ATRIAL ACTIVATION DURING CHRONIC ATRIAL-FIBRILLATION IN PATIENTS WITHISOLATED MITRAL-VALVE DISEASE

Background. A computerized 32-channel mapping system has been develope d to investigate the characteristics of the atrial activation sequence . The system is capable of displaying sequential atrial maps and provi des a rapid and dynamic means of verifying the activation sequence of atrial fibrillation. Methods. Using this system, we performed intraope rative atrial activation mapping in 10 patients with chronic atrial fi brillation who were undergoing isolated mitral valve operations. Resul ts. Regular and repetitive activation (cycle length ranged from 131 to 228 milliseconds) originated in the left atrium in all 10 patients. T wo patterns of repetitive activation in 2 patients and three patterns in 1 patient appeared alternately during the observation period in the left atrium. In contrast to the repetitive activation in the left atr ium, the activation sequence of the right atrium was extremely complex and chaotic. In 7 of the 10 patients, the same pattern of right atria l activation was never repeated during the observation period. In 2 pa tients, revolution of repetitive activation in the right atrium sporad ically appeared, but the pattern of activation immediately deteriorate d to a complex and chaotic pattern. In 1 patient, repetitive activatio n emerged from the low lateral portion of the right atrium. Because ou r mapping technique was limited by the number of available atrial elec trodes, discrete reentrant circuits or ectopic foci could not be demon strated in the present study. However, the activation sequences during chronic atrial fibrillation suggested that (1) the left atrium would act as an electrical driving chamber for atrial fibrillation in the ma jority of the patients and (2) atrial activation patterns are differen t in each case. Conclusions. Computerized intraoperative mapping shoul d guide surgeons in determining the appropriate surgical procedure and facilitate operation for chronic atrial fibrillation associated with mitral valve disease.