Efficacy Of Radiofrequency Modified Maze Procedure Combined With Open-heart Surgery For Atrial Fibrillation

Background: Atrial fibrillation with its prevalence of 0.4% is the most common cardiac arrhythmia in clinic prevalence,and the prevalence increases with age,10% of Chineses older than 70years have atrial fibrillation. Atrial fibrillation remains an important incremental risk factor for death. It is associated with a five- seven fold increase in the risk of stroke and decrease life quality and increases health care spending. Therefore,method of low-risk, minimally invasive, low cost-effective to ablate atrial fibrillation is of great value. Clinical patterns of atrial fibrillation include paroxysmal,persistent and permanent.Now the mechanisms of atrial fibrillation is incompletely understood. In the past,treatment of atrial fibrillation include medicine,electrical conversion,catheter ablation.But these ways have no ideal results. Therefore,surgical treatnent of atrial fibrillation is highly concerned and expected.In 1987,Cox firstly carryed out Maze operation,and made alterations twice after.MazeⅢoperation is the standard surgical procedure for treatment of atrial fibrillation at present.It is a the most successful surgical treatment for atrial fibrillation,with eliminating the arrhythmia in more than 90% of patients. The Cox-Maze III operation is the gold standard for surgical treatment of trial fibrillation.This operation has not become popular due to its disadvantages such as complexity,cost of time,hemorrhage, complication in perioperational period. In recent years, it has been of increasing interest trying to simplify this procedure, using new and different energy sources such as refrigeration,microwave,laser,radiofrequency and so on in stead of cutting and suture to create ablation lines. Radiofrequency ablation is the most popular of them. In the late 1990s, unipolar radiofrequency ablation was introduced, obtaining rate of sinus rhythm restoration, ranging from 69% to 76.9% .But unipolar radiofrequency ablation applications have some limitations, such as high tissue temperature, resulting in neighboring mediastinal structure damage and atrial damage not enough to penetrate thoroughly,unavoidable paradamage. Atricure bipolar radiofrequency ablation systerm overcome the problems mentioned above.In 2007,we introduce the AtriCure bipolar radiofrequency ablation systerm,and treat rheumatic valvular heart disease underwent radiofrequency ablation modified maze procedure combine with atrial fibrillation. In this study we report and evaluate the clinical results obtained in 10-26 months of experience surgically treating atrial fibrillation .Objective : To evaluate the efficacy of Radiofrequency modified maze procedure combined with open-heart surgery for atrial fibrillation.Methods:From January 2007 to May 2008, 16 patients of atrial fibrillation with rheumatic valvular heart disease underwent radiofrequency ablation modified maze procedure combined with open-heart surgery , following heart valve replacement in cardiovascular surgery department of china-japan union hospital of jilin university。Rhythm after recovery of heart beat,extracorporeal circulation minutes,blocking minutes,the radiofrequency maze procedure minutes,respirator supported,draining quantity after operation,ICU days,complications after operation,electrocardiogram and echocardiogram in 1 week after operation are collected and observed. ECGs(in 1 month,3 months,6 months,10-26 months,),echocardiogram of preoperative and postoperative indexes (left atrial long diameter,ejection fraction,enddiastolic left ventricular long diameter),Postoperative cardiac function and thromboembolic events were evaluated through out-patient clinic and telephone. Follow-up duration was10-26months .Results :There was no operative death. The radiofrequency maze procedure only took 15-38 mins . Atrial fibrillation disappeared in all patients after surgery,sinus rhythm, conjunctional rhythm, and atrialflutter were documented in 12, 2, and 2 patients respectively soon after operation while noⅢ°atrial- ventricular block occurred in this group. One patient died from heart failure, the second day after operation. Neither TIA nor throm boem bolic events were seen. 14 patients (93.3 %)were followed up 10 to 26 months. One patient died during follow up. Among the 14 short-term survivors ,12 were in NYHA functional class I ,2 inclass II. Atrioventricular activation sequence was normal ,and the atrial function was good during follow-up.Sinus rhythm was restored in 78.5% of patients after 3 months in 85.7% of patients after 6 months to 26 months. Echocardiograms showed that left atrial long diameter was significantly smaller than that of preoperation [(42.8±6.6) mm vs (55.8±8.7) mm];enddiastolic left ventricular long diameter was significantly smaller than that of preoperation [(42.1±5.1±) mm vs (47.4±9.5)mm] . Left ventricle contractile function was normal in all cases with the mean Left ventricle ejection fractions being (69.3±18)% more than 10 months to 26 months.Disscussion:Atrial fibrillation is the most common cardiac arrhythmia in clinic prevalence,it remains an important incremental risk factor for death. It is associated with a five- seven fold increase in the risk of stroke and decrease life quality and increases health care spending. Therefore,method of low-risk, minimally invasive, low cost-effective to ablate atrial fibrillation is of great value. Treatment of atrial fibrillation include medicine,electrical conversion,catheter ablation,surgical treatnent. Surgical treatnent of atrial fibrillation of the total have ideal results. Maze operation is the standard surgical procedure for treatment of atrial fibrillation at present.It is a the most successful surgical treatment for atrial fibrillation. The Cox-Maze III operation is the gold standard for surgical treatment of trial fibrillation. In recent years, it has been of increasing interest trying to simplify this procedure, using new and different energy sources such as refrigeration,microwave,laser,radiofrequency and so on in stead of cutting and suture to create ablation lines. Radiofrequency ablation is the most popular of them.Bipolar radiofrequency ablation energy has several advantages over other unipolar energy sources for this application. Bipolar radiofrequency ablation modified maze procedure is a simple method,and the energy isapplied between the two electrodes which are closely approximated in the jaws of the clamp, there were short ablation times, with 5-6 cm long transmural ablations performed in 5-15 seconds. An algorithm measuring conductance allows for the real-time determination of lesion transmurality. Moreover, the lesions are narrow and injury is confined to tissue within the clamp, as mean temperatures just one mm from the electrode have been shown to be less than 50°C. This virtually eliminates the possibility of collateral injury to cardiac and extra-cardiac structures.We introduce the AtriCure bipolar radiofrequency ablation systerm,and treat rheumatic valvular heart disease underwent radiofrequency ablation modified maze procedure combine with atrial fibrillation. Atrial fibrillation disappeared in all patients after surgery,sinus rhythm, conjunctional rhythm, and atrialflutter were documented in 12, 2, and 2 patients respectively soon after operation while noⅢ°atrial- ventricular block occurred in this group. One patient died from heart failure, the second day after operation. Neither TIA nor throm boem bolic events were seen. Sinus rhythm was restored in 78.5% of patients after 3 months in 85.7% of patients after 6 months to 26 months. Atrioventricular activation sequence was normal ,and the atrial function was good during follow-up.We have several viewpoints for this application. (1) The patients underwent radiofrequency ablation modified maze procedure combined with open-heart surgery for atrial fibrillation have only one chance of radical treatment. (2) Paying close attention to the heart failure patients, specially in NYHA functional classⅢ-Ⅳ, intraoperative some more operation are adverse to cardiac patients of preoperation. (3) To early use amiodarone. The patients after radiofrequency ablation should be oral amiodarone in six months. (4) Left atrial long diameter and atrial fibrillation history of preoperation may be the main factors which influence sinus rhythm restored and maintained of postoperation. Currently, conjunctional rhythm, and atrial fibrillation were documented in 1 and 1 patients,showed that left atrial long diameter was 75 mm,80 mm respectively,in 10 years history of atrial fibrillation. Therefore,the larger is the left atrial long diameter,the longer is the atrial fibrillation history,the lower is the proportion of restored sinus rhythm of postoperation.Conclusion:Radiofrequency ablation modified maze procedure is a simple , safe and effective method to treat atrial fibrillation.