Surgery for atrial fibrillation

OBJECTIVE: The mechanisms of atrial fibrillation arc multiple reentrycircuits spinning around the atrial surface, and these baffle any attemptto direct surgical interruption. The purpose of this article is to reportthe surgical experience in the treatment of isolated and concomitant atrialfibrillation 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 surgerycan prevent atrial fibrillation from involving the right atrium, which canexert its diastolic pump function on the right ventricle. Left atrialisolation was performed on 205 patients at the time of mitral valvesurgery. Atrial partitioning ("maze operation") creates straight and blindatrial alleys so that non-recentry circuits can take place. Five patientsunderwent this procedure. In eight-cases of atrial fibrillation secondaryto atrial septal defect, the adult patients with atrial septal defect andchronic or paroxysmal atrial fibrillation underwent surgical isolation ofthe right atrium associated which surgical correction of the defect, inorder 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 fibrillationsecondary to mitral valve disease, left atrial isolation was performed on205 patients at the time of mitral valve surgery with an overall sinusrhythm recovery of 44%. In the same period, sinus rhythm was recovered andpersisted in only 19% of 252 patients who underwent mitral valvereplacement along (P < 0.001). Sinus rhythm was less likely to recoverin patients with right atriomegaly requiring tricuspid valve annuloplasty:59% vs 84% (P < 0.001). Restoration of the right atrial function raisedthe cardiac index from 2.25 +/- 0.55 1/min per m2 during atrialfibrillation to 2.54 +/- 0.58 1/min per m2, with a mean percentage increasein cardiac index of 13.5% (P < 0.00018). Atrial partitioning ("mazeoperation") was performed on five patients with an immediate sinus rhythmrecovery of 100%, but with two patients requiring pacemaker implant. Sevenout of eight patients (87.5%), with atrial fibrillation secondary to atrialseptal defect, who underwent surgical isolation of the right atrium at thetime of surgery were free from atrial fibrillation a