( PR interval, ? QRS with each P, PP and RR intervals, ? wide QRS, R-R'/R-S- R' in V1, V2, or V6; axis)

1. First Degree (1°) AV Block - PR interval >0.20-0.22 sec, all P's associated with QRS
2. Type I 2° AV Block Mobitz Type I, Wenckebach - increasing PR interval until QRS dropped, usually benign, usually 3:2 4:3 or 5:4
3. Type II 2° AV Block Mobitz Type II - QRS dropped without increasing PR interval(PR interval constant), increased clinical risk.
4. Third Degree AV Block Complete AV Block - atrial (P's) and ventricular beats (QRS) are independent, stable P-P intervals, width of QRS depends on location of escape PM (junctlonal, ventricular), usual rate 40 - 60/min.
5. RBBB R-R'/R-S-R' in V1 or V2 >= 0.12 sec with possible STdepression and flipped T waves; (incomplete RBBB R-R' < 0.12 sec), wide S - I, aVL, V5, V6; may be benign, possible T wave changes.
6. BBB R-R' (no Q or S) in I, aVL and V6;QRS >= 0.12 sec,wide S V1 - V2, no R-S-R' in V1, possible T wave changes, +- LAD, difficultydiagnosing infarct or ventricular hypertrophy when present.
7. LeftAnter.Hemiblock - LAFascicularBloc LAD, QRS 0.10 - 0.12 sec, small Q in I and aVL; R in II, III, and aVF; terminal R in aVR
8. Left Posterior Hemiblock - RAD; QRS 0.10 - 0.12 sec; S in I; Q in II, III, and aVF
9. Bifascicular RBBB + LAFB, or RBBB + LBFB, or LBBB
10.Trifascicular RBBB + (LAFB or LPFB) + 1° AVB, RBBB + LBBB