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Pubmed Article
Detection of Tissue Factor Antigen and Coagulation Activity in Coronary Artery Thrombi Isolated from Patients with ST-Segment Elevation Acute Myocardial Infarction.
PLoS ONE
PUBLISHED: 01-01-2013
Although ruptured atherosclerotic plaques have been extensively analyzed, the composition of thrombi causing arterial occlusion in patients with ST-segment elevation acute myocardial infarction has been less thoroughly investigated. We sought to investigate whether coagulant active tissue factor can be retrieved in thrombi of patients with STEMI undergoing primary percutaneous coronary intervention.
ABSTRACT
Heart failure is a syndrome in which the heart fails to pump blood at a rate commensurate with cellular oxygen requirements at rest or during stress. It is characterized by fluid retention, shortness of breath, and fatigue, in particular on exertion. Heart failure is a growing public health problem, the leading cause of hospitalization, and a major cause of mortality. Ischemic heart disease is the main cause of heart failure. Ventricular remodelling refers to changes in structure, size, and shape of the left ventricle. This architectural remodelling of the left ventricle is induced by injury (e.g., myocardial infarction), by pressure overload (e.g., systemic arterial hypertension or aortic stenosis), or by volume overload. Since ventricular remodelling affects wall stress, it has a profound impact on cardiac function and on the development of heart failure. A model of permanent ligation of the left anterior descending coronary artery in mice is used to investigate ventricular remodelling and cardiac function post-myocardial infarction. This model is fundamentally different in terms of objectives and pathophysiological relevance compared to the model of transient ligation of the left anterior descending coronary artery. In this latter model of ischemia/reperfusion injury, the initial extent of the infarct may be modulated by factors that affect myocardial salvage following reperfusion. In contrast, the infarct area at 24 hr after permanent ligation of the left anterior descending coronary artery is fixed. Cardiac function in this model will be affected by 1) the process of infarct expansion, infarct healing, and scar formation; and 2) the concomitant development of left ventricular dilatation, cardiac hypertrophy, and ventricular remodelling. Besides the model of permanent ligation of the left anterior descending coronary artery, the technique of invasive hemodynamic measurements in mice is presented in detail.
17 Related JoVE Articles!
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A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis
Authors: Michele M. Pelter, Teri M. Kozik, Denise L. Loranger, Mary G. Carey.
Institutions: University of Nevada, Reno, St. Joseph's Medical Center, University of Rochester Medical Center .
Each year, an estimated 785,000 Americans will have a new coronary attack, or acute coronary syndrome (ACS). The pathophysiology of ACS involves rupture of an atherosclerotic plaque; hence, treatment is aimed at plaque stabilization in order to prevent cellular death. However, there is considerable debate among clinicians, about which treatment pathway is best: early invasive using percutaneous coronary intervention (PCI/stent) when indicated or a conservative approach (i.e., medication only with PCI/stent if recurrent symptoms occur). There are three types of ACS: ST elevation myocardial infarction (STEMI), non-ST elevation MI (NSTEMI), and unstable angina (UA). Among the three types, NSTEMI/UA is nearly four times as common as STEMI. Treatment decisions for NSTEMI/UA are based largely on symptoms and resting or exercise electrocardiograms (ECG). However, because of the dynamic and unpredictable nature of the atherosclerotic plaque, these methods often under detect myocardial ischemia because symptoms are unreliable, and/or continuous ECG monitoring was not utilized. Continuous 12-lead ECG monitoring, which is both inexpensive and non-invasive, can identify transient episodes of myocardial ischemia, a precursor to MI, even when asymptomatic. However, continuous 12-lead ECG monitoring is not usual hospital practice; rather, only two leads are typically monitored. Information obtained with 12-lead ECG monitoring might provide useful information for deciding the best ACS treatment. Purpose. Therefore, using 12-lead ECG monitoring, the COMPARE Study (electroCardiographic evaluatiOn of ischeMia comParing invAsive to phaRmacological trEatment) was designed to assess the frequency and clinical consequences of transient myocardial ischemia, in patients with NSTEMI/UA treated with either early invasive PCI/stent or those managed conservatively (medications or PCI/stent following recurrent symptoms). The purpose of this manuscript is to describe the methodology used in the COMPARE Study. Method. Permission to proceed with this study was obtained from the Institutional Review Board of the hospital and the university. Research nurses identify hospitalized patients from the emergency department and telemetry unit with suspected ACS. Once consented, a 12-lead ECG Holter monitor is applied, and remains in place during the patient's entire hospital stay. Patients are also maintained on the routine bedside ECG monitoring system per hospital protocol. Off-line ECG analysis is done using sophisticated software and careful human oversight.
Medicine, Issue 70, Anatomy, Physiology, Cardiology, Myocardial Ischemia, Cardiovascular Diseases, Health Occupations, Health Care, transient myocardial ischemia, Acute Coronary Syndrome, electrocardiogram, ST-segment monitoring, Holter monitoring, research methodology
50124
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Evaluation of a Novel Laser-assisted Coronary Anastomotic Connector - the Trinity Clip - in a Porcine Off-pump Bypass Model
Authors: David Stecher, Glenn Bronkers, Jappe O.T. Noest, Cornelis A.F. Tulleken, Imo E. Hoefer, Lex A. van Herwerden, Gerard Pasterkamp, Marc P. Buijsrogge.
Institutions: University Medical Center Utrecht, Vascular Connect b.v., University Medical Center Utrecht, University Medical Center Utrecht.
To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e., occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated.
Medicine, Issue 93, Anastomosis, coronary, anastomotic connector, anastomotic coupler, excimer laser-assisted nonocclusive anastomosis (ELANA), coronary artery bypass graft (CABG), off-pump coronary artery bypass (OPCAB), beating heart surgery, excimer laser, porcine model, experimental, medical device
52127
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Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Authors: Hugh Alley, Christopher D. Owens, Warren J. Gasper, S. Marlene Grenon.
Institutions: University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, Veterans Affairs Medical Center, San Francisco.
The vascular endothelium is a monolayer of cells that cover the interior of blood vessels and provide both structural and functional roles. The endothelium acts as a barrier, preventing leukocyte adhesion and aggregation, as well as controlling permeability to plasma components. Functionally, the endothelium affects vessel tone. Endothelial dysfunction is an imbalance between the chemical species which regulate vessel tone, thombroresistance, cellular proliferation and mitosis. It is the first step in atherosclerosis and is associated with coronary artery disease, peripheral artery disease, heart failure, hypertension, and hyperlipidemia. The first demonstration of endothelial dysfunction involved direct infusion of acetylcholine and quantitative coronary angiography. Acetylcholine binds to muscarinic receptors on the endothelial cell surface, leading to an increase of intracellular calcium and increased nitric oxide (NO) production. In subjects with an intact endothelium, vasodilation was observed while subjects with endothelial damage experienced paradoxical vasoconstriction. There exists a non-invasive, in vivo method for measuring endothelial function in peripheral arteries using high-resolution B-mode ultrasound. The endothelial function of peripheral arteries is closely related to coronary artery function. This technique measures the percent diameter change in the brachial artery during a period of reactive hyperemia following limb ischemia. This technique, known as endothelium-dependent, flow-mediated vasodilation (FMD) has value in clinical research settings. However, a number of physiological and technical issues can affect the accuracy of the results and appropriate guidelines for the technique have been published. Despite the guidelines, FMD remains heavily operator dependent and presents a steep learning curve. This article presents a standardized method for measuring FMD in the brachial artery on the upper arm and offers suggestions to reduce intra-operator variability.
Medicine, Issue 92, endothelial function, endothelial dysfunction, brachial artery, peripheral artery disease, ultrasound, vascular, endothelium, cardiovascular disease.
52070
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Analysis of Tubular Membrane Networks in Cardiac Myocytes from Atria and Ventricles
Authors: Eva Wagner, Sören Brandenburg, Tobias Kohl, Stephan E. Lehnart.
Institutions: Heart Research Center Goettingen, University Medical Center Goettingen, German Center for Cardiovascular Research (DZHK) partner site Goettingen, University of Maryland School of Medicine.
In cardiac myocytes a complex network of membrane tubules - the transverse-axial tubule system (TATS) - controls deep intracellular signaling functions. While the outer surface membrane and associated TATS membrane components appear to be continuous, there are substantial differences in lipid and protein content. In ventricular myocytes (VMs), certain TATS components are highly abundant contributing to rectilinear tubule networks and regular branching 3D architectures. It is thought that peripheral TATS components propagate action potentials from the cell surface to thousands of remote intracellular sarcoendoplasmic reticulum (SER) membrane contact domains, thereby activating intracellular Ca2+ release units (CRUs). In contrast to VMs, the organization and functional role of TATS membranes in atrial myocytes (AMs) is significantly different and much less understood. Taken together, quantitative structural characterization of TATS membrane networks in healthy and diseased myocytes is an essential prerequisite towards better understanding of functional plasticity and pathophysiological reorganization. Here, we present a strategic combination of protocols for direct quantitative analysis of TATS membrane networks in living VMs and AMs. For this, we accompany primary cell isolations of mouse VMs and/or AMs with critical quality control steps and direct membrane staining protocols for fluorescence imaging of TATS membranes. Using an optimized workflow for confocal or superresolution TATS image processing, binarized and skeletonized data are generated for quantitative analysis of the TATS network and its components. Unlike previously published indirect regional aggregate image analysis strategies, our protocols enable direct characterization of specific components and derive complex physiological properties of TATS membrane networks in living myocytes with high throughput and open access software tools. In summary, the combined protocol strategy can be readily applied for quantitative TATS network studies during physiological myocyte adaptation or disease changes, comparison of different cardiac or skeletal muscle cell types, phenotyping of transgenic models, and pharmacological or therapeutic interventions.
Bioengineering, Issue 92, cardiac myocyte, atria, ventricle, heart, primary cell isolation, fluorescence microscopy, membrane tubule, transverse-axial tubule system, image analysis, image processing, T-tubule, collagenase
51823
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A Murine Model of Myocardial Ischemia-reperfusion Injury through Ligation of the Left Anterior Descending Artery
Authors: Zhaobin Xu, Jenna Alloush, Eric Beck, Noah Weisleder.
Institutions: The Ohio State University.
Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms at work during MI and developing effective therapeutic approaches requires methodology to reproducibly simulate the clinical incidence and reflect the pathophysiological changes associated with MI. Here, we describe a surgical method to induce MI in mouse models that can be used for short-term ischemia-reperfusion (I/R) injury as well as permanent ligation. The major advantage of this method is to facilitate location of the left anterior descending artery (LAD) to allow for accurate ligation of this artery to induce ischemia in the left ventricle of the mouse heart. Accurate positioning of the ligature on the LAD increases reproducibility of infarct size and thus produces more reliable results. Greater precision in placement of the ligature will improve the standard surgical approaches to simulate MI in mice, thus reducing the number of experimental animals necessary for statistically relevant studies and improving our understanding of the mechanisms producing cardiac dysfunction following MI. This mouse model of MI is also useful for the preclinical testing of treatments targeting myocardial damage following MI.
Medicine, Issue 86, Myocardial Ischemia/Reperfusion, permanent ligation, left anterior descending artery, myocardial infarction, LAD, ligation, Cardiac troponin I
51329
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Myocardial Infarction and Functional Outcome Assessment in Pigs
Authors: Stefan Koudstaal, Sanne J. Jansen of Lorkeers, Johannes M.I.H. Gho, Gerardus P.J van Hout, Marlijn S. Jansen, Paul F. Gründeman, Gerard Pasterkamp, Pieter A. Doevendans, Imo E. Hoefer, Steven A.J. Chamuleau.
Institutions: University Medical Center Utrecht, Interuniversity Cardiology Institute of the Netherlands.
Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One important prerequisite is a good understanding of all safety and efficacy aspects obtained in a large animal model that validly reflect the human scenario of myocardial infarction (MI). Pigs are widely used in this regard since their cardiac size, hemodynamics, and coronary anatomy are close to that of humans. Here, we present an effective protocol for using the porcine MI model using a closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. This approach is based on 90 min of myocardial ischemia, inducing large left ventricle infarction of the anterior, septal and inferoseptal walls. Furthermore, we present protocols for various measures of outcome that provide a wide range of information on the heart, such as cardiac systolic and diastolic function, hemodynamics, coronary flow velocity, microvascular resistance, and infarct size. This protocol can be easily tailored to meet study specific requirements for the validation of novel cardioregenerative biologics at different stages (i.e. directly after the acute ischemic insult, in the subacute setting or even in the chronic MI once scar formation has been completed). This model therefore provides a useful translational tool to study MI, subsequent adverse remodeling, and the potential of novel cardioregenerative agents.
Medicine, Issue 86, myocardial infarction (MI), AMI, large animal model, pig, translational medicine, ischemic heart disease
51269
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Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples
Authors: Raffaele Coppini, Cecila Ferrantini, Alessandro Aiazzi, Luca Mazzoni, Laura Sartiani, Alessandro Mugelli, Corrado Poggesi, Elisabetta Cerbai.
Institutions: University of Florence, University of Florence.
Cardiomyocytes from diseased hearts are subjected to complex remodeling processes involving changes in cell structure, excitation contraction coupling and membrane ion currents. Those changes are likely to be responsible for the increased arrhythmogenic risk and the contractile alterations leading to systolic and diastolic dysfunction in cardiac patients. However, most information on the alterations of myocyte function in cardiac diseases has come from animal models. Here we describe and validate a protocol to isolate viable myocytes from small surgical samples of ventricular myocardium from patients undergoing cardiac surgery operations. The protocol is described in detail. Electrophysiological and intracellular calcium measurements are reported to demonstrate the feasibility of a number of single cell measurements in human ventricular cardiomyocytes obtained with this method. The protocol reported here can be useful for future investigations of the cellular and molecular basis of functional alterations of the human heart in the presence of different cardiac diseases. Further, this method can be used to identify novel therapeutic targets at cellular level and to test the effectiveness of new compounds on human cardiomyocytes, with direct translational value.
Medicine, Issue 86, cardiology, cardiac cells, electrophysiology, excitation-contraction coupling, action potential, calcium, myocardium, hypertrophic cardiomyopathy, cardiac patients, cardiac disease
51116
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Intramyocardial Cell Delivery: Observations in Murine Hearts
Authors: Tommaso Poggioli, Padmini Sarathchandra, Nadia Rosenthal, Maria P. Santini.
Institutions: Imperial College London, Imperial College London, Monash University.
Previous studies showed that cell delivery promotes cardiac function amelioration by release of cytokines and factors that increase cardiac tissue revascularization and cell survival. In addition, further observations revealed that specific stem cells, such as cardiac stem cells, mesenchymal stem cells and cardiospheres have the ability to integrate within the surrounding myocardium by differentiating into cardiomyocytes, smooth muscle cells and endothelial cells. Here, we present the materials and methods to reliably deliver noncontractile cells into the left ventricular wall of immunodepleted mice. The salient steps of this microsurgical procedure involve anesthesia and analgesia injection, intratracheal intubation, incision to open the chest and expose the heart and delivery of cells by a sterile 30-gauge needle and a precision microliter syringe. Tissue processing consisting of heart harvesting, embedding, sectioning and histological staining showed that intramyocardial cell injection produced a small damage in the epicardial area, as well as in the ventricular wall. Noncontractile cells were retained into the myocardial wall of immunocompromised mice and were surrounded by a layer of fibrotic tissue, likely to protect from cardiac pressure and mechanical load.
Medicine, Issue 83, intramyocardial cell injection, heart, grafting, cell therapy, stem cells, fibrotic tissue
51064
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A Human Ex Vivo Atherosclerotic Plaque Model to Study Lesion Biology
Authors: Christian Erbel, Deniz Okuyucu, Mohammadreza Akhavanpoor, Li Zhao, Susanne Wangler, Maani Hakimi, Andreas Doesch, Thomas J. Dengler, Hugo A. Katus, Christian A. Gleissner.
Institutions: University of Heidelberg, University of Heidelberg, SLK Hospital am Plattenwald.
Atherosclerosis is a chronic inflammatory disease of the vasculature. There are various methods to study the inflammatory compound in atherosclerotic lesions. Mouse models are an important tool to investigate inflammatory processes in atherogenesis, but these models suffer from the phenotypic and functional differences between the murine and human immune system. In vitro cell experiments are used to specifically evaluate cell type-dependent changes caused by a substance of interest, but culture-dependent variations and the inability to analyze the influence of specific molecules in the context of the inflammatory compound in atherosclerotic lesions limit the impact of the results. In addition, measuring levels of a molecule of interest in human blood helps to further investigate its clinical relevance, but this represents systemic and not local inflammation. Therefore, we here describe a plaque culture model to study human atherosclerotic lesion biology ex vivo. In short, fresh plaques are obtained from patients undergoing endarterectomy or coronary artery bypass grafting and stored in RPMI medium on ice until usage. The specimens are cut into small pieces followed by random distribution into a 48-well plate, containing RPMI medium in addition to a substance of interest such as cytokines or chemokines alone or in combination for defined periods of time. After incubation, the plaque pieces can be shock frozen for mRNA isolation, embedded in Paraffin or OCT for immunohistochemistry staining or smashed and lysed for western blotting. Furthermore, cells may be isolated from the plaque for flow cytometry analysis. In addition, supernatants can be collected for protein measurement by ELISA. In conclusion, the presented ex vivo model opens the possibility to further study inflammatory lesional biology, which may result in identification of novel disease mechanisms and therapeutic targets.
Medicine, Issue 87, ex vivo model, human, tissue culture, atherosclerosis, immune response, inflammation, chronic inflammatory disease
50542
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A Murine Model of Stent Implantation in the Carotid Artery for the Study of Restenosis
Authors: Sakine Simsekyilmaz, Fabian Schreiber, Stefan Weinandy, Felix Gremse, Tolga Taha Sönmez, Elisa A. Liehn.
Institutions: RWTH Aachen University, RWTH Aachen University, Helmholtz-Institute of RWTH Aachen University, RWTH Aachen University, RWTH Aachen University.
Despite the considerable progress made in the stent development in the last decades, cardiovascular diseases remain the main cause of death in western countries. Beside the benefits offered by the development of different drug-eluting stents, the coronary revascularization bears also the life-threatening risks of in-stent thrombosis and restenosis. Research on new therapeutic strategies is impaired by the lack of appropriate methods to study stent implantation and restenosis processes. Here, we describe a rapid and accessible procedure of stent implantation in mouse carotid artery, which offers the possibility to study in a convenient way the molecular mechanisms of vessel remodeling and the effects of different drug coatings.
Medicine, Issue 75, Anatomy, Physiology, Biomedical Engineering, Mechanical Engineering, Cardiology, Surgery, Microsurgery, Animal Experimentation, Models, Animal, Cardiovascular Diseases, Stent implantation, atherosclerosis, restenosis, in-stent thrombosis, stent, mouse carotid artery, arteries, blood vessels, mouse, animal model, surgical techniques
50233
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Quantification of Atherosclerotic Plaque Activity and Vascular Inflammation using [18-F] Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (FDG-PET/CT)
Authors: Nehal N. Mehta, Drew A. Torigian, Joel M. Gelfand, Babak Saboury, Abass Alavi.
Institutions: University of Pennsylvania, Perelman School of Medicine, University of Pennsylvania, Perelman School of Medicine, University of Pennsylvania, Perelman School of Medicine.
Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC)1 and carotid intimal medial thickness (C-IMT)2 provide information about the burden of disease. However, despite multiple validation studies of CAC3-5, and C-IMT2,6, these modalities do not accurately assess plaque characteristics7,8, and the composition and inflammatory state of the plaque determine its stability and, therefore, the risk of clinical events9-13. [18F]-2-fluoro-2-deoxy-D-glucose (FDG) imaging using positron-emission tomography (PET)/computed tomography (CT) has been extensively studied in oncologic metabolism14,15. Studies using animal models and immunohistochemistry in humans show that FDG-PET/CT is exquisitely sensitive for detecting macrophage activity16, an important source of cellular inflammation in vessel walls. More recently, we17,18 and others have shown that FDG-PET/CT enables highly precise, novel measurements of inflammatory activity of activity of atherosclerotic plaques in large and medium-sized arteries9,16,19,20. FDG-PET/CT studies have many advantages over other imaging modalities: 1) high contrast resolution; 2) quantification of plaque volume and metabolic activity allowing for multi-modal atherosclerotic plaque quantification; 3) dynamic, real-time, in vivo imaging; 4) minimal operator dependence. Finally, vascular inflammation detected by FDG-PET/CT has been shown to predict cardiovascular (CV) events independent of traditional risk factors21,22 and is also highly associated with overall burden of atherosclerosis23. Plaque activity by FDG-PET/CT is modulated by known beneficial CV interventions such as short term (12 week) statin therapy24 as well as longer term therapeutic lifestyle changes (16 months)25. The current methodology for quantification of FDG uptake in atherosclerotic plaque involves measurement of the standardized uptake value (SUV) of an artery of interest and of the venous blood pool in order to calculate a target to background ratio (TBR), which is calculated by dividing the arterial SUV by the venous blood pool SUV. This method has shown to represent a stable, reproducible phenotype over time, has a high sensitivity for detection of vascular inflammation, and also has high inter-and intra-reader reliability26. Here we present our methodology for patient preparation, image acquisition, and quantification of atherosclerotic plaque activity and vascular inflammation using SUV, TBR, and a global parameter called the metabolic volumetric product (MVP). These approaches may be applied to assess vascular inflammation in various study samples of interest in a consistent fashion as we have shown in several prior publications.9,20,27,28
Medicine, Issue 63, FDG-PET/CT, atherosclerosis, vascular inflammation, quantitative radiology, imaging
3777
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Gene Transfer for Ischemic Heart Failure in a Preclinical Model
Authors: Kiyotake Ishikawa, Dennis Ladage, Lisa Tilemann, Kenneth Fish, Yoshiaki Kawase, Roger J. Hajjar.
Institutions: Mount Sinai School of Medicine .
Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine their efficacy and safety. Gene therapy using viral vectors is one of the most promising approaches for treating cardiac diseases. Viral delivery of various different genes by changing the carrier gene has immeasurable therapeutic potential. In this video, the full process of an animal model of heart failure creation followed by gene transfer is presented using a swine model. First, myocardial infarction is created by occluding the proximal left anterior descending coronary artery. Heart remodeling results in chronic heart failure. Unique to our model is a fairly large scar which truly reflects patients with severe heart failure who require aggressive therapy for positive outcomes. After myocardial infarct creation and development of scar tissue, an intracoronary injection of virus is demonstrated with simultaneous nitroglycerine infusion. Our injection method provides simple and efficient gene transfer with enhanced gene expression. This combination of a myocardial infarct swine model with intracoronary virus delivery has proven to be a consistent and reproducible methodology, which helps not only to test the effect of individual gene, but also compare the efficacy of many genes as therapeutic candidates.
Medicine, Issue 51, Myocardial infarction, Gene therapy, Intracoronary injection, Viral vector, Ischemic heart failure
2778
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Use of a Hanging Weight System for Coronary Artery Occlusion in Mice
Authors: Tobias Eckle, Michael Koeppen, Holger Eltzschig.
Institutions: University of Colorado Denver.
Murine studies of acute injury are an area of intense investigation, as knockout mice for different genes are becoming increasingly available 1-38. Cardioprotection by ischemic preconditioning (IP) remains an area of intense investigation. To further elucidate its molecular basis, the use of knockout mouse studies is particularly important 7, 14, 30, 39. Despite the fact that previous studies have already successfully performed cardiac ischemia and reperfusion in mice, this model is technically very challenging. Particularly, visual identification of the coronary artery, placement of the suture around the vessel and coronary occlusion by tying off the vessel with a supported knot is technically difficult. In addition, re-opening the knot for intermittent reperfusion of the coronary artery during IP without causing surgical trauma adds additional challenge. Moreover, if the knot is not tied down strong enough, inadvertent reperfusion due to imperfect occlusion of the coronary may affect the results. In fact, this can easily occur due to the movement of the beating heart. Based on potential problems associated with using a knotted coronary occlusion system, we adopted a previously published model of chronic cardiomyopathy based on a hanging weight system for intermittent coronary artery occlusion during IP 39. In fact, coronary artery occlusion can thus be achieved without having to occlude the coronary by a knot. Moreover, reperfusion of the vessel can be easily achieved by supporting the hanging weights which are in a remote localization from cardiac tissues. We tested this system systematically, including variation of ischemia and reperfusion times, preconditioning regiments, body temperature and genetic backgrounds39. In addition to infarct staining, we tested cardiac troponin I (cTnI) as a marker of myocardial infarction in this model. In fact, plasma levels of cTnI correlated with infarct sizes (R2=0.8). Finally, we could show in several studies that this technique yields highly reproducible infarct sizes during murine IP and myocardial infarction6, 8, 30, 40, 41. Therefore, this technique may be helpful for researchers who pursue molecular mechanisms involved in cardioprotection by IP using a genetic approach in mice with targeted gene deletion. Further studies on cardiac IP using transgenic mice may consider this technique.
Medicine, Issue 50, Cardioprotection, preconditioning, targeted gene deletion, murine, model, ischemia, reperfusion, heart
2526
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Vascular Occlusion Training for Inclusion Body Myositis: A Novel Therapeutic Approach
Authors: Bruno Gualano, Carlos Ugrinowitsch, Manoel Neves Jr., Fernanda R. Lima, Ana Lúcia S. Pinto, Gilberto Laurentino, Valmor A.A. Tricoli, Antonio H. Lancha Jr., Hamilton Roschel.
Institutions: University of São Paulo, University of São Paulo.
Inclusion body myositis (IBM) is a rare idiopathic inflammatory myopathy. It is known to produces remarkable muscle weakness and to greatly compromise function and quality of life. Moreover, clinical practice suggests that, unlike other inflammatory myopathies, the majority of IBM patients are not responsive to treatment with immunosuppressive or immunomodulatory drugs to counteract disease progression1. Additionally, conventional resistance training programs have been proven ineffective in restoring muscle function and muscle mass in these patients2,3. Nevertheless, we have recently observed that restricting muscle blood flow using tourniquet cuffs in association with moderate intensity resistance training in an IBM patient produced a significant gain in muscle mass and function, along with substantial benefits in quality of life4. Thus, a new non-pharmacological approach for IBM patients has been proposed. Herein, we describe the details of a proposed protocol for vascular occlusion associated with a resistance training program for this population.
Medicine, Issue 40, exercise training, therapeutical, myositis, vascular occlusion
1894
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Catheter Ablation in Combination With Left Atrial Appendage Closure for Atrial Fibrillation
Authors: Martin J. Swaans, Arash Alipour, Benno J.W.M. Rensing, Martijn C. Post, Lucas V.A. Boersma.
Institutions: St. Antonius Hospital, The Netherlands.
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting millions of individuals worldwide 1-3. The rapid, irregular, and disordered electrical activity in the atria gives rise to palpitations, fatigue, dyspnea, chest pain and dizziness with or without syncope 4, 5. Patients with AF have a five-fold higher risk of stroke 6. Oral anticoagulation (OAC) with warfarin is commonly used for stroke prevention in patients with AF and has been shown to reduce the risk of stroke by 64% 7. Warfarin therapy has several major disadvantages, however, including bleeding, non-tolerance, interactions with other medications and foods, non-compliance and a narrow therapeutic range 8-11. These issues, together with poor appreciation of the risk-benefit ratio, unawareness of guidelines, or absence of an OAC monitoring outpatient clinic may explain why only 30-60% of patients with AF are prescribed this drug 8. The problems associated with warfarin, combined with the limited efficacy and/or serious side effects associated with other medications used for AF 12,13, highlight the need for effective non-pharmacological approaches to treatment. One such approach is catheter ablation (CA), a procedure in which a radiofrequency electrical current is applied to regions of the heart to create small ablation lesions that electrically isolate potential AF triggers 4. CA is a well-established treatment for AF symptoms 14, 15, that may also decrease the risk of stroke. Recent data showed a significant decrease in the relative risk of stroke and transient ischemic attack events among patients who underwent ablation compared with those undergoing antiarrhythmic drug therapy 16. Since the left atrial appendage (LAA) is the source of thrombi in more than 90% of patients with non-valvular atrial fibrillation 17, another approach to stroke prevention is to physically block clots from exiting the LAA. One method for occluding the LAA is via percutaneous placement of the WATCHMAN LAA closure device. The WATCHMAN device resembles a small parachute. It consists of a nitinol frame covered by fabric polyethyl terephthalate that prevents emboli, but not blood, from exiting during the healing process. Fixation anchors around the perimeter secure the device in the LAA (Figure 1). To date, the WATCHMAN is the only implanted percutaneous device for which a randomized clinical trial has been reported. In this study, implantation of the WATCHMAN was found to be at least as effective as warfarin in preventing stroke (all-causes) and death (all-causes) 18. This device received the Conformité Européenne (CE) mark for use in the European Union for warfarin eligible patients and in those who have a contraindication to anticoagulation therapy 19. Given the proven effectiveness of CA to alleviate AF symptoms and the promising data with regard to reduction of thromboembolic events with both CA and WATCHMAN implantation, combining the two procedures is hoped to further reduce the incidence of stroke in high-risk patients while simultaneously relieving symptoms. The combined procedure may eventually enable patients to undergo implantation of the WATCHMAN device without subsequent warfarin treatment, since the CA procedure itself reduces thromboembolic events. This would present an avenue of treatment previously unavailable to patients ineligible for warfarin treatment because of recurrent bleeding 20 or other warfarin-associated problems. The combined procedure is performed under general anesthesia with biplane fluoroscopy and TEE guidance. Catheter ablation is followed by implantation of the WATCHMAN LAA closure device. Data from a non-randomized trial with 10 patients demonstrates that this procedure can be safely performed in patients with a CHADS2 score of greater than 1 21. Further studies to examine the effectiveness of the combined procedure in reducing symptoms from AF and associated stroke are therefore warranted.
Medicine, Issue 72, Anatomy, Physiology, Biomedical Engineering, Immunology, Cardiology, Surgery, catheter ablation, WATCHMAN, LAA occlusion, atrial fibrillation, left atrial appendage, warfarin, oral anticoagulation alternatives, catheterization, ischemia, stroke, heart, vein, clinical, surgical device, surgical techniques, Vitamin K antagonist
3818
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Modified Technique for Coronary Artery Ligation in Mice
Authors: Yangzhen Shao, Björn Redfors, Elmir Omerovic.
Institutions: Sahlgrenska Academy, University of Gothenburg.
Myocardial infarction (MI) is one of the most important causes of mortality in humans1-3. In order to improve morbidity and mortality in patients with MI we need better knowledge about pathophysiology of myocardial ischemia. This knowledge may be valuable to define new therapeutic targets for innovative cardiovascular therapies4. Experimental MI model in mice is an increasingly popular small-animal model in preclinical research in which MI is induced by means of permanent or temporary ligation of left coronary artery (LCA)5. In this video, we describe the step-by-step method of how to induce experimental MI in mice. The animal is first anesthetized with 2% isoflurane. The unconscious mouse is then intubated and connected to a ventilator for artificial ventilation. The left chest is shaved and 1.5 cm incision along mid-axillary line is made in the skin. The left pectoralis major muscle is bluntly dissociated until the ribs are exposed. The muscle layers are pulled aside and fixed with an eyelid-retractor. After these preparations, left thoracotomy is performed between the third and fourth ribs in order to visualize the anterior surface of the heart and left lung. The proximal segment of LCA artery is then ligated with a 7-0 ethilon suture which typically induces an infarct size ~40% of left ventricle. At the end, the chest is closed and the animals receive postoperative analgesia (Temgesic, 0.3 mg/50 ml, ip). The animals are kept in a warm cage until spontaneous recovery.
Medicine, Issue 73, Anatomy, Physiology, Biomedical Engineering, Surgery, Cardiology, Hematology, myocardial infarction, coronary artery, ligation, ischemia, ECG, electrocardiology, mice, animal model
3093
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Microsurgical Clip Obliteration of Middle Cerebral Aneurysm Using Intraoperative Flow Assessment
Authors: Bob S. Carter, Christopher Farrell, Christopher Owen.
Institutions: Havard Medical School, Massachusetts General Hospital.
Cerebral aneurysms are abnormal widening or ballooning of a localized segment of an intracranial blood vessel. Surgical clipping is an important treatment for aneurysms which attempts to exclude blood from flowing into the aneurysmal segment of the vessel while preserving blood flow in a normal fashion. Improper clip placement may result in residual aneurysm with the potential for subsequent aneurysm rupture or partial or full occlusion of distal arteries resulting in cerebral infarction. Here we describe the use of an ultrasonic flow probe to provide quantitative evaluation of arterial flow before and after microsurgical clip placement at the base of a middle cerebral artery aneurysm. This information helps ensure adequate aneurysm reconstruction with preservation of normal distal blood flow.
Medicine, Issue 31, Aneurysm, intraoperative, brain, surgery, surgical clipping, blood flow, aneurysmal segment, ultrasonic flow probe
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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