Open Access Medical Books

TEXTBOOK : DIAGNOSIS AND TREATMENT OF MYOCARDITIS


MYOCARDITIS

Edited by José Milei and Giuseppe Ambrosio .

206 pages .
Open Access .


Myocarditis is a clinical syndrome, most frequently of infectious etiology, that presents itself with a broad range of relatively non-specific symptoms, and consists of an inflammatory process of the heart with necrosis and degeneration of the myocardium by inflammatory infiltration of immune cells. The infection can cause direct injury of cardiomyocytes as well as immune-mediated destruction of the myocardium, leading to cardiac dysfunction.
In this book, the broad aspects of myocarditis are fully presented by leading international experts. The texts are devoted to both clinical aspects and pathophysiology, and they present comprehensive reviews of the causes of myocarditis, its classification, diagnosis, and treatment, as well as myocarditis in special populations such as pediatric, peripartum and chronic chagasic myocarditis. Mention is made also of diagnostic aspects, especially by cardiac magnetic resonance (CMR) imaging and endomyocardial biopsy. Pathogenesis of myocarditis, regarding pathways and mechanisms activated during viral infection and host immune response, is discussed. The immune-mediated responses operating in myocarditis result from a myriad of etiologies including infectious, autoimmune, myocardial toxins, hypersensitivity reactions and physical agents, although human myocarditis is most frequently caused by viral infection. Among the viral agents, enteroviruses (particularly Coxsackie) and adenovirus are recognized as the major etiologic factor. However, in the past 10 years, parvovirus B19, hepatitis C, and herpes virus 6, have emerged as significant viral pathogens. Persistence of viral infection, myocardial injury, and adverse remodeling can lead to persistent ventricular dysfunction and dilated cardiomyopathy. Furthermore, acute fulminant myocarditis is a lifethreatening condition, which requires careful management.
Clinical manifestations of myocarditis are highly variable, ranging from asymptomatic electrocardiographic or echocardiographic abnormalities to acute myocardial infarction-like syndrome, overt congestive heart failure, malignant arrhythmias, cardiogenic shock, and death. On the other hand, myocarditis is occasionally an unrecognized cause of sudden cardiac death.
Despite the development of diagnostic and therapeutic techniques, acute myocarditis continues to be an important cause of morbidity and mortality among children and young adults.
To date, there is no specific treatment for this viral infection Myocarditis is an uncommon but potentially life-threatening syndrome in pediatric patients who may require critical care transport. Patients may suffer from malignant arrhythmias and hemodynamic collapse and may require transport to a center which offers extracorporeal life support. In one of the chapters a brief overview of pediatric myocarditis is provided, with a particular focus on considerations for stabilization and transport in acute fulminant myocarditis.

Peripartum cardiomyopathy has recently been defined as “an idiopathic cardiomyopathy presented by heart failure secondary to left ventricular systolic dysfunction towards the end of pregnancy or in the months following delivery, where no other cause of heart failure is found”. Although, the etiology of this disease remains uncertain, overall, there is more evidence to support myocarditis or an autoimmune process as the cause of the disease than for other proposed etiologies.
Because of these various considerations, it is imperative to have adequate diagnostic tools and effective drug armamentarium. Yet, despite a variety of diagnostic methods, the diagnosis of myocarditis is often difficult to establish. The diagnosis requires a high index of suspicion, particularly in children, as it may mimic other common diseases More refined, but controversial diagnostic modalities include CMR imaging and endomyocardial biopsy. In general, these techniques would not be employed in an acute setting in a non-tertiary care center. CMR has the advantage of being non-invasive; it requires specialty equipment and radiologists familiar with the interpretation of findings. CMR has a unique potential for tissue characterization, particularly with the utilization of T1 and T2 weighted images, can assess 3 markers of tissue injury, namely hyperemia and capillary leakage, necrosis and fibrosis, and intracellular and interstitial edema, and it may help to increase the diagnostic yield of biopsy for detecting myocarditis due to guiding for biopsy sampling.
The routine indication for performing endomyocardial biopsy in myocarditis has long been a matter of debate; nonetheless, it continues to be the “gold standard” for the diagnosis of myocarditis.
Accordingly, the Dallas criteria still remain a reference method for establishing diagnosis. The introduction of immunohistochemical techniques and PCR provided new tools for evaluating endomyocardial samples. Although not yet standardized, they have shown to give valuable prognostic and therapeutic information and are routine testing in myocarditis.
Viral serological analyses in suspected myocarditis are still widely used, although their utility remains unproven. The book also presents results in a murine model of viral myocarditis caused by CVB3. The chapter also describes the characteristics of the infiltrating immune effector cells and their mechanism of cytotoxicity, especially the role of perforin with which killer lymphocytes directly injure target cells and the mechanism of infiltrating T-cell activation.
In the last decades, a number of new strategies have emerged in drug development for the treatment of myocarditis and its sequelae, most notably dilated cardiomyopathy. However, there is no specific treatment for this viral infection. Anyhow, as myocarditis can be induced by a number of viruses, rapid and timely pathogen identification is critically important for guiding early and targeted treatments. Certainly, rapid, sensitive and specific detection of a particular virus or even viral subtype in human samples by detection of virus-specific genes would facilitate targeted treatments. This is particularly crucial for those treatments using nucleic acidbased antiviral agents targeting viral RNA. Interferon beta, immunosuppressive therapy, immunoglobulin, adsorptive immune therapy and monoclonal antibodies, have all been proposed as potentially useful treatments and are fully discussed in the chapters.
In the case of Chagas myocarditis, nifurtimox and benznidazole have been widely used; their therapeutic efficacy varies according to the phase of the disease (acute or chronic), duration of treatment, patient age and geographical area of original infection. The best results are obtained with recently infected patients, when cure rates of 60 to 80% can be achieved, as opposed to the chronic phase, depending on the severity of cardiac dysfunction.

As shown, this book presents a broad spectrum of new aspects of Myocarditis, and we hope it will be useful to general practitioners, internists and cardiologists.

Prof. Dr. José Milei
Director of Instituto de Investigaciones Cardiológicas

"Prof. Dr. Alberto C. Taquini"
- UBA- CONICET (ININCA), Buenos Aires, Argentina

Prof. Giuseppe Ambrosio
Professor of Cardiology and the Director of the Division of Cardiology,
University of Perugia, Italy
Honorary Professor at the Instituto de Investigaciones Cardiológicas

"Prof. Dr. Alberto C. Taquini",
Universidad de Buenos Aires, Argentina.




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CONTENTS : 



Section 1 Clinical Aspects .


 1 Clinical Presentation 3 Rafid Fayadh Al-Aqeedi

Section 2 Pathogenesis .


 2 Targeting T Cells to Treat Trypanosoma cruzi-Induced Myocarditis 47 Andrea Henriques-Pons and Marcelo P. Villa-Forte Gomes

 3 Findings in Murine Viral Myocarditis 65 Yoshinori Seko

Section 3 Diagnosis .


 4 Endomyocardial Biopsy: A Clinical Research Tool and a Useful Diagnostic Method 83 Julián González, Francisco Salgado, Francisco Azzato, Giuseppe Ambrosio and Jose Milei

Section 4 Myocarditis in Special Populations .


 5 Pathogenesis of Chronic Chagasic Myocarditis 105 Julián González, Francisco Azzato, Giusepe Ambrosio and José Milei

 6 Peripartum Myocarditis 135 Marina Deljanin Ilic and Dejan Simonovic

 7 Myocarditis in Children Requiring Critical Care Transport 151 Jordan S. Rettig and Gerhard K. Wolf

Section 5 Treatment .


 8 New Trends in the Development of Treatments of Viral Myocarditis 167 Decheng Yang, Huifang Mary Zhang, Xin Ye, Lixin Zhang and Huanqin Dai





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Published by: younes younes - Wednesday, May 8, 2013

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