The clinical manifestations of chronic heart failure are closely related to which side of the ventricle or atrium is affected. Clinically, left heart failure is the most common. The clinical characteristics of left heart failure are mainly pulmonary congestion and pulmonary edema caused by left atrial and (or) right ventricular failure; while the clinical characteristics of right heart failure are systemic venous congestion and water and sodium retention caused by right atrial and (or) right ventricular failure. After the occurrence of left heart failure, the right heart often suffers from functional impairment, eventually leading to total heart failure. When right heart failure occurs, the symptoms of left heart failure may be alleviated.