Do you have a seperate incision for the heart lung machine, or did they hook it up in your incision they made to work on your heart? Justin Didn't have his subclavian artery used, but did have a 3-4 inch incision at his groin (where they do caths) for the bypass machine on his 5th OHS and had pain and numbness in his leg, it gradually (over a couple months) got better but in the beginiing it botherred him more than his sternal incision that was a full incision. I know others who had a second incision for the heart/lung and many (most?) have problems with either pain or numbness or both. Most people that have a 2nd incision is because they have a min invasive surgery and the tubes won't fit in the smaller incisions.
IF you didn't have a different incision for the machine, and just had the regular incision, then it is also pretty common to have pain or numbness in your arms or neck/back ect, it is usually because of the position they have your body in all those hours while they have to open for the surgery