Please view the following video animation on Second Degree AV Block (Wenckebach | Mobitz I).  There is also a supplemental audio file which may be

Characterized by an AV node malfunction as follows: Each PR-interval gets progressively longer until a beat is dropped. Then the cycle repeats itself. This is

Please see the animated video below with optional audio covering Second Degree AV Block (Wenckebach | Mobitz I).  The audio may be played simultaneously with