Amal Mattu gives us a very simple way to distinguish the type of advanced AV block by looking at the PR intervals.
You may also find this link to LITFL on SVT vs VT most informative.
Dr. Mattu walks us through a three step method to make identifying heart blocks easy. Just ask three qestions
1) What is the atrium doing? (regular, irregular rate?)
2) What is the ventricle doing? (morphology and thus location? rate?)
3) How are the two related? (Look at PR interval, is it regular? long then dropped QRS, longer, longer then drop? or randomly related? 1st, 2nd, 3rd degree blocks).
Our thanks to Dr. Tim Davie for assembling the Copa Cardiogram each week. Please follow this link to get to spreadsheet of all Copa Cardiograms.
Our favorite ECG Resources