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[A case of the atrial dissociation after maze procedure: the coexistence of the sinus node potential and the focal atrial potential in high right atrium].

In a 58-year-old man, who was suffered from atrial fibrillation for a period of 20 years due to mitral stenosis and aortic valve regurgitation, mitral and aortic valve replacement and maze procedure were underwent. We have, whenever possible, substituted the cryoablation for the incision in the maze procedure in attempt to prevent massive bleeding. We found the oscillation of the baseline in lead I, II, III, aVL, aVF on postoperative surface electrocardiogram. We recognized the coexistence of 90/min sinus node potential and 375/min independent focal atrial potential in high right atrium (HRA) of intra-cardiac recording and only the sinus node potential in middle and lower right atrium of that. It was thought that the incision of maze procedure and cryoablation occurred to the atrial dissociation which coexisted segmental atrial fibrillation and sinus rhythm by electrophysiological block. In the postoperative electrophysiological study the sinus node automaticity and sinoatrial conduction were within normal limit and atrial tachycardia and atrial fibrillation were not induced. A wave of both atria was recognized in transesophageal echocardiography, though the segmental atrial fibrillation was left in a small region of HRA. It was supposed to be useful for maze procedure at the point of cardiac function, which included the maintenance of sinus rhythm with segmental atrial fibrillation, atrial kick and the recovery of the atrio-ventricular synchrony.