The document describes 10 cases of arrhythmias with electrocardiogram (ECG) findings. Case 1 involves paroxysmal supraventricular tachycardia (PSVT) with right bundle branch block (RBBB) and cycle length alternans due to dual atrioventricular node (AVN) physiology, consistent with orthodromic atrioventricular reentrant tachycardia (AVRT). Case 2 involves a narrow P wave indicating simultaneous right and left atrial depolarization, consistent with slow-fast AVNRT with 2:1 atrioventricular block. Case 3 demonstrates initiation of supraventricular tachycardia from normal sinus rhythm with preexcitation due to a retrograde

1. ECG Tracing

2. Case 1 A 57 Y/O male patient had an arrhythmic attack during hospitalization. PSVT with (RBBB) cycle length alternans and a fixed short RP interval Cycle length alternans due to one longer and another shorter PR interval

3. Case 1 A 57 Y/O male patient had an arrhythmic attack during hospitalization. PSVT with (RBBB) cycle length alternans and a fixed short RP interval Cycle length alternans due to one longer and another shorter PR interval Diagnosis: Orthodromic AVRT with dual AVN physiology

4. Case 1:RAS1S2 500/380 ms One P with three Q 1. FAVN 2. SAVN 3. AVRT echo

5. Case 1: Spontaneous Initiation of SVT Orthodromic AVRT with antegrade FAVN and retrograde LL AP One P with Two Q

6. Case 2

7. Case 2 Small & narrow P wave  RA & LA depolarization simultaneously Diagnosis: SF AVNRT with 2:1 AV block A P wave in the midpoint between the two QRS beats

8. Case 2 AT with 2:1 AV block? What’s the next step?

9. Case 2: VOP 2:1 to 1:1 conduction

10. Case 3: What’s the mechanism of initiation of SVT? NSR with Preexcitation (RT AP)

11. Case 3 1 Q 2 P: one fast and one slow AP with the same atrial sequence Retrograde AP with longitudinal dissociation

12. Case 3 AP with decremental conduction

13. Case 4: W  N QRS tachycardia

14. Case 4: W  N QRS tachycardia VA dissociation VT H PSVT No H Wide to Narrow

15. Case 4 PPI-TCL=130 ms (>115 ms) V  A  V Diagnosis: FS AVNRT

16. Atypical AVNRT vs Septal AVRT (Michaud GF et al. JACC 2001)

17. Case 5 Two different retrograde P waves: two different pathways Pseudo R’ Pseudo S

18. Case 5 VA=102 ms VA=72 ms HV=178 ms HV=190 ms AVRT AVNRT alternatively

19. Case 6 RAS1S2 induced SF AVNRT

20. Case 6: After successful modification of SAVN RA burst induce narrow SVT with VA dissociation

21. Case 6:VOP terminate tachycardia Diagnosis: Junctional Tachycardia after ablation of SAVN

22. Case 7 PSVT with cycle length alternans and electrical alternans A fixed RP interval suggesting orthodromic AVRT Cycle length alternans due to dual AVN physiology Diagnosis: Orthodromic AVRT with dual AVN physiology long short

23. Case 7 NSR with intermittent preexcitation (RT AP)

24. Case 7 Diagnosis: Orthodromic AVRT using RT AP and Dual AVN physiology A fixed VA interval using RT AP Two different AH interval through fast and slow AVN

25. Case 8 Wide QRS complex tachycardia? (VA 1:1 conduction) PSVT with RBBB? (Atypical RBBB) Idiopathic LV-VT? (RBBB+LAD) Preexcitated tachycardia? (no delta wave)

26. Case 8: 60 seconds after adenosine Wide QRS=  Narrow QRS

27. Case 8: 65 seconds after adenosine H WQRS NQRS SF AVNRT No H V earlier VT

28. Case 9  Progressive Preexcitation Orthodromic AVRT with RBBB TCL=340 ms TCL=322 ms TCL=322 ms

29. Case 9 Change of retrograde accessory pathway

30. Case 10 Narrow QRS complex tachycardia with VA dissociation (V>A)

31. Case 10 Diagnosis: One VPC induced SF AVNRT with VA 2:1 conduction

32. 謝謝聆聽 敬請指教