Ultrasound and Arterial Wall Disease

Racial and Sex Disparities in Catheter Use and Dialysis Access in the United States Medicare Population

BACKGROUND

Despite efforts to increase arteriovenous fistula and graft use, 80% of patients in the United States start hemodialysis on a central venous catheter (CVC).

METHODS

To better understand in incident hemodialysis patients how sex and race/ethnicity are associated with time on a central venous catheter and transition to an arteriovenous fistula and graft, our observational cohort study analyzed US Renal Data System data for patients with incident ESKD aged ≥66 years who started hemodialysis on a CVC in July 2010 through 2013.

RESULTS

At 1 year, 32.7% of 74,194 patients transitioned to an arteriovenous fistula, 10.8% transitioned to an arteriovenous graft, 32.1% stayed on a CVC, and 24.5% died. Women spent a significantly longer time on a CVC than men. Compared with white patients, patients who were black, Hispanic, or of another racial/ethnicity minority spent significantly more days on a CVC. In competing risk regression, women were significantly less likely than men to transition to a fistula and more likely to transition to a graft. Compared with white patients, blacks were significantly less likely to transition to a fistula but more likely to transition to a graft, Hispanics were significantly more likely to transition to a fistula, and other races/ethnicities were significantly more likely to transition to either a fistula or a graft.

CONCLUSIONS

Female patients spend a longer time on a CVC and are less likely to transition to permanent access. Compared with white patients, minorities also spend longer time on a CVC, but are more likely to eventually transition to permanent access. Strategies to speed transition to permanent access should target groups that currently lag in this area.

Comparing the feasibility and accuracy of three-dimensional ultrasound to two-dimensional ultrasound and computed tomography angiography in the assessment of carotid atherosclerosis

AIMS

Two-dimensional ultrasound (2D-US) is the mainstay imaging technique used to evaluate carotid atherosclerosis. An automated single sweep three-dimensional ultrasound (3D-US) technique became available. We evaluated the feasibility and accuracy of 3D-US in the assessment of carotid plaques compared to those of 2D-US. Carotid computed tomography angiography (CTA) was used as a reference.

METHODS AND RESULTS

Among 126 stroke patients who underwent carotid 2D-US, 73 underwent 3D-US and carotid CTA. 3D-US was pursued when there were carotid plaques or when area stenosis was ≥ 20% by 2D-US. Both 2D- and 3D-US images of the carotid arteries were acquired using a dedicated ultrasound system that was equipped with the single sweep volumetric transducer. In total, 266 arteries from 73 patients were selected for comparison of the detection rate of carotid plaques between 2D- and 3D-US. Among the 73 patients, carotid CTA detected 139 plaques. 3D-US demonstrated a higher detection rate of carotid plaques than did 2D-US (108 plaques (77.9%) vs. 70 plaques (50.4%)) when using carotid CTA as a reference standard. Carotid plaque volume (PV) of 133 vessels from 73 patients were quantitatively evaluated using both 3D-US and carotid CTA. Plaque volume of carotid artery was comparable between 3D-US and CTA (148.5 ± 133.0 mm³ vs. 154.1 ± 134.6 mm³ , P = .998, R: 0.9825, P-value for r < .001).

CONCLUSION

3D-US using a single sweep technique was a feasible and accurate method of detecting arterial plaques and assessing plaque volume.

Research progress in ultrasound use for the diagnosis and treatment of cerebrovascular diseases

Cerebrovascular diseases pose a serious threat to human survival and quality of life and represent a major cause of human death and disability. Recently, the incidence of cerebrovascular diseases has increased yearly. Rapid and accurate diagnosis and evaluation of cerebrovascular diseases are of great importance to reduce the incidence, morbidity and mortality of cerebrovascular diseases. With the rapid development of medical ultrasound, the clinical relationship between ultrasound imaging technology and the diagnosis and treatment of cerebrovascular diseases has become increasingly close. Ultrasound techniques such as transcranial acoustic angiography, doppler energy imaging, three-dimensional craniocerebral imaging and ultrasound thrombolysis are novel and valuable techniques in the study of cerebrovascular diseases. In this review, we introduce some of the new ultrasound techniques from both published studies and ongoing trials that have been confirmed to be convenient and effective methods. However, additional evidence from future studies will be required before some of these techniques can be widely applied or recommended as alternatives.

Synthesis of Monocyte-targeting Peptide Amphiphile Micelles for Imaging of Atherosclerosis

Atherosclerosis is a major contributor to cardiovascular disease, the leading cause of death worldwide, which claims 17.3 million lives annually. Atherosclerosis is also the leading cause of sudden death and myocardial infarction, instigated by unstable plaques that rupture and occlude the blood vessel without warning. Current imaging modalities cannot differentiate between stable and unstable plaques that rupture. Peptide amphiphiles micelles (PAMs) can overcome this drawback as they can be modified with a variety of targeting moieties that bind specifically to diseased tissue. Monocytes have been shown to be early markers of atherosclerosis, while large accumulation of monocytes is associated with plaques prone to rupture. Hence, nanoparticles that can target monocytes can be used to discriminate different stages of atherosclerosis. To that end, here, we describe a protocol for the preparation of monocyte-targeting PAMs (monocyte chemoattractant protein-1 (MCP-1) PAMs). MCP-1 PAMs are self-assembled through synthesis under mild conditions to form nanoparticles of 15 nm in diameter with near neutral surface charge. In vitro, PAMs were found to be biocompatible and had a high binding affinity for monocytes. The methods described herein show promise for a wide range of applications in atherosclerosis as well as other inflammatory diseases.

Nakagami-m Parametric Imaging for Atherosclerotic Plaque Characterization Using the Coarse-to-Fine Method

The Nakagami model was used to analyze the statistical differences in ultrasound backscattered signals between different plaque types. To improve image resolution, Nakagami-m parametric imaging using the coarse-to-fine method based on the maximum likelihood estimation (CTF-BOW) was proposed for atherosclerotic plaque characterization. Simulation results confirmed that the CTF-BOW method significantly outperforms the sliding window method in precision, smoothness and resolution. Preliminary in vivo results (n = 45) indicated that the ranges of the m parameters for calcified, mixed and echolucent plaques are, respectively, 0.2852-0.5225, 0.6532-0.8784 and 0.8908-1.4011, with no overlap. Results revealed that the CTF-BOW method significantly improves image resolution without sacrificing accuracy and can distinguish between calcified, mixed and echolucent plaques. Moreover, it was found that the parameter m is related to the composition of the plaque, indicating that Nakagami-m parametric imaging has the potential to characterize plaques.

Imaging Carotid Atherosclerosis Plaque Ulceration: Comparison of Advanced Imaging Modalities and Recent Developments

Atherosclerosis remains the leading cause of long-term mortality and morbidity worldwide, despite remarkable advancement in its management. Vulnerable atherosclerotic plaques are principally responsible for thromboembolic events in various arterial territories such as carotid, coronary, and lower limb vessels. Carotid plaque ulceration is one of the key features associated with plaque vulnerability and is considered a notable indicator of previous plaque rupture and possible future cerebrovascular events. Multiple imaging modalities have been used to assess the degree of carotid plaque ulceration for diagnostic and research purposes. Early diagnosis and management of carotid artery disease could prevent further cerebrovascular events. In this review, we highlight the merits and limitations of various imaging techniques for identifying plaque ulceration.

Echocardiography and Carotid Sonography in Diabetic Patients after Cerebrovascular Attacks

This study evaluated the aetiological factors for cerebrovascular attack (CVA) using echocardiography and sonography of the carotid arteries. Results from 253 patients with CVA were evaluated retrospectively and analysed according to the presence or absence of diabetes and atrial fibrillation. In patients with sinus rhythm ( n = 182), the presence of diabetes was associated with an increased incidence of atherosclerotic changes and significant stenosis of the carotid artery as well as greater intima-media thickness. In contrast, when evaluating signs of thromboembolic risk, there were no statistically significant differences in left atrial diameter or left ventricular ejection fraction between the two groups. In patients with atrial fibrillation ( n = 71), no significant differences were observed between diabetic and non-diabetic patients in any of the parameters measured. These findings suggest that the increased risk of ischaemic CVA in diabetic patients is due to atherosclerosis in the carotid vessels rather than embolism of cardiac origin.

Time-averaged level of fibroblast growth factor-23 and clinical events in chronic kidney disease

BACKGROUND

A single time-point fibroblast growth factor-23 (FGF23) level is a strong, well-established risk factor for clinical events in chronic kidney disease (CKD). This study investigated whether repeated measurements of FGF23 after 2 years, allowing the calculation of time-averaged FGF23 and the rate of change in FGF23, provided a better prediction of clinical events in CKD than a single time-point value.

METHODS

A post-hoc analysis was performed in a subset of 439 adult patients with a median estimated glomerular filtration rate of 36 (interquartile range 28-48) mL/min per 1.73 m(2) of the prospective multicentre MASTERPLAN study, in which paired samples to measure FGF23 were available. The primary outcome was defined as a composite of myocardial infarction, stroke and cardiovascular mortality and secondary end points, which were overall mortality, congestive heart failure (CHF) and start of renal replacement therapy. Only events occurring after Month 24 were included in the analysis.

RESULTS

Analysis of different FGF23 measures showed that a single time-point value and time-averaged FGF23 were positively associated with the primary end point, and also with overall mortality, start of renal replacement therapy and CHF. The adjusted hazard ratios of a single value of FGF23 and of time-averaged FGF23 for the composite end points were 1.71 (CI 1.20-2.43) and 1.91 (CI 1.29-2.82), respectively. Change in FGF23 was not associated with any outcome except for the initiation of renal replacement therapy.

CONCLUSIONS

Our study confirms that FGF23 is an important cardiovascular risk factor. Two measurements of FGF23 have no added value over a single value to predict the cardiovascular outcome. This study demonstrates that, under routine clinical practice, the variability of FGF23 in 2 years' time is small. Concomitantly, this study showed no benefit of consecutive FGF23 testing for estimating the risk of a clinical event in an individual patient.

Three-dimensional ultrasound scanning

The past two decades have witnessed developments of new imaging techniques that provide three-dimensional images about the interior of the human body in a manner never before available. Ultrasound (US) imaging is an important cost-effective technique used routinely in the management of a number of diseases. However, two-dimensional viewing of three-dimensional anatomy, using conventional two-dimensional US, limits our ability to quantify and visualize the anatomy and guide therapy, because multiple two-dimensional images must be integrated mentally. This practice is inefficient, and may lead to variability and incorrect diagnoses. Investigators and companies have addressed these limitations by developing three-dimensional US techniques. Thus, in this paper, we review the various techniques that are in current use in three-dimensional US imaging systems, with a particular emphasis placed on the geometric accuracy of the generation of three-dimensional images. The principles involved in three-dimensional US imaging are then illustrated with a diagnostic and an interventional application: (i) three-dimensional carotid US imaging for quantification and monitoring of carotid atherosclerosis and (ii) three-dimensional US-guided prostate biopsy.

Dynamic assessment of carotid plaque motion

Assessment of dynamic plaque behaviour may help identify vulnerable carotid plaque before rupture and hence has potential clinical value for screening patients at risk of stroke. The aim of this study was to develop non-invasive ultrasound methods for quantifying dynamic plaque and vessel wall behaviour and assess their potential clinical utility. Ultrasound data from the carotid arteries of one normal subject and four patients with atherosclerotic disease were acquired using a 10 MHz linear array transducer recording raw RF/IQ data at a frame rate up to 80 Hz for 3–6 seconds. Image reconstruction and processing was performed using Matlab. Speckle tracking techniques were developed to characterize: (1) intraplaque deformation; and (2) plaque surface and vessel wall motion. Speckle tracking techniques were able to measure the range of intraplaque tissue deformation (–1.3 to 1.7 mm), plaque surface displacement (0.2–0.7 mm) and vessel wall radial strain (0.02–0.13) throughout the cardiac cycle. The feasibility of using an intraplaque deformation parameter, based on the deformation of a square template, is demonstrated. Speckle tracking techniques can be used to assess dynamic carotid plaque behaviour. Further work is required to evaluate how best to quantify biomechanical behaviour to help predict plaque rupture and hence improve risk stratification models for stroke.

Common carotid intima media thickness as a marker of clinical severity in patients with symptomatic extracranial carotid artery stenosis

OBJECTIVES

Increased common carotid artery intima-media thickness (CCA-IMT) is a risk factor for ischemic stroke and especially large vessel atherothrombotic infarction. However, the potential association of stroke severity with the intima-media thickening has not been previously studied. We sought to investigate the association between CCA-IMT and clinical severity of ischemic stroke in patients with symptomatic extracranial carotid artery stenosis (SCAS).

PATIENTS AND METHODS

Consecutive patients with acute, first-ever ischemic stroke and SCAS (50%-99%) were prospectively evaluated. All subjects underwent IMT measurements at the far wall of CCA. Stroke severity was assessed using the National Institute of Health Stroke Scale (NIHSS) on hospital admission and Barthel Ambulatory Index (BI) at hospital discharge.

RESULTS

CCA-IMT was strongly correlated to NIH (Spearman's correlation coefficient: r=0.546, p<0.001) and BI (r=-0.450, p<0.001) in the study population (n=102). A 0.1mm increase in CCA-IMT was independently associated with increasing NIHSS-scores on hospital admission (beta: 0.510; p<0.001) and decreasing BI-scores at hospital discharge (beta: -0.483; p<0.001) even after adjustment for demographic characteristics and cardiovascular risk factors. After including baseline stroke severity (NIHSS) in the multivariate linear regressions models evaluating early functional outcome, only NIHSS was independently related to BI (standardized linear regression coefficient: -0.776, p<0.001), while the initial association between IMT and BI did not retain its statistical significance (beta: -0.074, p=0.276).

CONCLUSIONS

Increased CCA-IMT is independently associated with more severe stroke on admission in patients with SCAS.

Vascular access use and outcomes: an international perspective from the Dialysis Outcomes and Practice Patterns Study

BACKGROUND

A well-functioning vascular access (VA) is essential to efficient dialysis therapy. Guidelines have been implemented improving care, yet access use varies widely across countries and VA complications remain a problem. This study took advantage of the unique opportunity to utilize data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) to examine international trends in VA use and trends in patient characteristics and practices associated with VA use from 1996 to 2007. DOPPS is a prospective, observational study of haemodialysis (HD) practices and patient outcomes at >300 HD units from 12 countries and has collected data thus far from >35,000 randomly selected patients.

METHODS

VA data were collected for each patient at study entry (1996-2007). Practice pattern data from the facility medical director, nurse manager and VA surgeon were also analysed.

RESULTS

Since 2005, a native arteriovenous fistula (AVF) was used by 67-91% of prevalent patients in Japan, Italy, Germany, France, Spain, the UK, Australia and New Zealand, and 50-59% in Belgium, Sweden and Canada. From 1996 to 2007, AVF use rose from 24% to 47% in the USA but declined in Italy, Germany and Spain. Moreover, graft use fell by 50% in the USA from 58% use in 1996 to 28% by 2007. Across three phases of data collection, patients consistently were less likely to use an AVF versus other VA types if female, of older age, having greater body mass index, diabetes, peripheral vascular disease or recurrent cellulitis/gangrene. In addition, countries with a greater prevalence of diabetes in HD patients had a significantly lower percentage of patients using an AVF. Despite poorer outcomes for central vein catheters, catheter use rose 1.5- to 3-fold among prevalent patients in many countries from 1996 to 2007, even among non-diabetic patients 18-70 years old. Furthermore, 58-73% of patients new to end-stage renal disease (ESRD) used a catheter for the initiation of HD in five countries despite 60-79% of patients having been seen by a nephrologist >4 months prior to ESRD. Patients were significantly (P < 0.05) less likely to start dialysis with a permanent VA if treated in a faciity that (1) had a longer time from referral to access surgery evaluation or from evaluation to access creation and (2) had longer time from access creation until first AVF cannulation. The median time from referral until access creation varied from 5-6 days in Italy, Japan and Germany to 40-43 days in the UK and Canada. Compared to patients using an AVF, patients with a catheter displayed significantly lower mean Kt/V levels.

CONCLUSIONS

Most countries meet the contemporary National Kidney Foundation's Kidney Disease Outcomes Quality Initiative goal for AVF use; however, there is still a wide variation in VA preference. Delays between the creation and cannulation must be improved to enhance the chances of a future permanent VA. Native arteriovenous fistula is the VA of choice ensuring dialysis adequacy and better patient outcomes. Graft is, however, a better alternative than catheter for patients where the creation of an attempted AVF failed or could not be created for different reasons.

Impaired vascular function in patients with Fontan circulation

BACKGROUND

This study was performed to evaluate the endothelial function in Fontan patients, and to investigate the associated factors which influence the endothelial function in these patients.

METHODS

Flow mediated dilatation (FMD) and nitroglycerin induced dilatation (NG) of the brachial artery, and intima media thickness (IMT) of common carotid artery (CCA) were measured in nonselected Fontan patients (n=44, age 5 to 29 years, median 14 years, 18 females) by means of high-resolution ultrasound according to the standard protocols. The results were compared to age and sex matched controls (n=25, age 5 to 27 years, median 13 years, 10 females).

RESULTS

Fontan patients presented significantly reduced FMD and NG compared with controls (FMD; 6.5+/-2.4 vs. 11.1+/-1.4%, p<0.001, NG; 13.3+/-5.2 vs. 19.4+/-6.2%; p=0.035). Twenty two percent of Fontan patients presented pure endothelial dysfunction, and 34% of patients presented combined endothelial and smooth muscle dysfunction. Although there was no correlation between FMD and IMT, Fontan patients presented increased carotid IMT (0.44+/-0.07 vs. 0.38+/-0.06 mm, p=0.008). In multivariate analysis, duration of exposure to chronic hypoxia was inversely correlated with FMD (p=0.117, hazards ratio=1.294, 95% confidence interval=0.938-1.786). There was higher FMD in patients receiving angiotensin-converting enzyme inhibitors (ACEi) compared with those not receiving ACEi (7.0+/-2.5 vs. 5.5+/-2.2%, p=0.069).

CONCLUSIONS

Endothelial dysfunction is more prevalent in Fontan patients compared with healthy controls, and the previous hypoxia is an independent factor. Although it is not statistically significant, those patients on treatment with ACEi seem to have better endothelial function.

Validation of 3D ultrasound vessel wall volume: an imaging phenotype of carotid atherosclerosis

Carotid atherosclerotic lesions are a major cause of stroke and the identification and quantification of such lesions in patients is important for the development of a better understanding of atherogenesis in high risk populations and for the design of studies to assess treatment efficacy. Our objective was to develop and validate a new three-dimensional ultrasound (3DUS) measurement or phenotype of carotid atherosclerosis, vessel wall volume (VWV), which is a three-dimensional measurement of vessel wall thickness and plaque within the carotid arteries measured in 3DUS images. To assess both intraobserver and interscan variability, 3DUS images were acquired from the right and left carotid arteries of ten subjects with carotid atherosclerosis scanned twice within a period of 2 wk. For both VWV and total plaque volume (TPV), an expert observer performed five measurement trials of all images acquired at baseline scan and 2-wk rescan with a 5-d period between measurement trials for images. Images were re-randomized for each measurement trial and both TPV and VWV were measured by observers who were blinded to subject identification for each time-point measurement. Coefficients of variation (COV) and intraclass correlation coefficients (ICC), for VWV measurements indicated higher intraobserver (scan COV = 4.6% ICC = 0.95, rescan COV = 3.4%, ICC = 0.96) and interscan reproducibility (COV = 5.7%, ICC = 0.85) than TPV measurements (intraobserver variability scan COV = 22.7% ICC = 0.85, rescan COV = 21.1% ICC = 0.88 and interscan variability, COV = 31.1%, ICC = 0.83), although absolute variances for both phenotypes were very similar (VWV = 90 mm3, TPV = 80 mm3).

Common carotid artery wall thickness and external diameter as predictors of prevalent and incident cardiac events in a large population study

Background

Arterial diameters enlarge in response to wall thickening, plaques, and many atherosclerotic risk factors. We hypothesized that right common carotid artery (RCCA) diameter would be independently associated with cardiac disease and improve risk discrimination.

Methods

In a middle-aged, biracial population (baseline n = 11225), we examined associations between 1 standard deviation increments of baseline RCCA diameter with prevalent myocardial infarction (MI) and incident cardiac events (MI or cardiac death) using logistic regression and Cox proportional hazards models, respectively. Areas under the receiver operator characteristic curve (AUC) were used to estimate model discrimination.

Results

MI was present in 451 (4%) participants at baseline (1987–89), and incident cardiac events occurred among 646 (6%) others through 1999. Adjusting for IMT, RCCA diameter was associated with prevalent MI (female OR = 2.0, 95%CI = 1.61–2.49; male OR = 1.16, 95% CI = 1.04–1.30) and incident cardiac events (female HR = 1.75, 95% CI = 1.51–2.02; male HR = 1.27, 95% CI = 1.15–1.40). Associations were attenuated but persisted after adjustment for risk factors (not including IMT) (prevalent MI: female OR = 1.73, 95% CI = 1.40–2.14; male OR = 1.14, 95% CI = 1.02–1.28, and incident cardiac events: female HR = 1.26, 95% CI = 1.08–1.48; male HR = 1.19, 95% CI = 1.08–1.32). After additional adjustment for IMT, diameter was associated with incident cardiac events in women (HR = 1.18, 95% CI = 1.00–1.40) and men (HR = 1.17, 95% CI = 1.06–1.29), and with prevalent MI only in women (OR = 1.73; 95% CI = 1.37–2.17). In women, when adjustment was limited, diameter models had larger AUC than other models.

Conclusion

RCCA diameter is an important correlate of cardiac events, independent of IMT, but adds little to overall risk discrimination after risk factor adjustment.

Changes in Hyaluronan Metabolism and RHAMM Receptor Expression Accompany Formation of Complicated Carotid Lesions and May be Pro-Angiogenic Mediators of Intimal Neovessel Growth

Previous studies have shown that changes in expression of the glycosaminoglycan, hyaluronan (HA) were associated with erosion in areas of post-mortem coronary artery liable to rupture. Angiogenesis is an important feature of ulcerating haemorrhagic plaques prone to rupture. HA is a glycosaminoglycan known to possess potent angiogenic properties on metabolism to oligosaccharides of HA (o-HA) in the presence of hyaluronidase (HYAL) enzymes. In this study we have examined HA receptor and HYAL enzyme expression in a series of carotid artery specimens used as vascular transplants and exhibiting various stages of atherosclerotic lesions as determined by anatomo-pathology. Our results demonstrated dramatically increased expression of HYAL-1 in regions of inflammation associated with complicated plaques. Receptor for HA-mediated motility (RHAMM), which is known to be important in transducing angiogenic signals in vascular endothelium, was strongly expressed on intimal blood vessels from complicated lesions but almost absent from other regions including adventitial vessels. Metabolism of HA, together with up-regulation of RHAMM in complicated plaque lesions might be partly responsible for over-production of leaky neovessels and predisposition to plaque rupture.

Carotid ultrasound phenotypes in vulnerable populations

Background

Biomarkers of carotid atherosclerosis range from those that are widely available and relatively simple to measure such as serum cholesterol levels, and B-mode Ultrasound measurement of intima media thickness (IMT) to those that are more complex and technologically demanding but perhaps potentially more sensitive and specific to disease such as total plaque volume and total plaque area measured from 3-dimensional ultrasound images. In this study we measured and compared intima media thickness (IMT), total plaque volume (TPV) and total plaque area (TPA) in two separate populations, both vulnerable to carotid atherosclerosis.

Methods

In total, 88 subjects (mean age 72.8) with carotid stenosis of at least 60%, based on a peak Doppler flow, and 82 subjects (mean age 60.9) with diabetic nephropathy were assessed in a cross-sectional study. Conventional atherosclerotic risk factors were examined and the associations and correlations between these and carotid ultrasound phenotypes measured from B-mode and 3-dimensional ultrasound images were assessed.

Results

IMT and TPV were only modestly correlated in the two separate populations (r = .6, p < .01). ANOVA analyses indicated that both IMT and TPV were significantly associated with age (p < .001) and Framingham score (p < .05), but only TPV was associated with diabetes (p < .001) and presence of plaque ulcerations (p < .01)

Conclusion

IMT and TPV were modestly correlated in a diabetic patient population and only TPV was associated with diabetes and the presence of plaque ulcerations in a diabetic population and carotid stenosis group. The 3-dimensional information provided by TPV can be critically important in unmasking association with risk factors not observed with less complex single-dimension assessments of carotid atherosclerosis such as those provided by IMT.

The kind of vascular access influences the baseline inflammatory status and epoetin response in chronic hemodialysis patients

BACKGROUND

Arteriovenous grafts (AVG) and tunneled permanent catheters (TPC) are increasingly being used in hemodialysis (HD) patients. However, their role in baseline inflammatory status has not been fully evaluated. Aim of the study was to evaluate the influence of the current kind of vascular access on the baseline inflammatory status, marked by serum C-reactive protein (CRP), and the response to epoetin therapy in a group of iron-replete HD patients, under steady clinical conditions, without evidence of acute infections and/or inflammatory diseases.

METHODS

We studied 79 patients who had been on bicarbonate HD for 8-410 months and were receiving epoetin therapy. They all had adequate iron stores and stable hemoglobin (Hb) levels. Exclusion criteria were fever, signs of infection, white blood cell count (WBC) > 10 x 1,000/microl, for at least 4 weeks before study. 48 patients (group A) had arteriovenous fistula (AVF), 18 patients (group B) AVG, 13 patients (group C) TPC. CRP, Hb, transferrin saturation, serum ferritin, WBC, serum albumin, protein catabolic rate, Kt/V, and epoetin dose (U/kg body weight/week) were measured. CRP values were log-transformed to normalize the distribution.

RESULTS

Log-transformed CRP values among the 3 groups were significantly different: group A 1.81 +/- 0.48; group B 2.12 +/- 0.50, and group C 3.00 +/- 0.25 (group A vs. B p < 0.003; group B vs. C p < 0.001; group A vs. C p < 0.0001). CRP and the epoetin dose were directly correlated (r = 0.519; p < 0.0001). The epoetin doses among the 3 groups were significantly different. Multiple regression analysis confirmed AVG and TPC as factors independently influencing CRP levels.

CONCLUSIONS

AVG and TPC have a higher degree of chronic inflammation than AVF. The epoetin requirement is increased in TPC and AVG compared with AVF.

Asymptomatic cerebrovascular disease and systemic diagnosis in stroke, atherothrombosis as a disease of the vascular tree

Atherosclerosis is a chronic vascular disease of true epidemic proportions. It is the first cause of death in developed countries and responsible for one quarter of documented deaths worldwide. Arteriosclerotic vascular disease is a systemic process which affects different organs; principally the heart, brain, and peripheral artery system. Despite well-documented differences, all manifestations of the disease share the same risk factors; albeit with varying degrees of impact. The concept of asymptomatic cerebrovascular disease is an important one for clinicians who treat stroke patients. The development of new neuroimaging and vascular evaluation techniques has enabled the presence of apparently silent lesions to be detected and their progress monitored in follow-up. Ultrasonography techniques enable the identification of atheromatous disease. Asymptomatic involvement of the cerebral parenchyma consists of ischemia, leukoaraiosis, and silent hemorrhage and can be detected using the available radiological techniques such as cranial CT, magnetic resonance, or gradient echo magnetic resonance imaging. From the point of view of prevention, it is of considerable importance to identify diagnostic markers for arteriosclerosis in asymptomatic patients in some, if not all, vascular territories. In view of the natural history of this disease and the impact it has on society, there is an increasing need to identify and understand the risk factors or vascular disease risk markers, so that the stratification of risk of an individual patient or in a specific population can be established, appropriate cerebrovascular assessments conducted, and appropriate therapeutic intervention initiated.

Ultrasound measurement of the fibrous cap in symptomatic and asymptomatic atheromatous carotid plaques

BACKGROUND

Fibrous cap thickness (FCT) is an important determinant of atheroma stability. We evaluated the feasibility and potential clinical implications of measuring the FCT of internal carotid artery plaques with a new ultrasound system based on boundary detection by dynamic programming.

METHODS AND RESULTS

We assessed agreement between ultrasound-obtained FCT values and those measured histologically in 20 patients (symptomatic [S]=9, asymptomatic [AS]=11) who underwent carotid endarterectomy for stenosing (>70%) carotid atheromas. We subsequently measured in vivo the FCT of 58 stenosing internal carotid artery plaques (S=22, AS=36) in 54 patients. The accuracy in discriminating symptomatic from asymptomatic plaques was assessed by receiver operating characteristic curves for the minimal, mean, and maximal FCT. Decision FCT thresholds that provided the best correct classification rates were identified. Agreement between ultrasound and histology was excellent, and interobserver variability was small. Ultrasound showed that symptomatic atheromas had thinner fibrous caps (S versus AS, median [95% CI]: minimal FCT=0.42 [0.34 to 0.48] versus 0.50 [0.44 to 0.53] mm, P=0.024; mean FCT=0.58 [0.52 to 0.63] versus 0.79 [0.69 to 0.85] mm, P<0.0001; maximal FCT=0.73 [0.66 to 0.92] versus 1.04 [0.94 to 1.20] mm, P<0.0001). Mean FCT measurement demonstrated the best discriminatory accuracy (area under the curve [95% CI]: minimal 0.74 [0.61 to 0.87]; mean 0.88 [0.79 to 0.97]; maximal 0.82 [0.71 to 0.93]). The decision threshold of 0.65 mm (mean FTC) demonstrated the best correct classification rate (82.8%; positive predictive value 75%, negative predictive value 88.2%).

CONCLUSIONS

FCT measurement of carotid atheroma with ultrasound is feasible. Discrimination of symptomatic from asymptomatic plaques with mean FCT values is good. Prospective studies should determine whether this ultrasound marker is reliable.

Vascular reactivity and atheromatous plaques in post-menopausal women on tibolone treatment

BACKGROUND

Arteriosclerosis is the main cause of ischaemic ictus. The middle cerebral and anterior cerebral arteries, which irrigate over 70% of the entire cerebral tissue, spring from the internal carotid. Additionally, it is in the extracraneal vessels that embolism, thrombosis and stenosis originate more frequently.

AIM

To evaluate the variations in blood flow (pulsatility index: PI) and to assess the evolution of atherogenic lesions (thickening of the vascular intima and the presence of atheromatous plaques) in the internal carotid artery after tibolone therapy.

SUBJECTS AND METHODS

A total of 116 healthy menopausal women were included in this open, prospective and comparative study. Of them, 101 subjects completed the 48 weeks follow-up. Subjects were allocated in two groups: group T (n = 55) received 2.5mg/day of tibolone daily and group C (n = 61) was a free-treatment control group. To evaluate both resistance to blood flow and the existence and evolution of atheromatous plaques in the internal carotid, an ultrasonograph with a pulsed Doppler was used. The PI was used as the parameter of vascular tone. To study atherosclerotic lesions in the internal carotid artery, we used morphological criteria. Measurements were done before entering in the study, and at 12, 24, 36 and 48 weeks of treatment.

RESULTS

After tibolone treatment the PI in the internal carotid artery was observed markedly diminished. Moreover, tibolone reduces both the thickness and length of atheromatous plaque and the degree of vascular stenosis.

CONCLUSION

tibolone administration reduced the carotid atheromatous plaque in thickness and length and improved cerebral perfusion.

Design, Baseline Characteristics and Carotid Intima-Media Thickness Reproducibility in the PARC Study

BACKGROUND

Intima-media thickness (IMT) is associated with an increased risk of cardiovascular and cerebral ischemic events, but its correlation with the absolute cardiovascular risk is not known in large populations. The Paroi Arterielle et Risque Cardiovasculaire (PARC) Study is an epidemiological study designed to correlate conventional assessment of cardiovascular risk with the mean IMT of the common carotid.

METHODS

In the PARC study, 6,416 subjects were enrolled, including 80.7% subjects with cardiovascular risk factors and 19.3% without. A specific methodology was designed to harmonize the acquisition and processing of data at the 283 centers. Interreader agreement on image quality and IMT measurement of the common carotid artery (CCAIMT) was assessed from a random sample of 10% of the PARC study population.

RESULTS

The intraclass correlation coefficient was 0.98 (95% CI 0.966-0.985), and the accuracy was high (standard deviation of the error measurement: 0.0185 mm).

CONCLUSIONS

The reproducibility of the measurements assessed by means of the intraclass correlation coefficient and the accuracy of the CCAIMT measurement obtained in the PARC Study demonstrate the feasibility of large multicenter studies of IMT measurement.