The people involved were actually pretty separate, in my case. The cardiologist was the one who ordered the echoes and determined it was time to look for a cardiothoracic surgeon. That was it for the original cardiologist for a while.
I went to the surgeon, we explored his credentials and philosophy, talked valves a while, chose one, and afterwards set up a date with his people. Then there was a third cardiologist - the interventional cardiologist - contacted by the cardiologist at the surgeon's request.
The interventional cardiologist is the one who does the cardiac catheterization, if you haven't already had one. They do it to see if bypass grafts should be done at the same time as the valve surgery. My cath was done the day before my surgery at that hospital. Then he was gone.
My surgeon saw me briefly before the surgery and afterwards daily, for a brief time. The cardiologist may have had someone visit daily, perhaps a Physician's Assistant, but I am not certain, as I didn't know any of them. The surgeon also had a PA check up on me several times a day. The cardiologist did have one of his partners there to determine whether I should go from Intensive Care to the regular cardiac ward after the first night. The surgeon is the one who released me from the hospital, though.
After I went home, the care of the wound was entirely for the surgeon's group,as well as initial prescriptions. As far as instructions, the hospital had handed out a set, and the surgeon's PA asked if I had read them. I said, "sort of," so she checked "yes." I really didn't go into them all that deeply, as many of them plainly didn't apply to me, dealing with fluid problems and special diets, which I didn't have. The last time I saw the surgeon was ten days after surgery, when his staff took the staples out (ouch!).
At about four weeks, I called the cardiologist to see if they wanted me to come in for anything. They set up a six-weeks-out appointment, and did an echo, a 24-hour Holter monitor, and an ambulatory blood pressure test. My BP was always high at their office, but I fervently denied having high blood pressure. The monitor was to break the stalemate. End result was that I proved that cardiologists cause high blood pressure, and that my BP was fine when I was at home.
At six months, my cardiologist was going to stress test me, because of an inverted T wave I had developed before the surgery and was still showing afterwards. (A T wave is like a degaussing wave that neutralizes the heart's electrical potential between beats; mine was flowing in the wrong direction through the heart.) I was reluctant, so he did an EKG to convince me that I should. As he read the EKG, he noted that my inverted T wave was reverting to normal. So I escaped another test.
Then he sent me to a cardiac electrophysiologist, who is expert in the electrical impulses that run the heart, and thus also arrhythmias. It was because of one ventricular triplet I had shown on the Holter at six weeks, and which I felt was ignorable, as it had been so soon after the surgery.
The EP spent quite a while with my files, then examined me. He said that my heart muscle was very strong, the beat was very regular, and my valve was making perfect closing noises. He declined to monitor or test me further, as he said that with no current issues and good heart muscle strength, I would be a very minimal risk even if I did have occasional ventricular triplets, which he did not believe I was still having. He also said that one triplet six weeks after surgery is not significant, given my heart's condition otherwise, as it was so soon after the surgery (hah!). Houdini stikes again - I escaped more testing and monitoring.
So now I'm back to just the cardiologist, who I'll see again in six months.
I imagine you'll get many different answers to this, as each place seems to have its own way of doing things. I was well served by the folks I dealt with, and content with their modus operandi. I hope you will be, too.
Best wishes,