Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ New ventricular dysfunction with an antecedent viral syndrome Elevated erythrocyte sedimentation rate and/or cardiac biomarkers with acute myocarditis ECG shows sinus tachycardia, nonspecific ST-T changes, atrial or ventricular arrhythmias, or conduction abnormalities Echocardiogram demonstrates chamber enlargement and globally reduced left ventricular (LV) contractility, sometimes with regional variations Mural thrombi may be present +++ GENERAL CONSIDERATIONS ++ Myocardial inflammation and secondary immune response leading to cardiac injury and ventricular dysfunction Can present as fulminant, acute, chronic active, and chronic persistent with variable natural histories Focal or diffuse myocardial inflammation that may also involve the endocardium, pericardium, or valvular structures Most commonly initiated by viral infection, although may occur as a result of other infectious organisms, drugs, toxins, collagen vascular diseases, or autoimmune or hypersensitivity reactions Most common viral causes in the United States are parvovirus, adenovirus, and enteroviruses. Other viruses include Coxsackie B echovirus, influenza, hepatitis C, and cytomegalovirus Routine endomyocardial biopsy not recommended because inflammatory changes are often focal and nonspecific. Endomyocardial biopsy can be useful when giant cell myocarditis, fulminant lymphocytic myocarditis, or cardiac sarcoidosis is suspected When positive, the inflammatory changes include inflammatory infiltrate with adjacent myocyte injury +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ Clinical presentation is variable Most commonly asymptomatic Symptomatic patients may describe an antecedent viral syndrome, including fever, malaise, fatigue, arthralgias, myalgias, and skin rash Chest pain (pleuritic, ischemic, or atypical) is common Dyspnea, fatigue, decreased exercise tolerance Palpitations, dizziness, or syncope Cardiogenic shock +++ PHYSICAL EXAM FINDINGS ++ Exam findings vary widely Tachycardia (rarely, bradycardia) Hypotension Fever Signs of fluid overload Murmurs of mitral or tricuspid regurgitation (diastolic murmurs are rare) S3 and occasionally S4 gallops Pleural rubs and pericardial friction Circulatory collapse and shock (rare) +++ DIFFERENTIAL DIAGNOSIS ++ Acute myocardial ischemia or infarction due to coronary artery disease Pneumonia Congestive heart failure due to other causes +++ DIAGNOSTIC EVALUATION +++ LABORATORY TESTS ++ Elevated erythrocyte sedimentation rate Elevated cardiac troponin seen in some patients +++ ELECTROCARDIOGRAPHY ++ May be normal, but more commonly, there are nonspecific changes Atrial or ventricular ectopic beats Atrial tachycardia or fibrillation Atrioventricular block or interventricular conduction block (eg, left bundle branch block) Regional ST elevations and Q waves that mimic acute myocardial infarction or diffuse ST elevations that simulate pericarditis +++ IMAGING STUDIES ++ Chest x-ray: may be normal or demonstrate cardiomegaly with or without pulmonary edema Echocardiography: LV enlargement; globally reduced LV contractility, sometimes with regional variation mimicking myocardial infarction; increased LV wall thickness due to edematous inflammation occasionally in early disease; mural thrombi Cardiac MRI can be useful in detecting areas of inflammation... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free a profile for additional features.