Early Appearance of an Edematous Tissue Reaction During Left Atrial Linear Ablation Using Intracardiac Echo Imaging
Left atrial linear ablation is difficult and sometimes impossible to achieve using currently available catheter ablation technology. Left isthmus ablation (between the lateral mitral annulus and left inferior pulmonary vein) is a promising strategy for achieving “substrate modification” as, analogous to the right (cavotricuspid) isthmus, the creation of a relatively short lesion results in electrical transection of the left atrium as demonstrated by differential pacing and conduction detour around the mitral annulus recorded in the coronary sinus. Intracardiac echocardiographic (ICE) imaging provided useful insights about the thickness of the left isthmus and the distance to adjacent structures including the left atrial appendage and left circumflex coronary artery, thus facilitating optimal catheter positioning. In addition, use of this imaging modality demonstrated the behavior of the left isthmus during ablation. In 14 patients, ultrasound imaging was performed using a Sequoia ultrasound system (Acuson Corporation, Mountain View, Calif) with a 10F, 5.5- to 10-MHz diagnostic catheter (AcuNav, Acuson), which was inserted either within the coronary sinus or across the atrial septum into the left atrium after excluding the presence of left atrial thrombus and under appropriate anticoagulation. We observed with ICE imaging the early appearance (within 15 seconds) of edema during energy delivery in all except 1 patient, as demonstrated in these movies. This early edema during ablation may partly explain why linear transmural left atrial ablation is sometimes difficult to achieve.
Dr Weerasooriya is supported by the Athelstan and Amy Saw Overseas Medical Research Scholarship of the University of Western Australia.
Movies are available in the online-only Data Supplement at http://www.circulationaha.org.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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