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Objective:To explore the feasibility and safety of making the right atrial septum pace by adopting capsure fix; study the influence on the pacing parameters by pacing from different parts of the right atrium; to assess the effects on the conduction sequence and the synchronism of the atrium activation (including left and right) through the comparison of duration and P wave morphology of pacing electrocardiogram (ECG) between right atrial septum (RAS) and right atrial appendage (RAA), to guide the selection of the implantation position of right atrium pacing electrode in the surgery.Methods:First, select 50 patients with sick sinus syndrome (SSS) who need the pacemakers, 27 males and 23 females, aged 70.97±10.86 (31～88), and implant DDD pacemaker to them. Before the operation, record the 12-lead synchronous ECG of routine body surface (25mm/s paper speed,10mm= 1mV), and randomly divide the patients into RAS pacing group and RAA pacing group,25 cases respectively, according to different implantation locations of RAS pacing electrode, both groups select capsure fix and fix them respectively in the corresponding position. The records of the 12-lead pacing ECG should be made following the ways as above on the surgery day and the 7th postoperative day. Measure P wave duration of preoperative and postoperative pacing ECG of the body surface, including P wave maximum duration (Pmax) and P-wave minimum duration (Pmin), and calculate P-wave dispersion (Pd), compare P wave maximum duration and P-wave dispersion (Pd) between the two groups. Chosen from the synchronous 12-lead ECG, the objects measured above were all the clear cardiac cycle graphs whose baseline is stable, and by the same person. Define P wave beginning as the starting point of the earliest baseline leaving of negative P-wave downward or positive P-wave upward, and the P-wave end as the ending point of the latest baseline return of negative P-wave upward from the bottom or positive P-wave downward from the top. Compare and study the preoperative ECGⅡ,Ⅲ, avF and V1 lead P-wave morphology between the two groups. Record the parameters of different pacing parts, and compare the operation time, X-ray exposure time, pacing parameters, and complication of the implantation of different pacing parts.Results:①Before surgery, the comparison of the sinus P wave duration and morphology between the two groups are statistically meaningless (P>0.05).②After surgery, on the same day, the comparison of P wave maximum duration and P-wave dispersion between the preoperative and postoperative data is statistically meaningless (P>0.05).③After surgery, on the same day, the comparison of pacing P-wave morphology according to different implantation positions of atrium electrode between the preoperative and postoperative data is obviously different.④One week after surgery, compare the data of P wave maximum duration and P-wave dispersion to that before surgery, the RAS pacing group has a noticeable reduction, while the RAA pacing group has a noticeable increase; the comparison is statistically meaningful (P<0.05).⑤One week after surgery, compared to the pacing P wave maximum duration and P-wave dispersion of RAA, the data of RAS group is significantly reduced, and this is statistically meaningful(P<0.05).⑥The implantation time and X-ray exposure time is obviously different between the two groups, with statistical significance (P<0.05). RAS pacing group has more prolonged implantation time and X-ray exposure time than the RAA pacing group.⑦Tne week after implantation, the pacing thresholds of the two groups both rise (P<0.05); 1 month and 3 months after the surgery, compared the data to that in the surgery, no statistic significance (P>0.05); the impedance after surgery is lower than that in the surgery (P<0.05).⑧The comparison between the two groups of the pacing threshold, impedance, and implantation complication is not statistically significant (P>0.05).Conclusion:It is safe and feasible to make the RAS pace by adopting capsure fix. Compared to RAA, RAS pacing can significantly shorten the right and left atrial activation time, and different right atrium pacing positions can change P wave maximum duration and P-wave dispersion; the change of the characteristic of ECG P wave can direct the choice of the right atrium pacing position of the pacemaker.
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