I consider what you describe to be bypass surgery, not open heart surgery, that is your heart was not opened. I could be wrong on that "fine" point, but to your cold limbs question I can say I had open heart surgery to repair my mitral valve and to do a mini-maze procedure on the inside of my heart to try to stop atrial fibrillation.
This was done in November of 2007, and I have not noticed any increased sensitivity to cold temperatures or colder hands/feet...
The 40 mg of Simvastatin may be something to discuss with your doctor. I understand there is some evidence that drug has had some problem side effects in high dose usage, 40 mg is high dose. In fact my cardiologist had me cut from 20 mg to 10 mg about two months ago. In my case there was a concern about interactions of Samvastatin with the calcium channel blocker I take. I am going in tomorrow to get my cholesterol checked and I suspect it will go up due to the lower dose. As Lipator is now available as a low cost generic I will ask my cardiologist if I can return to using Lipator. I changed to Simvastatin a few years back to save money.
This is a Heart Rhythm forum. We talk electrical here... you're talking pump and plumbing.
You might want to try a different forum. Heart disease??
http://www.medhelp.org/forums/Heart-Disease/show/72
Good luck.