UPDATE

I just received my test results from my cardiologist and he says that after careful examination of the imaging and discussing matters with the cardiovascular surgeon, there is no reason for my fistula surgery not to go forward. My heart itself is in excellent condition, though there is a scar toward the lower region, but that could be due to my diabetes or a number of other things. The point it that I am in no immediate danger and no stent or other heart procedure is required. 

I asked him about my recent issues with occasional chest pains, and he stated that that could also be due to any number of factors — I've narrowed it down to a combination of endless worry over my medical issues, my mother's medical issues, the pandemic, and the lack of regular exercise at the gym for just under four months, plus dread over having to take yesterday's nuclear stress test (which proved to be unwarranted, as I was able to opt out of the treadmill) — but there was nothing in the imaging that pointed to anything being wrong. Not that I should ignore it if it happens again (don't worry, I won't), but it's all good enough for now.

I'm still confined to quarters for a few hours due to yesterday's two doses of that radioactive isotope serum, but that's fine by me. I'm also still kind of sluggish and loopy from the drug that dilated my arteries for the imaging, and part of its effects are feelings of nausea, wooziness, that sort of thing, so I'll mostly be staying in bed for the rest of the day. And with the dread over possibly croaking during the nuclear stress test out of the way, last night was the deepest sleep I've had in a couple of weeks.