Thanks for writing in. I am a qualified and certified cardiologist and I read your mail with diligence. The site must have been used for cardiac catheterization
that is a small tube is inserted for doing angiography
prior to surgery. Usually no stitches are applied and it heals without even leaving a scar. In your husband's case what you are describing non healing of skin wound possibly because of local infection just beneath the skin. If that is what it is then solution is simple. You have to show to the surgeon who may give small nick to clean out all the infection gathered there followed by cleaning with antiseptic solution. It may need a stich or two afterwards and perhaps some antibiotics. Please do not worry, it will heal eventually without much of a problem. It must be hidden under clothes he would have been wearing and perhaps not noticed before discharge. Goof Luck.
Dr Anil Grover