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 decreases to less than 35%. So what are the main causes of low ejection fraction? Ejection fraction: LVEF (LeftVentricularEjectionFractions) is the percentage of ventricular end-diastolic volume per beat. When the ventricles contract, not all the blood from the ventricles can be ejected into the arteries. In the resting state of normal adults, the volume of ventricular diastole is about 145ml for the left ventricle and 137ml for the right ventricle, and the ejection volume is 60-80ml, that is, there is still a certain amount of residual blood in the ventricles when the ejection is completed. The ejection fraction of the human body during quiet time is about 55%~65%. The ejection fraction is related to the contractility of the myocardium. The stronger the contractility of the myocardium, the greater the output per beat, and the greater the ejection fraction. In cases of abnormal ventricular enlargement and ventricular hypoperfusion, the beat output may not be significantly discriminated from normal, but it does not correspond to the already increased end-diastolic volume and the ejection fraction decreases significantly. Low ejection fraction: mainly due to abnormal enlargement of the ventricle (enlarged right ventricle i.e. posterior anterior position, seen as flattening or bulging of the heart waist, lengthening of the pulmonary artery segment and thus a downward shift of the opposite beat point. The transverse cardiac diameter is enlarged and extends mainly to the left. The left ventricle is compressed and the apex may consist of the right ventricle, which is obtusely rounded and, in severe cases, upward. The right ventricle extends to the right and may push the right atrium upward. When enlargement is significant, the heart rotates to the left, which is related to factors such as lower anterior sternal resistance, the relatively free left heart, and the more fixed right heart. (After rotation, the heart waist becomes more prominent and the ventricular segment may consist entirely of the anterior wall of the right ventricle, while the aortic bulb is not evident.) , low ejection fraction due to ventricular hypoperfusion.