BACKGROUND: Although patent ductus arteriosus (PDA) is more prevalent among infants and children, it might be seen among adults as well. It is not usually seen among adults, since it is often diagnosed and treated in childhood.CASE REPORT: In the present case, a 73-year-old man referred to the hospital with symptoms including dyspnea, cold sweating, and chest pain with a burning nature which was lasting for 30 minutes. Angiography revealed coronary artery obstruction, so he became a coronary artery bypass grafting (CABG) candidate. Except for dilatation of the left atrium, no specific findings were reported in the patient's echocardiography report. When the pump was turned off by the surgeon, the patient’s heart filled up and he was not able to get off the pump. Simultaneously, the patient started to have bloody respiratory secretions. With all that in mind, the surgeon suspected that he might suffer from a PDA, then he found an 8-mm PDA and closed it. Then, the patient was taken off the cardiorespiratory pump.CONCLUSION: Although PDA is more common among children and infants, it can be found among adults according to previous cases and our case as well. Since patients with PDA refer to physicians for other clinical issues, it is recommended to apply more precision in diagnostic methods such as taking a good history, echocardiography, and electrocardiogram (ECG). Moreover, it is recommended that if a patient has conditions similar to our patient, the surgeon must be sure of a possible PDA.