Surgery for atrial fibrillation.

Objective. The mechanisms of atrial fibrillation are multiple reentry circuits spinning around the atrial surface, and these baffle any attempt to direct surgical interruption. The purpose of this article is to report the surgical experience in the treatment of isolated and concomitant atrial fibrillation at the Cardiac Surgical Institute of the University of Pavia. Methods. In cases of atrial fibrillation secondary to mitral/valve disease, surgical isolation of the left atrium at the time of mitral valve surgery can prevent atrial fibrillation from involving the right atrium, which can exert its diastolic pump function on the right ventricle. Left atrial isolation was performed on 205 patients at the time of mitral valve surgery. Atrial partitioning ("maze operation") creates straight and blind atrial alleys so that non-recentry circuits can take place. Five patients underwent this procedure. In eight-cases of atrial fibrillation secondary to atrial septal defect, the adult patients with atrial septal defect and chronic or paroxysmal atrial fibrillation underwent surgical isolation of the right atrium associated which surgical correction of the defect, in order to let sinus rhythm govern the left atrium and the ventricles. "Lone" atrial fibrillation occurs in hearts with no detectable organic disease. Bi-atrial isolation with creation of an atrial septal internodal "corridor" was performed on 14 patients. Results. In cases of atrial fibrillation secondary to mitral valve disease, left atrial isolation was performed on 205 patients at the time of mitral valve surgery with an overall sinus rhythm recovery of 77%. In the same period, sinus rhythm was recovered and persisted in only 19% of 252 patients who underwent mitral valve replacement along (P<0.001). Sinus rhythm was less likely to recover in patients with right atriomegaly requiring tricuspid valve annuloplasty: 59% vs 84% (P<0.001). Restoration of the right atrial function raised the cardiac index from 2.25+/-0.55 1/min per m(2) during atrial fibrillation to 2.54+/-0.58 1/min per m(2), with a mean percentage increase in cardiac index of 13.5% (P<0.00018). Atrial partitioning ("maze operation") was performed on five patients with an immediate sinus rhythm recovery of 100%, but with two patients requiring pacemaker implant. Seven out of eight patients (87.58), with atrial fibrillation secondary to atrial septal defect, who underwent surgical isolation of the right atrium at the time of surgery were free from atrial fibrillation and without medications 2-52 months after operation. Thirteen of 14 patients with "lone" atrial fibrillation who underwent corridor procedure remained in sinus rhythm with a sinus rhythm recovery rate of 92%. Conclusions. Different surgical options can be chosen for different cases of atrial fibrillation, according to the underlying cardiac disease.