High grade AV Block is defined as having > 1 dropped P wave. It generally implies a more distal level of block, and hence is considered a more unstable rhythm.
High Grade AV Block can progress to complete heart block.
ECG Criteria:
1. More P waves than QRS complexes
2. More than 1 dropped P Wave
-The arrows point to P waves
-Of the black arrows, the first two P waves are blocked somewhere in the conduction system, below the AV node.
-The last black P wave (P wave #3) conducts to produce a QRS complex
-The red arrows then mark the remaining P waves of this tracing.
-It essentially shows 2:1 Block.