Major Causes of Myocarditis
Infectious agents Viral.
Rickettsial Bacterial Protozoal Metazoal Allergic reactions Pharmacologic agents Systemic diseases such as vasculitis.
Peripartum state (90 days before to 90 days after end of pregnancy)
Toxic agents (alcohol, toxic metals such as cobalt)
Describe the patient complaints and clinical findings that frequently accompany myocarditis.
The symptoms vary with the etiology, but most commonly myocarditis is subclinical, especially when it accompanies a generalized infectious processes. Patients may note fatigue, dyspnea, precordial discomfort, or palpitations. Frequently tachycardia is noted; the first heart sound may be muted and an S4 gallop is often described.
What electrocardiographic (ECG) changes are commonly seen in myocarditis?
ST-segment elevation or depression and T-wave inversions are the most frequently noted changes. Atrial arrhythmia are commonly noted, and transient heart block (first, second, or third) may be noted.
How are patients with presumed viral myocarditis treated?
Treatment is supportive and responsive to the clinical presentation.
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Because atrioventricular conduction abnormalities are common in some forms of myocarditis, these patients should be watched carefully for evidence of conduction disturbances. In addition, exercise has been shown in animal models to increase the cell damage in myocarditis, so rest is usually prescribed. When congestive heart failure is noted, the usual treatment is indicated, although digoxin must be used carefully since there may be an increased incidence of digitalis toxic rhythms during active myocarditis. There is no consensus on the use of corticosteroids to decrease the acute inflammation associated with myocarditis; the concern is that they may increase viral replication. Nonsteroidal anti-inflammatory agents, aspirin, and cyclosporine are contraindicated during the first several weeks of an acute viral myocarditis because they increase myocyte damage. In cases possibly caused by atypical pneumonia or psittacosis, antibiotics are indicated.