Thanks for the response Sarah21.

So my speculative theory is that if you have ATOS on the left side with a depressed shoulder, you are basically crimping your circulation close to your heart. Then you get the heart attack like symptoms since, in both cases, your heart is not getting enough oxygen.

I am familiar with costochondritis although I did not know what the name was for it until Anne4tos posted here. I developed it after TOS and I think possibly in response to extreme muscle spasms which were themselves in response to my ATOS episode from hell. Anyway the costochondritis pain and the artery backup pain are very different feelings. The artery problem is deep under the pec and/or under the sternum. The costo is right there at the sternum where the ribs connect. Besides location, the feel is just different.

Fun, fun, fun!

P.S. If you're in the Los Angeles area, it was Joyce Wilkinson PT who helped me with the costo. One session knocked out 80% of it.