Are you taking medication. Can be the side effect of a beta blocker. The reason, if heart med related, is that blood output from the heart goes to areas that have a higher priority than extremities such as the brain, the heart, etc.
I didn't have surgery, but I have CAD, etc. and experience some coldness in the extremities at times for the reason I have cited..
I had a cath done for both sides of the heart on 2-18. My experience was 3 hrs. late and they sent me home after only 2 hrs. because it was closing time. My entire leg was numb. It still gets numb after walking about 500 ft. Docs say unless my leg is swollen, red, or very cold, not to worry. My feet have been like ice cubes especially when I go to bed. I have found that wearing footies or socks help alot. The blood flow is still good, Doc checks it . Now I have aortic surgury this Friday. How are you getting along other than cold feet? Did you have open heart?