After having my heart mumble some untoward things during the Denver Century a couple weeks ago, I made an appointment with my doctor. We talked about my family history -- of two direct ancestors with loads of heart problems (although one of them just celebrated her 95th birthday yesterday, so let's take 'loads of heart problems' in context) and my homemade EKG and general nervousness leading me to think my heart isn't always operating quite how it should.
He listened to my heart, had me do deep knee bends, breathe, stuff like that, and said he thought I sounded like I was fine. Reassured me I was just noticing stuff everyone experienced because I was predisposed to notice it. Finally I talked him into setting up an EKG, which took like five minutes. It dumped out a bunch of plots and he looked at it and frowned, and got a ruler, and started measuring, and frowned some more, and said I need to see a cardiologist.
I may have something called long QT syndrome. There's a buncha stuff on wikipedia about it. To sum up, it's a hereditary congenital heart abnormality, no big deal (except for when you suddenly drop dead) and easily treated with beta blockers. And it's not even anything like for sure I have it: I just have a couple risk factors (male, father probably had it, and, well, a long qt period) so I get to go do a stress test with better instrumentation.
He said I should feel free to keep riding like a crazy person in the meantime, which is good because I was going to anyway no matter what he said.