Prolongation of the left ventricular segment of the heart shadow is the result of imaging tests, which may be caused by coronary heart disease, pericardial effusion, pulmonary heart disease and other diseases. 1. Coronary artery disease: Coronary artery disease is mainly caused by coronary artery stenosis or occlusion, and the main symptoms of patients are angina pectoris, chest pressure and other symptoms, as well as shortness of breath, dizziness and other symptoms, which will lead to coronary artery disease left ventricular segment prolongation of coronary artery disease when the patient is doing the imaging test. 2. Pericardial effusion: Pericardial effusion is mainly due to inflammatory or non-inflammatory pericardial lesions, and the main symptoms of the patient are dyspnea, hoarseness, hepatomegaly, etc., which will also lead to prolongation of the left ventricular segment of the cardiac shadow in the imaging test results of the patient. 3. Pulmonary heart disease: pulmonary heart disease is mainly due to the acute elevation of pulmonary arterial hypertension, patients will have symptoms such as dyspnea, chest pain, choking sensation, as well as fatigue, lack of appetite and other symptoms, which will lead to the phenomenon of prolongation of the left ventricular segment of the cardiac shadow when the patient undergoes imaging examination. Patients whose imaging findings show prolongation of the left ventricular segment of the cardiac shadow should seek prompt medical attention and follow medical advice.