Electrical Dissociation within the Left Atrium and Left Atrial Appendage Diagnosed with Transesophageal Echocardiography

The authors describe the case of a 79-year-old man with prior mitral valve repair and a maze procedure who developed recurrent atrial fibrillation, in whom transesophageal echocardiography revealed an accessory lobe of the left atrial appendage in sinus rhythm when the remaining body of the left atrial appendage was in atrial fibrillation or flutter. Electrophysiology confirmed dissociated rhythm within the left atrium. This case emphasizes the need for careful Doppler interrogation of the left atrial appendage and its lobes to look for dissociated atrial rhythm.