Neointimal cracks (plaque rupture?) and thrombosis in wrapped arteries without flow.
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Animals↗
Biomedical subjects
Erling Falk
Publications and source records attributed to Erling Falk.
Subclinical coronary and aortic atherosclerosis detected by magnetic resonance imaging in type 1 diabetes with and without diabetic nephropathy.
BACKGROUND: Patients with type 1 diabetes and nephropathy maintain an excess cardiovascular mortality compared with diabetic patients with normoalbuminuria. We sought to evaluate coronary and aortic atherosclerosis in a cohort of asymptomatic type 1 diabetic patients with and without diabetic nephropathy using cardiovascular magnetic resonance imaging. METHODS AND RESULTS: In a cross-sectional study, 136 subjects with long-standing type 1 diabetes without symptoms or history of cardiovascular disease, including 63 patients (46%) with nephropathy and 73 patients with normoalbuminuria, underwent cardiovascular magnetic resonance imaging. All subjects underwent cardiac exercise testing and noninvasive tests for peripheral artery disease and autonomic neuropathy. Coronary artery stenoses were identified in 10% of subjects with nephropathy (versus 0% with normoalbuminuria; P=0.007). Coronary plaque burden, expressed as right coronary artery mean wall thickness (1.7+/-0.3 versus 1.3+/-0.2 mm; P<0.001) and maximum right coronary artery wall thickness (2.2+/-0.5 versus 1.6+/-0.3 mm; P<0.001), was greater in subjects with nephropathy. The prevalence of thoracic (3% versus 0%; P=0.28) and abdominal aortic plaque (22% versus 16%; P=0.7) was similar in both groups. Subjects with and without abdominal aortic plaques had similar coronary plaque burden. CONCLUSIONS: In asymptomatic type 1 diabetes, cardiovascular magnetic resonance imaging reveals greater coronary plaque burden in subjects with nephropathy compared with those with normoalbuminuria.
Adult↗
Smooth muscle cells in atherosclerosis originate from the local vessel wall and not circulating progenitor cells in ApoE knockout mice.
OBJECTIVE: Recent studies of bone marrow (BM)-transplanted apoE knockout (apoE-/-) mice have concluded that a substantial fraction of smooth muscle cells (SMCs) in atherosclerosis arise from circulating progenitor cells of hematopoietic origin. This pathway, however, remains controversial. In the present study, we reexamined the origin of plaque SMCs in apoE-/- mice by a series of BM transplantations and in a novel model of atherosclerosis induced in surgically transferred arterial segments. METHODS AND RESULTS: We analyzed plaques in lethally irradiated apoE-/- mice reconstituted with sex-mismatched BM cells from eGFP+ apoE-/- mice, which ubiquitously express enhanced green fluorescent protein (eGFP), but did not find a single SMC of donor BM origin among approximately 10,000 SMC profiles analyzed. We then transplanted arterial segments between eGFP+ apoE-/- and apoE-/- mice (isotransplantation except for the eGFP transgene) and induced atherosclerosis focally within the graft by a recently invented collar technique. No eGFP+ SMCs were found in plaques that developed in apoE-/- artery segments grafted into eGFP+ apoE-/- mice. Concordantly, 96% of SMCs were eGFP+ in plaques induced in eGFP+ apoE-/- artery segments grafted into apoE-/- mice. CONCLUSIONS: These experiments show that SMCs in atherosclerotic plaques are exclusively derived from the local vessel wall in apoE-/- mice.
Animals↗
Imaging of vulnerable atherosclerotic plaques with FDG-microPET: no FDG accumulation.
BACKGROUND: Non-invasive methods of evaluating atherosclerosis in humans and experimental animals are needed. Studies indicate that FDG-PET has a potential to detect vulnerable, inflamed atherosclerotic lesions. METHODS: Nine atherosclerotic apoE-deficient mice were PET scanned. Four to determine optimal timing for imaging, and five post mortem after 1h redistribution of FDG and again after sequential removal of the interscapular brown fat and the atherosclerotic aortic arch. Uptake in various tissues in fasting (n=13) and non-fasting (n=7) apoE-deficient mice, including atherosclerotic and non-atherosclerotic aorta, was measured. Finally, accelerated atherosclerosis was induced by carotid ligation (n=12), and FDG-uptake was measured. RESULTS: FDG accumulation initially thought to correspond to the atherosclerotic aortic arch was recorded. Removal of interscapular brown fat, but not atherosclerotic aortic arch, removed the signal. The aortic arch accumulated less FDG than the non-atherosclerotic thoracic aorta both in fasting (ratio 0.5, p=0.008) and non-fasting (ratio 0.33, p=0.02) conditions. Carotid atherosclerosis likewise failed to increase FDG-uptake compared to the non-ligated artery (ratio 1.03). CONCLUSION: Spontaneously developed advanced atherosclerotic lesions in aorta were, paradoxically, associated with reduced FDG uptake, and accelerated carotid atherosclerosis also failed to increase FDG-uptake. The results seriously question the potential of FDG-PET for imagining of advanced, vulnerable atherosclerotic lesions.
Adipose Tissue, Brown↗
From vulnerable plaque to vulnerable patient--Part III: Executive summary of the Screening for Heart Attack Prevention and Education (SHAPE) Task Force report.
Screening for early-stage asymptomatic cancers (eg, cancers of breast and colon) to prevent late-stage malignancies has been widely accepted. However, although atherosclerotic cardiovascular disease (eg, heart attack and stroke) accounts for more death and disability than all cancers combined, there are no national screening guidelines for asymptomatic (subclinical) atherosclerosis, and there is no government- or healthcare-sponsored reimbursement for atherosclerosis screening. Part I and Part II of this consensus statement elaborated on new discoveries in the field of atherosclerosis that led to the concept of the "vulnerable patient." These landmark discoveries, along with new diagnostic and therapeutic options, have set the stage for the next step: translation of this knowledge into a new practice of preventive cardiology. The identification and treatment of the vulnerable patient are the focuses of this consensus statement. In this report, the Screening for Heart Attack Prevention and Education (SHAPE) Task Force presents a new practice guideline for cardiovascular screening in the asymptomatic at-risk population. In summary, the SHAPE Guideline calls for noninvasive screening of all asymptomatic men 45-75 years of age and asymptomatic women 55-75 years of age (except those defined as very low risk) to detect and treat those with subclinical atherosclerosis. A variety of screening tests are available, and the cost-effectiveness of their use in a comprehensive strategy must be validated. Some of these screening tests, such as measurement of coronary artery calcification by computed tomography scanning and carotid artery intima-media thickness and plaque by ultrasonography, have been available longer than others and are capable of providing direct evidence for the presence and extent of atherosclerosis. Both of these imaging methods provide prognostic information of proven value regarding the future risk of heart attack and stroke. Careful and responsible implementation of these tests as part of a comprehensive risk assessment and reduction approach is warranted and outlined by this report. Other tests for the detection of atherosclerosis and abnormal arterial structure and function, such as magnetic resonance imaging of the great arteries, studies of small and large artery stiffness, and assessment of systemic endothelial dysfunction, are emerging and must be further validated. The screening results (severity of subclinical arterial disease) combined with risk factor assessment are used for risk stratification to identify the vulnerable patient and initiate appropriate therapy. The higher the risk, the more vulnerable an individual is to a near-term adverse event. Because <10% of the population who test positive for atherosclerosis will experience a near-term event, additional risk stratification based on reliable markers of disease activity is needed and is expected to further focus the search for the vulnerable patient in the future. All individuals with asymptomatic atherosclerosis should be counseled and treated to prevent progression to overt clinical disease. The aggressiveness of the treatment should be proportional to the level of risk. Individuals with no evidence of subclinical disease may be reassured of the low risk of a future near-term event, yet encouraged to adhere to a healthy lifestyle and maintain appropriate risk factor levels. Early heart attack care education is urged for all individuals with a positive test for atherosclerosis. The SHAPE Task Force reinforces existing guidelines for the screening and treatment of risk factors in younger populations. Cardiovascular healthcare professionals and policymakers are urged to adopt the SHAPE proposal and its attendant cost-effectiveness as a new strategy to contain the epidemic of atherosclerotic cardiovascular disease and the rising cost of therapies associated with this epidemic.
Coronary Artery Disease↗
Pathogenesis of atherosclerosis.
Atherosclerosis is a multifocal, smoldering, immunoinflammatory disease of medium-sized and large arteries fuelled by lipids. Endothelial cells, leukocytes, and intimal smooth muscle cells are the major players in the development of this disease. The most devastating consequences of atherosclerosis, such as heart attack and stroke, are caused by superimposed thrombosis. Therefore, the vital question is not why atherosclerosis develops but rather why atherosclerosis, after years of indolent growth, suddenly becomes complicated with luminal thrombosis. If thrombosis-prone plaques could be detected and thrombosis averted, atherosclerosis would be a much more benign disease. Approximately 76% of all fatal coronary thrombi are precipitated by plaque rupture. Plaque rupture is a more frequent cause of coronary thrombosis in men (approximately 80%) than in women (approximately 60%). Ruptured plaques are characterized by a large lipid-rich core, a thin fibrous cap that contains few smooth muscle cells and many macrophages, angiogenesis, adventitial inflammation, and outward remodeling. Plaque rupture is the most common cause of coronary thrombosis. Ruptured plaques and, by inference, rupture-prone plaques have characteristic pathoanatomical features that might be useful for their detection in vivo by imaging. This article describes the pathogenesis of atherosclerosis, how it begets thrombosis, and the possibility to detect thrombosis-prone plaques and prevent heart attack.
Atherosclerosis↗
Size of myocardial infarction induced by ischaemia/reperfusion is unaltered in rats with metabolic syndrome.
Obesity is associated with metabolic syndrome and increased incidence of and mortality from myocardial infarction. The aim of the present study was to develop an animal model with metabolic syndrome and examine how that influences size of myocardial infarcts induced by occlusion and reperfusion of the left anterior descending coronary artery. Sprague-Dawley rats (n = 105) were fed either LF (low-fat) or MHF (moderately high-fat) diets for 13 weeks before coronary occlusion for 45 min, followed by reperfusion for 60 min. Compared with LF-fed and lean MHF-fed rats, obese MHF-fed rats developed metabolic disturbances similar to those seen in the metabolic syndrome, including being overweight by 24% (compared with lean MHF-fed rats), having 74% more visceral fat (compared with LF-fed rats), 15% higher blood pressure (compared with LF-fed rats), 116% higher plasma insulin (compared with lean MHF-fed rats), 10% higher fasting plasma glucose (compared with LF-fed rats), 35% higher non-fasting plasma glucose (compared with lean MHF-fed rats), 36% higher plasma leptin (compared with lean MHF-fed rats) and a tendency to lower plasma adiponectin and higher plasma non-esterified fatty acids. Infarct size was similar in the three groups of rats (36+/-14, 42+/-18 and 41+/-14% in obese MHF-fed, lean MHF-fed and LF-fed rats respectively). In conclusion, rats fed a MHF diet developed metabolic syndrome, but this did not influence myocardial infarct size.
Adiponectin↗
Surfactant protein D is proatherogenic in mice.
Surfactant protein D (SP-D) is an important innate immune defense molecule that mediates clearance of pathogens and modulates the inflammatory response. Moreover, SP-D is involved in lipid homeostasis, and pulmonary accumulation of phospholipids has previously been observed in SP-D-deficient (Spd-/-) mice. Atherogenesis involves both inflammation and lipid deposition, and we investigated the role of SP-D in the development of atherosclerosis. SP-D synthesis was localized to vascular endothelial cells. Atherosclerotic lesion areas were 5.6-fold smaller in the aortic roots in Spd-/- mice compared with wild-type C57BL/6N mice on an atherogenic diet. HDL cholesterol (HDL-C) was significantly elevated in Spd-/- mice. Treatment of Spd-/- mice with a recombinant fragment of human SP-D resulted in decreases of HDL-C (21%) as well as total cholesterol (26%), and LDL cholesterol (28%). Plasma TNF-alpha was reduced in Spd-/- mice (45% difference). SP-D was proatherogenic in the mouse model used. The effect is likely to be due to the observed disturbances of plasma lipid metabolism and alteration of the inflammatory process, which underlie the reduced susceptibility to atherosclerosis in Spd-/- mice.
Animals↗
Contrasting effect of fish oil supplementation on the development of atherosclerosis in murine models.
OBJECTIVE: Increased fish oil intake is associated with protection against coronary heart disease and sudden death, while effects on atherosclerosis are controversial. We explored the effects of supplementing fish oil (rich in n-3 polyunsaturated fatty acids, PUFA) or corn oil (rich in n-6 PUFA) in two different models of atherosclerosis. METHODS AND RESULTS: Sixty-three low density lipoprotein receptor-deficient (LDLR(-/-)) mice and sixty-nine apolipoprotein E-deficient (apoE(-/-)) mice were fed diets without supplementations or supplemented with either 1% fish oil or 1% corn oil. In apoE(-/-) mice, neither fish oil nor corn oil had any major impact on plasma lipids or atherosclerosis. In LDLR(-/-) mice, conversely, the fish oil and the corn oil group had lower levels of LDL-cholesterol and triglycerides and had lesser atherosclerosis in the aortic root and in the entire aorta (p < 0.01 versus unsupplemented group). Atherosclerosis was significantly less in the fish oil group compared with the corn oil group when evaluated en face in the aortic arch (area positive to lipid staining: 32% with fish oil versus 38% with corn oil; 48% with unsupplemented diet). CONCLUSIONS: n-3 and n-6 PUFA supplementation retarded the development of atherosclerosis in LDLR(-/-) mice, with a stronger effect seen with n-3 PUFA. There was an important strain-dependence of the effect, with no protection against atherosclerosis in apoE(-/-) mice.
Animals↗
Vasa vasorum imaging: a new window to the clinical detection of vulnerable atherosclerotic plaques.
Complications of vulnerable atherosclerotic plaques (rupture, luminal and mural thrombosis, intraplaque hemorrhage, rapid progression to stenosis, spasm, and so forth) lead to heart attacks and strokes. It remains difficult to identify what plaques are vulnerable to these complications. Despite recent developments such as thermography, spectroscopy, and magnetic resonance imaging, none of them is approved for clinical use. Intravascular ultrasound (IVUS), a relatively old yet widely available clinical tool for guiding intracoronary procedures, is increasingly used for characterization of atherosclerotic plaques. However, inability of IVUS in measuring plaque activity limits its value in detection of vulnerable plaques. In this review, we present new information suggesting that microbubble contrast-enhanced IVUS can measure activity and inflammation within atherosclerotic plaques by imaging vasa vasorum density. An increasing body of evidence indicates that vasa vasorum density may be a strong marker for plaque vulnerability. We suggest that a combination of structural assessment (cap thickness, lipid core, calcification, etc) and vasa vasorum density imaging by IVUS can serve as the most powerful clinically available tool for characterization of vulnerable plaques. Due to space limitations, all IVUS images and movies are posted on the website of the Ultimate IVUS Collaborative Project: http://www.ultimateivus.com.
Albumins↗
In vivo heating of pacemaker leads during magnetic resonance imaging.
AIMS: Magnetic resonance imaging (MRI) is well established as an important diagnostic tool in medicine. However, the presence of a cardiac pacemaker is usually regarded as a contraindication for MRI due to safety reasons. In this study, heating effects at the myocardium-pacemaker lead tip interface have been investigated in a chronic animal model during MRI at 1.5 Tesla. METHODS AND RESULTS: Pacemaker leads with additional thermocouple wires as temperature sensors were implanted in nine animals. Temperature increases of up to 20 degrees C were measured during MRI of the heart. Significant impedance and minor stimulation threshold changes could be seen. However, pathology and histology could not clearly demonstrate heat-induced damage. CONCLUSIONS: MRI may produce considerable heating at the lead tip. Changes of pacing parameters due to MRI could be seen in chronic experiments. Potential risk of tissue damage cannot be excluded even though no reproducible alterations at the histological level could be found.
Animals↗
Widespread targets for friendly fire in acute coronary syndromes.
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Acute Disease↗
Association of multiple cellular stress pathways with accelerated atherosclerosis in hyperhomocysteinemic apolipoprotein E-deficient mice.
BACKGROUND: A causal relation between hyperhomocysteinemia (HHcy) and accelerated atherosclerosis has been established in apolipoprotein E-deficient (apoE-/-) mice. Although several cellular stress mechanisms have been proposed to explain the atherogenic effects of HHcy, including oxidative stress, endoplasmic reticulum (ER) stress, and inflammation, their association with atherogenesis has not been completely elucidated. METHODS AND RESULTS: ApoE-/- mice were fed a control or a high-methionine (HM) diet for 4 (early lesion group) or 18 (advanced lesion group) weeks to induce HHcy. Total plasma homocysteine levels and atherosclerotic lesion size were significantly increased in early and advanced lesion groups fed the HM diet compared with control groups. Markers of ER stress (GRP78/94, phospho-PERK), oxidative stress (HSP70), and inflammation (phospho-IkappaB-alpha) were assessed by immunohistochemical staining of these atherosclerotic lesions. GRP78/94, HSP70, and phospho-IkappaB-alpha immunostaining were significantly increased in the advanced lesion group fed the HM diet compared with the control group. HSP47, an ER-resident molecular chaperone involved in collagen folding and secretion, was also increased in advanced lesions of mice fed the HM diet. GRP78/94 and HSP47 were predominantly localized to the smooth muscle cell-rich fibrous cap, whereas HSP70 and phospho-IkappaB-alpha were observed in the lipid-rich necrotic core. Increased HSP70 and phospho-IkappaB-alpha immunostaining in advanced lesions of mice fed the HM diet are consistent with enhanced carotid artery dihydroethidium staining. Interestingly, GRP78/94 and phospho-PERK were markedly increased in macrophage foam cells from early lesions of mice fed the control or the HM diet. CONCLUSIONS: Multiple cellular stress pathways, including ER stress, are associated with atherosclerotic lesion development in apoE-/- mice.
Animals↗
Thrombin inhibitor reduces myocardial infarction in apoE-/- x LDLR-/- mice.
We have previously shown that atherosclerotic apolipoprotein E-deficient (apoE(-/-)) x LDL receptor-deficient (LDLR(-/-)) mice develop myocardial infarction when exposed to hypoxic stress. This study was performed to assess the role of thrombin and thrombosis in this process. ApoE(-/-) x LDLR(-/-) mice were fed a cholesterol-rich diet for 8 mo and were then subjected to hypoxic stress while receiving isoflurane anesthesia. One group received a bolus dose (5.6 micromol/kg) of the thrombin inhibitor melagatran, and control animals received PBS 10 min before the hypoxic stress. The mice were exposed to 10 min of hypoxia followed by normoxia. Ten minutes after the stress, Alzet pumps delivering melagatran (20 nmol x kg x (-1)min(-1)) or PBS were implanted, and the mice were allowed to recover for 48 h. The cardiac response was analyzed by histology, immunohistochemistry, and serum troponin T assay. All animals showed reversible ECG changes as a sign of ischemia during hypoxic stress, and 50% developed infarctions afterward as judged by troponin T levels. The group that received thrombin inhibitor had significantly lower troponin T and smaller myocardial infarctions than the PBS-treated group. These data show that thrombin generation is an important pathogenetic factor and suggest that coronary thrombosis is involved in myocardial infarction in atherosclerotic mice. Exposure of atherosclerotic mice to hypoxia leads to myocardial infarction through a two-phase pathway in which acute transient ischemia is followed by thrombin-dependent, irreversible, myocardial ischemia and myocardial cell death.
Animals↗
Terminology for high-risk and vulnerable coronary artery plaques. Report of a meeting on the vulnerable plaque, June 17 and 18, 2003, Santorini, Greece.
A group of investigators met for two days in Santorini, Greece, to discuss progress in the field of identification and treatment of high risk/vulnerable atherosclerotic plaques and patients. Many differences in the manner in which terms are being utilized were noted. It was recognized that increased understanding of the pathophysiology of coronary thrombosis and onset of acute coronary syndromes has created the need for agreement on nomenclature. The participants spent considerable time discussing the topic and reached agreement on their own usage of the terms as described below. It is the hope that this usage might be of value to the larger community of scientists working in this field, and that widespread adoption of a common nomenclature would accelerate progress in the prevention of acute coronary events.
Calcinosis↗
[Regeneration of myocardium by stem cell therapy. Historical and biological perspective].
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Cell Differentiation↗
From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part II.
Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document will focus on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.
Animals↗
From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part I.
Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document focuses on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.
Acute Disease↗