Bhupesh Pathik1, Geoffrey Lee1, Chrishan Nalliah1, Stephen Joseph2, Joseph B Morton3, Paul B Sparks1, Prashanthan Sanders4, Peter M Kistler5, Jonathan M Kalman6. 1. Department of Cardiology, Royal Melbourne Hospital, Melbourne, Australia; Faculty of Medicine, Dentistry, and Health Sciences, University of Melbourne, Melbourne, Australia. 2. Department of Cardiology, Royal Melbourne Hospital, Melbourne, Australia; Department of Cardiology, Western Health, Melbourne, Australia. 3. Department of Cardiology, Royal Melbourne Hospital, Melbourne, Australia; Faculty of Medicine, Dentistry, and Health Sciences, University of Melbourne, Melbourne, Australia; Department of Cardiology, Western Health, Melbourne, Australia. 4. Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Melbourne, Australia. 5. Faculty of Medicine, Dentistry, and Health Sciences, University of Melbourne, Melbourne, Australia; Department of Cardiology, Alfred Hospital and Baker IDI Heart and Diabetes Institute, Department of Cardiology, Alfred Hospital and Baker IDI Heart and Diabetes Institute, Melbourne, Australia. 6. Department of Cardiology, Royal Melbourne Hospital, Melbourne, Australia; Faculty of Medicine, Dentistry, and Health Sciences, University of Melbourne, Melbourne, Australia. Electronic address: jon.kalman@mh.org.au.
Abstract
BACKGROUND: With the recent advent of high-density (HD) 3-dimensional (3D) mapping, the utility of entrainment is uncertain. However, the limitations of visual representation and interpretation of these high-resolution 3D maps are unclear. OBJECTIVE: The purpose of this study was to determine the strengths and limitations of both HD 3D mapping and entrainment mapping during mapping of right atrial macroreentry. METHODS: Fifteen patients were studied. The number and type of circuits accounting for ≥90% of the tachycardia cycle length using HD 3D mapping were verified using systematic entrainment mapping. Entrainment sites with an unexpectedly long postpacing interval despite proximity to the active circuit were evaluated. RESULTS: Based on HD 3D mapping, 27 circuits were observed: 12 peritricuspid, 2 upper loop reentry, 10 lower loop reentry, and 3 lateral wall circuits. With entrainment, 17 of the 27 circuits were active: all 12 peritricuspid and 2 upper loop reentry. However, lower loop reentry was confirmed in only 3 of 10, and none of the 3 lateral wall circuits were present. Mean percentage of tachycardia cycle length covered by active circuits was 98% ± 1% vs 97% ± 2% for passive circuits (P = .09). None of the 345 entrainment runs terminated tachycardia or changed tachycardia mechanism. In 8 of 15 patients, 13 examples of unexpectedly long postpacing interval were observed at entrainment sites located distal to localized zones of slow conduction seen on HD 3D mapping. CONCLUSION: Using HD 3D mapping, "visual reentry" may be due to passive circuitous propagation rather than a critical reentrant circuit. HD 3D mapping provides new insights into regional conduction and helps explain unusual entrainment phenomena.
BACKGROUND: With the recent advent of high-density (HD) 3-dimensional (3D) mapping, the utility of entrainment is uncertain. However, the limitations of visual representation and interpretation of these high-resolution 3D maps are unclear. OBJECTIVE: The purpose of this study was to determine the strengths and limitations of both HD 3D mapping and entrainment mapping during mapping of right atrial macroreentry. METHODS: Fifteen patients were studied. The number and type of circuits accounting for ≥90% of the tachycardia cycle length using HD 3D mapping were verified using systematic entrainment mapping. Entrainment sites with an unexpectedly long postpacing interval despite proximity to the active circuit were evaluated. RESULTS: Based on HD 3D mapping, 27 circuits were observed: 12 peritricuspid, 2 upper loop reentry, 10 lower loop reentry, and 3 lateral wall circuits. With entrainment, 17 of the 27 circuits were active: all 12 peritricuspid and 2 upper loop reentry. However, lower loop reentry was confirmed in only 3 of 10, and none of the 3 lateral wall circuits were present. Mean percentage of tachycardia cycle length covered by active circuits was 98% ± 1% vs 97% ± 2% for passive circuits (P = .09). None of the 345 entrainment runs terminated tachycardia or changed tachycardia mechanism. In 8 of 15 patients, 13 examples of unexpectedly long postpacing interval were observed at entrainment sites located distal to localized zones of slow conduction seen on HD 3D mapping. CONCLUSION: Using HD 3D mapping, "visual reentry" may be due to passive circuitous propagation rather than a critical reentrant circuit. HD 3D mapping provides new insights into regional conduction and helps explain unusual entrainment phenomena.