Accessory pathways - What are the targets for ablation?

Raja Selvaraj
Cardiac Electrophysiologist
Professor of Cardiology
JIPMER

Setting up the signals

Bipolar signals

Identifying annulus location
Earliest activation
Identifying individual components of the signal may be difficult

Identify components of the signal

Pathway potential

Warin JF, Haissaguerre M, Lemetayer P, Guillem JP, Blanchot P. Catheter ablation of accessory pathways with a direct approach. Results in 35 patients. Circulation. 1988 Oct;78(4):800-15. doi: 10.1161/01.cir.78.4.800.

Cappato R, Schlüter M, Mont L, Kuck KH. Anatomic, electrical, and mechanical factors affecting bipolar endocardial electrograms. Impact on catheter ablation of manifest left free-wall accessory pathways. Circulation. 1994 Aug;90(2):884-94. doi: 10.1161/01.cir.90.2.884. PMID: 8044960.

Jackman WM, Friday KJ, Yeung-Lai-Wah JA, Fitzgerald DM, Beck B, Bowman AJ, Stelzer P, Harrison L, Lazzara R. New catheter technique for recording left free-wall accessory atrioventricular pathway activation. Identification of pathway fiber orientation. Circulation. 1988 Sep;78(3):598-611. doi: 10.1161/01.cir.78.3.598.

Jackmans team laid emphasis on verifying AP potentials

Panel A: Rapid atrial pacing or atrialextrastimulus may result in an atrial impulse (A) that fails to excite the accessory pathway. The loss of the AP potential(open arrow) without change in the local atrial potential strongly suggests that the atrial and AP potentials result fromactivation of separate structures. Panel B: Ventricular extrastimulus (SJ) is introduced during atrial pacing at constantcycle length so that the resulting premature ventricular impulse (VJ activates the accessory pathway in the retrogradedirection, which advances the AP potential (APJ) without altering the timing or morphology of the atrial impulse (A).Ability to advance the AP potential by 15-20 msec without altering the atrial potential is probably sufficient evidence toestablish that the atrial and AP potentials result from activation of separate structures. Panel C: During rapid atrialpacing or the delivery of an atrial extrastimulus, the loss of ventricular activation (open arrow) with persistence of theAP potential is strong evidence that the AP and ventricular potentials resultfrom activation ofseparate structures. PanelD: Delivery of a late diastolic ventricular extrastimulus (SJ) during atrial pacing at constant cycle length advancesventricular activation (VJ) without altering the timing or morphology of the antegrade AP potential. Advancing theventricular potential (V,) by 15-20 msec without altering the antegrade AP potential is probably sufficient evidence toestablish the separate origin of the AP and ventricular potentials.

Panel A: During rapid ventricular pacing or after a ventricularextrastimulus, the loss of retrograde atrial activation (open arrow) while maintaining the retrograde AP potentialprovides strong evidence that the retrograde AP and atrial potentials result from activation ofphysiologically separatestructures. Panel B: Introduction ofa late atrial extrastimulus (Sx) during ventricular pacing at constant cycle length (oratrioventricular reentrant tachycardia) advances the timing of atrial activation (Ax) without altering the timing ormorphology of the retrograde AP potential. Because the field of view of the orthogonal electrode in the coronary sinusis probably far less than 1 cm, the ability to advance the atrial potential by 15-20 msec without altering the retrogradeAP potential is probably sufficient to establish that these two potentials result from activation of different structures. Panel C: Rapid ventricular pacing or ventricular extrastimulus may result in a ventricular impulse thatfails to excite theaccessory pathway. The absence of the AP potential (open arrow) without change in the local ventricular potential (V)strongly suggests separate origins for the ventricular and AP potentials. Panel D: During ventricular pacing (oratrioventricular reentrant tachycardia), an atrial extrastimulus (Sx) introduced earlier than in Panel B may result in earlyantegrade activation of the accessory pathway, advancing the AP potential (APx) without altering the timing ormorphology of the ventricular potential (V). The ability to advance the AP potential by 15-20 msec without altering theventricular potential is probably sufficient evidence to establish separate origins for the AP and ventricular poten

Retrograde potential

Recording and interpreting unipolar electrograms to guide catheter ablation. Usha B. Tedrow, MD, MSc William G. Stevenson, MD, FHRS. Heart Rhythm HANDS ON. VOLUME 8, ISSUE 5, P791-796, MAY 2011

EGM setup

EGM set up

Unipolar

EGM target

Earliest A or shortest VA ?

Earliest A or Potential ?

The “isolated AP potential” identifies the middle of the AP and is the ideal target for ablation

Warren Jackman

Accessory pathway recording and ablation. Heart Rhythm, Vol 18, No 5, May 2021;834, https://doi.org/10.1016/j.hrthm.2021.01.008

What is AP slant?

Otomo K, Gonzalez MD, Beckman KJ, Nakagawa H, Becker AE, Shah N, Matsudaira K, Wang Z, Lazzara R, Jackman WM. Reversing the direction of paced ventricular and atrial wavefronts reveals an oblique course in accessory AV pathways and improves localization for catheter ablation. Circulation. 2001 Jul 31;104(5):550-6. doi: 10.1161/hc3001.093499. PMID: 11479252.

Specific locations

Posteroseptal / Left posterior pathways

LA-CS potentials

CS pathways

Negative delta in lead II
Previous failed ablation
Atrial fibrillation - clinical or during EPS
May or may not have diverticulum

Selvaraj RJ et al. Radiofrequency ablation of posteroseptal accessory pathways associated with coronary sinus diverticula. J Interv Card Electrophysiol. 2016 Nov;47(2):253-259. doi: 10.1007/s10840-016-0113-x.

CS diverticulum

Mapping in diverticulum

Mapping in diverticulum - CSE potential most important

In absence of diverticulum, map along tributaries

Specific locations

Anteroseptal / midseptal

Map and ablate during tachycardia

Anteroseptal AP may be ablated from non coronary cusp

Specific situations

Left free wall

Mapping during

Right ventricular pacing (eccentric at long CL)
CS pacing (manifest preexcitation)
Orthodromic tachycardia (sustained tachycardia)
Left ventricular pacing

Entrain when ablating free wall AP during tachycardia

Pacing from LV

Pacing from CS tributary

Isthmus block

Non annular location of AP

Appendage pathways

RAA to RV
LAA to LV
Endocardial ablation from within AA may be difficult
Epicardial approach may be required
Proximity of major coronary arteries to LAA

Nikola Dragisic, MD, FACC, Emily R. Backes, MD, Lindsey Malloy-Walton, DO, MPH, Philip M. Chang, MD, FACC, FHRS. Atrial appendage accessory pathway ablation: Tips for recognition and approach to ablation. Heart Rhythm Case Reports, Vol 9, No 12, December 2023 876

Specific locations

Right free wall

Sheath

Under valve approach

Yang J, Yang G, Chen H, Ju W, Yang B, Zhang F, Jin Y, Cao J, Qian L, Chen M. An alternative under-valve approach to ablate right-sided accessory pathways. Heart Rhythm. 2019 Jan;16(1):51-56. doi: 10.1016/j.hrthm.2018.07.022. Epub 2018 Jul 19. PMID: 30031200.

3D mapping for AP ablation

Benefits of 3D mapping

Reduces Fluoro
Non annular pathways
Tag areas for ablation

Long RP - Activation mapping

Short RP - Open window mapping

Open window mapping

Epicardial ablation

Epicardial ablation - CS pathway

Courtesy of Dr.John Roshan, CMC

Epicardial ablation - CS diverticulum with ostial atresia

Sternick EB, Faustino M, Correa FS, Pisani C, Scanavacca MI. Percutaneous Catheter Ablation of Epicardial Accessory Pathways. Arrhythm Electrophysiol Rev. 2017 Jun;6(2):80-84. doi: 10.15420/aer.2017.6.2. PMID: 28835839; PMCID: PMC5522715.

Summary

Signals more important than colours
Combination of bipolar and unipolar signals
Recording AP potential is critical