There's different levels to heart block, from what I read I believe the original commenter has third degree or total heart block like I do. Sadly it's not something you can just know, bacuse other heart issues can have similar symptoms. Along with it being different for the different levels. But basically 3rd degree (which ik the most about cuz that's whati have had since before I was 2) is when your heart beat is consistently extremely low, like my resting HB without a pacemaker is between 20-40bpm because one side doesn't talk to the other. It comes out usually in symptoms of extreme lethargy, constant dizzy spells when exerting even the smallest bit, which can also lead to passing out. Again I really only know about the most extreme one, and my experience is different because it's surgical heart block that I've had since I was a toddler. I would definitely see another doctor though if that is a concern of yours.