I'm writing part of a paper on AV heart block and was wondering what kinds of heart block there are. My patient had 3rd degree AV block, but I wasn't able to find enough information for how much I need to write on that so I'm writing about the other types as well. What I found so far is 1st degree AV block, 2nd degree type 1 and 2, and 3rd degree. One source I have says a bundle branch block is also in this category, but other places I have looked don't mention it. Does BBB belong in this category? Also what is the difference between 2nd degree type 2 and a BBB? From what I have read they both occur below the bundle of His.