1. Identification and Ablation of Epicardial VT
Yi-Gang Li, MD
Xinhua Hospital, Shanghai Jiaotong University

2. When to go epicardially
Identification of Epicardial VT
When to go epicardially
Present clinical data
Previous history
Surface ECG during VT
Mapping data
Cardiac Image

3. When to go epicardially ?
Present clinical data
Echocardiography:
-- LV thrombus if their anticoagulation can be safely interrupted for the procedure
1 Daniels DV, et al. Circulation 2006

4. Frequency of Epicardial Origin
Presence of SHD
Chagas’s disease
- 36% of a series of 138 VT pts1
Non-ischemic SHD - 25%-45%1,2,3
Ischemic SHD
- 1/3 P subepicardial reentry circuits4
-- Posterolateral MI 4,5
-- Aneurism related VT
1 Sosa E, et al. JCE Hsia HH, et al. Circulation 2003, 3 Soejima, et al. JACC, Svenson, et al. JACC Berruezo et al. Circulation 2004.

5. Frequency of Epicardial Origin
Presence of SHD
AVRT – 5-10%?
Other (“Idiopathic” LV aneurysm, sarcoid, noncompaction)
- Idiopathic LVOTVT(12%-30%)
- LV epicardium (1/3) – perivascular1
Absence of SHD
1 Daniels DV, et al. Circulation 2006

6. When to go epicardially
Previous history
Previous failed VT ablation attempt 1
- Select truly epicardial VTs Suc. rate
150 VT ablation Pts
Incessant VT: 19 Pts(12.7%)
Endo abl. 10 Pts (53%)
Epi abl. 8 Pts (42%)
Suc. Rate: 95%
1 Brugada et al, JACC 2003;41:2036–2043
ESC 2008

7. Identification of Epicardial VT
Mapping data in presence of SHD
Mapping data inability to identify the reentry circuit isthmus on the endocardium by entrainment mapping
Identification of a focal point of earliest endocardial activation, entrainment indicates an exit or outer loop site, but abl. fails to interrupt VT

8. Identification of Epicardial VT
Mapping data in absence of SHD (LVOT?)
Mapping data within CS and accessible LV branches suggest an epicardial VT circuit or focus

9. ECG Recognition of the Epicardial Origin of VT
Analysis of ECG pattern in
(A): 14 successful epicardial VT ablation after failed endocardial approach,
(B): 27 successful endocardial VT ablation,
(C): 28 additional VTs that could not be ablated from the endocardium
Four distinct intervals of ventricular activation were measured:
the pseudo-delta wave: from the earliest ventricular activation to the earliest fast deflection in any precordial lead
the intrinsicoid deflection time: interval measured from the earliest ventricular activation to the peak of the R wave in V2.
the shortest RS complex: interval measured from the earliest ventricular activation to the nadir of the first S wave in any precordial lead.
(4) the QRS complex: earliest ventricular activation to the offset of QRS in the precordial leads.
Berruezo A. Circ 2004;109:1842

10. Groups A & C (unsuccessful endocardial ablation) showed longer intrinsicoid deflection in V2, slurred initial part of QRS (pseudo  wave) vs Group B (endocardially ablated VT)

11. ECG Characteristics of VTs
(msec)
Group A
(n=14)
Group B
(n=27)
Group C
(n=28)
Pseudo-delta wave
43±9
16±9
42±9
Intrinsicoid deflection
97±21
65±15
98±14
Shortest RS interval
149±39
91±20
132±30
QRS complex
217±24
174±37
195±27
Group C vs B, group A vs B, P<0.05.
Group A vs C, P=NS
VTs from epicardial origin (groups A & C) showed a significantly longer pseudo-delta wave, intrinsicoid deflection, and RS complex duration compared to VT with endocardial origin (group B).
Identification of Epicardial Origin of VT
Sensitivity
Specificity
Pseudo-delta wave ≥ 34 ms
83%
95%
intrinsicoid deflection ≥ 85 ms
87%
90%
RS complex duration ≥ 121 ms
76%
85%
Berruezo A. Circ 2004;109:1842

12. ECG Recognition of the Epicardial Origin of VT
PDI=A/QRS
Hachiya H, et al. Circulation 2010;74:

13. ECG Recognition of the Epicardial Origin of VT
Hachiya H, et al. Circulation 2010;74:

14. Hachiya H, et al. Circulation 2010;74:256-261

15. ECG Recognition of the Epicardial Origin of VT
Hachiya H, et al. Circulation 2010;74:

16. Valles E, et al. Circulation 2010;3:63-71
MDI= IDT(Shortest)/QRSd
Valles E, et al. Circulation 2010;3:63-71

17. Epi vs End. Pace maps
Valles E, et al. Circulation 2010;3:63-71

18. Valles E, et al. Circulation 2010;3:63-71

19. Epi vs End. VT Morphology
Valles E, et al. Circulation 2010;3:63-71

21. 11 Pts, 21 VTs from basal superior or lateral origin
ECG Recognition of the Epicardial Origin of VT
11 Pts, 21 VTs from basal superior or lateral origin
Valles E, et al. Circulation 2010;3:63-71

22. Ablation of Epicardial VT

25. Ablation of Epicardial VT
Sosa E, Scanavacca M. JCE 2005;16:449–452

26. Mapping of Epicardial VT
Mapping of the epicardium can be performed using fluoroscopy and/or CARTO system.
Areas of infarction or scar have low amplitude electrograms similar to findings during endocardial mapping.
Epicardial fat may create low amplitude regions.
- Inability to capture during epicardial pacing
- High pacing tresholds: Epicardial fat;
difficult catheter stability

27. Mapping and Ablation of Epicardial VT
Mapping using conventional or Navi-Star Catheter (Biosense-Webster)
Internally or externally irrigated catheter can be used for RF ablation to avoid high impedance
Power limit of 50 W with temperature limit of 45ºC, infusion rate of 17 ml/min and duration of 110 sec
Aspiration of pericardial fluid after 5 RF applications to prevent fluid accumulation

28. Ablation of Epicardial VT
Pts
[n]
Acute suc.rate
[%]
Late suc. Rate
complication
Sosa 1 14 39
100
Schweikert ² 30 71 97
Brugada ³ 10 80 90
Soejima 4 28 73 54
Sosa: 14 ICM; FU 14 months. Schweikert: 6 ICM, 3 DCM, 15 NH. FU success auch wenn PVC weniger. Brugada: 8 ICM, 1 DCM, 1 ILVT. FU 18 months.
1 J Am Coll Cardiol 2000;35:1442–9; 2 Circulation 2003;108: ; 3 J Am Coll Cardiol 2003;41:2036–43, 4 J Am Coll Cardiol 2004;43:1834–42

29. QRS=180 ms
CL=585 ms

31. Ablation of Epicardial VT

32. Complications Phrenic nerve injury
Pacing shoud be performed before energy delivery to indenify phrenic nerve capture, indicating where ablation might cause diaphragmatic paralysis.
phrenic nerve injury can be avoided by:
- interposing a sheath,baloon, or even air in the pericardium between the abl. Site and the nerve.

33. Complications Coronary nerve injury
- Coronary angiography before RF ablation
- Requiring a minimum of 4 mm between epicardial coronary vessels and the ablation catheter.
- the catheter is not touching the vessel at any point of cardiac cycle
Pericartitis
- mild, limited duration, often responds well to anti-inflammatory medication

34. Problems in epicardial ablation
Epicardial mapping will not prevent all VT abl. failures.
- Tachycardia circuits can originate from deep within the ventricular septum/myocardium, may require transcoronary ethanol ablation, or irrigated needle catheters.
Ablaion can be limmited by
- epicardial fat,
- proximity to coronary arteries and other other stuctures

35. Conclusion
Epicardial VT can be identify by previous history, present clinical data and surface ECG
Mapping data and cardiac Image facilitate VT ablation
Epicardial VT is rare, but it can be either focal or macroreentry
Epicardial catheter techniques expand the options for investigating and treating VT

36. Thank You！