Pulmonary stasis refers to localized blood pooling in the blood vessels of the lungs, usually caused by left heart failure, where the pressure in the left heart cavity is elevated, obstructing pulmonary venous return and causing pulmonary stasis. In pulmonary stasis, the lungs increase in volume and are dark red in color, with foamy red bloody fluid flowing from the cut surface. Patients with pulmonary stasis have clinical manifestations of shortness of breath, hypoxia, cyanosis, and coughing up large amounts of plasma pink foamy sputum when coughing. So why is pulmonary stasis predominant in left heart failure? In heart failure, the pumping function of the heart decreases, causing blood from the pulmonary veins to stagnate in the lungs, resulting in pulmonary stasis over time. The right atrium receives blood from the superior vena cava and inferior vena cava. In right heart failure, the pumping function of the heart decreases, resulting in a large amount of blood from the superior vena cava and inferior vena cava stagnating in the blood vessels, which in time becomes stasis in the body circulation. Early manifestations of acute heart failure 1. Early signs of reduced left heart function are fatigue, significantly reduced exercise tolerance, increased heart rate of 15-20 beats/min, followed by exertional dyspnea, paroxysmal dyspnea at night, high sleep, etc.; examination reveals enlarged left ventricle, early or mid diastolic gallop rhythm, wet rales, dry rales and croup at the bottom of both lungs. 2. The onset of the disease is rapid, and the condition can develop rapidly to a critical state. Sudden onset of severe dyspnea, seated breathing, wheezing, irritability and fear, respiratory rate of 30-50 breaths/min; frequent coughing and coughing of large amounts of pink foamy sputum; rapid heart rate, apical rhythm can often be heard; wet rales and rales in both lungs.