What Causes Swelling In The Legs After An Aortic Valve Replacement?

I had heart failure Jan.2016, had aorta valve replaced, was doing well, in April of this year my legs started to swell (never had swollen legs-well maybe when pregnant) but I m 83 yrs old. My whole legs swell, ache, more the left one, but the groin on the right is sore. I take 5 meds) since surgery no haven t had problem, this is totally new. My GP, told me to increase my diredic (p), don t work.