Translational anatomy of the left atrium and esophagus as relevant to the pulmonary vein antral isolation for atrial fibrillation.

PURPOSE

Pulmonary vein antrum isolation by radiofrequency ablation has become a preferred treatment for atrial fibrillation. The aim of our research is to study the anatomy of the PVantrum and its related structures with special emphasis on the esophageal relation to the various components of the antrum, as thermal injury is a common complication.

METHODS

Mediastinal contents were extracted "en bloc" from 30 human formalin fixed adult cadavers to study the posterior wall of the left atrium along with the esophagus.

RESULTS

The pulmonary antrum was measured. Each pulmonary ostium was assessed for circumference and muscle thickness. The esophagus was related to the left superior ostium in 90% of cases. The esophagus was traced on the atrial wall in each case; the distance from endocardium was measured at five equidistant lines. AV node distance from the right inferior pulmonary vein was 5 cm. The atrioventricular part of the membranous septum measured 4.2 mm.

CONCLUSIONS

For antral isolation the ablation lines are about 3 cm superior, 3.5 cm inferior and about 1 cm apart. The esophagus is ~ 12 mm away at the superior and ~ 7 mm away at the inferior ablation line. On the left ablation line this distance would diminish from 15 to 7 mm. The pulmonary ostial circumference is ~ 5 cm with muscle thickness varying from 0.7 to 4 mm. The left ostia need more ablative power as they have a 60% (1 mm) thicker muscle coat. Care should be taken while ablating round the left superior ostium as the esophagus lies 1-3 cm behind it in 90% of the cases.