Study Feasibility Of Clinical Application Of Low Atrial Septal Pacing And Relations Between It And Long-term Atrial Tachyarrhythmia

Right atrial appendage is the traditional site of atrial pacing,but with the development of physiological pacing,it was discovered that pacing this site repeatedly mought change the normal electrophysiology pathway, which led to biatrial electrical activity loss of synchronization and mought promote the atrial tachyarrhythmia frequency.While the region of Koch triangle on atrial septal is close to the physiological AV conduction pathway.Pacing this site can reduce the anisotropy of conduction,can coordinate the synchronization of atrial electrical machinery activities, can help to improve the long-term atrial electrophysiological remodeling. As a result,it should become a more physiological pacing mode.Base on this point,we intend to study the feasibility of clinical application of low atrial septal pacing(Koch triangle) and compare with the traditional right atrial appendage pacing on long-term atrial tachyarrhythmia frequency by following up.The partⅠof this article evaluate the feasibility and safety of low atrial septal(RAS,the region of Koch triangle) pacing compared with the traditional right atrial appendage(RAA) pacing.Sixty patients who need DDD pacemaker were randomized equally to RAA and RAS pacing groups.In the RAS pacing group,active fixation lead was used to locate to the site of RAA first followed by screwing in the site of RAS.The difference in the pacing parameters,lead implantation success rate,X ray exposure time and dislocation rate during and after operation were investigated.The results of study are as follows:①pacing parameters:There are no difference in pacing threshold and impedance between two pacing sites. However,compared with RAA pacing site,the amplitude of P waves was higher (3.8±0.7mV vs 2.2±0.8mV,P value＜0.01) and width of pacing P wave was narrower(88±18 ms vs 154±37ms,P value＜0.01) in RAS pacing site; meanwhile,dispersion of pacing P wave was decreased(20.1±7.4ms vs 14.3±8.5ms,P value＜0.05) in it.②lead implantation success rate and X ray exposure time:the success rate of RAS was a little lower than RAA group(90%vs 100%,P value＞0.05),and the X ray exposure time in RAS site was much longer than RAA site(128±45svs 12±4s,P value＜0.01).③lead dislocation:during operation the lead dislocation of RAS and RAA site was 33.3%and 0%(P value＜0.05),respectively.2 cases of RAS group were found atrial lead dislocation during follow up,which no dislocation in RAA group.RAS pacing is feasible and markedly shorten biatrial activation times though the fixation to the RAS is more complicated compared with RAA placement.The partⅡof this article compare the frequency of long-term atrial tachyarrhythmia in RAA pacing group and RAS pacing group;and try to explore the possible mechanisms of it.Study observed the difference of maximum P wave duration(Pmax) and P wave dispersion(Pd) on electrocardiogram(ECG) owing to pacing different sites in atrium(including RAA and RAS) of patients with bradycardia-tachycardia syndrome(BTS).60 patients with BTS had successively accepted RAA pacing and RAS pacing,then the differences of Pmax and Pd on ECG were compared when sinus rhythm and both sites pacing.Afterwards they were randomly divided into the RAA pacing group and RAS pacing group.The frequency of long-term atrial tachyarrhythmia was followed up and recorded.The results of study are as follows:Pmax and Pd both increased when pacing different sites of atrium compared with when sinus rhythm,especially RAA pacing group increased significantly(152±16ms vs 92±15ms,19.9±8.6ms vs 14.1±7.6ms,Pvalue all＜0.05);on other hand,RAS pacing group increased slightly(135±16ms vs 128±15ms,16.3±8.1ms vs 14.1±7.6ms,P value all＞0.05).When followed up,the lower frequency of atrial tachyarrhythmia was observed in RAS pacing group(19±4 vs 23±6,P value＜0.05).From what have been discussed above,we may safely draw the conclusion: RAA pacing leads to an obvious increase in Pmax,Pd and intra-atrial anisotropy.While RAS pacing mimics physiological electropbysiological activity better,and deduces the frequency of long-term atrial tachyarrhythmia in the result.In RAA pacing group,an apparent increase in Pmax,Pd may contribute to a high frequency of atrial tachyarrhythmia. Low atrial septal pacing would play a meaningful role on prevention and treatment to atrial tachyarrhythmia.