Usefulness of new imaging techniques to identify complex arrhytmogenic

substrates in the ventricle

Venice Arrhythmias 2013“SOLAECE Corner”

Gerardo Rodríguez Diez MDNational Medical Center “20 de Noviembre”

ISSSTE. México D.F.SOLAECE Treasurer

NO CONFLICT OF INTEREST TO

DECLARE

Key points

o Backgroundo Ablation targetso New imaging techniques

• ICE• ce-CMR

o Conclusion

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

Pogwizd SM, et al. Circulation 1998. *Stevenson WG, Heart Rhythm 2013.

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.

Targets for ablationo 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

VT ablation targetso 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 mapso Normal Electrogram

amplitude• >1.5mVo Border zone electrogram• 0.5-1.5 mVo Core scar• < 0.5 mV

Catheter Ablation of reentrant VT

o Goal: Identification of critical isthmus of conduction that is part of the reentrant circuit

Conventional VT ablation limitations

o Hemodynamic intoleranceo Multiple changing morphologieso Hemodynamic collapseo Noninducible VT during EP testingo 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

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 anatomyo 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

Ablation with ICEo Allow us to watch the ablation tipo Identification of anatomic structures

• Coronary cuspids• Papillary Muscle• Akinetic and Scar zones

o Allow us to identify early complications during the procedure

Image ablation with ICE

Epicardial Ablation with ICE

Bala et al. Cir Arrhythm Electrophysiol. 2011

ICE mapping

o What we can´t do with ICE?• Identification of conduccion channels in

Scar and Border zones

ce-CMR

o Predictive value for ventricular arrhythmia • Inducibility • Mortality

o Scar tissue characterization• Quantification• Heterogeneity

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

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.

Image processing

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

Scar-Anatomy and 3D Structure of Scar-Anatomy and 3D Structure of Conducting ChannelsConducting Channels

Anatomy and Scar IntegrationAnatomy and Scar Integration

Scar - Anatomy and 3D Structure of Scar - Anatomy and 3D Structure of Conducting ChannelsConducting Channels

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

Identification of Conduction channels

Endo and Epicardial maps

Signal Intensity maps (SI)

Limitations of ce-CMRo 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

cc-CMR guided ablation

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