The virus invades the myocardium, causing degeneration, necrosis, and interstitial inflammation of myocardial cells, which is termed viral myocarditis. Viruses currently confirmed to cause viral myocarditis include Coxsackie, ECHO, poliomyelitis, influenza, parainfluenza, mumps, measles, rubella, and vesicular viruses. The pathological changes vary in severity, primarily involving interstitial inflammation, which can be focal or diffuse. As the disease progresses, the inflammation may resolve or lead to fibrous tissue proliferation and scar formation. In addition to the myocardium, the virus can also affect the endocardium, conduction system, and coronary arteries. In recent years, the incidence has gradually increased, affecting all age groups but predominantly preschool and school-aged children, with a higher occurrence in summer and autumn. Most cases have a prodromal history of upper respiratory or gastrointestinal infections 1–2 weeks before onset or concurrently. Clinical manifestations vary widely, ranging from mild symptoms resembling a "common cold" to severe cases that rapidly progress to heart failure, cardiogenic shock, or even sudden death.

bubble_chart Clinical Manifestations

1. Precursory symptoms such as upper respiratory infection, diarrhea, vomiting, abdominal pain, and fever may occur 1-3 weeks or a few days before onset. 2. Poor mental state, pallor, lack of strength, profuse sweating, anorexia, nausea, vomiting, and upper abdominal discomfort or pain. 3. In severe cases, symptoms may include edema, shortness of breath, limited activity, and other manifestations of cardiac insufficiency. 4. A small number of cases may suddenly develop heart failure, pulmonary edema, severe arrhythmia, cardiogenic shock, or cardiac-cerebral syndrome. 5. The heart size may be normal or enlarged, with weakened heart sounds, dull first heart sound, or even fetal heart sounds or gallop rhythm. 6. Increased or decreased heart rate, frequent premature beats. 7. In some cases, grade I-III systolic murmurs, pericardial friction rub, or signs of pericardial effusion may be heard over the precordial area. 8. Severe cases may present with shortness of breath, cyanosis, pulmonary rales, hepatomegaly, edema, and other signs of heart failure, as well as thready pulse, decreased blood pressure, mottled skin, and cold extremities—manifestations of cardiogenic shock.

1. Acute or chronic cardiac insufficiency or cardiocerebral syndrome; 2. Presence of gallop rhythm or pericarditis manifestations; 3. Cardiomegaly; 4. Electrocardiogram showing significant arrhythmia, ST-T changes persisting for more than 3 days, or positive exercise test; 5. History of viral infection concurrent with onset or 1–3 weeks prior; 6. Presence of at least two myocardial inflammatory symptoms; 7. Markedly diminished first heart sound at the apex or tachycardia at rest; 8. Electrocardiogram showing grade I abnormality; 9. Elevated serum enzyme activity in the early stage of the disease and increased anti-myocardial antibodies during the course of the illness.

bubble_chart Treatment Measures

Principles of Treatment:

1. Bed rest. 2. Enhance myocardial nutrition. 3. Anti-heart failure treatment; 4. Cardiogenic shock treatment; 5. Anti-arrhythmia treatment.

Medication Principles:

1. Ventricular tachycardia: Lidocaine is the first choice, 1–2 mg per kg each time, intravenous injection. After effectiveness, maintain with 2 mg per kg diluted in 100–200 ml of glucose solution for drip infusion, adjusting the drip rate or concentration based on heart rate. 2. Third-degree atrioventricular block: Start with isoproterenol 0.2 mg + glucose 100 ml for drip infusion, maintaining the heart rate at 60–70 beats per minute (adjust the drip rate or increase concentration).

Auxiliary Examinations:

When this disease needs to be differentiated from simple myocardial invasion by wind-dampness heat, additional tests such as C-RP and ASO may be performed. For mild cases, apart from electrocardiogram (ECG) examination, other special or optional tests may not be necessary, as mild cases typically only show ECG changes or early serum enzyme alterations, while most other test results remain normal.

AD

1. Cure: Clinical symptoms and signs disappear, electrocardiogram returns to normal or nearly normal, X-ray review shows normal heart size and normal pulsation, and serum enzymes return to normal. 2. Improvement: Clinical symptoms and signs are alleviated, and electrocardiogram, cardiac X-ray, and serum enzymes show varying degrees of recovery. 3. No cure: Clinical symptoms and signs show no relief, and examinations such as electrocardiogram, cardiac X-ray, ultrasound, and serum enzymes show no improvement or even deterioration.

Expert Tips

This is a disease that most easily affects children and adolescents. If there are no early typical symptoms, it is often overlooked. Additionally, children and adolescents are less sensitive to subjective symptoms, leading to diagnosis only after myocardial damage has occurred, resulting in the loss of early treatment opportunities. Currently, there are no specific therapies or medications for myocarditis. During the acute phase, bed rest for one month and continued rest for 3 to 6 months, or even up to a year, is necessary until cardiac symptoms disappear to achieve full recovery. Enhancing overall resistance, supplementing nutrition, and boosting immune function are the most feasible methods. For young children and adolescents, parents must follow the doctor’s instructions and provide meticulous monitoring, as children and teens lack the ability to recognize the severity of the disease’s consequences. Medication should be used rationally under the guidance of a qualified doctor, and avoid seeking unprofessional treatment or using medications indiscriminately. If a child suddenly exhibits symptoms such as lack of strength, cyanosis, shortness of breath, cold limbs, excessive sweating, pallor, unexplained crying, abdominal pain, complaints of discomfort in the precordial area, or chest tightness during or 1–3 weeks after recovery from an upper respiratory infection or diarrhea, they should see a doctor promptly. It is best to consult an experienced pediatric cardiologist to avoid misdiagnosis or mistaking it for another disease, which could lead to severe consequences.