I sometimes woke up at night with big difficulties in breathing and panicking about it with heart racing and pain in my chest - just like a heart attack I think. It was TOS related (vascular TOS, bilateral). I think it is related to the intercostobrachial nerve which can be affected by TOS. Check this out:

"Spreading or radiation of pain is also important in evaluation of neuropathic pain. If retrosternal pain (radiation from intercostobrachial nerve, a branch of T2 intercostal nerve) is noticed on the left side, it can be confused with pain of cardiac or pulmonary origin" http://emedicine.medscape.com/article/1143532-clinical