Thumper to "back off" because he wasn't handling play activity very well, but saw that Thumper was nowhere near Pepper, so Pepper must have had another heart event; either another angina attack or a heart attack. He didn't recover his breathing for the rest of the day because every time I tried to help with the oxygen tent we had fashioned, he would do great until he could breath and then had to escape, which put him back into distress.
If you can get the oxygen into a cat, I could see that it helps as there was one point where Pepper's tongue was looking blue and it returned more to its pink color, but he just never managed to pull out of the nose dive. He had a constant need to try to stretch, either to get away from pain, or what looked like trying to undo a cramping. When we finally decided the risk of taking him to the vet was less formidable than that we needed to take to relieve ongoing discomfort we found a large sturdy storage bin lid and lined it with towelling, putting him in the car with me at his side supporting him from any jerky moves. I think he was beyond understand what was happening by this time as he wasn't struggling to take control of the situation as he usually did and seemed oblivious of the fact that he was in the car.
We lost him two minutes into the trip at 6PM, June 18, 2010. After we left the vet's office where his death had been confirmed, DH said on the way back to the car, "he was a blast", and I couldn't have put it better myself.
Pepper had a fun life, not too much pain considering the major flaw in his makeup, and his beautiful "lemur" tail was pointing skyward up to the day of his death.
He had a major hole in his heart, and now we have that major hole in all our lives. He is so missed.