LR - many thanks for your response. Yes, due to go back to the OS in June to discuss next steps with my hip but a replacement is on the cards at some point.
I have done all the Halter tests and, like I said, they wanted to do an ablation but after a couple of hours of poking around, they couldn't find anything wrong so didn't ablate. They suggested that the top part of the heart is "sensitive" and various triggers could cause the problem. I have lived with this since 1998 and, although frightening at times, I am so used to it. I was taken OFF beta blockers after this procedure but now back on Propranolol 40mg, one a day - they make me feel pretty odd too!
Doc suggested I carry on as normal as possible but sometimes it is worrying