Thank you for your question.
When you say that her valve replacement failed do you mean that they were unable to replace the valve ?
I worked many years in ICU and at some point she may need dialysis.
I don't understand why her doctor doesn't have her in the hospital right now.
Her prognosis sounds poor.
If her kidneys shut down then her only option is really dialysis. or iv drugs to increase her output.
I have seen patients like this just get worse and worse and practically live in the hospital
Things to think about would be getting a living will for her.
That would mean that no life sustaining meansure would be done if she passed away.
Also getting power of attorney.
If she is so short of breath that she is in distress she should go to the ER.
I would think her diagnosis would be kidney and heart faiolure but her doctor would have to tell you for sure.