There are some misconceptions about the diagnosis and treatment of pediatric myocarditis, and parents are often confused about “Is my child suffering from myocarditis?” 1. It is not uncommon for parents to bring their children to the clinic with the main complaint of “chest tightness and breathlessness”. Chest tightness and shortness of breath can be a concomitant symptom of myocarditis. However, they are more often seen as “psychogenic (functional changes)”, and these children often have personality deviations, such as being cautious and angry. Sinus tachycardia can be caused by fever, activity, stress, etc. The diagnosis of true sinus tachycardia cannot be made unilaterally by a single electrocardiogram, but must be determined by a comprehensive 24-hour ambulatory electrocardiogram. Myocarditis can manifest sinus tachycardia. If sinus tachycardia alone is not accompanied by other abnormalities, pay attention to the exclusion of hyperthyroidism and β-receptor hyperfunction. 2. Can myocarditis be diagnosed with an increase in cardiac enzymes alone? CK-MB and troponin (CTnI, CTnT) abnormalities are one of the main indicators for the diagnosis of myocarditis, but should be considered in conjunction with clinical considerations. For example, the influence of age on the normal value of cardiac enzymes; the significant increase of CK or LDH should be noted to exclude myopathy; only the increase of AST should be excluded from the liver function damage, check the liver function; take the blood does not obey the hemolysis to make cardiac enzymes false positive, etc. 3. Premature beats (preterm contraction). Premature beats are the most common clinical arrhythmia in pediatrics. Most children are finally diagnosed with simple premature beats after comprehensive and systematic examination without evidence of organic cardiac lesions. The presence of premature beats alone should not be used as diagnostic evidence for myocarditis. 4. ST-T changes. Some pediatric myocarditis ECGs may show changes in ST-T waves, sometimes even as the only abnormal ECG manifestation. The diagnosis of myocarditis emphasizes ST-T wave changes lasting more than 4 days, with dynamic changes. It should also be noted here that because of the obvious age-specific features of the pediatric ECG, the criteria for determining whether ST-T wave changes are pathologically significant cannot be fully followed in adults. 5. Paroxysmal supraventricular tachycardia. It is more common in pediatric patients and is easily misdiagnosed as myocarditis. Paroxysmal supraventricular tachycardia is mostly due to congenital atrioventricular node folding. Some episodes of tachycardia are followed by electrocardiographic ST-T wave changes and myocardial enzyme abnormalities, which cannot be used as a basis for the diagnosis of myocarditis. 6. Short P-R syndrome. Pediatric P-R interval can be less than 0.12 seconds, and 0.09 seconds is considered normal in small infants. The electrocardiogram room sometimes diagnoses short P-R syndrome according to adult criteria. 7. The right heart is predominant and normal in small infants.