Myocarditis is a limited or diffuse inflammatory lesion of the myocardium caused by a variety of etiologies. Inflammatory lesions can involve the myocardium, interstitium, vessels, pericardium or endocardium. The etiology can be a variety of infections, autoimmune reactions, and physicochemical factors. The course of the disease can be acute (less than 3 months), subacute (3-6 months) and chronic (more than 6 months). Viral myocarditis is more common in China. Clinical manifestations are usually related to the amount of damaged myocardium. Mild myocarditis has fewer clinical manifestations and is more difficult to diagnose, so the pathological diagnosis is far more prevalent than the clinical morbidity. Laboratory tests: Laboratory tests: white blood cell count may be elevated, erythrocyte sedimentation rate may increase rapidly during the acute phase, and patients with rheumatic myocarditis may have increased anti-hemolytic streptococcal O. A few patients have increased serum enzymes such as aminotransferase (ALT), lactate dehydrogenase (LDH), creatine phosphokinase (CK) and its isoenzyme CK-MB. Natural killer cell viability in peripheral blood was decreased, alpha interferon potency induced by Newcastle chicken plague virus was low, and gamma interferon potency induced by phytochelatin was higher than normal. In addition, the positive rates of antinuclear antibodies, anticardial antibodies, rheumatoid factor, and anti-complement antibodies were often higher than normal, and complement C3 and CH50 were often lower than normal. However, none of the test results have etiologic differential diagnostic value. Other auxiliary examinations: 1. ECG: mainly ST segment and T wave changes, T wave depression or inversion, sometimes coronal T wave changes, ST segment changes are generally mild; arrhythmias are more common, except sinus tachycardia and sinus bradycardia, various ectopic rhythms can appear, such as atrial premature, paroxysmal tachycardia or atrial fibrillation, junctional zone precontraction, ventricular premature, ventricular tachycardia, ventricular fibrillation; and different parts of different The patients may have different degrees of conduction block. About 1/3 of patients may have first- to second-degree AV block, which rapidly progresses to third-degree AV block. The conduction block may appear in the acute phase and disappear during the recovery period, or may be permanent due to scar healing or intermittent premature beats, prolonged Q-T interval, and low voltage due to scar foci; a few patients may have Q waves similar to those of acute myocardial infarction. 2. X-ray examination: no abnormal findings in focal myocarditis. If the lesion is diffuse, the heart shadow is enlarged, the heart beat is weakened, and if there is heart failure, there is pulmonary congestion or pulmonary edema. The heart shadow may be enlarged due to pericardial effusion in cases of combined pericarditis.