Not much of insight, but I do have either this or a similar condition. It was found a the end of MVr surgery. It's fairly small, about 3-4 mm. At that time I was told that:
- This should not cause any issues.
- It's very unlikely to grow. But if it does, there is a transcatheter method they could use to plug it.
So basically at the next echo scheduled (in ~1.5 years from now) my cardiologist also plans to use the test version "with bubbles".
I cannot quite translate your test result into the hole size, except that "it looks small". Would agree with
@Deidra that by itself the hole may not explain the low oxygen issue. I wonder if something else is going on. Did your cardiologist say they understand the reason for the low oxygen?