Dr. Hany Abed

1. Dr. Hany Abed Bundles of Joy

3. The Case� PMH Premature birth 27/40 Chronic lung disease requiring ventilation VLBW and anaemia Normal CV examination at the time SH Non-smoker, drinker. No illicit drug use. Year 8 FH 6 siblings. No sudden deaths, drowning, single driver MVA. No CV history of note. Lebanese background

4. The Case No medications Examination Anxious HR 205/min. 125/70. SaO2 100% RA Nil dysmorphic features. Descended testes Femoral pulses present Normal CV exam Other systems - NAD

5. The Case � ECG (arrhythmia)

6. The Case � ECG (Sinus Rhythm)

7. The Case Ix: Isolated hyperbilirubinaemia Rx IV Adenosine � No effect IV Verapamil � Reversion Remained in Sinus Rhythm during observation Discharged for O.P. Echo and follow-up

8. Follow-up Normal echo. PASP 27mmHg Rx: Sotalol and limitation on sporting activities Re-admission 2005 Non-compliant IV sotalol failed 150J DC cardioversion Booked for diagnostic EPS (Dx: RVOT VT) under GA

9. Results Normal antegrade and retrograde conduction No evidence of accessory pathway or dual AV node physiology No VT inducible in presence of isoprenaline Re-presented 2006 Conscious WCT during tennis Was off sotalol. No response to adenosine Failed 50Jx1, 100Jx1, 150Jx1, 200Jx3 DCCV Reverted with IV amiodarone

10. Progress Re-admission 2007 Associated TnI rise Rx: Adenosine, Amiodarone, Metoprolol, Sotalol Dx: BBR VT Re-booked EPS under LA Discharged on Sotalol MRI? SAECG?

11. High Resolution Electrocardiography X,Y,Z Leads Analogue ? Digital Signal conversion QRS template Averaging successive QRS complexes Low frequency filtering Quantifying ventricular high frequency late potentials

12. HR-ECG Late potentials Scar-related slow depolarizing currents within viable myocardial channels Inferoposterior ventricular regions Broad QRS Results of HR-ECG QRSd Root Mean Square Voltage at terminal Low Amplitude signal

13. Signal Averaged ECG - SAECG Detects areas of microvolt slow conduction in re-entry circuit too low to observe on surface ECG Occur as late potentials after QRS Used as a stratifying tool in ICM/NICM/ARVD/Brugada/Idiopathic VT, for risk of SCD

14. SAECG Low amplitude, high frequency signals Reflect slow and fragmented myocardial conduction Critical components for re-entry: heterogeneous tissue conduction velocity and refractoriness Predictive value for SCD and ventricular arrhythmias Post- MI Comparison to LVEF%

15. Re-Admission ECG Close analysis of ECG Rapid intriscoid deflections Likely circuit utilising rapidly conducting specialised cardiac tissue

16. The His-Purkinje System Rapidly conducting network: 1-4 m/sec. Penetrate inner 1/3 of endocardial surface Long refractory period Free running Purkinje fibres organised in series (false tendons) are capable of contraction Connexins play a role in apparent current-to-load mismatch

17. Cellular characteristics of human Purkinje tissue. 1982. Kenneth Dangman, et al. Micro-electrode testing of ex-vivo (transplant recipients) purkinje tissue Highest maximum phase 0 upstroke velocity (Vmax) of all cardiac tissue � significantly greater than ventricular tissue

18. Gap Junctions and Connexions: Cx43 Cx43 gap junction protein channel subunit Continuous IHC staining over entire purkinje cell-purkinje cell borders within fiber strand

19. Cable Theory and Current-Load Mismatch Conduction Velocity 8 vRadius Circumferential gap junction channel distribution in purkinje fibres Functional increase in conducting fibre radius Rapid conduction velocity independent of any change in active membrane properties

20. Role of subjacent collagen Collagen separates Purkinje bundles from subjacent ventricular tissue Prevents premature current dissipation

21. HPS � Site of Re-entrant Arrhythmias Fascicular VT Left anterior fascicle Left posterior fascicle Bundle Branch Re-entry Macro re-entrant circuit between the left and right bundles Inter-fascicular VT

22. Fascicular Ventricular Tachycardia

23. Fascicular Ventricular Tachycardia Idiopathic Ca-sensitive Macro re-entrant localised circuit Molecular abnormality: Verapamil sensitive zone with slow conduction

24. Fascicular VT Age: 15-40 years, ?>? No macro structural heart disease Paroxysmal catecholamine-dependent May be incessant ? Tachycardiomyopathy

25. Left Posterior Hemi-Bundle Subtype

26. Fascicular VT � Anatomy and Physiology Relatively narrow WCT 90% originate from left posterior fascicle Anatomic substrate: LV �false tendon� or postero-inferior fibromuscular band to basal septum Diagnostically � may require isoprenaline to facilitate induction

27. Three Subtypes

28. Fascicular VT - Circuit

29. Purkinje and Pre-Purkinje Potentials

30. The Circuit - Electrograms

31. Diagnostic Pitt falls Robust VA conduction may cloud VA dissociation Circuit may be entered via atrial pacing and cycle length of circuit re-set (entrained) 25% have concomitant inducible A-V accessory pathways with inducible SVT

32. Rapid atrial pacing required to dissociate A from V

33. Fascicular VT � Rare mimics Inter-fascicular VT RBBB and right or leftward axis Structurally abnormal heart: Previous anterior infracts and LAFB or LPFB A subtype of BBR VT Idiopathic mitral annular VT RBBB and rightward axis Variable verapamil-sensitivity Ill-defined

34. Fascicular VT - Treatment Treatment is cure � 80% in single procedure RF ablation during VT Ablation at PP Ablation at Pre-PP RF ablation during sinus rhythm Pace mapping Electro anatomic mapping

35. RF Ablation During VT Purkinje potential target Mapping the posterior LV septum, 1/3 distance from apex over 3 sq. cm. PP identified and ablated PP-QRS interval ~ 18�6 msec. for success Entrainment from ablation site: Concealed fusion and Post Pacing Interval � VT Cycle Length < 30msec.

36. Ablation at Pre-Purkinje Potential site Higher risk of AV block or LBBB Requires higher RF applications compared to a strategy targeting Purkinje potential

37. Ablation During Sinus Rhythm Tachycardia may be non-inducible or non-sustained Pace mapping technique A perfect pace map may not be essential for success Successful ablation still occurred in (9.6�2.1)/12 ECG leads matched Electro Anatomic mapping Useful in those with recurrences

38. Bundle Branch Re-Entry Ventricular Tachycardia

39. BBR VT Macro re-entrant (?Ventricular flutter) circuit employing� Both bundle branches Ramifications of the left bundle Hallmark: His-Purkinje system disease � functional or structural Acquired heart disease or apparently normal hearts Ischemic (6%) vs. non-ischemic (40%) cardiac disease

40. Purkinje fibre Connexion Cx43 and Cardiomyopathy Quantitative electro micrograph and immuno-labelling Selective gap junction Cx43 remodelling Decreased density (33%) in bordering scar and hibernating myocardium Exquisite vulnerability of His-Purkinje system Slowed conduction and fragmented depolarizing waveform

41. Akhtar and Damato 1973 � antecubital vein approach Ventricular extra-stimulus with a critical V-H delay blocked in the right bundle and activated the His via the left bundle A �V3� response conducted down via the right bundle with an H-V interval longer than that of sinus beat Importantly � complete RBBB abolished the V3 response

42. HPS integral to VT mechanism Critical V-H interval to initiate (HPS conduction delay) Prolonged H-V H-RB/LB-V-LB/RB activation sequence consistent with VT QRS morphology H-H oscillations precede changes in V-V during VT

44. BBR VT and valve surgery Early (~3 weeks) post-operative state Correlates with historical literature on post-op peak sudden death time-course ~30% as sole VT mechanism (spontaneous, sustained monomorphic. Non-VF) Systolic function usually preserved

46. BBR VT � Pitt Falls Exclusion of SVT with aberrancy Need to prove A-V dissociation Need to prove active HPS participation in the VT mechanism � rather than passive participation For BBR VT, entrainment from RV apex: Post Pacing Interval � Tachycardia Cycle Length < 30 msec.

47. BBR VT � Differentials and Management Differentials Intra-myocardial re-entry VT (ICM vs NICM) Interfascicular VT (form of BBRVT) � RBBB and LPFB Intrafascicular VT (Idiopathic LV VT) 1:1 Supraventricular tachycardia with aberrancy Atrio-fascicular re-entry (Mahaim) Management

48. Issues His-Purkinje network Sophisticated system Pathology begets specific but diverse arrhythmic syndromes Recognition is critical Specific management Terminology is crucial

49. Management�1 Patient developed AF and hemodynamically stable VT during study VT had RBBB and, after AF cardioversion, 1:1 V?A conduction Atrial and ventricular programmed stimulation could not re-initiate VT

50. Management�2 3-D left ventricular map constructed using Ensite NavX electroanatomic mapping Pace mapping revealed earliest (pre-systolic) activation in mid posterior LV septum 4 x RF applications terminated VT without further recurrence

51. Summery Diagnosis Idiopathic Left Ventricular Verapamil-sensitive VT arising from left posterior hemi-bundle Management Purkinje potential mapped between mid and apico posterior LV septum. Abnormal tissue ablated with subsequent cure

52. Outcome