Thanks for the replies. The surgeon did not specifically say what was compressing the vein. She saw where it was (as did I) and stated it was right there where the first rib and scalenes were. I did ask her why they could not bypass the vein, and her answer was something to the effect that too many collateral veins had formed. She stated that the decompression should allow more room for the collaterals. My concern is that if they can't fix the vein (according to her) why am I going to go through this surgery. Almost seems like PT/OT and cortisone injections would relieve the pressure. Maybe I'm wrong.