Myocarditis is a disease in which a limited or diffuse inflammatory lesion of the myocardium is the main manifestation. The clinical manifestations of myocarditis vary, depending on the extensiveness and severity of the lesion. A few may be completely asymptomatic, while milder cases may show nonspecific symptoms such as fever, cough and diarrhea, and severe cases may show severe arrhythmias, heart failure, cardiogenic shock or even death. Thus, it is less likely to rely on clinical symptoms alone to diagnose myocarditis. According to the typology of clinical manifestations, myocarditis is classified as mild, subclinical, insidiously progressive, acute dilated cardiomyopathy, atrioventricular block, cool myocardial infarction, and sudden death. Viral myocarditis usually presents 1-3 weeks after infection with symptoms of myocardial injury, including: chest pain, chest tightness, shortness of breath on activity, fatigue, sweating, and weakness. Myocarditis can be progressive and aggravated. Palpitations can be caused by arrhythmia due to reduced blood displacement and weakness. When the pericardium and pleura are involved, chest tightness, chest pain, and angina-like manifestations are also present, and severe symptoms of cardiac insufficiency and suffocating sensations can occur. If hemodynamic disorders are caused, the patient may appear pale, sweat profusely, and go into cardiogenic shock. Patients with myocarditis often show arrhythmias on physical examination, with atrial and ventricular asystole and atrioventricular block being the most common. On auscultation, a third or fourth heart sound or gallop rhythm may be heard. On chest X-ray, enlarged heart shadow and flask-like changes may be seen in the presence of pericardial effusion. ECG changes are S-T segment changes, mild ST segment shift and T-wave inversion. Patients with myocarditis should be given a low-fat, low-salt diet and limited physical activity to reduce the burden on the heart, especially in the acute phase of acute myocarditis and fulminant myocarditis, and should be put on bed rest or limited physical activity for at least 6 months until the left ventricular systolic function returns to normal, the heart chambers are normal in size, and there are no arrhythmias.