SECOND DEGREE SINOATRIAL (SA) EXIT BLOCK:

•Mobitz 1: A disorder of the sinus node in which there is progressive shortening of the P to P interval until a P wave is blocked in the SA node (shortening of the PP interval then a dropped P wave)

•Mobitz 2: A disorder of the sinus node in which there is consistent P to P interval until a P wave is blocked in the SA node (Constant PP interval then a dropped P wave)