الفهرس 
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Abstract
A high percentage of patients with mitral valve disease suffer from atrial fibrillation (AF) which results in a variety of morbidities including hemodynamic compromise, syncope, dizziness, fatigue, palpitations, chest pain and an increased probability of a thromboembolic event.
At the time of mitral valve surgery the incidence of concomitant AF can reach up to 50%. Spontaneous sinus rhythm recovery occurs in not more than 10 % of patients with mitral valve disease undergoing mitral valve surgery so mitral valve surgery alone usually does not abolish AF and the persistence of AF after surgery increases postoperative morbidity and mortality hence he need for an additional intervention to target the AF itself.
It is hypothesized that AF is initiated by rapid erratic electrical activity, most often arising from arrhythmogenic foci or triggers located in the muscular sleeves of pulmonary veins. This likely relates to the anatomic transition from pulmonary vein endothelium to left atrial endocardium; at this juncture, two types of tissue with different electrical properties are juxtaposed, and this may potentiate development of the disease. This observation mainly explains the pathogenesis of paroxysmal or lone AF however, for AF to be sustained and become persistent or permanent, macro-reentrant wavelets need to exist in the atrial musculature. This requires an underlying cardiopulmonary disease, a factor that is absent in lone AF.
Occurrence of AF is known to correlate with LA size; the incidence of AF rises from 3% when the left atrial diameter is < 40mm to 54% if the left atri¬al diameter is > 40 mm.3 Mitral valve disease is as¬sociated with large left atria, and the elevated left atrial pressure causes myocardial stretch, which in turn results in slow conduction velocities, in¬creased dispersion of refractoriness and increased automaticity, all of which create the milieu for ini¬tiating and perpetuating sustained AF.
Surgery for the treatment of atrial fibrillation culminated in the development of the Cox-Maze III, the Gold standard of treatment and still, the procedure with the highest success rate (up to 98% according to some studies). However, it has not been widely adopted due to it’s complexity, it’s need for cardiopulmonary by-pass and it’s significant prolongation of by-pass time. Efforts have focused on developing a potentially less invasive and less time-consuming operation by simplifying the pattern of atrial lesions and using alternative energy sources that can create them quickly, without a cut-and-sew technique.
One promising modality is radiofrequency ablation for atrial fibrillation for patients with atrial fibrillation undergoing cardiac surgery or patients with highly symptomatic atrial fibrillation not responding to other therapies.
In our study on thirty eight patients Cardioblate Medtronic BP2 irrigated radiofrequency surgical ablation system was used ablating the pulmonary veins and left atrial appendage on bypass before mitral valve surgery with completion mitral ablation line after left atriotomy and isolating right atrial appendage at the end of bypass had good outcomes (almost 79% success rate at 6 months post-operatively) including rheumatic(mainly), degenerative and ischaemic pathologies. We employed a simple and relatively short procedure that focused exclusively on the left atrium taking into account the main lines of the maze operation.. Antiarrhythmic medical therapy was used for 3 months post-operatively and anticoagulation was stopped after 3 months in those with stable sinus rhythm along that period. except in otherwise indicated anticoagulation as in cases when patients preferred mechanical valves
The success rate of bipolar RF ablation in our study is similar to that of the bi-atrial RF maze reported in other studies with a major difference being the much longer duration of the latter. Also found suprior to monopolar RF ablation regarding proven transmurality and lesser transmitted thermal damage and less time consuming.