1. Atrial rate: 60 ~ 100
2. P-wave UPRIGHT in lead I, II, III, aVF (& aVL) 反之是ectopic atrial
3. PR-interval: 0.12 ~ 0.20 sec <0.12: preexcitation or AV-junctional; >0.2: AV-block
4. Every P FOLLOWED by QRS
5. Every QRS PRECEEDED BY P
6. TWI in V1 & aVR
