Diagnostic criteria for viral myocarditis

Part I: History and signs

Abnormal cardiac manifestations, such as severe fatigue, chest tightness, and dizziness, occur within 3 weeks after viral infection such as upper respiratory tract infection and diarrhea. Doctor's examination may find: the apical first heart sound is significantly weakened, diastolic gallop, pericardial fricative sound, heart enlargement, congestive heart failure or AS-S syndrome.

Part 2: Heart-related abnormalities 3 weeks after infection

The following arrhythmias or electrocardiogram changes were new within 3 weeks of the above infection
Sinus tachycardia, atrioventricular block, sinoatrial block, or bundle branch block.

Multisource, paired ventricular premature beats, spontaneous atrial or junctional tachycardia, paroxysmal or non-paroxysmal ventricular tachycardia, atrial or ventricular flutter or fibrillation.

The ST segment of two or more leads shows a horizontal or downsloping downward movement > 0.01mV or abnormal elevation of ST segment or abnormal Q wave.

Part Three: Reference index of myocardial injury

During the course of disease, serum troponin I or troponin T (emphasis on quantitative determination) and creatine kinase isoenzyme (CK-MB) were significantly increased.

Echocardiography revealed enlarged cardiac cavity or abnormal ventricular wall activity, and/or decreased left ventricular systolic or diastolic function as confirmed by nuclide cardiac function.

Part IV: etiological basis

Virus, viral gene fragment or viral protein antigen were detected from endocardium, myocardium, pericardium or pericardial puncture fluid in acute phase.

Virus antibody positive, must be judged according to different detection methods;

Virus-specific lgM positive (according to each laboratory diagnostic criteria, under strict quality control conditions). If enterovirus nucleic acid is detected in the patient's blood at the same time, it is more supportive that the patient has a recent viral infection.

Acute viral myocarditis can be clinically diagnosed with any one of the above parts 1, 2, or 2 of the above parts at the same time, and after excluding myocardial diseases caused by other causes. If you have the first item of Part 4 at the same time, you can directly diagnose acute viral myocarditis from the etiology; If only the second and third of the fourth part, the etiology can only be considered as acute viral myocarditis.

Severe viral myocarditis may be diagnosed in patients with or without one or more manifestations of the syndrome, congestive heart failure with or without myocardial infarct-like ECG changes, cardiogenic shock, acute renal failure, persistent ventricular tachycardia with hypotension, or myocardial pericarditis.

If only a few premature beats or mild T-wave changes occur within 3 weeks after viral infection, doctors generally do not readily diagnose acute viral myocarditis.

For those who are difficult to make a clear diagnosis, the doctor will arrange long-term follow-up, and when possible, it is recommended to do endocardial myocardial biopsy for viral genetic detection and pathological examination.

Diagnostic criteria for fulminant myocarditis

The clinical manifestations of fulminant myocarditis are rapid, serious and life-threatening. In medicine, fulminant myocarditis is generally defined as myocardial inflammatory disease with sudden onset and severe hemodynamic disorders. Doctors will make a comprehensive analysis of clinical manifestations, laboratory and imaging examinations of patients when making diagnosis.

A clinical diagnosis of fulminant myocarditis is made when the onset is sudden and severe hemodynamic disturbance (syncope, sudden death) occurs rapidly, when laboratory tests show severe myocardial damage, and when echocardiography shows diffuse decreased ventricular wall motion.

Differential diagnosis

Care should be taken to exclude hyperthyroidism, mitral valve prolapse syndrome, coronary heart disease (such as acute myocardial infarction), stress cardiomyopathy (Takotsubo syndrome) and other diseases affecting the heart muscle such as connective tissue diseases, metabolic diseases and Keshan disease.