Isosorbide nitrate tablets can dilate coronary artery blood vessels, improve the coronary blood supply of the heart, improve, prevent angina attacks, after cardiac bypass surgery, whether the need for long-term oral isosorbide nitrate needs to be decided according to the specific postoperative conditions. In general, after cardiac bypass surgery, myocardial ischemia caused by coronary atherosclerosis can be significantly improved, angina pectoris, limitation of physical activity and other clinical symptoms can be significantly relieved, so there is no need for long-term oral isosorbide nitrate. Some patients still have a certain degree of postoperative coronary stenosis, insufficient blood supply to the heart, this situation can be long-term administration of isosorbide nitrate to improve the blood supply to the heart. Some side effects or adverse reactions of isosorbide nitrate need to be noted, such as vascular throbbing headache, facial congestion and flushing, vertigo, upright hypotension, reflex tachycardia. Note that severe hypotension, hypertrophic obstructive cardiomyopathy, severe anemia, glaucoma, increased intracranial pressure, primary pulmonary artery, and hypersensitivity are contraindicated. It should be noted that after heart bypass surgery, patients need to strictly follow the doctor’s instructions for rational use of medication, should be based on the doctor’s guidance to determine the type of medication and duration of medication, do not change the medication without authorization to stop.