Mapping and ablation of left sided pathways - How do I do it

Raja Selvaraj, JIPMER

Introduction

50 to 60% of all pathways
Highest success rate
Lowest recurrence rate

Points

Approach - Retrograde vs transseptal
Mapping - Coronary sinus
Mapping - Separating A and V
Difficult / failed ablations

Retrograde vs transseptal

Approaches

Retrograde or Transseptal - Evidence

Similar success rate
Similar procedure / fluoro time
More complications with retrograde approach

Manolis AS, Wang PJ, Estes NA 3rd. Radiofrequency ablation of left-sided accessory pathways: transaortic versus transseptal approach. Am Heart J. 1994 Nov;128(5):896-902.

Choosing an approach

Personal preference
Train in both
May have to choose according to patient
- Pediatric / Peripheral arterial disease / Aortic valve disease
- Kyphoscoliosis
Transseptal - more mobility, less stability
Ready to switch

Coronary sinus

CS located away from annulus

Shinbane JS, Lesh MD, Stevenson WG et al. Anatomic and electrophysiologic relation between the coronary sinus and mitral annulus: implications for ablation of left-sided accessory pathways. Am Heart J. 1998 Jan;135(1):93-8

CS LA connections

Chauvin M, Shah DC, Haïssaguerre M et al. The anatomic basis of connections between the coronary sinus musculature and the left atrium in humans. Circulation. 2000 Feb 15;101(6):647-52.

LA - CS block

CS ventricular connections

About a third of all posteroseptal / left posterior APs
70% of them had no diverticulum

Sun Y, Arruda M, Otomo K et al. Coronary sinus-ventricular accessory connections producing posteroseptal and left posterior accessory pathways: incidence and electrophysiological identification. Circulation. 2002;106(11):1362-7.

Mapping - Rhythm

Mapping - Options

Atrial activation during ventricular pacing
- Can intermittently check in sinus rhythm / atrial pacing
- May have to pace from RVOT / LV
Ventricular activation during atrial pacing / sinus rhythm
Ablation during tachycardia

RVOT pacing

LV pacing

Entrained tachycardia

Mapping - Differentiating A and V

Separating A and V

Information from other electrodes

Unipolar

Non preexcited beats

Mapping - Pseudodisappearance

Raja Selvaraj et al. Pseudodisappearance of atrial electrogram during accessory pathway ablation, EP Europace 2012;14(7):993

Simultaneous pacing

Nakao, Seto, Iliev et al. Simultaneous Atrial and Ventricular Pacing to Facilitate Mapping of Concealed Left-Sided Accessory Pathways. PACE 2002; 25:922–928

Reversal of activation in oblique pathway

Otomo K, Gonzalez MD, Jackman WM et al. 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.

Difficult / failed ablations

Reasons for failed ablation

Inability to position catheter at target site
Instability of catheter
Mapping error due to oblique course
Localisation errors
Epicardial location
Recurrent AF
Unusual locations

Morady F, Strickberger A, Man KC et al. Reasons for prolonged or failed attempts at radiofrequency catheter ablation of accessory pathways. J Am Coll Cardiol. 1996;27(3):683-9.

Stability

Sheath
Catheter course
Retrograde approach
Pacing if possible
Entrain if during tachycardia

Oblique pathways

Oblique course

Misleading VA interval
Obscures AP potential
Change pacing location
Map for earliest activation (A/V)

Isthmus block

Luria DM, Nemec J, Etheridge SP et al. Intra-atrial conduction block along the mitral valve annulus during accessory pathway ablation: evidence for a left atrial "isthmus". J Cardiovasc Electrophysiol. 2001;12(7):744-9.

Isthmus block

AF

CS ventricular connection - CS muscle potential

LAA pathway

Summary

Left sided pathways in general are easiest to ablate and have best long term results
However, may occasionally present a challenge
Use of different pacing patterns to differentiate A and V
Mapping for earliest A / V
Use of unipolar mapping
Awareness of alternate pathway locations