1, clinical manifestations: clinical manifestations of chronic systolic heart failure: ① left ventricular enlargement, LV end-systolic volume increase and LVEF ≤ 40%; ② history of underlying heart disease, symptoms and signs; ③ with or without dyspnea, weakness and fluid retention (edema) and other symptoms. Clinical manifestations of chronic diastolic heart failure: ① left ventricular normal LVEF ≥ 50%; ② left ventricular end-diastolic pressure and volume are elevated; ③ common in coronary artery disease, hypertension and hypertrophic cardiomyopathy. 2.X-ray chest film: it can show the enlarged heart and pulmonary stasis which can help to determine the severity of left heart failure. 3.Echocardiography: M-mode, 2D or Doppler ultrasound techniques can be used to determine the systolic and diastolic functions of the left ventricle: ①Quantitative atrial internal diameter, ventricular wall thickness, valve stenosis, degree of closure insufficiency, etc., qualitative heart geometry, ventricular wall motion, valve and vascular structure, and LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) can be measured to calculate LVEF; ②Differentiate between diastolic insufficiency and systolic insufficiency. LVEF and LVESV are the most valuable indicators to determine systolic function and prognosis. 4, nuclear ventriculography and nuclear myocardial perfusion imaging: the former can accurately determine the ventricular volume, LVEF and ventricular wall motion; the latter can diagnose myocardial ischemia and myocardial infarction, which is helpful to distinguish dilated cardiomyopathy from ischemic cardiomyopathy. 5.Electrocardiogram: It can provide information on previous myocardial infarction, left ventricular hypertrophy, extensive myocardial damage and arrhythmias. Its main detection of cardiac electrophysiological activity and myocardial ischemic performance, the mechanical activity of the heart contraction, diastolic function is poor relative. 6.Left ventriculography: It is mainly used to: ① observe the myocardial motion of the left ventricular wall and the size of the left ventricle; ② observe the mitral valve and aortic regurgitation; ③ determine the maximum ventricular volume at the end of diastole and the minimum ventricular volume at the end of systole, and calculate the left ventricular cardiac output (CO), cardiac index (CI) and LVEF, etc. 7.Invasive and non-invasive hemodynamics: The former uses a floating catheter to determine the pressure and blood oxygen content at each site and calculate CO, CI and small pulmonary artery wedge pressure (PCMP); the latter applies a non-invasive hemodynamic testing system to determine CO, cardiac output per beat (SV), CI, LVEF, peripheral vascular resistance, etc. 8.Magnetic resonance imaging: To evaluate cardiac function by detecting and calculating left ventricular volume, SV, LVEF, short-axis shortening rate and CO and other indicators. 9.Judgment of surviving myocardium to evaluate cardiac function: low-dose dobutamine echocardiographic stress test (DSE) to stimulate myocardial contractile reserve, nuclear myocardial perfusion imaging (201TI and 99mTC-MBI SPECT) and positron emission tomography (PET) to determine myocardial activity by metabolic tracer fluorodeoxyglucose (FDG) are commonly used. 10. Biomarkers in the diagnosis and prognostic assessment of heart failure: The biomarkers of heart failure are: ① Cardiac genetic markers. ②Neuroendocrine hormone markers. ③Left ventricular remodeling markers. ④Myocardial necrosis markers. ⑤ inflammatory markers. ⑥Hemodynamic load markers. (vii) Thrombosis markers. At present, biomarker testing is mainly used in research, but not further promoted in clinical use, mainly because of the lack of gold standard and unified method for biomarker testing. 11, the criteria for determining cardiac insufficiency: At present, there are three main clinical criteria for assessing cardiac function: ① In 1928, the New York Heart Association (NYHA) divided cardiac function into four grades (subjective grading): Grade I, with heart disease, no symptoms of heart failure in daily activities; Grade II, physical activity is mildly limited, and symptoms of heart failure (dyspnea, weakness) appear in heavy physical activity; Grade III, physical activity Class III, physical activity is obviously limited, and heart failure symptoms appear below daily activities; Class IV, physical activity is completely limited, and heart failure symptoms appear at rest. ②In 1994, the American Heart Association (AHA) used electrocardiogram, stress test, X-ray, echocardiography to assess the severity of heart disease, and divided into four levels (objective grading): Grade A, no objective basis for cardiovascular disease; Grade B, the basis for mild cardiovascular disease; Grade C, the basis for moderate cardiovascular disease; Grade D, the basis for severe cardiovascular disease. The 6-minute walk test is not only to evaluate the exercise endurance of the patient, but also to predict the prognosis. Specific operation: the patient is asked to walk as fast as possible in a flat corridor and the 6-minute walking distance is measured. <150 m is considered severe, 150-425 m is considered moderate, and 426-550 m is considered mild cardiac insufficiency.