There are many methods of cardiac function tests, which are usually divided into two categories: invasive and noninvasive. Invasive tests mainly refer to cardiac catheterization; non-invasive tests are more common, such as echocardiography, radionuclide cardiovascular imaging, systolic time interval, cardiac impedance, and so on. Echocardiography is the most widely used non-invasive method for cardiac function testing. The following is a brief introduction to the methods of ultrasound determination of cardiac function. Echocardiography can measure the change in the internal diameter of the heart chambers in different phases or different cardiac cycles, calculate the change in the volume of the heart chambers, and deduce the systolic and diastolic functions of the heart in combination with other physiological parameters; it can measure the blood flow velocity through a certain section and deduce the ejection volume of the heart; it can also measure the time to indirectly reflect the heart function. A large number of clinical and animal studies have demonstrated that echocardiographic measurements of cardiac function are accurate and reliable. However, it should be noted that most of the cardiac function indicators measured by ultrasound reflect left heart function, because of the characteristics of the right ventricle shape, it is often difficult to measure its volume by ultrasound, and the measurement of right ventricular function by ultrasound is still in the research stage. Ultrasound measurement of cardiac function indicators mainly include the following three aspects: 1, cardiac systolic function (1) ejection fraction, reflecting the pumping function of the left ventricle, ejection fraction decreased often indicates that myocardial contractility is reduced, poor cardiac function. Normal ejection fraction should be higher than 50%. (2) Left ventricular short-axis shortening rate, its clinical significance is the same as the ejection fraction. The normal left ventricular short-axis shortening rate should be higher than 28%. (3) The average left ventricular circumferential radial shortening rate, reflecting the speed of short-axis circumference change during left ventricular contraction, is a more sensitive index. Normal should be greater than 1.0 circumference/sec. (4) Left ventricular volume per beat, which refers to the volume of blood ejected during each left ventricular contraction. The volume per beat can further be used to calculate the cardiac index and other indicators reflecting the overall function of the left ventricle. (5) Aortic and pulmonary artery blood flow velocity integral, reflecting the heart beat volume of the left and right ventricles. (2) Diastolic function (1) The slope of EF in the anterior mitral valve leaflet reflects the compliance of the left ventricle, and decreases when it indicates a decrease in compliance. (2) The ratio of the E peak to the A peak of the mitral flow spectrum can be measured directly, and the normal ratio should be less than 1. A ratio greater than or equal to 1 indicates reduced left ventricular diastolic function. The ratio is sometimes greater than 1 in the elderly and in newborns within one month of birth. (3) The ratio of the E and A peaks of the tricuspid flow spectrum reflects the diastolic function of the right ventricle. (3) Systolic time interval is an indicator that reflects ventricular function by time, and is actually the earliest indicator of cardiac function measurement. Traditionally, it was mainly measured by cardiac mechanics in the past, i.e., by synchronized tracing of carotid beatogram, phonocardiogram and electrocardiogram, and now it is mainly measured by echocardiogram. It is usually measured by electrocardiogram and simultaneous recording of aortic or pulmonary artery blood flow spectrum, and the method is simple. The main indicators include the pre-ejection phase and the left or right ventricular ejection phase, with the ratio of pre-ejection to ejection phase often being more meaningful. The isovolumic diastolic time of the left ventricle can also be measured to reflect the diastolic function of the left ventricle.