Sinus node function in patients operated for mitral valve disease. Indirect evaluation with epimyocardial electrodes Função do nó sinusal em pacientes submetido a correção cirúrgica da valvopatia mitral. Avaliação indireta com eletrodos epimiocárdicos

Purpose: To study the interatrial conduction times and atrial node performance in patients submitted to mitral valve surgery with the aid of temporary atrial epicardic electrodes. Methods: The atriograms were carried out in the first postoperative day and before the hospital discharge of ten consecutive patients. Results: Sixty percent of the patients could complete the post-operative study protocol. The main results were: a) Post-operative arrhythmias were detected in 50% of the patients; b) There were no statistical differences between the pre and post-operative 12 lead EKGs. c) The interatrial conduction time (IACT) ranged from 90 to 140ms in the first post-operative day, and from 110 to 130ms at hospital discharge; d) The sinus node recovery time (SNRT) ranged from 250 to 560 ms in the first post-operative day and from 180 to 360ms at hospital discharge; e) The sinus atrial conduction time (SACT) remained between 70 and 140ms, both in the first post-operative day and at hospital discharge, and; f) The IACT was normal in patients whose left atrium (LA) was less than 50mm in diameter but supra normal in the remaining cases. Conclusions: Sinus node function and inter-atrial conduction are not altered by mitral valve operation. Post-operative programmed epicardic atrial stimulation is easy and safe.