Shortness of breath after heart bypass refers to dyspnea, its abnormal and may be caused by heart failure. 1, due to the long-term ischemic state of the myocardium in coronary artery disease, the heart will enlarge, myocardial fibers remodel, and ischemic cardiomyopathy will appear. And ischemic cardiomyopathy appears exertional dyspnea in the early stage, and shortness of breath gradually worsens in the late stage, and dyspnea in the calm state or not lying down or sitting down to breathe at night.2. Ultrasound examination of the heart helps to detect abnormalities in ventricular wall motion phases and a decrease in ejection fraction. If the ejection fraction is less than 30% or less, the heart function is poor and the risk of sudden death is easy to occur.3. If checking whether there is heart failure, a clearer indicator is brain natriuretic peptide precursors. The presence of heart failure is determined by age. The normal value is less than 500 pg/ml, if the young and middle-aged people are greater than 1000 pg/ml it means that there is heart failure, and the elderly people are greater than 2000 pg/ml with heart failure. If shortness of breath is present, drugs such as diuretics, ACEI or ARB class should be taken according to the patient’s specific clinical condition.