Systolic reflux murmur. It is a murmur produced by the regurgitation of blood from a high-pressure chamber to a low-pressure chamber through an abnormal pathway, also known as a reflux murmur. The systolic regurgitant murmur is seen in organic heart disease: (1) when the atrioventricular valve is not closed; (2) when the arteriovenous septum is defective or perforated; and (3) when the main interpulmonary artery communication is accompanied by pulmonary hypertension. What are the symptoms that are easily confused? Mid-systolic jet murmur (jet murmur for short): seen in stenosis of the semilunar valve or ventricular outflow tract, or normal semilunar valve with excessive ventricular ejection velocity, or blood shunting from a high pressure cardiovascular chamber to a low pressure cardiovascular chamber. It is primarily heard or recorded at the base of the heart. The phonogram is characterized by a murmur that follows the high-frequency component of S1 and has a gap between it and S1, corresponding to the ventricular isovolumic systole. The murmur has an increasing-decreasing diamond shape. The rhombus of the murmur is delayed by the prolongation of the ejection time of the corresponding ventricle due to semilunar stenosis. The degree of rhombic delay is proportional to the degree of stenosis, and the amplitude of the murmur is proportional to the mean velocity of ventricular ejection. The frequency of the murmur is parallel to the intensity of the murmur. The jet murmur on one side finally precedes the ipsilateral semilunar valve closure tone but may cross over the contralateral semilunar valve closure tone. The location of the murmur during systole, duration, early and late rhombic peak, and morphology are also related to ventricular ejection volume, jet onset time, ejection phase length, and instantaneous blood flow changes during the ejection phase. It is commonly seen in pulmonary stenosis (PS), etc. The systolic regurgitant murmur is characterized by a consistent or increasing or decreasing variation of the murmur, which starts immediately after S1 and often masks S1; it lasts for a long time, mostly occupies the whole systolic period, and has a high frequency. The murmur of mitral valve insufficiency (loudest outside the apical and apical regions and may also be transmitted to the left subscapular angle) appears in early systole or occupies most of systole. It has an intensity of 2 to 3 or more, is high pitched, coarse, brushy or musical, and can have multiple morphologies on the cardiac sound map. The ventricular septal defect murmur is loudest at the left sternal margin between 3 and 4 ribs.