What Is Life Expectancy When Having Heart Failure?

My mother is 84 and had a aortic valve replacement (pig) about 15 years ago. It has been leaking for the last 12 months and we have been told she is now suffering heart failure. Her ankles and legs are severely swollen and her blood pressure taken at hospital today was 133/35 on the first reading and then 122/28 on the second. What does that mean? She also has CRF too. What is her life expectancy with these conditions?