Methodological Study On The Establishment Of Swine Atrial Fibrillation Model By Different Methods

Objective(s): Compare the differences of the atrial fibrillation(Atrial fibrillation,AF)model established by the endocardial method and the epicardial method in ultrasound,electrocardiogram(Electrocardiogram,ECG),CT examination and atrial fibrillation induction rate,so as to further understand the application value of the two pacing models.Methods: 19 Southern Yunnan small ear pigs were randomly divided into control group(6),epicardial pacing model group(7),and endocardial pacing model group(6).In the epicardial pacing model group,a temporary pacemaker TPW 30 pacing lead was implanted in the left atrium(Left atrium,LA),and an external temporary pacemaker was used for pacing maintenance.The endocardial pacing model group punctured the left external jugular vein and entered the right atrium through the superior vena cava(Right atrium,RA),and the implantable cardiac pacemaker lead(QM7211)was implanted at the high RA.After the dual chamber pacing system analyzer(QM2353)tested the pacing electrode parameters satisfactorily,the AF programmer(QM0852)controlled the maintenance of pacing,and tested the induction of AF in OFF,AOO,AOS and ASS mode.The control group was operated similar to the epicardial group,but was not pacing.ECG,echocardiography and CT were performed at weeks 0 and 4.Results:1.Overall experiment: 19 pigs were included in the whole experiment,and one pig in the epicardial pacing model group died due to blood loss.The rest are alive.Pacing was alive for all 4 weeks.In the epicardial pacing model group,although minimally invasive thoracotomy reduced the surgical injury to pigs,it was more damaging than that in the endocardial pacing model group.2.Inductive rate of atrial fibrillation and ECG: AF was induced after immediate intraoperative transatrial rapid pacing.After 30 s of rapid pacing,each one was stimulated 10 times,AF was induced 24 times,and AF induction rate was 40%.The stimulus was set to 800(90)ppm,3.0V,6.0m V.Four weeks after stimulation,the AF was 70%.AF was successfully induced in 50% of the animals at 600(90)stimulation frequency and stimulation amplitude at 4.0-5.0V.The highest incidence of AF was observed under the stimulation protocol of 800(90),5.0V.In the endocardial pacing model group,AF was induced after immediate intra-atrial rapid pacing,and after 30 s,AF was induced 30 times,and AF induction was 50%.The stimulus was set to300 ppm,1.5V.Four weeks after stimulation,AF was 80%.In the total cluster,the occurrence of AF events can be detected in the ASS mode with the frequency 300 ppm and the voltage 0.1V.300 ppm,1.5V AOO mode 8h / day stimulation for two weeks,the AF induction rate increased with time,the higher the pacing frequency,the higher the AF induction rate decreased,and the incidence of AF did not increase significantly with the increase of voltage.After rapid atrial pacing,the heart rate and ventricular rate were significantly faster in the epicardial and endocardial groups compared with the control group.The QRS width and the QT interval was shortened in the epicardial and endocardial group was longer than the control group.3.Ultrasound and CT results: Pulmonary venous flow rate(left,S,D peaks),pulmonary venous flow rate(right,S,D peaks)and mitral valve velocity(E peaks)were reduced in the epicardial pacing model group and endocardial pacing model group compared with the control group.After 4 weeks,ultrasound and CT showed the maximum LA volume and the epicardial LA volume in the endocardial group.There was no significant difference in LVEF.Conclusion(s): 1.Both epicardial and endocardial methods can be used for the establishment of swine atrial fibrillation model.Epicardial surgical conditions and postoperative management requirements are relatively high and easy to adjust;endocardial method has less trauma and easy management after surgery,but there are certain requirements for pacemaker implantation.2.The endocardial method has a higher AF induction rate and earlier atrial remodeling,so the endocardial method may be more suitable for the establishment of pig atrial fibrillation model.