Bradyarrhythmias

Rate < 60
Physiological/fit, B-blockers, pathological

1st Degree Heart block
Prolonged PR (>0.2s/five "squares")
AV conduction delay - Atheletes, drugs, conduction pathway fibrosis
Rarely needs treatment

2nd Degree Heart block
Some, but not all P-waves conducted
Mobitz I: Wenckebach AV block - progressive prolonged PR
Mobitz II: 2:1, 3:1 block

3rd Degree Heart block
Atria and ventricles beat independently
High risk of asystole