What is pace mapping ?
Comparison of paced morphology during sinus rhythm to morphology during tachycardia
What is pace mapping ?
Using information obtained from pacing during sinus rhythm in different locations to understand the mechanism and focus / circuit of tachycardia
Technique
- Pace from region of interest
- Pace at or just above threshold
- Pace at same rate as tachycardia
- Manual comparison or automated comparison
Unipolar or bipolar pacing ?
How important is it ?
Kadish AH, Schmaltz S, Morady F. A comparison of QRS complexes resulting from unipolar and bipolar pacing: implications for pace-mapping. Pacing Clin Electrophysiol. 1991 May;14(5 Pt 1):823-32.
Automated matching
Automated matching
Jakob Lüker et al. Automated template matching correlates with earliest activation during mapping of idiopathic premature ventricular contractions. IJC Heart & Vessels Volume 4 2014 Pages 25-29
Pacemapping in Outflow tract
MILLER, J. M et al. Catheter Mapping and Ablation of Right Ventricular Outflow Tract Ventricular Tachycardia. Journal of Cardiovascular Electrophysiology 2006, 17(7), 800–802.
Pacemapping in ILVT
Pacemapping in reentrant VT
Can be similar at exit .. also very different
Josephson ME et al. Ventricular activation during ventricular endocardial pacing. II. Role of pace-mapping to localize origin of ventricular tachycardia. Am J Cardiol. 1982 Jul;50(1):11-22.
Entrainment from isthmus
Pace mapping from isthmus
Christian de Chillou … Francis Marchlinski. Localizing the critical isthmus of post infarct ventricular tachycardia: The value of pace-mapping during sinus rhythm. Heart Rhythm 2014;11:175-181
Illustrative case
Beyond match
- Latency
- Multiple morphologies
- Correlation maps
Latency
Multiple exits from one location
Multiple exits
Functional Pacemapping
Multiple exit sites
Tung R .. Shivkumar K. Functional pace-mapping responses for identification of targets for catheter ablation of scar-mediated ventricular tachycardia. Circ Arrhythm Electrophysiol. 2012 Apr;5(2):264-72.
Correlation with outcomes
Pacemapped induction
Pacing correlation map
Guenancia .. Marchlinski F. How to use pace mapping for ventricular tachycardia ablation in postinfarct patients. J Cardiovasc Electrophysiol. 2022 Aug;33(8):1801-1809.
Pacing correlation map - 3 patterns
- Focal pattern with good match (Endocardial focus, endocardial breakthrough of epicardial focus, usually focal VT in normal heart)
- Focal pattern, no good match (Epicardial VT, intramural VT, epi to endo circuit)
- Abrupt transition between good and poor match (Endocardial reentry)
Guenancia .. Marchlinski F. How to use pace mapping for ventricular tachycardia ablation in postinfarct patients. J Cardiovasc Electrophysiol. 2022 Aug;33(8):1801-1809.
Epicardial circuit with endocardial breakthrough
Abrupt transition at mid isthmus
Pacing Correlation maps
Can we pacemap in atria ?
- In atrium, similar P wave morphology upto 1.7 cm (RA) or 3.2 cm (CS) (1)
- Resolution in ventricle is 5 mm
Multi electrode surface ECG - resolution of 3.5 cm2 (8)
Man KC .. Morady F. Spatial resolution of atrial pace mapping as determined by unipolar atrial pacing at adjacent sites. Circulation. 1996 Sep 15;94(6):1357-63.
Widely spaced bipolar EGM
Selvaraj RJ et al. Pace mapping in the atrium using bipolar electrograms from widely spaced electrodes. Journal of Arrhythmia 2015; 31: 274-278
Widely spaced bipolar EGM
Conclusions
- Pacemapping is a useful secondary tool for mapping
- Most useful in focal, idiopathic VT
- Least useful in conduction system mediated VT
- Useful information also in reentrant VT
- Automatic matching incorporated in modern mapping systems