Histological evaluation of atrial muscle sleeve of pulmonary veins as relevant to trigger mapping and ablation
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ORIGINAL ARTICLE
Histological evaluation of atrial muscle sleeve of pulmonary veins as relevant to trigger mapping and ablation Tulika Gupta1 · Arpan Randhawa1 · Daisy Sahni1 Received: 18 March 2020 / Accepted: 11 April 2020 © Springer-Verlag France SAS, part of Springer Nature 2020
Abstract Background The atrial myocardial sleeve of the pulmonary vein is the most common source of arrhythmogenic triggers in atrial fibrillation. The present study was designed to study the atrial muscle sleeve in detail, to help in planning and execution of “trigger mapping and ablation” procedure, used for treating resistant atrial fibrillation. Methods A longitudinal tissue section was taken along the length of each pulmonary vein including the posterior wall of the left atrium, from 15 normal human formalin fixed hearts. The histological and micro-morphometric details of the atrial muscle sleeve were studied. Results A muscle sleeve composed of cardiac muscle was found in each pulmonary vein, situated between adventitia and media, and separated from media by clearly defined connective tissue. The fiber arrangement was non uniform and angular changes in the fiber direction were frequent. Autonomic ganglia were found in the adventitia. The sleeve was tapering distally but reduction was not circumferentially uniform, minimum thickness was more for right (~ 0.2 mm) than for left veins (0.1 mm). The mean atrial sleeve length was 6.3 mm; the left veins had longer sleeve then right while left inferior veins had the maximum mean length. Conclusion The trigger mapping should be done for 2 cm on pulmonary veins to fully cover the atrial muscle sleeve. The gradual tapering of the atrial sleeve indicates that the maximum intensity ablative lesions would be needed at the veno-atrial junction while the ablation power should be reduced distally. Distal triggers on right veins would need more ablation then on the left veins. Keywords Atrial muscle · Pulmonary veins · Atrial fibrillation · Histomorphometry Abbreviations ANS Autonomic nervous system H&E Haematoxylin and eosin RSPV Right superior pulmonary vein RIPV Right inferior pulmonary vein LSPV Left superior pulmonary vein LIPV Left inferior pulmonary vein PV Pulmonary vein
* Tulika Gupta [email protected] 1
Department of Anatomy, Post Graduate Institute of Medical Education and Research, PGIMER, Chandigarh 160012, India
Introduction Atrial fibrillation is one of the most common cardiac arrhythmias [10, 16, 17] and is associated with high morbidity and mortality. The “triggers” that start and then maintain this abnormal electrical activity have been electro physiologically mapped. Though they have been found within the left atrium on the: pulmonary vein ostia, left lateral ridge and left atrial appendage but predominantly (90–95%) these are present on the pulmonary veins outside the heart. These triggers are present within the atrial muscle sleeve, a layer of cardiac muscle which extends from the posterior wall of the left atrium onto the pulmonary veins, regarded as part
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