Heart failure can be detected by cardiac ultrasound. Patients with heart failure will clinically present mainly with chest tightness and shortness of breath after activity, or even with breath-holding and profuse sweating. Patients with heart failure who undergo a cardiac ultrasound will often be found to have an enlarged heart to the sides, thinning of the heart muscle cells, and a decreased ejection fraction of the heart. The normal value of cardiac ejection fraction should be more than 60%, even for older patients, we will relax the standard of cardiac ejection fraction should be more than 50%. That is, the heart should eject at least 50% of the blood within the ventricles in a single ejection. In patients with heart failure, a cardiac ultrasound will often reveal an ejection fraction of less than 50%, and even less than 40% in patients with severe heart failure. In patients with heart failure with an ejection fraction of less than 40%, there is always a clinical risk of sudden death. Therefore, cardiac ultrasound can detect heart failure and is a good aid in grading heart failure.