SURGERY FOR ATRIAL-FIBRILLATION

Objective. The mechanisms of atrial fibrillation are multiple reentry circuits spinning around the atrial surface, and these baffle any atte mpt to direct surgical interruption. The purpose of this article is to report the surgical experience in the treatment of isolated and conco mitant atrial fibrillation at the Cardiac Surgical Institute of the Un iversity 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 invo lving the right atrium, which can exert its diastolic pump function on the right ventricle. Left atrial isolation was performed on 205 patie nts at the time of mitral valve surgery. Atrial partitioning (''maze o peration'') creates straight and blind atrial alleys so that non-recen try circuits can take place. Five patients underwent this procedure. I n eight-cases of atrial fibrillation secondary to atrial septal defect , the adult patients with atrial septal defect and chronic or paroxysm al atrial fibrillation underwent surgical isolation of the right atriu m associated which surgical correction of the defect, in order to let sinus rhythm govern the left atrium and the ventricles. ''Lone'' atria l fibrillation occurs in hearts with no detectable organic disease. Bi -atrial isolation with creation of an atrial septal internodal ''corri dor'' was performed on 14 patients. Results. In cases of atrial fibril lation secondary to mitral valve disease, left atrial isolation was pe rformed on 205 patients at the time of mitral valve surgery with an ov erall sinus rhythm recovery of 77%. In the same period, sinus rhythm w as recovered and persisted in only 19% of 252 patients who underwent m itral valve replacement along (P<0.001). Sinus rhythm was less likely to recover in patients with right atriomegaly requiring tricuspid valv e 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) duri ng atrial fibrillation to 2.54+/-0.58 1/min per m(2), with a mean perc entage increase in cardiac index of 13.5% (P<0.00018). Atrial partitio ning (''maze operation'') was performed on five patients with an immed iate sinus rhythm recovery of 100%, but with two patients requiring pa cemaker implant. Seven out of eight patients (87.58), with atrial fibr illation secondary to atrial septal defect, who underwent surgical iso lation of the right atrium at the time of surgery were free from atria l fibrillation and without medications 2-52 months after operation. Th irteen of 14 patients with ''lone'' atrial fibrillation who underwent corridor procedure remained in sinus rhythm with a sinus rhythm recove ry rate of 92%. Conclusions. Different surgical options can be chosen for different cases of atrial fibrillation, according to the underlyin g cardiac disease.