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Biomedical subjects

Valentin Fuster

Publications and source records attributed to Valentin Fuster.

At least 163 records · Page 9Linked to original sources
PubMed2002

Intimomedial interface damage and adventitial inflammation is increased beneath disrupted atherosclerosis in the aorta: implications for plaque vulnerability.

BACKGROUND: Atherosclerotic plaque progression is frequently accompanied by compensatory enlargement to preserve the lumen. These enlarging plaques develop features of vulnerability, however, leading to disruption and lumen obstruction. This complex transition from compensatory expansion to plaque disruption may not derive solely from progressive intimal disease. Concurrent changes at the intimomedial interface and within the tunica media and adventitia may play a role in plaque instability. We tested this hypothesis by investigating whether interface changes, including internal elastic lamina (IEL) rupture, and medial and adventitial changes, including inflammation, fibrosis, and atrophy, more frequently accompany disrupted than nondisrupted atherosclerotic plaques. METHODS AND RESULTS: Computerized planimetry and ocular micrometry were used for systematic quantification of intimal, medial, and adventitial histopathological features in 598 human aortic plaques according to the AHA classification. Disrupted plaques exhibited larger plaque and lipid pool areas (P=0.0001) and a higher incidence of rupture of the IEL (P=0.0001). Medial and adventitial inflammation (P=0.01), medial fibrosis (P=0.0001), and medial atrophy (P=0.0001) were also higher in disrupted plaques. Furthermore, medial thickness was reduced in disrupted plaques (P=0.0001). Logistic regression analysis identified rupture of the IEL as an independent predictor for fibrous cap disruption (P=0.0001). CONCLUSIONS: Compared with nondisrupted plaques, disrupted plaques have an increased incidence of IEL rupture, medial and adventitial inflammation, medial fibrosis, and medial atrophy. These intimomedial interface and adventitial changes may play a role in the natural history of complex atherosclerotic lesions. The interaction between medial and adventitial pathology and the intimal atherosclerotic process deserves further investigation.

Aorta, Abdominal↗
PubMed2002

In vivo noninvasive detection and age definition of arterial thrombus by MRI.

OBJECTIVES: The purpose of this study was to evaluate the potential of magnetic resonance (MR) to detect arterial thrombotic obstruction and define thrombus age. BACKGROUND; Arterial thrombi underlie the clinical consequences of atherosclerosis and are not reliably detected by current noninvasive diagnostic techniques. METHODS: Carotid thrombi were induced in swine (n = 7) by arterial injury. Serial high-resolution in vivo MR images were obtained using black-blood T1-weighted (T1W) and T2-weighted (T2W) sequences in a clinical 1.5T MR system at 6 h, 1 day and at 1, 2, 3, 6 and 9 weeks. At each time point one animal was sacrificed and the occluded carotid artery processed for histopathology. Thrombus signal intensity (SI) was normalized to that of the adjacent muscle. Thrombus age was assessed based on MR appearance by two blinded independent observers. RESULTS: Thrombus appearance and relative SI revealed characteristic temporal changes in multicontrast-weighted MR images, reflecting histologic changes in the composition. Acute thrombus appeared very bright on the T2W images, facilitating the detection. Signal intensity was 197 +/- 25% at 6 h, peaking at 1 week (246 +/- 51%), reaching a plateau by 6 weeks (120 +/- 15%). At six weeks, complete thrombus organization was confirmed histologically. The T1W images had similar pattern with lower SI than T2W. Age definition using visual appearance was highly accurate (Pearson's chi-square with 4 df ranging from 96 to 132 and Cohen's kappa at 0.81 to 0.94). Agreement between observers was substantial (Pearson chi-square with 4 df = 91.5, kappa = 0.79). CONCLUSIONS: Magnetic resonance imaging is a promising tool to noninvasively detect arterial thrombosis. Measurement of SI and the characteristic visual appearance of the thrombus have the potential to define thrombus age.

Age Factors↗
PubMed2002

Progression and regression of atherosclerotic lesions: monitoring with serial noninvasive magnetic resonance imaging.

BACKGROUND: Modification or stabilization of atherosclerotic plaques has been proposed as the mechanism responsible for the beneficial clinical effect of lipid-lowering therapies. An imaging modality able to quantify atherosclerotic plaque composition could potentially allow not only the identification of these vulnerable atherosclerotic lesions, but also monitoring of the effects of therapeutic interventions on plaque composition. Our aim was to monitor changes in burden and composition of atherosclerotic plaques in a rabbit model of complex atherosclerosis using serial noninvasive magnetic resonance imaging (MRI). METHODS AND RESULTS: Aortic atherosclerotic lesions were induced in rabbits and the animals randomized to continue an atherogenic diet (atherosclerosis progression) or resume normal chow (atherosclerosis regression) for 6 months. MRI of the aorta was performed at 3 time points in each rabbit, as follows: baseline, after atherosclerosis induction (9 months old), and after atherosclerosis regression or progression (15 months old). Histopathologic correlation with MRI was performed. There was a significant (P<0.0001) reduction in atherosclerotic burden in the regression group, and an increase in the progression group. There was a significant (P<0.001) reduction in the lipidic component of plaques in the regression group, and an increase in the progression group. A small, nonsignificant increase in the fibrotic plaque components was noted in the regression group, but a significant decrease in the fibrotic composition of lesions in the progression group. A significant correlation (P<0.001) was found between MRI and histopathology for atherosclerotic burden and plaque composition. CONCLUSIONS: These findings indicate that serial noninvasive MRI can monitor changes in atherosclerotic plaque composition under conditions of atherosclerotic progression and regression.

Aging↗
PubMed2002

Atherosclerotic lesions in genetically modified mice quantified in vivo by non-invasive high-resolution magnetic resonance microscopy.

We have previously shown that magnetic resonance microscopy (MRM) accurately quantifies atherosclerosis in Apolipoprotein E deficient (ApoE(-/-)) mice aged 36-84 weeks. The present study tests MRM in the quantification of aortic atherosclerosis over a broader range of lesion severity. Younger mice with less advanced disease were imaged in order to evaluate sensitivity, specificity and maximum practical resolution of MRM. Nineteen mice underwent in vivo MRM. Wall area measurements by MRM and light microscopy (LM) (n=43) were highly correlated (r=0.85, slope=0.88, P<0.0001). Wall areas by MRM ranged from 0.114 to 0.934 (median, 0.334) mm(2). A threshold of 0.35 mm(2), for the upper limit of normal, gave MRM positive predictive value (PPV) for detecting abnormally thickened arteries=89.5% and negative predictive value (NPV)=75%, referred to LM. Lesion shape assessed by LM and MRM were also well correlated (r=0.72, P<0.001). Increased wall area in atherosclerosis was found by MRM (P=0.01) and LM (P<0.0001) to be accommodated entirely by 'positive remodeling', confirming the importance of determining plaque size directly. MRM accurately quantifies mouse aortic atherosclerosis and will enhance studies in this important animal model.

Animals↗
PubMed2002

Atherothrombotic plaques and the need for imaging.

The assessment of atherothrombotic plaques by imaging techniques is essential for the in vivo identification of vulnerable plaques. Several invasive and noninvasive imaging techniques are available to assess atherothrombotic disease. The use of some of the available imaging modalities for the study of regression and progression of atherothrombosis are described in more detail in the subsequent articles.

Angiography↗