Here is something you can also look at.
One of our little ones (of 8 cats & 3 dogs), Casey, our 7 year old poodle, has heart failure also. He was diagnosed in April with 1-2 months to live. Heart failure can cause two things, 1 is to fill the lungs full of fluid due to inefficient pumping and the other is to fill the body cavity. Casey was afflicted with the body cavity fill.
the doctor gave us the medicine DIGOXIN, I believe. this helps to improve the action of the heart. He also is on a medicine which helps to get rid of the fluid buildup through urination. this led to several problems of extreme thirst and extreme urination. We opted to keep him around us and comfortable. Peeing every 5 minutes can make that difficult. Well, 6-8 months past his due-date with heaven, he is still with us. the medicine helped immensely, and we take him to the vet about every 2-3 weeks to have him suctioned. They stick a needle in his stomach and drain all the liquid they can get. It is January now, and he is still with us, he is getting worse, due to his breathing and his heart giving out. He can't really control his urine so he changes diapers many times a day. I guess my advice would be to keep him with you and your family. Don't put him to sleep cause he is so much trouble, Bug your vet for any possible solution and just have faith and the belief that your Rudy wants to be around you as you want to be around him.