The left ventricular end-diastolic internal diameter of the dilated heart is significantly increased, exceeding 5.5 cm in men and 5.0 cm in women. For patients with clinical manifestations of chronic heart failure, echocardiography is mainly used as a diagnostic basis in clinical practice. 1. Clinical manifestations of chronic heart failure: dyspnea and decreased activity tolerance during activity. With the aggravation of the condition, symptoms of left heart insufficiency such as nocturnal paroxysmal dyspnea and sedentary respiration may appear, and symptoms of right heart insufficiency such as loss of appetite, abdominal distension and lower limb edema may appear gradually. 2. Echocardiography may only show mild enlargement of the left ventricle in the early stage, but in the later stage, all chambers of the heart are enlarged, with the left ventricle enlarged, and the end-diastolic internal diameter of the left ventricle is more than 2.7 cm per square meter. the wall motion is generally weakened, the myocardial contractile function decreases, the ejection fraction is less than 45%, and the shortening rate of the left ventricle is less than 25%. Regular follow-up is recommended, and treatment under the guidance of a physician is recommended to avoid delays.