Bhupesh Pathik1, Geoffrey Lee1, Frédéric Sacher2, Michel Haïssaguerre2, Pierre Jaïs2, Grégoire Massoullié2, Nicolas Derval2, Prashanthan Sanders3, Peter Kistler4, Jonathan M Kalman5. 1. Department of Cardiology, Royal Melbourne Hospital, Parkville, Victoria, Australia; Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia. 2. Department of Cardiac Electrophysiology, Bordeaux University Hospital, Bordeaux, France. 3. Centre for Heart Rhythm Disorders, Royal Adelaide Hospital, University of Adelaide, Adelaide, South Australia, Australia. 4. Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia; Department of Cardiology, Alfred Hospital, Melbourne, Victoria, Australia; Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia. 5. Department of Cardiology, Royal Melbourne Hospital, Parkville, Victoria, Australia; Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia. Electronic address: jon.kalman@mh.org.au.
Abstract
BACKGROUND: Evidence for epicardial-endocardial breakthrough (EEB) is derived from mapping inferences in patients with atrial fibrillation who may also have focal activations. OBJECTIVE: The purpose of this study was to investigate whether EEB could be discerned during stable right atrial (RA) macroreentry using high-density high-spatial resolution 3-dimensional mapping. METHODS: Macroreentry was diagnosed using 3-dimensional mapping and entrainment. Bipolar maps were reviewed for EEB defined as (1) presence of focal endocardial activation with radial spread unaccounted for by an endocardial wavefront and (2) present with the same timing on every tachycardia cycle. The EEB site was always in proximity to a line of endocardial conduction slowing or block. Distance and conduction velocity from the line of block to the EEB site was calculated. Electrograms at EEB sites were individually analyzed for morphology and to confirm direction of activation. Entrainment was performed at EEB sites. RESULTS: Twenty-six patients were studied. Fourteen examples of EEB were seen: 11 at the posterior RA (4 at the superior portion of the posterior wall and 7 at the inferior section) and 1 each at the cavotricuspid isthmus postablation, RA septum, and inferolateral RA. The mean area of the EEB site was 0.6 ± 0.2 cm2. A mean of 79.5% ± 18.6% of unipolar electrograms at the EEB site demonstrated an rS morphology. The mean distance and conduction velocity from the line of endocardial block to the EEB site at the posterior RA was 13.6 ± 2.3 mm and 59.3 ± 12.3 cm/s, respectively. In 4 patients, entrainment demonstrated that EEB sites were within the circuit and in 1 of these patients critical to arrhythmia maintenance. Activation maps during tachycardia and coronary sinus pacing demonstrated EEB at the same anatomic site. CONCLUSION: EEB sites were demonstrated in stable atrial macroreentry supported by systematic entrainment confirmation and demonstration of the same phenomenon during pacing.
BACKGROUND: Evidence for epicardial-endocardial breakthrough (EEB) is derived from mapping inferences in patients with atrial fibrillation who may also have focal activations. OBJECTIVE: The purpose of this study was to investigate whether EEB could be discerned during stable right atrial (RA) macroreentry using high-density high-spatial resolution 3-dimensional mapping. METHODS: Macroreentry was diagnosed using 3-dimensional mapping and entrainment. Bipolar maps were reviewed for EEB defined as (1) presence of focal endocardial activation with radial spread unaccounted for by an endocardial wavefront and (2) present with the same timing on every tachycardia cycle. The EEB site was always in proximity to a line of endocardial conduction slowing or block. Distance and conduction velocity from the line of block to the EEB site was calculated. Electrograms at EEB sites were individually analyzed for morphology and to confirm direction of activation. Entrainment was performed at EEB sites. RESULTS: Twenty-six patients were studied. Fourteen examples of EEB were seen: 11 at the posterior RA (4 at the superior portion of the posterior wall and 7 at the inferior section) and 1 each at the cavotricuspid isthmus postablation, RA septum, and inferolateral RA. The mean area of the EEB site was 0.6 ± 0.2 cm2. A mean of 79.5% ± 18.6% of unipolar electrograms at the EEB site demonstrated an rS morphology. The mean distance and conduction velocity from the line of endocardial block to the EEB site at the posterior RA was 13.6 ± 2.3 mm and 59.3 ± 12.3 cm/s, respectively. In 4 patients, entrainment demonstrated that EEB sites were within the circuit and in 1 of these patients critical to arrhythmia maintenance. Activation maps during tachycardia and coronary sinus pacing demonstrated EEB at the same anatomic site. CONCLUSION: EEB sites were demonstrated in stable atrial macroreentry supported by systematic entrainment confirmation and demonstration of the same phenomenon during pacing.