists showing the effects of perturbing the canonical Wnt pathway in a complete microvascular network undergoing physiological remodeling in vivo. Our objective was to investigate the effects of canonical Wnt inhibition on the microvascular remodeling of adult rats. Methods:, Canonical Wnt inhibitor DKK-1, Wnt inhibitor sFRP-1, BSA or saline was superfused onto the exteriorized mesenteric windows of 300 g adult female Sprague-Dawley rats for 20 minutes. Three days following surgery, mesenteric windows were imaged intravitally and harvested for immunofluorescence staining with smooth muscle alpha-actin and BRDU. Results:, We observed prominent differences in the response of the mesenteric microvasculature amongst the various treatment groups. Significant increases in hemorrhage area, vascular density, and draining vessel diameter were observed in windows treated with Wnt inhibitors as compared to control-treated windows. Additionally, confocal imaging analysis showed significant increases in proliferating cells as well as evidence of proliferating smooth muscle cells along venules. Conclusions:, Together, our results suggest that canonical Wnt inhibition plays an important role in microvascular remodeling, specifically venular remodeling. [source] A Theoretical Model for the Myogenic Response Based on the Length,Tension Characteristics of Vascular Smooth MuscleMICROCIRCULATION, Issue 4 2005BRIAN E. CARLSON ABSTRACT Objective: A theoretical model is developed to describe the myogenic response of resistance vessels to changes in intravascular pressure, based on a consideration of the active and passive length,tension characteristics of vascular smooth muscle (VSM). The dependence of model parameters on vessel diameter is examined. Methods: The vessel wall is represented mechanically as a nonlinear passive component in parallel with an active contractile component. The level of VSM tone is assumed to have a sigmoidal dependence on circumferential wall tension or stress. Model parameters are optimized for each of 18 independent experimental data sets previously obtained using pressure or wire myograph systems. Results: Close fits between model predictions and experimental data are found in each case. An alternative formulation in which VSM tone depends on circumferential wall stress is found also to be consistent with available data. Significant trends in model parameters as a function of diameter are found. Conclusions: The results support the hypothesis that circumferential tension or stress in the wall provides the signal for myogenic responses. The model provides a basis for simulating steady-state myogenic responses in vascular networks containing a range of vessel diameters. [source] Regulation of In Situ Skeletal Muscle Arteriolar Tone: Interactions Between Two ParametersMICROCIRCULATION, Issue 6 2002JEFFERSON C. FRISBEEArticle first published online: 26 JAN 2010 ABSTRACT Objective: The growing understanding of the complexity of mechanisms regulating arteriolar tone demands that a systematic determination of how these processes interact to alter diameter be undertaken. This study examined how five mediators of skeletal muscle distal arteriolar tone [adenosine concentration, oxygen content, ,-adrenergic activation (norepinephrine), intravascular pressure and wall shear rate], taken two parameters at a time, interact to regulate vessel diameter. Methods: The reactivity of distal arterioles of in situ rat cremaster muscle after alterations in each of the above mediators was assessed. In addition, arteriolar responses to all two-parameter combinations were evaluated to determine the effect of altered environment on vascular reactivity to stimuli. Results: Arteriolar dilation to adenosine was unaltered by changes in other parameters. In contrast, wall shear rate-induced arteriolar dilation was impaired by 60,88% after increases in the other parameters. Myogenic reactivity was reduced by 28% with elevated O2 and by 65% with norepinephrine (because of vessel closure) and was impaired by 89% with elevated adenosine. O2 -induced arteriolar reactivity was impaired by 56% with increased adenosine and by 44% with increased norepinephrine concentration but was largely unaffected by elevated intravascular pressure. Adrenergic reactivity was attenuated with elevated intravascular pressure (by 69%) and O2 (by 54%) because of vessel closure but was unaltered with elevated adenosine. Conclusions: These data suggest that (1) individual mediators contributing to the regulation of arteriolar tone exist within a hierarchy of importance and (2) mechanisms regulating arteriolar tone can be impacted by unidentified alterations in other processes. Ongoing investigation into interactions between multiple processes regulating arteriolar tone will allow for a more integrated understanding of how microvessels regulate their diameter. [source] Reverse flow facial artery as recipient vessel for perforator flapsMICROSURGERY, Issue 6 2009D.D.S., Frank Hölzle M.D., Ph.D. In perforator flaps, anastomosis between flap and recipient vessels in the neck area is often difficult due to small vessel diameter and short pedicle. The aim of this study was to investigate whether the retrograde flow of the distal, paramandibular part of the facial artery would provide sufficient pressure and size to perfuse perforator flaps. Before and after occlusion of the contralateral facial artery, retrograde and anterograde arterial pressure was measured on both sides of the facial artery in 50 patients. The values were compared with the mean systemic arterial pressure. Diameters of facial arteries in the paramandibular region and perforator flap vessels were evaluated by morphometry. Arterial pressure in the distal facial artery with retrograde flow was 76% of the systemic arterial pressure. The latter equaled approximately the anterograde arterial pressure in the proximal end of the facial artery. Mean arterial pressure of the facial arteries decreased after proximal occlusion of the contralateral facial artery, which was not significant (P = 0.09). Mean diameter of the distal facial arteries in the mandibular region was 1.6 mm (range 1.3,2.2 mm; standard deviation 0.3 mm; n = 50), that of the perforator flap arteries 1.3 mm (0.9,2.6 mm; 0.4 mm; n = 20). Facial arteries, based on reverse flow, successfully supported all 20 perforator flaps. Retrograde pulsatile flow in the distal facial artery sustains perforator flaps even if the contralateral facial artery is occluded. Proximity of the distal facial arteries to the defect compensates for short pedicles. Matching diameters of the arteries are ideal for end-to-end anastomosis. © 2009 Wiley-Liss, Inc. Microsurgery, 2009. [source] What You See (Sonographically) Is What You Get: Vein and Patient Characteristics Associated With Successful Ultrasound-guided Peripheral Intravenous Placement in Patients With Difficult AccessACADEMIC EMERGENCY MEDICINE, Issue 12 2009Nova L. Panebianco MD Abstract Objectives:, Ultrasound (US) has been shown to facilitate peripheral intravenous (IV) placement in emergency department (ED) patients with difficult IV access (DIVA). This study sought to define patient and vein characteristics that affect successful US-guided peripheral IV placement. Methods:, This was a prospective observational study of US-guided IV placement in a convenience sample of DIVA patients in an urban, tertiary care ED. DIVA patients were defined as having any of the following: at least two failed IV attempts or a history of difficult access plus the inability to visualize or palpate any veins on physical exam. Patient characteristics (demographic information, vital signs, and medical history) were collected on enrolled patients. The relationships between patient characteristics, vein depth and diameter, US probe orientation, and successful IV placement were analyzed. Results:, A total of 169 patients were enrolled, with 236 attempts at access. Increasing vessel diameter was associated with a higher likelihood of success (odds ratio [OR] = 1.79 per 0.1-cm increase in vessel diameter, 95% confidence interval [CI] = 1.37 to 2.34). Increasing vessel depth did not affect success rates (OR = 0.96 per 0.1-cm increase of depth, 95% CI = 0.89 to 1.04) until a threshold depth of 1.6 cm, beyond which no vessels were successfully cannulated. Probe orientation and patient characteristics were unrelated to success. Conclusions:, Success was solely related to vessel characteristics detected with US and not influenced by patient characteristics or probe orientation. Successful DIVA was primarily associated with larger vessel, while vessel depth up to >1.6 cm and patient characteristics were unrelated to success. Clinically, if two vessels are identified at a depth of <1.6 cm, the larger diameter vessel, even if comparatively deeper, should yield the greatest likelihood of success. [source] The spatial pattern of air seeding thresholds in mature sugar maple treesPLANT CELL & ENVIRONMENT, Issue 9 2005BRENDAN CHOAT ABSTRACT Air seeding threshold (Pa) of xylem vessels from current year growth rings were measured along the vertical axis of mature sugar maple trees (Acer saccharum Marsh.), with sampling points in primary leaf veins, petioles, 1-, 3-, and 7-year-old branches, large branches, the trunk and roots. The air seeding threshold was taken as the pressure required to force nitrogen gas through intervessel pit membranes. Although all measurements were made on wood produced in the same year, Pa varied between different regions of A. saccharum, with distal organs such as leaves and petioles having lower Pa than basal regions. Mean (SE) Pa ranged from 1.0 (± 0.1) MPa in primary leaf veins to 4.8 (± 0.1) MPa in the main trunk. Roots exhibited a Pa of 2.8 (± 0.2) MPa, lower than all other regions of the tree except leaf veins and petioles. Mean xylem vessel diameter increased basipetally, with the widest vessels occurring in the trunk and roots. Within the shoot, wider vessels had greater air seeding thresholds, contrasting with trends previously reported. However, further experimentation revealed that differences in Pa between regions of the stem were driven by the presence of primary xylem conduits, rather than differences in vessel diameter. In 1-year-old branches, Pa was significantly lower in primary xylem vessels than in adjacent secondary xylem vessels. This explained the lower values of Pa measured in petioles and leaf veins, which possessed a greater ratio of primary xylem to secondary xylem than other regions. The difference in Pa between primary and secondary xylem was attributed to the greater area of primary cell wall (pit membrane) exposed in primary xylem conduits with helical or annular thickening. [source] Effect of impeller clearance on liquid flow within an unbaffled vessel agitated with a forward,reverse rotating impellerTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009Masanori Yoshida Abstract For an unbaffled agitated vessel with an unsteadily forward,reverse rotating impeller whose rotation proceeds with repeated acceleration, deceleration, and stop,reverse processes, liquid flow was studied through visualisation and measurement using particle tracking velocimetry (PTV). A disk turbine impeller with six flat blades was used with varied height settings. The impeller clearance and its forward,reverse rotation cycle characterised the impeller region flow: the radially outward flow in the deceleration process for the larger clearance relative to the vessel diameter of 1/3, and the axially downward flow in the acceleration process for the smaller clearance relative to the vessel diameter of 1/8. The flow patterns within the vessel resulting from the impeller's larger and smaller clearances were outlined, respectively, by double loops and a single loop of circulation, resembling the pattern produced by unidirectionally rotating turbine-type impellers. The discharge flow was revealed to contain a comparable level of periodic circumferential velocity component, irrespective of the impeller clearance. On a étudié l'écoulement liquide par visualisation et mesure en utilisant la vélocimétrie avec poursuite de trajectoire pour une cuve non compartimentée et agitée avec un agitateur rotatif avant-arrière non stable dont la rotation est composée de périodes répétées d'accélération, de ralentissement et d'arrêt-marche arrière. Un agitateur à six pales plates a été utilisé avec quatre réglages de hauteur différents. Le dégagement de l'agitateur et son cycle de rotation avant-arrière caractérisaient l'écoulement liquide dans la région de l'agitateur : l'écoulement radial vers l'extérieur dans le processus de décélération pour le dégagement le plus important par rapport au diamètre de la cuve de 1/3 et l'écoulement axial vers le bas dans le processus d'accélération pour le dégagement le plus petit par rapport au diamètre de la cuve de 1/8. Les modèles d'écoulement intérieurs de la cuve résultant du plus grand et du plus petit dégagements de l'agitateur ont été décrits, respectivement, par des doubles boucles et une simple boucle de circulation, ce qui ressemble au modèle produit par des agitateurs à hélice unidirectionnels. On a révélé que l'écoulement de sortie contenait un niveau comparable de vélocité périodique périphérique, indépendamment du dégagement de l'agitateur. [source] Experimental Evaluation of a New Antithrombogenic Stent Using Ion Beam Surface ModificationARTIFICIAL ORGANS, Issue 6 2009Yoichi Sugita Abstract A new antithrombogenic stent using ion beam surface modification nanotechnology was evaluated. The ion stent is being developed to inhibit acute and chronic stent-related thrombosis. Thirty self-expanding mesh stents were fabricated from Ti-Ni metal wires with a dimension of 4 mm (diameter) × 25 mm (length) × 0.15 mm (thickness). Twenty stents were coated with type I collagen and irradiated with a He+ ion beam at an energy of 150 keV with fluences of 1 × 1014 ions/cm2 (ion stent group). Ten stents had no treatment (non-ion stent group). The self-expanding stents were implanted into the right and left peripheral femoral arteries of 15 beagle dogs (vessel diameter approximately 3 mm) via a 6Fr catheter under fluoroscopic guidance. Heparin (100 units/kg) was administered intravenously before implantation. Following stent implantation, no antiplatelet or anticoagulant drugs were administered. The 1-month patency rate for the non-ion stent group was 10% (1/10), and for the ion stent group it was 80% (16/20) with no anticoagulant or antiplatelet drugs given after stent implantation (P = 0.0004 by Fisher's exact test). Ten stents remain patent after 2 years in vivo with no anticoagulant or antiplatelet drugs. These results indicate that He+ ion-implanted collagen-coated Ti-Ni self-expanding stents have excellent antithrombogenicity and biocompatibility. This ion stent is promising for coronary and cerebral stent applications. [source] Pulsed electrical stimulation for control of vasculature: Temporary vasoconstriction and permanent thrombosisBIOELECTROMAGNETICS, Issue 2 2008Daniel Palanker Abstract A variety of medical procedures is aimed to selectively compromise or destroy vascular function. Such procedures include cancer therapies, treatments of cutaneous vascular disorders, and temporary hemostasis during surgery. Currently, technologies such as lasers, cryosurgery and radio frequency coagulation, produce significant collateral damage due to the thermal nature of these interactions and corresponding heat exchange with surrounding tissues. We describe a non-thermal method of inducing temporary vasoconstriction and permanent thrombosis using short pulse (microseconds) electrical stimulation. The current density required for vasoconstriction increases with decreasing pulse duration approximately as t,0.25. The threshold of electroporation has a steeper dependence on pulse duration,exceeding t,0.5. At pulse durations shorter than 5,µs, damage threshold exceeds the vasoconstriction threshold, thus allowing for temporary hemostasis without direct damage to surrounding tissue. With a pulse repetition rate of 0.1,Hz, vasoconstriction is achieved approximately 1 min after the beginning of treatment in both arteries and veins. Thrombosis occurs at higher electric fields, and its threshold increases with vessel diameter. Histology demonstrated a lack of tissue damage during vasoconstriction, but vascular endothelium was damaged during thrombosis. The temperature increase does not exceed 0.1,°C during these treatments. Bioelectromagnetics 29:100,107, 2008. © 2007 Wiley-Liss, Inc. [source] Anandamide mediates hyperdynamic circulation in cirrhotic rats via CB1 and VR1 receptorsBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2006L Moezi Background and purpose: Hyperdynamic circulation and mesenteric hyperaemia are found in cirrhosis. To delineate the role of endocannabinoids in these changes, we examined the cardiovascular effects of anandamide, AM251 (CB1 antagonist), AM630 (CB2 antagonist) and capsazepine (VR1 antagonist), in a rat model of cirrhosis. Experimental approach: Cirrhosis was induced by bile duct ligation. Controls underwent sham operation. Four weeks later, diameters of mesenteric arteriole and venule (intravital microscopy), arterial pressure, cardiac output, systemic vascular resistance and superior mesenteric artery (SMA) flow were measured after anandamide, AM251 (with or without anandamide), AM630 and capsazepine administration. CB1, CB2 and VR1 receptor expression in SMA was assessed by western blot and RT-PCR. Key results: Anandamide increased mesenteric vessel diameter and flow, and cardiac output in cirrhotic rats, but did not affect controls. Anandamide induced a triphasic arterial pressure response in controls, but this pattern differed markedly in cirrhotic rats. Pre-administration of AM251 blocked the effects of anandamide. AM251 (without anandamide) increased arterial pressure and systemic vascular resistance, constricted mesenteric arterioles, decreased SMA flow and changed cardiac output in a time-dependent fashion in cirrhotic rats. Capsazepine decreased cardiac output and mesenteric arteriolar diameter and flow, and increased systemic vascular resistance in cirrhotic rats, but lacked effect in controls. Expression of CB1 and VR1 receptor proteins were increased in cirrhotic rats. AM630 did not affect any cardiovascular parameter in either group. Conclusions and implications: These data suggest that endocannabinoids contribute to hyperdynamic circulation and mesenteric hyperaemia in cirrhosis, via CB1 - and VR1-mediated mechanisms. British Journal of Pharmacology (2006) 149, 898,908. doi:10.1038/sj.bjp.0706928 [source] Influence of muscle training on resting blood flow and forearm vessel diameter in patients with chronic renal failure,BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 6 2010S. Kumar Background: Blood flow and vessel diameter are predictors of the success of vascular access procedures. This study investigated whether a simple exercise programme could influence these variables. Methods: Twenty-three patients with chronic kidney disease were prescribed a simple exercise programme for one arm only; the investigators were blinded to the patients' choice. All underwent arterial and venous duplex imaging, handgrip strength and blood pressure measurements before and 1 month after the exercise programme. Results: Twelve patients exercised their dominant and 11 their non-dominant arm. In the trained arm, the exercise programme resulted in a significant increase in handgrip strength, by a median (interquartile range) of 4 (0,8) kg (P < 0·001), and in the diameter of the brachial artery (0·2 (0·1,0·3) mm; P < 0·001), radial artery (0·3 (0·2,0·4) mm; P < 0·001), and cephalic vein (0·6 (0·4,1·2) mm in the forearm and 1·1 (0·4,1·2) mm above the elbow; P < 0·001). There was an increase in brachial artery mean velocity (3 (1,7) cm/s; P = 0·009) and peak systolic velocity (8 (1,15) cm/s; P = 0·020), despite a marginally lower systolic blood pressure (,8 (,16 to 0) mmHg; P = 0·007). There was no change in any of these parameters in the non-exercised arm. Conclusion: In patients with chronic kidney disease, forearm exercise increased blood flow and vessel diameters. This may be beneficial before vascular access formation. Copyright © 2010 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] The Extracellular Signal-Regulated Kinase Is Involved in the Effects of Sildenafil on Pulmonary Vascular RemodelingCARDIOVASCULAR THERAPEUTICS, Issue 1 2010Zhen Zeng Pulmonary hypertension is a group of diseases comprising vascular constriction and obstructive changes of the pulmonary vasculature. Phosphodiesterase type 5 inhibitors, for example, sildenafil, can alleviate vascular remodeling in the monocrotaline pulmonary hypertension model in rats. We investigate the mechanisms of sildenafil on the pulmonary vascular remodeling of pulmonary hypertension induced by monocrotaline (MCT) in rats. Thirty Sprague-Dawley rats (weighing 200,220 g) were administered with MCT abdominal cavity injection or equivalent volume of normal saline (NS) (which were treated as C group n = 10) to induce pulmonary hypertension model. Fourteen days later, 20 MCT treated rats were randomly fed with sildenafil (25mg/kg/day) or placebo as S, P group (10 rats for each group), respectively. Another 6 weeks later, mean pulmonary artery pressure (mPAP), index of right ventricular hypertrophy (RV/LV+S) of all animals were measured under general anesthesia. Pulmonary tissue was collected to investigate pathological features of pulmonary arteries and to measure protein expression of ERK1/ERK2 and MKP1. After 6 weeks, there were significant elevated mPAP and RV/LV+S in both P and S groups. The ratio of wall thickness to vessel diameter in pulmonary arteries with diameters <200 ,m were increased in both P and S groups. But the ratio of wall thickness to vessel diameter was smaller in S group than that in P group. The phosphorylation level of ERK1/ERK2 were elevated in both P and S groups, but the level of phosphorlation ERK1/ERK2 were lower in S group than that in P group. Intriguingly, the expression level of MKP1 was significantly increased in both S and P groups, while it was higher in S group than that in P group. The Sildenafil can decrease mPAP and inhibit the progress of pulmonary vascular remodeling in pulmonary hypertension rats. The ERK-MAP kinase signaling pathway might play a role during this process. [source] Left coronary artery thrombus characterized by a fully automatic three-dimensional gated reconstruction,CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 1 2009Gert A.F. Schoonenberg MSc Abstract Rotational coronary angiography and subsequent automatic modeling or reconstruction can result in clinically valuable three-dimensional (3D) representations of the coronaries. From these 3D representations information can be derived for specific coronary segments, such as lesion length, vessel diameter, bifurcation angles, and optimal viewing angles. In this case report, we highlight the characterization of a left coronary artery thrombus by a fully automatic 3D gated reconstruction. This case also shows that detailed 3D morphology of a lesion can be assessed during percutaneous coronary interventions using rotational coronary angiography and subsequent automated image processing. © 2009 Wiley-Liss, Inc. [source] Results of the multicenter first-in-man study of a novel scoring balloon catheter for the treatment of infra-popliteal peripheral arterial diseaseCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 7 2007Dierk Scheinert MD Abstract Objective: To evaluate the AngioSculpt® (ASC), a novel scoring balloon catheter designed to treat complex diffuse fibro-calcific atherosclerotic lesions and avoid device slippage during deployment, in patients with infra-popliteal disease. Methods: The ASC incorporates a flexible nitinol scoring element containing three or more spiral struts which encircle a minimally compliant balloon to create focal concentration of the dilating force. Patients scheduled for percutaneous intervention of infra-popliteal arteries or planned amputation and with a reference vessel diameter of 1.5,3.5 mm were included in the study. Results: A total of 42 patients and 56 lesions were treated at five sites. Of these, 38 patients (90.5%) presented with critical limb ischemia (Rutherford Class , 4). The ASC was successfully deployed in 98.2% (55/56) of lesions attempted and was used as primary therapy without stenting in 89.3% (50/56). Lesion morphology was complex, including moderate/severe calcification in 73%, lesion length 33.9 ± 42.2 mm, bifurcation in 26.8%, and ostial in 12.5%. There was no significant device slippage and no perforations. Post-ASC dissections occurred in only six (10.7%) lesions and were minor or resolved with stenting. In 13 patients initially referred for amputation, ASC treatment resulted in limb salvage. Conclusions: The ASC is highly effective in a broad range of complex lesion morphologies, in most cases as stand-alone therapy, is associated with a very low complication rate and avoids device slippage during deployment. Additional studies are planned to assess the long term efficacy of this promising new technology. © 2007 Wiley-Liss, Inc. [source] Long-term outcomes of bifurcation lesions after implantation of drug-eluting stents with the "mini-crush technique"CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 7 2007Alfredo R. Galassi MD, FSCAI Abstract Objectives: To evaluate clinical and angiographic long-term outcome of "the mini-crush" technique for treating bifurcation lesions. Background: Despite proven efficacy of drug-eluting stent (DES) within most lesions subsets, bifurcation lesions continue to exhibit high restenosis rate using current DES stenting technique. Methods: We report a new stenting technique which was employed in 45 consecutive patients (52 lesions) between April 2004 and July 2005 to treat true bifurcation lesions using DES in both branches. Results: Using this technique procedural success was obtained in 100% of cases, without complications and with excellent angiographic result in 96.1% and 98.1% of main vessel and side branch. Preprocedure reference vessel diameter and minimal lumen diameter (MLD) were 2.68 ± 0.48 and 0.90 ± 0.55 mm for the main branch, respectively and 2.28 ± 0.34 and 1.14 ± 0.47 mm for the side branch, respectively. Postprocedure MLD was 2.56 ± 0.39 mm for the main branch and 2.16 ± 0.29 mm for the side branch. There were no in-hospital major adverse cardiac events (MACE). At 72 days after procedure there was one case of side branch stent thrombosis (2.2%), which resulted in non Q-wave MI. Angiographic follow up was obtained in 100% of patients at 7.5 ± 1.3 months. Target lesion revascularization (TLR) was 12.2%; no death and Q-wave MI were observed; reference vessel diameter and MLD for the main branch were 2.79 ± 0.51 and 1.99 ± 0.65 mm respectively and for the side branch 2.28 ± 0.40 and 1.63 ± 0.48 mm respectively. Restenosis rate in the main branch was 12.2% while in the side branch was 2.0%. Conclusions: In-hospital outcome indicates that the mini-crush technique for bifurcation lesions with DES can be easily performed. It provides very low total MACE rate and restenosis at 8-month follow-up. These results confirmed the advantage of this specific technique to give complete coverage of the ostium of the side branch using two stents technique. © 2007 Wiley-Liss, Inc. [source] Use of Taxus polymer-coated paclitaxel-eluting stents for treatment of in-stent restenosis in real world patients: Results of clinical and angiographic follow-up at six months in a single-center registryCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 3 2006Victor Y. Lim MRCP Abstract Objective:To evaluate the safety and efficacy of Taxus paclitaxel-eluting stents in a real world group of unselected patients with coronary in-stent restenosis (ISR) lesions. Methods: This is a prospective single-center registry of a consecutive series of 94 patients with 104 ISR lesions, without previous brachytherapy, over a period of 1 year. Quantitative coronary angiographic analyses were performed at baseline and at 6-month angiographic follow-up. Clinical follow-up were obtained at 6 months. Results:Pre-intervention mean reference vessel diameter was 2.62 ± 0.50 mm and mean lesion length was 13.95 ± 6.78 mm. Baseline ISR patterns were mostly either Type I focal (32.7%) or Type II diffuse intrastent (48.1%). At 6-month angiographic follow-up, the in-stent and in-segment binary restenosis was 3.8% (4/105) and 7.6% (8/105) respectively, and the in-stent and in-segment late loss was 0.30 ± 0.50 mm and 0.57 ± 0.54 mm, respectively. Seven of these eight restenosed lesions had a diffuse or proliferative ISR pattern prior to intervention. Lesions that restenosed had longer mean stent length per lesion (37.3 mm vs. 22.5 mm in nonrestenosed group; P = 0.001) and more likely to have had a pattern of total occlusion pre-intervention (25.0% vs. 3.1% in nonrestenosed group; P = 0.046). At 6-month clinical follow-up, the MACE rate was 8.5% and target lesion revascularization rate was 7.4%. There was no death but subacute stent thrombosis occurred in 1 patient (1.1%) at 3 days after intervention. Conclusions: Paclitaxel-eluting Taxus stent for the treatment of ISR effectively suppresses recurrent neointimal proliferation, and was safe and efficacious at 6-month follow-up. © 2006 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||