What you are saying sounds terribly familiar, as I've been going through the same things, and yes, heat seems to make it worse.
I, also have a CRT device, and take CHF medication, the doctor tells me I'm in GREAT shape, and that the turn around in my health is nothing short of amazing(a year ago I was on death's doorstep), but yet the heat knocks me off my feet.
This last week I received an Iron infusion, because I'm anemic, and I feel A LOT better. I would suggest that you talk to your doctor about what you're experiencing, and perhaps ask for a blood check.
Thanks so much to both of you - I am on CHF medications. I also have a biventricular pacemaker (I hope I spelled that correctly).
As for weather, I am living in Phoenix, and the temperatures were about 113, day after day, when this started. I had been running errands in the heat, and I wonder if I just exhausted myself.
I am so relieved to have a chance to talk to someone else about this-
God bless you both, Anne9325
I have to be extremly careful with weather changes. Both too hot or too cold. have a devastating effect.
Jesus
Are you on any kind of medications for the CHF? Usually a beta blocker / fluid pills. If you are not taking your fluid pills like you should it can cause the tiredness and the shortness of breath.
If you are still having these troubles, I would talk to your doc, they may just want to up your medication.