Cardiovascular Pathology

A review of state-of-the-art stereology for better quantitative 3D morphology in cardiac research

Christian Mühlfeld, Jens Randel Nyengaard, Terry M. Mayhew — 2009-01-15

Abstract: The aim of stereological methods in biomedical research is to obtain quantitative information about three-dimensional (3D) features of tissues, cells, or organelles from two-dimensional physical or optical sections. With immunogold labeling, stereology can even be used for the quantitative analysis of the distribution of molecules within tissues and cells. Nowadays, a large number of design-based stereological methods offer an efficient quantitative approach to intriguing questions in cardiac research, such as “Is there a significant loss of cardiomyocytes during progression from ventricular hypertrophy to heart failure?” or “Does a specific treatment reduce the degree of fibrosis in the heart?” Nevertheless, the use of stereological methods in cardiac research is rare. The present review article demonstrates how some of the potential pitfalls in quantitative microscopy may be avoided. To this end, we outline the concepts of design-based stereology and illustrate their practical applications to a wide range of biological questions in cardiac research. We hope that the present article will stimulate researchers in cardiac research to incorporate design-based stereology into their study designs, thus promoting an unbiased quantitative 3D microscopy.

In vivo characterization of cytokine profiles and viral load during murine cytomegalovirus-induced acute myocarditis

2009-02-17

Abstract: Background: Murine cytomegalovirus (MCMV) is an etiologic agent of acute and chronic myocarditis in BALB/c mice. Immunologic host responses appear to play a key role in pathogenesis but have been incompletely defined.Methods: BALB/c mice were infected with a sublethal dose of MCMV. Cytokine transcription and viral load (measured by quantitative real-time polymerase chain reaction) and histopathological analyses were performed at specified time points.Results: Increased tumor necrosis factor (TNF)-α, interleukin (IL)-6, and interferon (IFN)-γ, as well as IL-10 mRNA transcripts, were detected in the hearts of infected mice starting at Day 1 post-infection (p.i.), with peak levels occurring at Day 8 p.i. (7-fold, 14-fold, 41-fold, and 16-fold higher than background, respectively). Peak cytokine transcription significantly correlated with a 10-fold increase in viral load (P<.001) at Day 8 p.i. Myocarditis-related pathological changes, measured by infiltration foci, were greatest at Day 8 p.i., corresponding with peak cytokine transcription and significantly correlated with IFN-γ levels (P<.0001). Infiltration foci were predominantly composed of CD3+ T cells. Cardiac calcification was observed in most infected mice predominantly over the right ventricle. Histological analysis of heart sections from mice infected with recombinant enhanced green fluorescence protein-MCMV revealed a localized and sporadic pattern of virus throughout all heart layers.Conclusions: MCMV-induced myocarditis in BALB/c mice is characterized by in vivo production of proinflammatory cytokines in a pattern correlating with MCMV viral load. The infection pattern and inflammatory response is highly localized, sporadic, and involves endocardium, epicardium, as well as the myocardium, with greatest amounts of virus detected in areas of pathologic calcification.

The Ras antagonist farnesylthiosalicylic acid ameliorates experimental myocarditis in the rat

2009-01-15

Abstract: Background: Myocarditis is an inflammatory disorder of the heart in which T lymphocytes have a central role. No effective treatment is currently at hand for management of the myocarditis. Lymphocyte function requires the active signal transducer Ras. We thus hypothesized that S-farnesylthiosalicylic acid (FTS), a synthetic small molecule that detaches Ras from the inner cell membrane and induces its rapid degradation, will attenuate experimental autoimmune myocarditis (EAM).Methods and results: Two groups of Lewis rats were induced to develop EAM by immunization with porcine cardiac myosin. Group A received 5 mg/kg of FTS, and group B received phosphate-buffered saline (PBS) according to two protocols: FTS or PBS was given 2 days before myosin immunization in protocol 1 and FTS or PBS was given 14 days after myosin immunization in protocol 2. FTS significantly suppressed myocarditis, and this effect was accompanied by a reduction in myosin-specific cellular and humoral immune responses. In the longer regimen, FTS treatment for 6 weeks was associated with preservation of myocardial function made evident by echocardiography. In vitro, FTS significantly attenuated the proliferation of lymphocytes from untreated myocarditic rats to myosin.Conclusions: FTS is effective in suppressing the progression of EAM and its consequent functional myocardial dysfunction. The effect may be mediated by suppression of the cellular and humoral responses to myosin.

Atrial fibrillation is associated with cardiac hypoxia

2009-02-12

Abstract: Background: Atrial fibrillation (AF), the most common human arrhythmia, is responsible for substantial morbidity and mortality and may be promoted by selective atrial ischemia and atrial fibrosis. Consequently, we investigated markers for hypoxia and angiogenesis in AF.Methods: Right atrial appendages (n=158) were grouped according to heart rhythm [sinus rhythm (SR) or AF]. The degree of fibrosis and microvessel density of all patients were determined morphometrically using Sirius-Red- and CD34/CD105-stained sections, respectively. Next, sections (n=77) underwent immunostaining to detect hypoxia- and angiogenesis-related proteins [hypoxia-inducible factor (HIF)1α, HIF2α, vascular endothelial growth factor (VEGF), VEGF receptor 2 (KDR), phosphorylated KDR (pKDR), carboanhydrase IX, platelet-derived growth factor] and the apoptosis-related B-cell lymphoma 2 protein.Results: Fibrosis progressed significantly from 14.7±0.8% (SR) to 22.3±1.4% (AF). While the positive cytoplasmic staining of HIF1α, HIF2α, VEGF, KDR, and pKDR rose significantly from SR to AF, their nuclear fractions fell (only pKDR significantly). The median CD34/CD105-positive microvessel size increased significantly from SR to AF.Conclusions: AF is closely associated with an atrial up-regulation of hypoxic and angiogenic markers. Whether this is cause, effect, or co-phenomenon of fibrosis remains to be investigated. It is conceivable that fibrosis might lead to an increased O2 diffusion distance and thus induce ischemic signaling, which, in turn, leads to angiogenesis.

Mechanical ventricular assistance in heart failure: pathology of the cardiac apex removed during device implantation

2009-01-15

Abstract: Background: Ventricular assistance device (VAD) implantation provides large ventricular core biopsies available for pathological assessment. We present here the pathological data from 60 apex removed during a 7-year-period in a single institution.Results: The most frequent specific lesions were ischemic myocardial damage. Nonspecific pathological features were quite as frequently observed and correspond either to dilated cardiomyopathies, chronic ischemic cardiopathies, or miscellaneous conditions. Myocarditis represented 10 out of the 60 cases. The pathological data changed the clinical diagnosis in four cases: 1 case of juvenile hemochromatosis featuring as myocarditis and three cases of myocarditis featuring as dilated cardiomyopathies.Conclusion: Apex pathological analysis provides definite diagnosis and contributes to determine the cases which the cardiac disease have a possibility to recover under VAD.

Bradycardia and syncope as a presentation of cardiac allograft rejection involving the conducting system

2009-01-15

Abstract: Post-heart transplantation bradycardic syncope and arrest could be due to preferential rejection of the conduction system. We present six heart transplant patients with this presentation, two of whom died. The autopsy of one of those patients demonstrated severe rejection of the conduction system, with only mild rejection throughout the rest of the myocardium. We postulate that aggressive therapy for rejection and pacemaker placement may result in improved survival in heart transplant recipients with this clinical presentation.

Hemangioma of the right atrium: imaging and pathology

2009-01-09

Abstract: Background: Cardiac hemangiomas are benign neoplasms which have been reported to appear as well-circumscribed, homogenous, enhancing masses at imaging.Methods and results: We report a 49-year-old woman with a cardiac hemangioma detected by echocardiography, computed tomography, and magnetic resonance imaging. The multiple imaging modalities showed features which have been reported in cardiac hemangiomas. The tumor was surgically excised and the diagnosis of cardiac hemangioma was made.Conclusions: Cardiac hemangiomas are rare tumors with a variety of imaging features which may suggest the diagnosis.

Blue dye, green heart

Carmela D. Tan, E. Rene Rodriguez — 2008-08-15

Abstract: Methylene blue has been used for the rapid reversal of circulatory shock refractory to fluid administration, inotropic agents, and vasoconstrictors. Its clinical side effects have been well described. We report an interesting autopsy observation in patients who received methylene blue as adjunct therapy for septic shock. The exposed surface of cardiac myocardium on both fresh and fixed states rapidly turned green. In the presence of molecular oxygen, the colorless metabolite leukomethylene blue is readily oxidized to methylene blue, thus explaining the visible color change of the myocardium.

Biomechanical stress induces novel arterial intima-enriched genes: implications for vascular adaptation to stress

2009-02-12

Abstract: Background: The arterial vasculature is subjected to considerably greater biomechanical stress than the venous circulation. This is reflected in the difference in morphology between large arteries and veins, however little is known about the molecular differences that arise as a consequence of biomechanical stress. Previously, we identified a group of arterial intima-enriched (AIE) genes: sciellin, periplakin, SPRR3, envoplakin, galectin 7, and plakoglobin that are functionally related in that they contribute to the stress properties of stratified epithelium. We sought to test our hypothesis that these genes were regulated by biomechanical stress in vascular smooth muscle cells (VSMCs).Methods: Immunofluorescence was employed to determine the expression of the AIE genes in saphenous vein coronary artery bypass grafts. Furthermore, we used a model of cyclic stress to determine if the AIE genes were regulated by biomechanical stress in VSMCs in vitro.Results: Sciellin and periplakin were upregulated in saphenous vein coronary artery bypass grafts after arterialization, but were absent in non-arterialized saphenous veins. Sciellin, SPRR3, and periplakin transcripts were all upregulated (4.67-, 4.95-, 2.77-fold, respectively) by prolonged exposure to cyclic strain (24-72 h), but not at earlier time points.Conclusions: These findings suggest a novel role for several human AIE genes in the VSMC response to arterialization and extended cyclic strain.Summary: Biomechanical stress has long been implicated in vascular pathologies. We report the novel finding of a group of genes, previously studied in stratified epithelium, that were regulated by prolonged cyclic stress in vascular smooth muscle cells. This may have important implications to vascular disease.

Accumulation of mitochondrial genome variations in Persian LQTS patients: a possible risk factor?

2009-04-15

Abstract: Background: Long QT syndrome (LQTS) is among arrhythmia disorders of the heart that causes sudden cardiac death in young individuals. As yet, most of investigations have focused on nuclear genome for finding genetic defects in this disorder, but some of the cases with LQTS cannot be explained by mutations of identified genes. On the other hand, it has been reported that the activity of ion channels in cardiomyocytes is sensitive to ATP level. It prompted us to focus on the mitochondrial DNA and monitor the point mutations of genome which are probably the cause of respiratory chain defects and reduced ATP generation.Methods: We searched about 55% of the mitochondrial DNA (mtDNA) by temporal temperature gradient gel electrophoresis (TTGE), and DNA fragments showing abnormal banding patterns were sequenced for identification of exact mutations.Results: In 39 patients (33 familial and 6 sporadic cases), for the first time, we detected 35 mtDNA mutations in which 8 were novel (23%) and 27 (77%) have been reported in other mitochondrial diseases. Our results showed that these mutations in LQTS patients were higher than those in normal controls (P<.0001), and the number of mutations in LQTS patients with syncope is higher than in patients without syncope (P<.001).Conclusions: As the mitochondrion's ATP synthesis is important in heart, it is possible that mutations and their accumulation in mtDNA could constitute a predisposing factor that in combination with environmental factors may trigger the syncope in patients with LQTS.

Mycobacterium bovis abdominal aortic and femoral artery aneurysms following intravesical bacillus Calmette–Guérin therapy for bladder cancer

2008-11-21

Abstract: Background: Infectious complications of intravesical bacillus Calmette–Guérin (BCG) therapy are rare, but these have included a handful of cases of mycotic aneurysm.Methods and Results: We present the case of a patient with a ruptured abdominal aortic aneurysm and a femoral artery aneurysm who had previously received intravesical BCG therapy for bladder carcinoma. Histopathologic examination of resected tissue revealed numerous acid-fast bacilli, and subsequent mycobacterial culture of blood and resected tissue revealed BCG strain Mycobacterium bovis.Conclusions: Clinicians should be aware of the possible extravesical complications, albeit rare, of BCG therapy. Therapy should consist of combined medical and surgical management.

Ventricular fibrillation following autologous intramyocardial cell therapy for inherited cardiomyopathy

2008-11-25

Abstract: A 41-year-old male with cardiomyopathy from an inherited β myosin heavy-chain mutation underwent treatment for heart failure with intramyocardial cell transplantation. He received direct injections into his heart of autologous precursor cells isolated from his blood. He immediately suffered ventricular fibrillation. Although he was resuscitated, he experienced a prolonged downward course that prohibited his undergoing transplantation. His autopsy revealed marked fibrosis throughout the myocardium with areas of mononuclear cell infiltrate. This case highlights the potential adverse effects associated with intramyocardial therapy in the cardiomyopathic heart.

Giant cell myocarditis of the left atrium

Amal K. Bose, Mohua Bhattacharjee, Victor Martin, Simon Kendall — 2008-11-21

Abstract: Here we describe an unusual case of giant cell myocarditis (GCM) found in the left atrial appendage. Giant cell myocarditis is a rare entity in itself, while isolated left atrial GCM has only been reported on a few occasions. We describe a patient who underwent mitral valve replacement for rheumatic mitral stenosis and excision of a grossly abnormal, thickened, and enlarged left atrial appendage. Histological examination confirmed the presence of GCM.

A Braunwald-Cutter valve: a mitral prosthesis at 33 years

2009-01-09

Abstract: We present a case of a 76-year-old woman with a Braunwald-Cutter mitral caged-ball valve prosthesis excised after 33 years post implantation due to a paravalvular leak. The valve itself was intact and fully functional. We believe the longevity of this valve was due to the decreased flow velocities and the lower pressure in the mitral valve position.

Venous air embolism after cardiopulmonary resuscitation: the first case with histological confirmation

Vincenzo Arena, Arnaldo Capelli — 2009-01-15

Abstract: We report a case of intracerebral air embolism after cardiopulmonary resuscitation in a patient with a fatal myocardial infarct. Cases of cerebral air embolism rarely occur as a result of cardiopulmonary resuscitation in cases of cardiopulmonary arrest on arrival. This is the first case with postmortem histological confirmation.

Editorial Board

2010-03-01

Cardiovascular Pathology

A review of state-of-the-art stereology for better quantitative 3D morphology in cardiac research

In vivo characterization of cytokine profiles and viral load during murine cytomegalovirus-induced acute myocarditis

The Ras antagonist farnesylthiosalicylic acid ameliorates experimental myocarditis in the rat

Atrial fibrillation is associated with cardiac hypoxia

Mechanical ventricular assistance in heart failure: pathology of the cardiac apex removed during device implantation

Bradycardia and syncope as a presentation of cardiac allograft rejection involving the conducting system

Hemangioma of the right atrium: imaging and pathology

Blue dye, green heart

Biomechanical stress induces novel arterial intima-enriched genes: implications for vascular adaptation to stress

Accumulation of mitochondrial genome variations in Persian LQTS patients: a possible risk factor?

Mycobacterium bovis abdominal aortic and femoral artery aneurysms following intravesical bacillus Calmette–Guérin therapy for bladder cancer

Ventricular fibrillation following autologous intramyocardial cell therapy for inherited cardiomyopathy

Giant cell myocarditis of the left atrium

A Braunwald-Cutter valve: a mitral prosthesis at 33 years

Venous air embolism after cardiopulmonary resuscitation: the first case with histological confirmation

Editorial Board

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