What is heart failure? Heart failure, also known as heart failure, is a group of syndromes caused by various structural or functional heart diseases that result in impaired ventricular filling and/or ejection capacity. Due to decreased ventricular systolic function, impaired ejection, cardiac output cannot meet the metabolic needs of the body, organs and tissues are underperfused, and there is simultaneous pulmonary and (or) body circulation stasis, with clinical manifestations of dyspnea and weakness leading to limited physical activity and edema. Classification and grading of heart failure: In 1928, the New York Heart Association (NYHA) classified heart failure into four classes according to the degree of activity of the induced heart failure symptoms and the impaired state of heart function, which is clinically used to date because of the simplicity of operation. In 1994, when the American College of Cardiology revised the NYHA’s cardiac function classification scheme again, two parallel classification schemes were adopted. The first one is the four-grade scheme mentioned above, and the second one is objective assessment, that is, the severity of cardiac lesions is assessed according to objective examination means such as electrocardiogram, stress test, x-ray, echocardiogram, etc., and is classified into four grades A, B, C and D.