Hi Gill,
Thanks for your reply. I'm sorry your cats have heart conditions, but happy to hear they are doing OK with medication.
The vet said Charlie had an enlarged heart too, so I take it an enlarged heart and heart failure go hand in hand.
Charlie's breathing is still the same, so the diuretic injection couldn't have done the trick.
We're taking him to see the vet in the morning, he may be having an x-ray and also the fluid drained away. Maybe he'll need to go on water tablets permanently.
I'm scared the x-ray will show up something more sinister ... I won't sleep tonight!
Gill