Pain in the upper left chest after bypass surgery may be caused by unrecovered wound, wound infection, lung infection, etc. Different treatments are needed according to the causes. 1. Unrecovered wounds: Heart bypass surgery often results in larger wounds and slower recovery time resulting in pain. Patients should take good care of their wounds, rest in bed, and avoid premature activities that may lead to wound dehiscence. 2. Wound infection: postoperative wound infection can also cause pain in the upper left chest, the patient should follow the doctor’s instructions to change the medication regularly, under the guidance of the doctor to use iodine povidone every day to disinfect the wound, and if pus appears, you need to drain the pus in a timely manner, and at the same time, under the guidance of the doctor to use amoxicillin and other drugs for treatment. 3. Lung infection: lung infection may be caused after bypass surgery, resulting in pain in the upper left chest. Patients should carry out bacterial culture examination as early as possible, and use drugs such as cefixime and amoxicillin for treatment under the guidance of doctors for different situations, and if pleural effusion occurs, the effusion should be drained out in time. After bypass surgery, you should take good care of yourself, consult a doctor in time for checkups when discomfort occurs, and do not blindly use medication on your own.