Ventricular arrhythmias can originate from complex substrates involving scar tissue. New imaging techniques like intracardiac echocardiography (ICE) and contrast-enhanced cardiac magnetic resonance (ce-CMR) can help identify these substrates and guide ablation. CE-CMR can characterize scar tissue, quantify fibrosis, and identify conduction channels within scars. ICE allows visualization of catheter position and ablation lesions. Together these techniques aim to improve ablation outcomes by enabling better identification of arrhythmogenic substrates compared to conventional mapping alone.

1. Usefulness of new imaging techniques to
identify complex arrhytmogenic substrates in
the ventricle
Venice Arrhythmias 2013
“SOLAECE Corner”
Gerardo Rodríguez Diez MD
National Medical Center “20 de Noviembre” ISSSTE.
México D.F.
SOLAECE Treasurer

2. NO CONFLICT OF
INTEREST TO
DECLARE

3. Key points
o Background
o Ablation targets
o New imaging techniques
• ICE
• ce-CMR
o Conclusion

4. Background
o Non structural heart disease (focal origin)
• Increase Automaticity
• Triggered activity (early or delayed
afterdepolarizations)
o Structural Heart disease (scar-related)
• Ischemic or no Ischemic
• Relative large reentry circuits
• Complex substrates around the fibrosis scars
or border zones

5. Ventricular Arrhythmias and Scar
• Critical anatomic substrates sustaining VA’s, shows different
degrees of fibrosis / scar (even in cases of focal origin)
*90% of sustained
VT’s are due to
reentry involving
an area of ventricular
scar.
10% remaining are
due to reentry
or automaticity
involving the
Purkinje system.
Pogwizd SM, et al. Circulation 1998. *Stevenson WG, Heart Rhythm 2013.

7. Targets for ablation
o Conduction channels (CC’s)
•
•
Bundles of viable myocardium inside scars that
become part of reentrant circuit during VT
Are located at any level of the myocardium wall
with variable thickness and a 3D- structure

8. VT ablation targets
o Electroanatomic maps (EAM)
•
•
Is a depiction of cardiac anatomy (through a color-coded
display of the intracardiac electrogam)
Areas of interest
•
reduce electrogram amplitude in voltage maps
o Normal Electrogram amplitude
• >1.5mV
o Border zone electrogram
• 0.5-1.5 mV
o Core scar
• < 0.5 mV

9. Catheter Ablation of reentrant VT
o Goal: Identification of critical isthmus of
conduction that is part of the reentrant
circuit

10. Conventional VT ablation limitations
o
o
o
o
o
Hemodynamic intolerance
Multiple changing morphologies
Hemodynamic collapse
Noninducible VT during EP testing
Recurrences (50-88%)
o Identification of the underlying substrate
using voltage mapping with 3D
reconstruction point by point
• It’s cumbersome
• Requires considerable skill
• It’s time consuming

11. Complex imaging techniques
o Rationale
•
•
•
•
Characterization of arrhythmogenic substrates
Direct guidance and characterization of ablation lesions
Early detection or prevention of procedural complications
Earn time during procedure
o Imaging techniques are for defining the anatomy
o Intracardiac echocardiography (ICE)
• Accurate to describing the anatomy
o Contrast enhanced cardiac magnetic
resonance (ce-CMR)
• Accurate to identify CC’s into the core scar

12. Ablation with ICE
o
o
Allow us to watch the ablation tip
Identification of anatomic structures
•
•
•
o
Coronary cuspids
Papillary Muscle
Akinetic and Scar zones
Allow us to identify early complications during the
procedure

15. Image ablation with ICE

16. Epicardial Ablation with ICE
Bala et al. Cir Arrhythm Electrophysiol. 2011

17. ICE mapping
o What we can´t do with ICE?
• Identification of conduccion channels in Scar
and Border zones

18. ce-CMR
o Predictive value for ventricular arrhythmia
• Inducibility
• Mortality
o Scar tissue characterization
• Quantification
• Heterogeneity

19. Non-invasive Assessment of Cardiac Fibrosis
• Ce-Cardiac Magnetic Resonance
• Prognostic value for arrhythmia inducibility and mortality
• Scar tissue characterization (quantification / heterogeneity)
Infarct Core
Border Zone
Normal myocardium

20. Quantitative/qualitative estimation of Cardiac Fibrosis
High SCD risk patients
Low SCD risk patients
LVEF 35%
LVEF 35%
LVEF 35%
LVEF 35%
Fernández-Armenta J, Berruezo A, et al. Europace 2012.

21. Image processing
Fernandez-Armenta, Berruezo A, et al. Circ Arrhythm Electrophysiol 2013

22. Scar-Anatomy and 3D Structure of
Conducting Channels

23. Anatomy and Scar Integration

24. Scar - Anatomy and 3D Structure of
Conducting Channels

25. Signal Intensity Maps
o Myocardial wall
thickness 10%
and 25%
• Border zone
channel is
suggested
• Sequential
activation of
electrograms
Fernandez-Armenta, Berruezo A, et al. Circ Arrhythm Electrophysiol 2013

26. Identification of Conduction channels

27. Endo and Epicardial maps

28. Signal Intensity maps (SI)

29. Limitations of ce-CMR
o Image aquisition
•
•
•
•
The partial volume effect
The presence of ventricular arrhytmias
Lack of adequate apneas
Variability of gadolinium kinetics
o Identification of channels in EAM is manual
•
CC branching with a trajectory hard to define
o This technique larger and prospective studies

30. cc-CMR guided ablation

31. Summary
• Continuous improvement in cardiac imaging for
arrhythmias in last years
– Diagnosis and risk stratification
– Guiding interventions
– Saving time and be more accurate
• Evolution from gross anatomy to histology and function
• Need for cooperation between cardiac imaging specialist
and electrophisiologist