Blai Coll

Vasa Vasorum and Plaque Neovascularization on Contrast-Enhanced Carotid Ultrasound Imaging Correlates With Cardiovascular Disease and Past Cardiovascular Events

Background and Purpose— Histological data associate proliferation of adventitial vasa vasorum and intraplaque neovascularization with vulnerable plaques represented by symptomatic vascular disease. In this observational study, the presence of carotid intraplaque neovascularization and adventitial vasa vasorum were correlated with the presence and occurrence of cardiovascular disease (CVD) and events (CVE). Methods— The contrast-enhanced carotid ultrasound examinations of 147 subjects (mean age 64±11 years, 61% male) were analyzed for the presence of intraluminal plaque, plaque neovascularization (Grade 1=absent; Grade 2=present), and degree of adventitial vasa vasorum (Grade 1=absent, Grade 2=present). These observations were correlated with preexisting cardiovascular risk factors, presence of CVD, and history of CVE (myocardial infarction and transient ischemic attack/stroke). Results— The presence of intraluminal carotid plaque was directly correlated to cardiovascular risk factors, CVD, and CVE (P<0.05). Adventitial vasa vasorum Grade 2 was associated with significant more subjects with CVD than vasa vasorum Grade 1 (73 versus 54%, P=0.029). Subjects with intraplaque neovascularization Grade 2 had significantly more often a history of CVE than subjects with intraplaque neovascularization Grade 1 (38 versus 20%, P=0.031). Multivariate logistic regression analysis revealed that presence of plaque was significantly associated with CVD (odds ratio 4.7, 95% CI 1.6 to 13.8) and intraplaque neovascularization grade 2 with CVE (odds ratio 4.0, 95% CI 1.3 to 12.6). Conclusion— The presence and degree of adventitial vasa vasorum and plaque neovascularization were directly associated with CVD and CVE in a retrospective study of 147 patients undergoing contrast-enhanced carotid ultrasound.

RANKL Increases Vascular Smooth Muscle Cell Calcification Through a RANK-BMP4–Dependent Pathway

Vascular calcification commonly associated with several pathologies and it has been suggested to be similar to bone mineralization. The axis RANKL-OPG (receptor activator of nuclear factor &kgr;B ligand–osteoprotegerin) finely controls bone turnover. RANKL has been suggested to increase vascular calcification, but direct evidence is missing. Thus, in the present work, we assess the effect of RANKL in vascular smooth muscle cell (VSMC) calcification. VSMCs incubated with RANKL showed a dose-dependent increase in calcification, which was abolished by coincubation with OPG. To test whether the effect was mediated by signaling to its receptor, knockdown of RANK was accomplished by short hairpin (sh)RNA. Indeed, cells lacking RANK showed no increases in vascular calcification when incubated with RANKL. To further elucidate the mechanism by which RANK activation increases calcification, we blocked both nuclear factor (NF)-&kgr;B activation pathways. Only IKK&agr; inactivation inhibited calcification, pointing to an involvement of the alternative NF-&kgr;B activation pathway. Furthermore, RANKL addition increased bone morphogenetic protein (BMP)4 expression in VSMCs, and that increase disappeared in cells lacking RANK or IKK&agr;. The increase in calcification was also blunted by Noggin, pointing to a mediation of BMP4 in the calcification induced by RANKL. Furthermore, in an in vivo model, the increase in vascular calcium content was parallel to an increase in RANKL and BMP4 expression, which was localized in calcified areas. However, blood levels of the ratio RANKL/OPG did not change. We conclude that RANKL increases vascular smooth muscle cell calcification by binding to RANK and increasing BMP4 production through activation of the alternative NF-&kgr;B pathway.

Contrast-Enhanced Ultrasound Imaging of the Vasa Vasorum: From Early Atherosclerosis to the Identification of Unstable Plaques

Proliferation of the adventitial vasa vasorum (VV) is inherently linked with early atherosclerotic plaque development and vulnerability. Recently, direct visualization of arterial VV and intraplaque neovascularization has emerged as a new surrogate marker for the early detection of atherosclerotic disease. This clinical review focuses on contrast-enhanced ultrasound (CEUS) as a noninvasive application for identifying and quantifying carotid and coronary artery VV and intraplaque neovascularization. These novel approaches could potentially impact the clinicians ability to identify individuals with premature cardiovascular disease who are at high risk. Once clinically validated, the uses of CEUS may provide a method to noninvasively monitor therapeutic interventions. In the future, the therapeutic use of CEUS may include ultrasound-directed, site-specific therapies using microbubbles as vehicles for drug and gene delivery systems. The combined applications for diagnosis and therapy provide unique opportunities for clinicians to image and direct therapy for individuals with vulnerable lesions.

Correlation of Carotid Artery Atherosclerotic Lesion Echogenicity and Severity at Standard US with Intraplaque Neovascularization Detected at Contrast-enhanced US

PURPOSE To correlate echogenicity and severity of atherosclerotic carotid artery lesions at standard ultrasonography (US) with the degree of intraplaque neovascularization at contrast material-enhanced (CE) US. MATERIALS AND METHODS This HIPAA-compliant study was approved by the local ethics committee, and all patients provided informed consent. A total of 175 patients (113 [65%] men, 62 [35%] women; mean age, 67 years ± 10 [standard deviation]) underwent standard and CE US of the carotid artery. Lesion echogenicity (class I to IV), degree of stenosis, and maximal lesion thickness were evaluated for each documented atherosclerotic lesion. The degree of intraplaque neovascularization at CE US was categorized as absent (grade 1), moderate (grade 2), or extensive (grade 3). Correlation of neovascularization with echogenicity, degree of stenosis, and maximal lesion thickness was made by using Spearman ρ and χ(2) test for trend. RESULTS In a total of 293 atherosclerotic lesions, echogenicity was inversely correlated with grade of intraplaque neovascularization (ρ = -0.199, P < .001). More echolucent lesions had a higher degree of neovascularization compared with more echogenic ones (P < .001). The degree of stenosis was significantly correlated with grade of intraplaque neovascularization (ρ = 0.157, P = .003). Lesions with higher degree of stenosis had higher grade of neovascularization (P = .008), and maximal lesion thickness increased with the grade of neovascularization (P < .001) and was significantly correlated with grade of neovascularization (ρ = 0.233, P < .001). CONCLUSION Neovascularization visualized with CE US correlates with lesion severity and with morphologic features of plaque instability, contributing to the concept that more vulnerable plaques are more likely to have a greater degree of neovascularization. Therefore, CE US may be a valuable tool for further risk stratification of echolucent atherosclerotic lesions and carotid artery stenosis of different degrees. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10101008/-/DC1.

Noninvasive Imaging of the Vulnerable Atherosclerotic Plaque

Atherosclerosis is an inflammatory disease, complicated by progressively increasing atherosclerotic plaques that eventually may rupture. Plaque rupture is a major cause of cardiovascular events, such as unstable angina, myocardial infarction, and stroke. A number of noninvasive imaging techniques have been developed to evaluate the vascular wall in an attempt to identify so-called vulnerable atherosclerotic plaques that are prone to rupture. The purpose of the present review is to systematically investigate the accuracy of noninvasive imaging techniques in the identification of plaque components and morphologic characteristics associated with plaque vulnerability, assessing their clinical and diagnostic value.

Large Artery Calcification on Dialysis Patients Is Located in the Intima and Related to Atherosclerosis

BACKGROUND AND OBJECTIVES Vascular calcification (VC) has a significant effect in cardiovascular diseases on dialysis patients. However, VC is assessed with x-ray-based techniques, which do not inform about calcium localization (intima, media, atherosclerosis-related). The aim of this work is to study VC and its related factors using arterial ultrasound to report the exact location of calcium. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This was an observational, cross-sectional, case-control study that included 232 patients in dialysis and 208 age- and sex-matched controls with normal kidney function. Demographic data and laboratory values were collated. Carotid, femoral, and brachial ultrasounds were performed to assess VC and atherosclerosis burden using a standardized protocol. RESULTS Cardiovascular risk factors were predominantly found in controls, although the burden of atherosclerosis was higher in the dialysis group. VC was significantly more prevalent in the group of patients on dialysis than control subjects, and in both groups the most prevalent pattern of VC was linear calcification located in the intima of the artery wall. Age and undergoing dialysis (with or without previous cardiovascular diseases) were positively and significantly associated with linear calcification. Conversely, the absence of atherosclerosis and low levels of C-reactive protein and phosphorus significantly impeded the development of linear calcification. CONCLUSIONS VC in large, conduit arteries is more prevalent in patients on dialysis than controls and is predominantly located in a linear fashion in the intima of the arteries.

Contrast-enhanced ultrasound for imaging vasa vasorum: comparison with histopathology in a swine model of atherosclerosis.

AIM To evaluate the agreement between contrast-enhanced ultrasound imaging and histopathology in an animal model of atherosclerosis. METHODS AND RESULTS Atherosclerosis was studied in both femoral arteries of four Rapacz familial hypercholesterolaemia (RFH) swine. Contrast-enhanced ultrasound imaging of the eight femoral arteries was performed at baseline and at 5, 12, 26, and 43 weeks follow-up after percutaneous transluminal stimulation of atherosclerosis to assess the progression of intima-media thickness (IMT) and the density and extent of the vasa vasorum network. Contrast-enhanced ultrasound imaging allowed an early detection of atherosclerosis and showed a significant gradual progression of atherosclerosis over time. IMT increased from 0.22 +/- 0.05 mm at baseline to 0.45 +/- 0.06 mm (P < 0.001) at follow-up. The density of the vasa vasorum network increased during follow-up and was significantly higher in advanced than in early atherosclerosis. The findings with contrast-enhanced ultrasound were confirmed by histopathological specimens of the arterial wall. CONCLUSION Contrast-enhanced ultrasound is effective for in vivo detection of vasa vasorum in atherosclerotic plaques in the RFH swine model. After stimulation of atherosclerosis, contrast-enhanced ultrasound demonstrated a significantly increased IMT and significantly increased density of the vasa vasorum network in the developing atherosclerotic plaque, which was validated by histology.

Predicting cardiovascular disease morbidity and mortality in chronic kidney disease in Spain. The rationale and design of NEFRONA: a prospective, multicenter, observational cohort study

BackgroundCardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD). Cardiovascular risk assessment in this population is hampered by the failure of traditional risk factors to fully account for the elevated CVD risk (reverse epidemiology effect) and the presence of emerging risk factors specifically related to kidney failure. Therefore, diagnostic tools capable of improving cardiovascular risk assessment beyond traditional risk factors are currently warranted. We present the protocol of a 4-year prospective study aimed to assess the predictive value of non-invasive imaging techniques and biomarkers for CVD events and mortality in patients with CKD.MethodsFrom November 2009 to October 2010, 4137 asymptomatic adult patients with stages 2 to 5 CKD will be recruited from nephrology services and dialysis units throughout Spain. During the same period, 843 participants without CKD (control group) will be recruited from lists of primary care physicians, only at baseline. During the follow-up, CVD events and mortality will be recorded from all CKD patients. Clinical and laboratory characteristics will be collected in a medical documentation sheet. Three trained itinerant teams will carry out a carotid ultrasound to assess intima-media thickness and presence of plaques. A composite atherosclerosis score will be constructed based on carotid ultrasound data and measurement of ankle-brachial index. In CKD patients, presence and type of calcifications will be assessed in the wall of carotid, femoral and brachial arteries, and in cardiac valves, by ultrasound. From all participants, blood samples will be collected and stored in a biobank to study novel biomarkers.ConclusionsThe NEFRONA study is the first large, prospective study to examine the predictive value of several non-invasive imaging techniques and novel biomarkers in CKD patients throughout Spain. Hereby, we present the protocol of this study aimed to explore the most effective way in which these tests can be integrated with traditional risk factors to maximize CVD detection in this population.

Cardiovascular risk factors underestimate atherosclerotic burden in chronic kidney disease: usefulness of non-invasive tests in cardiovascular assessment

BACKGROUND Cardiovascular risk scoring (Score) does not specifically address chronic kidney disease (CKD) patients. The aim of our study is to quantify atherosclerosis using carotid ultrasound and ankle-brachial index (ABI) and to assess its additional value in risk scoring. METHODS In this cross-sectional, observational study, patients were studied according to a standardized protocol including carotid ultrasound and ABI to determine the atherosclerosis score (AS), ranging from absence of to severe atherosclerosis (AS 0 to AS 3). RESULTS We included 409 CKD-affected patients (231 on dialysis, 99 in CKD Stages IV-V and 79 in CKD Stages I-III) and 851 subjects with normal renal function. The presence and severity of atherosclerosis was significantly higher in the CKD group than in the controls at every decade of age studied. Among the CKD-affected subjects, the prevalence of carotid plaques was significantly higher in the dialysis group (78.3%) than in the group in CKD Stages I-III (55.6%, P < 0.001). We identified 174 patients at low-intermediate risk. Among them, 110 (63.2%) presented either moderate (AS 2) or severe (AS 3) atherosclerosis. Variables significantly (P < 0.05) and positively related to atherosclerosis were being on dialysis [OR = 3.40, 95% CI (1.73, 6.78) vs CKD Stages I-III], age [OR = 1.08, 95% CI (1.06-1.11)] and C-reactive protein [OR = 1.04, 95% CI (1.01-1.08)]. Conversely, female sex was negatively related to atherosclerosis [OR = 0.40, 95% CI (0.23-0.71), P = 0.002]. CONCLUSION The use of carotid ultrasound and ABI identifies atherosclerosis in a population of CKD patients in which risk scoring underestimates atherosclerosis burden.

Serum levels of matrix metalloproteinase-10 are associated with the severity of atherosclerosis in patients with chronic kidney disease.

Cardiovascular disease is the leading cause of mortality in chronic kidney disease (CKD). As matrix metalloproteinases have a major role in atherosclerosis, we hypothesized that alterations in metalloproteinases-8, -10 and their tissue inhibitor-1 can be associated with the severity of atherosclerosis in patients with kidney disease. This was evaluated in a cross-sectional, observational study of 111 patients with stages I-V kidney disease, 217 patients on dialysis and 50 healthy controls. The severity of atherosclerosis was estimated with the atherosclerosis score (AS), combining the results of ankle-brachial index and carotid ultrasound. Serum levels of the two metalloproteinases and tissue inhibitor-1 were measured by enzyme-linked immunosorbent assay and were significantly increased in patients with kidney disease compared with the healthy controls, and higher in patients on dialysis than in earlier stages of CKD. The severity of the AS was also more prevalent in the dialysis group, in which serum levels of both metalloproteinases and tissue inhibitor-1 were significantly higher. After multivariate analysis, metalloproteinase-10, dialysis, C-reactive protein, age, and male gender were associated with increased risk of atherosclerosis. Thus, patients with CKD exhibit elevated levels of circulating metalloproteinase-10, and this was independently associated with the severity of atherosclerosis and may represent a new biomarker of atherosclerotic diseases.