1. What are the manifestations of pediatric myocarditis? Myocarditis is a common heart disease in children, with varying clinical manifestations and a mostly good prognosis. The history of respiratory or gastrointestinal viral infections, such as colds and enteritis, is commonly used 1 to 3 weeks before the onset of the disease, and there are mostly mild and severe prodromal symptoms, such as fever, sore throat, myalgia, etc. Children with milder forms of the disease may have no obvious conscious symptoms and only show abnormal electrocardiograms. The clinical manifestations vary among children of different ages. Small infants may show poor feeding, irritability, crying, drowsiness, nausea, vomiting, etc., while young children may show lazy movement and long sighs. The first thing you need to do is to get a good idea of what you are getting into. 2.What auxiliary tests should be done for pediatric myocarditis? What is the specific performance of the various tests? When myocarditis is suspected, the following tests should be done: (1) serum cardiac enzyme profile and cardiac troponin measurement: serum creatine kinase (CK) is elevated in the early stages, of which the isoenzyme CK-MB from the myocardium is specific and sensitive, and elevated CK-MB is a major indicator for the diagnosis of myocarditis. The specificity of lactate dehydrogenase is poor, and many diseases such as cold, enteritis, pneumonia, fever, etc. can cause its elevation, so it cannot be used as a basis for the diagnosis of myocarditis. The results of electrocardiogram and echocardiogram should be taken into consideration. Troponin I or T may be elevated at an early stage, which is another major indicator for the diagnosis of myocarditis. (2) Sedimentation, anti-streptococcal hemolysin O (ASO), and C-reactive protein (CRP) measurements: Sedimentation, ASO, and CRP are generally normal in children with viral myocarditis, and rheumatic myocarditis should be ruled out if abnormal. (3) Electrocardiogram: The following changes are often observed: ①ST-T changes: ST segment downward or elevated in 2 or more leads (I, II, aVF, V5) dominated by R waves, low flat, bidirectional or inverted T waves, with dynamic changes and lasting for more than 4 days; ②QRS low voltage; ③Atrioventricular block or sinus block, bundle branch block; ④Various types of frequent premature beats, with ventricular premature beats being the most common. (5) Sinus bradycardia: the most common is ventricular premature beats, but also paroxysmal tachycardia, atrial flutter, atrial fibrillation, etc. (4) Ambulatory electrocardiogram: Those with significant arrhythmias such as frequent premature beats and conduction block need to undergo ambulatory electrocardiogram to observe the number of premature beats, heart rate, type of conduction block and time of occurrence to guide treatment. (5) Echocardiogram: The milder cases may be abnormal, but the abnormal cases often show enlarged heart (early stage often shows enlarged left atrium), hypokinesis, and may be combined with pericardial effusion (the depth of fluid dark area in the pericardium is more than 2mm). (6) Pathogenic examination: pathogenic examination is feasible in hospitals with conditions to find the basis of viral infection, and the virus can be isolated from pharyngeal swab, stool, blood and pericardial fluid in the early stage, but it needs to be combined with serum antibody measurement to be meaningful, and the titer of serum antibody in the recovery period is more than 4 times higher than that in the acute period or the titer of specific IgM antibody in the blood is above 1:128 in the early stage of the disease has diagnostic significance. The presence of viral nucleic acid in the blood by polymerase chain reaction (PCR) or in situ hybridization with a viral nucleic acid probe can be used as a basis for the presence of a particular type of virus. 3.How is pediatric myocarditis treated? What are the commonly used drugs? Once the diagnosis of myocarditis is confirmed, the following measures should be taken: (1) rest: the acute phase should rest until 3 to 4 weeks after the fever subsides, do not participate in sports activities until the disease is healed, with cardiac insufficiency and heart enlargement should be absolutely bed rest. (2) drugs to nourish the myocardium and improve myocardial metabolism: intravenous infusion of vitamin C, creatine phosphate or fructose 1,6-diphosphate, usually for 2 weeks, in severe cases (fulminant myocarditis) can be used for 3 to 4 weeks, after stopping the infusion, change to vitamin C and fructose 1,6-diphosphate (commonly used Rui’anji). Oral coenzyme Q10 can protect the myocardium, 10mg each time, once a day under 3 years old, twice a day over 3 years old, after meals, for 2-3 months, note that some patients can cause a rash after long-term use, which disappears after stopping. (3) Vitamin E: an antioxidant, applied in small doses of 5mg once daily under 3 years of age and twice daily over 3 years of age for 1 month. (4) antibiotics: intravenous penicillin (cephalosporins or other types of antibiotics for penicillin allergy) in the acute phase to remove potential foci of bacterial infection in the body to prevent myocarditis from recurring or turning into chronic myocarditis or cardiomyopathy for 7 to 10 days. (5) Astragalus: Astragalus granules can be taken orally, which has anti-viral and immune regulating effects, 4 grams each time, once a day under 3 years old, twice a day over 3 years old, for a course of 1 to 2 months. (6) Adrenocorticotropic hormone: general cases and light cases do not advocate the application, combined with cardiogenic shock, cardiac insufficiency, heart enlargement, severe arrhythmia (high or III degree atrioventricular block, ventricular tachycardia) and other serious cases still need to be applied as early as possible, with anti-inflammatory, anti-shock effect, can improve the success rate of rescue. Dexamethasone, methylprednisolone or hydrocortisone can be applied intravenously and changed to prednisone orally after the condition is relieved. (7) Anti-arrhythmic drugs: Combined arrhythmias need to be treated promptly according to the following different conditions. Preferably, propafenone (cardioplegia) should be taken orally at 5-7 mg/kg every 6 hours, and the dosage should be gradually reduced after 2 to 4 weeks. If propafenone is not effective, betalactone (0.5-1.5mg/kg, divided into 2-3 oral doses, pay attention to blood pressure and heart rate) or acetamidofurone (10-15mg/kg, divided into 2-3 oral doses, pay attention to monitoring thyroid function) can be used. Do electrocardiogram regularly during drug administration to prevent the occurrence of adverse reactions such as conduction block. Supraventricular tachycardia: intravenous propafenone (do not use if the heart function is low, to prevent aggravation) or acetaminophen to restore the heart rhythm. ③Ventricular tachycardia: mostly lidocaine intravenous drip or push, each time 0, 5mg ~ 1mg/kg, can be repeated after 20-30 minutes if not effective, the total amount does not exceed 5mg/kg. ④Atrioventricular block: intravenous dexamethasone or methylprednisolone can be applied to eliminate myocardial local edema and improve conduction function. For slow heart rate, intravenous isoproterenol or oral scopolamine (654-2) or atropine can be administered. (8) human blood immunoglobulin: heavy myocarditis (fulminant myocarditis) available, has the effect of neutralizing viral antibodies, improve immunity, can improve the success rate of rescue, generally 1 to 2g/kg, slow intravenous infusion, used up within 2 days, but need to pay attention to cardiac function, to prevent short-term rapid drip and lead to pulmonary edema and heart failure. 4.What are the precautions for pediatric myocarditis? What are the dietary precautions to be taken? Children with myocarditis need to take rest, do not participate in sports activities to reduce the burden on the heart, and review regularly according to the doctor’s orders. The diet should be light, easy to digest and nutritious, with plenty of fresh vegetables and fruits.