Low ejection fraction, on the other hand, is an ejection fraction that is lower than the normal percentage. This is mainly due to abnormal enlargement of the ventricles and reduced ventricular function. Patients presenting with cardiac insufficiency often have a reduced ejection fraction. The chance of sudden death from malignant arrhythmias increases significantly when the ejection fraction drops below 35%. What tests should be done for a low ejection fraction? Ultrasound can be used to measure the direction of blood flow, the nature of blood flow, blood velocity, blood flow, the pathway of the abnormal blood flow bundle, and the abnormal blood flow bundle can assist in two-dimensional echocardiography to clarify the site and course of structural abnormalities and to determine the timing of the abnormal shunt. 2.Contrast imaging is one of the most important means of diagnosing cardiovascular disease. It is a relatively complex and special examination method with certain risks and requires strict indications. The most commonly used tests for low ejection fraction are ultrasound and contrast. Ultrasound, cardiovascular ultrasound, is the simplest and easiest method. Clinically, when life-threatening malignant arrhythmias occur, drug therapy is often ineffective, and the only effective treatment is electrical shock (electrical cardioversion), which, if not given promptly, can quickly kill the patient. Prompt access to an automated external defibrillator (AED) or implantable cardioverter defibrillator (ICD) can save the lives of most patients who experience sudden death. ICD implantation is recommended to prevent low ejection fraction in patients with cardiac insufficiency due to various cardiac diseases, especially when EF is below 35%.