Do you think you have TOS and that is causing the distended veins?
Any hand arm or elbow symptoms?
Swelling? blueness, color changes?

Severe chest muscle spasms can cause you to feel like you are having palpitations.
Some with TOS /spasms have even gone to ER , and checked out fine for heart.

Perhaps you should skip the drs and find an advanced PT person to give you a hands on in depth assessment. Also a skilled expert chiro should be able to do same..

In the TOS forum sticky threads we have tons of info anda PTs & Drs listings.. TOS is not well known by many general MDs , you may need an expert..
http://neurotalk.psychcentral.com/thread135.html
http://neurotalk.psychcentral.com/thread84.html