The reason for the very small hole in the incision four months after the open heart surgery may be the sinus tract produced by the sternal wire or suture irritation or the pus cavity after the infection. After open heart surgery, the sternum is usually fixed by a wire for sternal fixation and then sutured layer by layer to close the muscle, subcutaneous tissue, skin, and so on. Recovery after open heart surgery generally takes 3 to 6 months, the sternum can be recovered, but the wire or suture can not be absorbed, some of the wire in repeated activities or muscle pulling, the wire broken end will stand up, stimulate the subcutaneous tissues, etc. to produce sinus tracts, pus, etc., and a few may be due to the result of similar rejection reaction produced by the suture. There is a very small hole in the incision four months after open heart surgery, and it is recommended that the thoracic surgery clinic be consulted and dealt with.