I. Clinical indicators (a) Main indicators 1. Positive blood culture: 2 blood cultures with the same microorganisms common to infective endocarditis (e.g. Streptococcus straw green, Staphylococcus aureus, Enterococcus, etc.) respectively. 2. Evidence of endocardial involvement: Echocardiography should be used to examine evidence of endocardial involvement with one of the following echocardiographic signs: (1) redundancy attached to a valve or valve device, or to the endothelium of the heart, great vessels, or implanted prosthetic material; (2) intracardiac abscess; (3) valve perforation, prosthetic valve, or defective patch with a new partial fracture. (3) Vascular signs: important arterial embolism, septic pulmonary infarction, or infected aneurysm. (ii) Secondary indications 1. susceptible to infectious conditions: underlying cardiac disease, cardiac surgery, cardiac catheterization, or intravenous central venous cannulation. 2.Prolonged fever (≥38℃) with anemia. 3, Exacerbation of existing heart murmur, appearance of new regurgitant murmur, or cardiac insufficiency. 4, Vascular signs: petechiae, splenomegaly, intracranial hemorrhage, conjunctival hemorrhage, microscopic hematuria, or Janeway spots. 5. Immunological signs: glomerulonephritis, Osler’s node, Roth’s spot, or positive rheumatoid factor. 6. Microbiological evidence: positive blood culture, but not meeting the requirements in the main index. II. Pathological indicators (a) Microorganisms were found by culture microscopy in the presence of superfluous organisms (including formed emboli) or intracardiac abscesses. (2) The presence of superfluous organisms or intracardiac abscesses with active endocarditis confirmed by pathological examination. (1) Infective endocarditis can be diagnosed with any of the following (1) to (5): (1) 2 major clinical indicators; (2) 3 minor clinical indicators; (3) evidence of endocardial involvement and 2 minor clinical indicators; (4) 5 minor clinical indicators; (5) 1 pathological indicator. (b) The diagnosis of infective endocarditis can be excluded if: there is a clear alternative diagnosis to explain the clinical manifestations; the clinical manifestations are eliminated by antibiotic treatment ga4d; there is no pathological evidence of infective endocarditis at surgery or autopsy ≤4d after antibiotic treatment. (c) Clinical consideration of infective endocarditis, but does not have the basis for a definitive diagnosis should still be treated, and the diagnosis of infective endocarditis should be confirmed or excluded based on clinical observations and further examination results.