Fluid retention is a clinical manifestation of patients with multiple organ failure and acute myocardial infarction, among others. Heart failure is also known as congestive heart failure or cardiac insufficiency. The heart is weakened by disease, overwork, and blood expulsion to the extent that the amount of blood expelled cannot meet the metabolic needs of organs and tissues. The main symptoms are dyspnea, wheezing, and edema. Due to the weakening of myocardial contraction cardiac excretion decreases to the point of insufficient perfusion of tissues and organs along with manifestations of stasis of blood in the pulmonary or and body circulation. Heart failure is defined as heart failure due to primary myocardial myogenic fiber contractile dysfunction, when pump dysfunction is primary. Heart failure occurs when the myocardium is unable to contract for various reasons and has the ability to eject sufficient blood to the peripheral vessels to meet the metabolic needs of the systemic tissues. What are the causes of fluid retention? First, heart failure. Heart failure is defined as heart failure due to primary myocardial myogenic fiber contractile dysfunction, when pump dysfunction is primary. Heart failure occurs when the myocardium is contractionally weak for various reasons and has the ability to eject enough blood to the peripheral vessels to meet the needs of systemic tissue metabolism. Secondly, heart failure caused by other reasons: for example, in heart valve disease, myocardial hypertrophy and heart enlargement occur due to myocardial overload, followed by relative lack of myocardial contractility leading to heart failure, when the pump dysfunction is secondary, and is more easily reversed when the valve disorder is removed. Third, heart failure caused by causes other than the myocardium is often accompanied by myocardial damage in the late stages. Fourth, in addition to diseases of the heart itself, such as congenital heart disease, myocarditis, cardiomyopathy, severe arrhythmia, endocarditis, etc., diseases outside the heart, such as acute nephritis, toxic pneumonia, severe anemia, hemolysis, massive intravenous rehydration, and complications after surgical procedures, etc., can also cause heart failure. According to the clinical manifestations, it is divided into left heart failure, right heart failure and total heart failure. Left heart failure refers to heart failure due to compensatory insufficiency of the left ventricle, which is more common clinically and is characterized by pulmonary circulation stasis. Pure right heart failure is mainly seen in pulmonary heart disease and certain congenital heart diseases and is characterized by stasis in the body circulation. After left heart failure, pulmonary artery pressure increases, which increases the load on the right heart, and after a long time, right heart failure also follows, which is total heart failure. In patients with myocarditis and cardiomyopathy, the right and left hearts are damaged at the same time, and left and right heart failure can occur at the same time. Heart failure is divided into left heart failure and right heart failure. The main manifestation of left heart failure is fatigue and dyspnea, which starts as exertional dyspnea and eventually evolves into dyspnea at rest and can only breathe in a sitting position. Paroxysmal dyspnea is a typical manifestation of left heart failure, which usually occurs in the middle of sleep, with chest tightness, shortness of breath, coughing and croup, and in particularly severe cases, it may evolve into acute pulmonary edema with severe shortness of breath, seated breathing, extreme anxiety and coughing up mucus sputum containing foam (typically pink foam-like sputum), cyanosis and other pulmonary stasis symptoms. The main signs of right heart failure are lower limb edema, jugular venous anger, loss of appetite, nausea and vomiting, scanty urination, nocturia, and separation of drinking and urination phenomenon. The main signs are wet rales at the base of the lungs or wet rales in the whole lungs, hyperactive second pulmonary valve sounds, gallop rhythm and alternating pulses, hepatomegaly, positive hepatic neck reflux, and an enlarged left ventricle or left atrium on X-ray. Laboratory tests include prolonged brachial time and increased pulmonary artery capillary wedge pressure as determined by floating catheter in left heart failure, and prolonged brachial time and significantly increased venous pressure in right heart failure.