Cardiac ultrasound can diagnose mitral valve insufficiency, and the quantitative diagnostic criteria are divided into three degrees: mild, moderate and severe. In mild mitral insufficiency, the ejection area is less than 4 cm², the regurgitant flow per beat is less than 30 ml, and the regurgitant fraction is less than 30%. In moderate degrees of insufficiency, the ejection area is 4-8 cm², the regurgitant flow per beat is 30-59 ml, and the regurgitant fraction is 30-49%. In severe degrees of insufficiency, the ejection area is greater than 8 cm², the regurgitant flow per beat is greater than 60 ml, and the regurgitant fraction is greater than 50%, which are the criteria for echocardiography.