ELECTROPHYSIOLOGICAL PROPERTIES IN PATIENTS UNDERGOING ATRIAL COMPARTMENT OPERATION FOR CHRONIC ATRIAL-FIBRILLATION WITH MITRAL-VALVE DISEASE

Aims Surgical treatment for atrial fibrillation is now feasible in sel ective cases. The aim of this study was to assess the electrophysiolog ical properties of patients undergoing atrial compartment operation fo r chronic atrial fibrillation. Methods and results Electrophysiologica l studies were performed in 20 mitral valve patients with atrial fibri llation who had been maintained in sinus rhythm for more than 1 year a fter atrial compartment operation. Intra-cardiac recording and program med electrical stimulation were performed in various atrial compartmen ts. The parameters studied included sinus node function, atrial conduc tion and refractoriness, atrioventricular conduction function and indu cible arrhythmias if any. Intra-cardiac recordings showed that the rhy thm was of sinus origin in all cases, with the earliest atrial activit y located in the high right atrium. The mean sinus cycle length was 75 0 +/- 110 ms, AH time 106 +/- 29 ms, and HV time 53 +/- 7 ms. The sinu s node function was normal in 18 patients (90%), and only two patients had prolonged sinus node recovery and sino-atrial conduction. The rig ht atrial appendage compartment was driven by the sinus node in all pa tients. However, the conduction time from the high right atrium to the right atrial appendage compartment was markedly prolonged in 12 of 15 patients (80%) undergoing the three-compartment operation in which an incision was placed between the high right atrium and right atrial ap pendage compartments. On the other hand, the electrical activities in the left atrial compartment were much more varied. In 13 of 20 patient s (65%), the left atrial compartment was driven by the sinus node; 11 of the 13 patients had a normal or mildly prolonged conduction time (r anged 75 to 146 ms), whereas two patients had a marked delay in conduc tion (200 ms and 266 ms, respectively). In the remaining seven patient s, the left atrial compartments were dissociated from the rest of the heart; five of them had a quiescent left atrium, one a fluttering left atrial rhythm, and one a slow left atrial rhythm. The effective refra ctory period was longer in the left atrial compartment (242 +/- 47 ms) as compared to that of the high right atrium (224 +/- 26 ms, P < 0.01 ) and right atrial appendage compartments (219 +/- 25 ms, P < 0.01). P rogrammed electrical stimulation could not induce atrial fibrillation in any patient, whereas two patients had inducible atrial flutter and three repetitive atrial responses. Conclusions (1) Atrial compartment operation does not impair sinus node function in most cases. (2) Elimi nation of atrial fibrillation while maintaining the electrical connect ion between different atrial compartments is feasible.