What Ross said.
Tell your cardiologist about it NOW.
Fluid retention is nothing to mess with and it's a sign of greater problems in your heart.
Try to go easy on how much you're drinking in a day and cut back some on your salt (sodium) intake. First step on that is to take the salt shaker off the table and just THROW IT OUT! =)
If you have it there, if not, good for you. Don't add salt to stuff when you cook.
There's all kinds of stuff in the Recipe section for you including advice on cutting back on the sodium.
Check with your doctors first though. Fluid retention is fairly common with heart conditions and can be easily treatable before having to go to the big OHS option.
My ankles used to get puffy like that as the day wore on. It wasn't noticable early in the day, but usually after dinner or later if I took my socks off it was there. And it wasn't always there either, some days I just didn't drink as much or I sweated out more (it was a hot summer) and the fluid retention wasn't as severe. if you have a good, accurate, scale, you might start watching your weight on a daily basis. Check it in the morning when you get up, after lunch, and before going to bed. Keep a log. If you're fluctuating 3-5 pounds or more in a day or two (or more often) you're retaining water.
The good thing is, if you've got a lot of water already "on board" the diuretics may (should) help you flush it out and you may actually lose some weight.
One thing to REALLY watch for is a "fullness" feeling. Almost like you're bloated (which you are) and that can be a real problem. Fluid retention comes in two forms, it's either in your extremeties (hands, legs, feet) or it's in your torso and head (face) depending on where in your heart the problem lies. It can some times be both.
I started out showing retention in my ankles, but then it started showing in my face, at times to the point that I looked like a frying pan and it felt like my face was swollen from a bee sting.
Bad stuff.
Diuretics are fairly easy to deal with and the most common side-effect may be muscle cramping because the extra trips to the bathroom can flush out important minerals your body needs. The simple fix to that is to eat more of foods that have those minerals. Potassium (in bananas, oranges and orange juice, and apricots) is the most common cuplrit for muscle cramps in legs and joints. If I feel a cramp coming on the easiest thing to do is just have a glass of orange juice or munch on a few dried apricots (I have a bag stashed away for "emergencies")
If it gets out of control, it can get really scary so it's best to get on top of it early. Since I've had surgery, I haven't had any real problems with fluid retnetion. I take 60mg of lasix twice a day plus another 20mg of spironolactone (again, twice a day) which is another diuretic that has a different "mechanism" to it and helps me retain some of the minerals I'd lose from just the lasix alone.