Hello, I too have swelling in my legs, primarily the left leg and my surgeon required me to have a cardiology clearance. Luckily they worked me in quickly and within five weeks of my initial consult with surgeon (5/21) I had surgery 6/29. All's well so far!
The cardiology clearance involved an EKG, an echocardiogram of my carotid arteries and my heart, an ultrasound of my legs to check for vein blockage (blood clots), and a stress test. I'm self-pay and had to put up another $1500 for the cardiology tests which was a bummer, but better safe than sorry on the operating table. Nothing painful except a little discomfort on the stress test as I have severe osteoarthritis in knees, so they induced stress through medicine. It wasn't bad, though.
Hope that helps. All doctors are different. Yours may not request the cardiology clearance, but one of the the worst possible things that could happen would be a blood clot to break lose during surgery.
Good luck!
p.s. the ultrasound and echocardiogram were kind of neat! The technician had the sound turned on so I could actually hear the blood swishing through the veins in my legs and also the sound of my heart. The biggest expense as a self-pay was the stress test -- almost $1,000!