Difference between revisions of "Myocarditis overview"

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===Physical Examination===
 
===Physical Examination===
Common findings on physical examination include [[tachycardia]], a [[cardiac gallop]], [[mitral regurgitation]] due to [[left ventricular dilation]] and [[pedal edema]] suggestive of [[cardiac failure]]. A [[pericardial friction rub]] may be noted in presence of concomitant [[pericarditis]], a condition sometimes referred to as [[myopericarditis]].
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There are no specific findings for myocarditis. [[Patients]] with myocarditis usually show [[signs]] of [[cardiac dysfunction]] and underlying [[diseases]]. The [[physical examination]] in [[patients]] with myocarditis may reveal [[tachycardia]], a [[cardiac gallop]], [[mitral regurgitation]] due to [[left ventricular dilation]], and [[pedal edema]] suggestive of [[cardiac failure]]. A [[pericardial friction rub]] may be noted in presence of concomitant [[pericarditis]], a condition sometimes referred to as [[myopericarditis]].
  
 
===Laboratory Findings===
 
===Laboratory Findings===

Revision as of 16:00, 16 January 2020

Myocarditis Microchapters

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Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Adrenergic Myocarditis
Giant Cell Myocarditis

Causes

Differentiating Myocarditis from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Study of Choice

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

X-ray

Echocardiography and Ultrasound

CT scan

MRI

Other Imaging Findings

Other Diagnostic Studies

Treatment

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Primary Prevention

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Varun Kumar, M.B.B.S. Maliha Shakil, M.D. [2] Homa Najafi, M.D.[3]

Overview

Myocarditis is defined as inflammation of the myocardium. It may present with chest pain, ST segment elevation, elevated biomarkers of myonecrosis, heart failure, and/ or sudden death. Myocarditis can be classified clinicopathologically into fulminant myocarditis, acute myocarditis, chronic active myocarditis, and chronic persistent myocarditis. During either an infection or a hypersensitivity reaction, the inflammatory response may cause myonecrosis either directly or indirectly as part of an autoimmune reaction. Life-threatening causes of myocarditis include carbon monoxide poisoning and Dengue fever. Common causes of myocarditis include infections, Lyme disease, and medications. Idiopathic myocarditis is the most common type of myocarditis and is often suspected to be secondary to a viral infection. Myocarditis must be distinguished from pericarditis and the life threatening condition of ST elevation myocardial infarction. In young adults, up to 20% of all cases of sudden death are due to myocarditis. Myocarditis is slightly more frequent among males than females. Myocarditis is usually self limiting and is associated with a good prognosis especially if it is secondary to a viral infection. Patients rarely develop cardiac failure, pulmonary edema, arrhythmias, or cardiogenic shock. In some instances, myocarditis may be associated with sudden death. Patients with fulminant myocarditis have a good long term prognosis if they survive the acute phase of the disease. The prognosis of fulminant myocarditis is better than that of either acute myocarditis or giant cell myocarditis. The presence of left bundle branch block, q waves, AV block, syncope and a left ventricular ejection fraction < 40% are associated with sudden death and cardiac transplantation. The physical examination in patients with myocarditis may reveal tachycardia, a cardiac gallop, mitral regurgitation due to left ventricular dilation, and pedal edema suggestive of cardiac failure. A pericardial friction rub may be noted in presence of concomitant pericarditis, a condition sometimes referred to as myopericarditis.

Historical Perspective

Myocarditis was first discovered by Jean Baptiste Senac, a French physician, in 1794. The term myocarditis was introduced by German physician Joseph Friedrich Sobernheim in 1837. In 1980s, the World Health Organization and the International Society and Federation of Cardiology were the first to differentiate between myocarditis and other cardiomyopathies. The Dallas criteria was published in 1986 as a guideline for classification of myocarditis.

Classification

Myocarditis can be classified based on the causative, histological, and clinicopathological criteria. Causative criteria include three main groups, as well as infectious, immune-mediated, and toxic myocarditis. Based on the type of infiltrating cells myocarditis divided in lymphocytic, eosinophilic, polymorphic, giant cell myocarditis, and cardiac sarcoidosis. Acute, fulminant, chronic active, and chronic persistent are subtypes of clinicopathopogical classification.

Pathophysiology

During either an infection or a hypersensitivity reaction, the inflammatory response may cause myonecrosis either directly or indirectly as part of an autoimmune reaction.

Causes

Life-threatening causes of myocarditis include carbon monoxide poisoning and Dengue fever. Common causes of myocarditis include infections such as Lyme disease and medications. Idiopathic myocarditis is the most common type of myocarditis and is often suspected to be secondary to a viral infection.

Differentiating Myocarditis from other Diseases

Myocarditis must be distinguished from pericarditis and the life threatening condition of ST elevation myocardial infarction.

Epidemiology and Demographics

In young adults, up to 20% of all cases of sudden death are due to myocarditis. Myocarditis is slightly more frequent among males than females.

Natural History, Complications and Prognosis

Myocarditis is usually self limiting and is associated with a good prognosis especially if it is secondary to a viral infection. Patients rarely develop cardiac failure, pulmonary edema, arrhythmias or cardiogenic shock. In some instances, myocarditis may be associated with sudden death. Patients with fulminant myocarditis have a good long term prognosis if they survive the acute phase of the disease. The prognosis of fulminant myocarditis is better than that of either acute myocarditis or giant cell myocarditis. The presence of left bundle branch block, q waves, AV block, syncope and a left ventricular ejection fraction < 40% are associated with cardiac transplantation and sudden death.

Diagnosis

History and Symptoms

Myocarditis should be suspected in a patient with acute decompensation of cardiac function who is at low risk of ischemic heart disease. A history of a recent (within the preceding 2-4 weeks) viral illness is often elicited in a large number of patients with myocarditis. Cardiac specific symptoms may become apparent usually in the subacute virus-clearing phase. In myocarditis due to drug hypersensitivity, patients may give a history of ingesting an offending drug. In fulminant myocarditis, patients present with the abrupt onset of flu-like symptoms and the abrupt onset of heart failure symptoms. In chronic and acute myocarditis, the onset of symptoms may be more insidious. Common symptoms of myocarditis include chest pain, pedal edema, palpitations, fever, and joint pains.

Physical Examination

There are no specific findings for myocarditis. Patients with myocarditis usually show signs of cardiac dysfunction and underlying diseases. The physical examination in patients with myocarditis may reveal tachycardia, a cardiac gallop, mitral regurgitation due to left ventricular dilation, and pedal edema suggestive of cardiac failure. A pericardial friction rub may be noted in presence of concomitant pericarditis, a condition sometimes referred to as myopericarditis.

Laboratory Findings

Laboratory findings consistent with the diagnosis of myocarditis include elevated markers of myonecrosis, inflammatory markers, and other biomarkers. Markers of myonecrosis include creatine kinase (CK-MB), cardiac troponin I (cTnI) or T (cTnT), lactate dehydrogenase (LDH), alanine transaminase (ALT), and aspartate transaminase (AST). Elevated levels of C-reactive protein and erythrocyte sedimentation rate (ESR), and leukocytosis are suggestive of myocarditis. Serological markers such as Fas, Fas ligand, interleukin-10 or antimyosin autoantibodies are of prognostic value in myocarditis. Other auto-antibodies such as ANA and rheumatoid factor may also be detected.

Electrocardiogram

The presence of ST segment elevation in patients with myocarditis can mimic pericarditis and myocardial infarction. Arrhythmias and heart block may also be observed in myocarditis patients. Myocarditis can be distinguished from pericarditis by the presence of PR depression in the patient with pericarditis.

Endomyocardial Biopsy

Endomyocardial biopsy remains the gold standard test to evaluate for the presence of and to subclassify the type of myocarditis. A small tissue sample of the endocardium and myocardium is obtained via right sided cardiac catheterization. The sample is then evaluated by a pathologist using immunochemistry and special staining techniques as necessary. Histopathological features include abundant edema in the myocardial interstitium and an inflammatory infiltrate which is rich in lymphocytes and macrophages. Focal destruction of myocytes as a result of the inflammatory process results in left ventricular dysfunction. Endomyocardial biopsy is recommended when the results would identify an underlying disease that is amenable to therapy. Routine performance of endomyocardial biopsy is not recommended in all patients with myocarditis.

Chest X Ray

Findings on chest x-ray suggestive of myocarditis include cardiomegaly, pericardial thickening in presence of pericarditis, pulmonary edema, and pleural effusion.

MRI

Cardiac MRI findings associated with myocarditis include myocardial inflammation, myocardial edema, capillary leak, and reduced left ventricular function. While the cardiac MRI pattern of gadolinium hyperenhancement in ST segment elevation myocardial infarction is transmural and extends from the endocardium to the epicardium, the patchy, non-segmental hyperenhancement pattern in myocarditis in contrast involves the epicardium and spares the subendocardium.

Echocardiography

Echocardiography in patients with myocarditis allows for serial assessment of left ventricular dysfunction and can be used to distinguish fulminant (non-dilated hypocontractile left ventricle with thick interventricular septum) from acute myocarditis (dilated hypocontractile left ventricle with normal interventricular septum).

Other Imaging Findings

Coronary angiography may be helpful in excluding either myocardial ischemia or infarction as the cause of ST segment elevation, elevated cardiac biomarkers, or left ventricular dysfunction.

Treatment

Medical Therapy

Symptomatic treatment is the mainstay of therapy for patients with viral myocarditis. Supportive therapy includes diuretics and inotropes for left ventricular failure. ACE inhibitor therapy may aid in left ventricular remodeling. Among patients with fulminant myocarditis, placement of either an intra-aortic balloon pump or a left ventricular assist device may be necessary as bridge to recovery. Administration of antimicrobial therapy is recommended for bacterial myocarditis. Immunosuppressive therapy may be effective in the management of giant cell myocarditis, autoimmune myocarditis, and eosinophilic myocarditis.

Cardiac Transplantation

Cardiac transplantation is sometimes required to treat refractory giant cell myocarditis. However, the condition can recur in post-transplant patients. Recurrence of biopsy proven giant cell myocarditis between 3 weeks to 9 years was observed in 9 of 34 cardiac transplant patients .

References



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