Myocarditis is the inflammation of the heart muscle due to infections, usually viral. This inflammation may eventually lead to global weakening and dilatation of the heart muscle causing severe heart failure (dilated cardiomyopathy). Certain viruses are known to cause myocarditis but the exact mechanism leading to the weakening of the heart muscle is unknown.
Viral myocarditis is usually preceded by flu-like symptoms with fever, fatigue and palpitations. The diagnosis is difficult as the initial symptoms may be mistaken as flu. It is usually when the patient presents with symptoms of heart failure (e.g. breathlessness) or abnormal ECG (Electrocardiogram) readings that lead to the diagnosis. Occasionally, it can also be mistaken as a heart attack.
The diagnosis of myocarditis is usually a diagnosis of exclusion because there are many causes of heart failure. Definite diagnosis of viral myocarditis can only be made with biopsy of the heart muscle, which is a high-risk test. However, there are usually some ECG and blood test abnormalities showing signs of heart muscle damage, while ultrasound of the heart (echocardiography) may show a dilated and weakened heart. Antibodies to the virus may be high in patients with viral myocarditis and can be detected in the blood after a few weeks.
The treatment goal is to relieve symptoms of heart failure and there is no effective proven treatment for myocarditis. Usually medications for heart failure are recommended. Patients are usually advised to have bed rest during the period of infection. Occasionally, the heart function of patients with viral myocarditis may recover after a few months. Although the prognosis of patients who develop heart failure after viral myocarditis is poor, not all patients with viral myocarditis will develop a weakened heart.
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