I am practicing to get my tele certification. The only thing I am having difficulty with is distinguishing between 2nd degree AV block type 1 and 2. I know that in type 1, usually the PR interval gets longer, longer, longer, then a block. But in some of my practice strips, this is not always the perfect case.
I figured someone here would be able to give a good explanation of the two!!! Thanks for any help. I take my exam on Thursday and I definitely want to pass. I've been an RN since the end of September and work on a tele floor, so it will be nice to finally read my own strips.
av blocks can be hard. in a mobitz 1 the conduction through the av node is delayed slightly with each beat until it finally drops one, then the pr interval "resets" itself. so the qrs is getting farther away with each conducted beat. interestingly enough, this rhythm was diagnosed prior to the onset of ekgs and the physician was just listening to the s1 and s2 sounds. sounds pretty tough (no pun intended).
with a mobitz 2 or classic heart block, an occasional beat is not conducted through the av node. with either of these 2 rhythms you can have 2:1, 3:1, etc or a mixture of everything, which makes it more difficult to determine. the best way of approaching it is just to look at the pr interval. you shouldn't have to break out your calipers, i've heard cardiologists-including my grandfather-say: if you're using calipers you're putting too much energy into it, don't split hairs over 1/100th of a second. if the pr interval is the same with each conducted beat and less than .20, then you have a type 2. if the interval is varying in a discernable pattern, then you have a type 1. but the bottom line of either rhythm is the hemodynamic stability. how are they tolerating the rhythm?
anyway, hope that helps some. good luck on your test, most tracings are notoriously horrible. don't let it throw you off track!
Last edit by getoverit on Jan 28, '09