Update as promised on the recent "thumping" as my CRT pacemaker kicks in. Went to my appointment at the pacemaker clinic on Monday and explained that I was getting this quite drastic "thumping" on my left side as the pacemaker kicked in. This after 5 years with no problem. Quite disconcerting, with one incident lasting 15 hours. No pain but I could see the left side of my chest twitching.
Anyway the technician knew straight away what the situation was. As I understand him the third lead from the pacemaker is routed on the left side of the chest close to the nerve that controls the diaphrahm. If the pacemaker senses the current sent to the heart via that lead is too strong a failsafe stops the current returning by that lead and uses the muscles in the body instead, causing the sensations I was experiencing.
He suspected from the readings that this was an isolated incident and turned the setting back on. All OK at present but if it happens again I am to contact them and they will adjust things furthur. It is apparently not at all dangerous and no damage is caused, the currents used are tiny, but the sensation feels massive.
Anyway there it is, sorry if I have not explained this too well but I hope it helps someone.
Pain under arm pit area following by pass surgery.
Progress post surgery 
ICD or not ICD
Living for the moment 
