Despite tremendous advances in our understanding of myocarditis, considerable controversy exists regarding etiology, pathogenesis, and the role of immunosuppressive therapy. Myocarditis can be caused by a variety of pathogens including bacteria, viruses, and parasites. Viruses, especially enteroviruses such as group B coxsackie and echovirus are probably the most common. Many cases remain idiopathic. The clinical diagnosis of myocarditis is difficult and many times is arrived at only after more common pediatric problems including asthma, recurrent vomiting, and chronic viral illness such as mononucleosis are excluded.
Viral myocarditis is preceded many times by a flu-like illness or gastroenteritis.
When patients present with the classical findings of congestive heart failure, tachypnea, tachycardia and hepatomegaly, the diagnosis is more apparent. Occasionally, patients present with respiratory distress or shock. The EKG can show low voltage QRS complexes, ST elevation, or heart block. Atrial or ventricular arrythmias are common. Serial 24-hour Holter recordings should be obtained in all patients.