Hello Thanks for query . Based on the facts that you have posted it appears that your male partner has undergone Coronary Bypass Surgery (CABG) and facing problem of erectile dysfunction . Having done CABG itself suggests that he has atherosclerotic vascular disease which also involves Penile Artery which supplies arterial blood flow to erectile tissue in penis to achieve erection .His problem of erectile dysfunction is mostly due to reduced blood flow to erectile tissue resulting from atherosclerosis of Penile artery . In a given situation I would suggest to get Color Doppler Ultrasound Scan of the Penis done to confirm the diagnosis . Since it is at high risk to take Viagra or other drugs I would suggest to put a penile implant to have penetrative intra vaginal sexual intercourse. Dr.Patil.