Effect Of Radiofrequency Catheter Ablation For Paroxysmal Atrial Fibrillation On Left Atrial Structure And Function

BackgroundAtrial fibrillation (AF) is the most common clinical arrhythmia, has a high fatality rate and disability. Therefore, in the early stages of cardioversion and maintenance of sinus rhythm, have a great significance for prevent cardiovascular events happen by atrial fibrillation. The treatment of conventional drugs were not satisfactory, often resulting in psychological and emotional burden, reduce the quality of life, some antiarrhythmic drugs also can cause other types of arrhythmias in the treatment of atrial fibrillation, while there was dangers of bleeding when eat anticoagulant drugs, even lethal, and monitoring was inconvenience. In recent years, with the development of technology and equipment for radiofrequency catheter ablation(RFCA), AF ablation as a means of non- cardiac drugs is lead to concern, because RFCA can avoid the side effects caused by medication long-term, and to maintain sinus rhythm, espially, have a high success rate in paroxismal atrial fibrillation. Some studies have shown that left atrial structural remodeling involved in the mechanisms of development and maintenance about atrial fibrillation, including both the reconstruction of anatomical organization, and reconstruction of electrical activity of cells. Previous studies have shown that the left atrium could remodeling after electrical cardioversion, but whether will reverse remodeling after radiofrequency ablation is unknown, while RFCA as a invasive treatment, whether will cause irreversible damage to left atrium, or further reduce the function, it is not clear, so deep study the change of left atrial structure and function after RFCA have important clinical significance. Traditional techniques such as M type, two-dimensional and Doppler ultrasound have been widely used to assess left atrial structure and function. new ultrasound technologies such as tissue Doppler and three-dimensional ultrasound also exploring in recent years, the tissue Doppler imaging (TDI) overcome some defects of the traditional M and two-dimensional echocardiography, it provide a new approach for quantitative analysis of myocardial motion and function. The observed object of conventional Doppler was the red blood cells witch with high-speed movement in blood, but the observed object of TDI was the myocardial witch with low speed, these low speed, high amplitude of the echo signal by reducing the total gain and after a high-pass filter The method of delivery to the estimated speed from the correlator, and then use two-dimensional color image or spectrum curve in the form shown in real time,it can detecte the myocardial velocities directly so as to reflect the local cardiac function, and making the heart function in a more convenient and reliable. Therefore, assess the changes in systolic function about paroxysmal atrial fibrillation with echocardiography, especially tissue Doppler imaging have a great significance for treatment and prognosis.Objective:52 patients with paroxysmal atrial fibrillation and 30 healthy controls participated in this study. establishment of clinical data, measure the left atrial diameter (LAD), left atrial area (LAA),left atrial volume (LAV), record mitral inflow A peak velocity (VA) and left atrial ejection force (LAF) by echocardiography, while measure the peak of late diastolic velocity (Va) from the front mitral annulus by using tissue Doppler, comparison the differences of left atrial structure and function between the patients of paroxysmal atrial fibrillation and conrol group. After RFCA for paroxysmal atrial fibrillation,Dynamic observation the changes of left atrial structure and function at different time, and thereby to explore the impact of RFCA for left atrium, so as to provide an objective basis in treatment and prognosis.Subjects:All subjects are from February 2008～March 2010 at NanFang medical university, total of 82 cases. Atrial fibrillation group inclusion criteria:(1) ECG, Holter monitoring showed episodes of atrial fibrillation at least 2 times, and transfer to sinus rhythm within 7 days; (2) one or more antiarrhythmic drugs ineffective or difficult to tolerate; (3) no significant enlargement of the left atrial (diameter less than 50mm), excluding the left atrial appendage thrombus by transesophageal ultrasound; (4)excluded the following diseases:valvular heart disease, dilated cardiomyopathy, severe dysfunction of left ventricular and other organic heart disease, PAF caused by hyperthyroidism or alcohol, thyroid dysfunction, liver disease, chest after major surgery, pericarditis, blood disease, electrolyte disorders, thromboembolic disease, connective tissue diseases, autoimmune diseases and cancer. Control group selection criteria:Asked by history and ECG or Holter monitoring has never been confirmed that atrial fibrillation occurred more than meet the healthy standard.The above study has been informed consent.Based on the above criteria, a total of 52 cases of selected patients with atrial fibrillation, the average age at onset of (56.98±6.42)years old. One of 42 cases of male, female 10 cases,18 cases of hypertension,9 cases of patients with coronary heart disease,8 cases of diabetes; selected 30 cases of healthy controls, average age (56.23±6.81) years old, one of 23 cases of male, female 7 cases,10 cases of hypertension,4 cases of patients with coronary heart disease,4 cases of diabetes. Methods:Both groups were set up observation of clinical data form, a detailed record of age, sex, height, weight, such as the general situation of patients; as well as hypertension, coronary heart disease, diabetes and other medical history, Holter monitoring inspection and the average heart rate was recorded.All subjects were examined in sinus rhythm, measure the left atrial diameter (LAD), left atrial area (LAA),left atrial volume (LAV), record mitral inflow A peak velocity (VA) and left atrial ejection force (LAF) by echocardiography(Vivid7, GE, USA),while measure the peak of late diastolic velocity (Va) from the front mitral annulus by using tissue Doppler.Compared the differences of left atrial structure and function between AF group and control group preoperative; in patients who maintain sinus rhythm after RFCA to compare the changes of left atrial structure and function of its own.Statistical analysis:SPSS13.0 statistical software was used, the count data of said frequency, to compare the groups of count data utilize testing X2. Measurement data as mean±standard deviation (x±s), two group samples were compared used the number of t test, paired-samples t test was used for comparison of paired measurement data within group. Standard testα=0.05, P<0.05 was considered statistically significant.Results:1. Paroxysmal atrial fibrillation and control groups between the age, sex, rate, body mass index (BMI), hypertension, coronary heart disease, diabetes, systolic pressure, diastolic pressure, LVEF, NT-proBNP were no significant difference. The value of P is 0.659,0.621,0.554,0.871,0.589,0.635,0.800,0.456,0.386,0.081,0.212.2. Paroxysmal atrial fibrillation and control groups between LAD, LAA, LAV, VA, LAF, Va have significant difference, The value of P is 0.002,0.005,0.012,0.038,0.005,0.003. the indicators of left atrial structural such as LAD, LAA, LAV of AF group were significantly greater than the control group, it suggesting that patients with paroxysmal atrial fibrillation have left atrial enlargement, while the indicators of left atrial function VA, LAEF, Va were converse.3.52 patients were successfully completed with pulmonary vein isolation; operative time was 132.7±14.5min; X-ray exposure time was 17.4±2.2min. there was 5.77% major complications,2 patients were vicious, vomiting and other gastrointestinal reactions, groin hematoma in 1 patient, nobody suffer with severe complications such as acute cardiac tamponade, pulmonary vein stenosis, left atrium-esophageal fistula. Followed up for 6 months,45 patients maintain in sinus rhythm, the success rate was 86.5%.4. One day after RFCA, the indicators of left atrial structure such as LAD, LAA, LAV were no significant change, The value of P is 0.477,0.298,0.109. the indicators of left atrial function such as VA, LAF, Va were decreased compare to preoperation, all the value of P<0.05, but the LVEF was not significant change, the value of P is 0.110.5. Six months after RFCA, the indicators of left atrial structure such as LAD, LAA, LAV were decreased compare to preoperation, The value of P is 0.001,0.000,0.003. the indicators of left atrial function improvement compare to 1 day post operation, but no significant change compare to preoperation, The value of P is 0.650,0.117,0.643.Conclusion:1. Patients with paroxysmal atrial fibrillation have left atrial enlargement and reduced systolic function.2. Shortly after ablation, the structure of left atrium unchanged, the function decreased, but no significant effect on cardiac function.3. After midterm follow-up, the reverse remodeling of left atrium is observed, the function had slightly increased compared with shortly after ablation.4. Radiofrequency catheter ablation is a safe and effective method for atrial fibrillation, maintain sinus rhythm effectively.