1. Outflow tract VT is the most common type of idiopathic VT, accounting for over 60% of cases in the study. 2. Pace mapping alone may not accurately locate ablation sites, especially for VT associated with scar tissue. Activation mapping and substrate identification are important complementary mapping techniques. 3. Successful ablation of substrate-based VT requires targeting abnormal electrograms within scar regions like late potentials or fractionated signals at the critical isthmus.

1. Ventricular Tachycardia
林彥璋 醫師,
Lin Yenn-Jiang MD. Chen Shih-Ann MD.
April 24, 2011
Advanced EP training, THRS
St. Jude Medical, Taipei
Division of Cardiology, Taipei Veterans General Hospital
and National Yang-Ming University, Taipei, Taiwan

2. Experience of VT EPS/ABL
in Taipei VGH 2000-2010
Outflow tract VT : 121 : 61%
Fascicular VT : 24:12%
ARVC :18: 9%
CAD : 18: 9%
DCM : 8: 4%

3. P=0.007
Survival curve of VT patients (N=200)
Fascicular VT
RVOT
ARVC
CPVT, idiopathic VF
Ischemic VT
DCM

4. How to Map VT
Mapping
Basic electrophysiologic study
Pace mapping
Activation mapping
Electroanatomic mapping
Ablation: RV, LV, and Epicardium

5. Outlines
Outflow tract VT
ARVC
Fascicular VT
Substrate VT

6. Outflow Tract Ventricular
Tachycardia (OT-VT)
VT arises from the right ventricular outflow
tract (RVOT-VT, left ventricular outflow
tract (LVOT-VT), aortic cusps (Cusp VT),
and from the pulmonary artery (PA VT)
OT-VT tend to occur in the absence of
structural heart disease and are focal in
origin, the 12-lead ECG recorded during
VT is a precise localizing tool.

7. Clinical Features of RVOT-VT
RVOT VT constitutes 75% of all patients
with outflow tract VT
RVOT VT is more common in females 30-
50 years old.
Symptoms include palpitations, dizziness,
atypical chest pain, and syncope.
Exercise testing reproduces the patient’s
clinical VT 25 to 50% of the time.

8. Mechanism of RVOT-VT
Most forms of RVOT VT are sensitive to
adenosine
Most likely mechanism is catecholamine
mediated DAD and triggered activity.
Mediated by the activation of cyclic AMP.
Can be induced in the EP lab with
isoproterenol, aminophylline, atropine, and
rapid burst pacing but rarely with
programmed ventricular extrastimuli.

9. 1. Important overlapping
nature of the outflow
tract course!
2. RVOT and PA lie
anterior and to the left
of the LVOT and aorta.

10. RVOT VT
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6

11. RVOT VT morphology

12. Pulmonary Artery VT

13. How to D/D RVOT and VT with
ASC in origin

14. Cross over of RVOT & LVOT region
I: biphasic,
V1 :W
L
R I: positive
L
V1 :RS
R
AP view Superior view
David Callans JCE 2009

15. Aortic Cusp VT Morphology

16. LVOT and Aortic Cuspid VT
VT arising from the LVOT shares similar
characteristics to the RVOT VT because of a
common embryonic origin.
ECG: LBBB with inferior axis with small R-
waves in V1 and early precordial transition
(R/S 1 by V2 or V3) or RBBB morphology with
inferior axis and S-wave in V6.
Aortic cusp VT accounts for up to 21% of
idiopathic VT.
More commonly arises from the LCC, than the
RCC and rarely arise from the NCC.

17. Tabatabaei and Asirvatham. Circ EP 2009;2:316-326

18. LVOT VT Morphology

19. Mapping Tool for OT-VT
ECG morphology:
Could be non-inducible
Pacing morphology
could be large area 2 cm2: different chamber, scar, or
epicardium,
Activation map
More accurate: remain unsuccess: more mapping sites,
epicardium, different energy sources,

20. Spontaneous PVC Pace Mapping
Taipei VGH 2010

21. PVC Disappearance Just After RF

22. Schema of the Ventricular Arrhythmia Origin, Breakout Site, and
Preferential Conduction From the LCC Origin to the RVOT or
Left Ventricular Septum
T. Yamada, et al
JACC, 2007,
Vol. 50, No. 9: 884-91

23. Difficulty in Pace Mapping in RVOT‐T With Scar
A VT PM 1 PM 2 B
RVOT
2 1
Septal wall
Anterior wall
Free wall
Taipei VGH 2010

24. Requirement of NCM
for VT mapping
Pacing mapping may not sensitive to
locate the sites of foci in certain patients
with focal VT, in the presence of large
scar area.
VT could be non-sustained and unstable.
It is difficult to map the entire chamber
One beat analysis of dynamic substrate by
NCM may be useful to treat these patients.

25. Ensite Array Location
ＲＡＯ ＬＡＯ
Taipei VGH 2010

26. RVOT VPC form the LVZ border
(Higa S: University of the Ryukyus, Okinawa, Japan) 2010
Taipei VGH

27. Conclusions
Carefully ECG interpretation and EP study to
localize the optimum ablation site for VT.
Usually not life threatening, and could be treated
conservatively.
3D mapping system can be helpful (activation
map or substrate map), but correct chamber, far-
field sensing, preferential conduction need to be
considered.

28. Outlines
Outflow tract VT
RV related VT and ARVC
Fascicular VT
Substrate VT

29. RVOT VT
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6

30. Idiopathic RVOT-T
Right ventricular outflow tract tachycardia
(RVOT-T) represents up to 10% of all ventricular
tachycardias (VTs), and is considered as a
benign disease.
Symptoms: Ranging from none to palpitations,
lightheadedness, dyspnea, or syncope.
Arrhythmias: Frequent isolated PVCs, bursts of
nonsustained VT, or sustained tachycardia often
facilitated by catecholamines or exercise.
Ablation: Acute success rate of focal ablation of
RVOT-T is 65–97% with rare complications.

32. ARVC

33. Arrhythmogenic RV Dysplasia
Cardiomyopathy begins in RV with poor contractile
function and dilatation, progresses to LV finally.
Histology: RV muscle becomes replaced by adipose
and fibrous tissue.
Arrhythmia: Re-entrant Type (scarring & late
Potentials) with LBBB type ECG;
ECG: Diffuse T wave inversion over precordial leads,
and Epsilon Wave.
Ablation: The effect of catheter ablation is
temporizing, 1/3 epicardium, mostly reentry.
Implanted cardioverter defibrillator (ICD) is the only
reliable therapy for sudden cardiac death.

34. Task Force Criteria
TF (Definite +) if meet 2 major or 1 major 2 minor criteria
McKenna et al. 1994, BMJ

35. Long-term Outcome
Mean follow-up period 23 ± 28 months (0.3 – 127)
Cumulative Incidence Cumulative Incidence
TF (-), 3.1% TF (-) : 14%
TF (+) , 7.4% TF (+): 36%:
P=0.511 P=0.019
Follow-Up Duration
Follow-Up Duration
All Cause Malignant
Mortality arrhythmias

36. Conclusions
Positive TF criteria is important to diagnose
ARVC/D and is specific to detect the future
VF/ICD implantation/ CV mortality
Malignant ventricular arrhythmia and late
recurrences may occur in patients with mild
or atypical form of arrhythmogenic RV
cardiomyopathy.

37. Posterior Fascicular VT

38. Outlines
Outflow tract VT
ARVC
Fascicular VT
Substrate VT

39. Diastolic potential & Purkinje potential

41. Posterior Fascicular VT

42. Where to Target
Diastolic potential (P1) in the
midseptum of LV. P1-QRS=28-130 msec
If P1 could not be identified, target the
fused and earliest Purkinje potential
(P2)
Successful ablation revealed P1 during
SR could be a marker of successful
ablation.

43. Outlines
Outflow tract VT
ARVC
Fascicular VT
Substrate VT

44. Structure heart related VT
• BBRT
• Ischemic heart disease (most common):
mostly Endocardium
• ARVC: Epi/Endo
• Non-ischemic cardiomyopathy: Epi/Edno
• Tetralogy of Fallot and other post
operation patients: Endo

45. Substrate VT
Identification of the critical ventricle
to be targeted (voltage mapping).
Identify the location of the scar
(bipolar voltage <0.5 mV, unipolar
PNV < 30%).
Conventional entrainment
techniques remain important.

46. Normal Electrogram
Bipolar Eg: < 3 deflection, > 2 mV, <
70 msec, amplitude/duration<0.05

47. Bystander Outer loop

48. Isthmus

49. Successful ablation site
• Abnormal site: LVZ, pre-systolic
potential, fractionated
electrograms Pacing during VT
• Concealed entrainment.
• Critical isthmus: with
– 30-70% of the critical isthmus Concealed Fusion
(S-QRS)
– Diastolic potentials
PPI=TCL
S-QRS/TCL PPI not =TCL PPI=TCL
>70% 30-70% <30% Bystander Outer loop
Critical isthmus
Inner loop Exit or outer loop

50. Mapping of Ventricular Tachycardia
Out-loop
• Activation mapping:
• Pacing mapping Inner-loop
– For focal VT
– For substrate VT: near the exit site
– S-QRS > 40 msec: isthmus
• Entrainment mapping:
– Concealed entrain, with PPI=TCL
– Outer loop vs. inner loop
– Critical isthmus, > 40 msec, < 70% of S-QRS, > 22%
of S-QRS interval
• Substrate mapping: Scar mapping

51. Case 1 Ventricular Tachycardia RV ICD Lead Pacing

52. Bi-Ventricular Voltage Map
LVZ
LVZ
LVZ
Ablation site
Lin YJ et al. HRS abstract 2009

53. Ischemic LV VT---Case 1
The important to identify chamber to ablate
RVOT
Septum
LV apex
ICD Lead
Lin YJ et al. HRS abstract 2009

54. Lin YJ et al. HRS abstract 2009

55. Ischemic LV VT‐‐‐Case 2
The important to identify the LVZ and exit site
Tsai WC et al. JCE in revision, 2010

56. Case: Ischemic LV VT
The important to identify the LVZ and exit site
Abnormal Substrate
Entrainment
Exit, entrance site
Diastolic potential
Tsai and Chen, Circ J, 2011

57. Voltage Map during SR (DSM 30%)
Taipei VGH 2010

58. RVOT-T Patient
Voltage of SR Spectral Analysis Activation of VT
3.5 cm
from PV
Successful site
septum
Free
wall
Eg during SR
Scar in the free wall site

59. Conclusions
Outflow tract VT is the commonest form of
idiopathic VT.
ECG morphology is important for localization of
focal VT and exit site of substrate VT before 3 D
mapping.
Pacing mapping may not sensitive to locate the
sites of foci in certain patients with focal VT, in
the presence of large scar area.
Substrate mapping and entrainment mapping
are important for the substrate VT.