| Objective:In 1998, P-wave dispersion is a new concept to reflect the atrial site compliance and non-homogeneous electrical activity that is ejected by Dilaveris. In recent years, studies have shown that, P-wave dispersion for predicting atrial arrhythmia, particularly atrial fibrillation occurred in a surface electrocardiogram as a new indicator. Some studies consider that Pd>40ms as a standard, predict idiopathic atrial fibrillation with sensitivity of 81%, specificity of 80%, positive predictive accuracy of 85%. P-wave maximum duration (Pmax) refers to the simultaneous 12-lead ECG in the largest P wave duration, which is considered of intraatrial and interatrial conduction block. It deems that the normal intraatrial conduction time, forward or reverse at all times in the 50ms or so. When intraatrial and interatrial conduction block development, the surface ECG P wave duration have experienced Pmax(≥ll0ms) or double-hump P-wave ,peaks' distance > 40ms, and it is easy to develop excitement reentrant and lead to atrial arrhythmia. In recent years, it often joint P-wave dispersion together as one of the indicators as a predictor of atrial fibrillation. The value for predicting atrial fibrillation is confirmed. The indicator for predicting atrial arrhythmia and atrial fibrillation sensitivity is as high as 85%. When it is combined with P-wave dispersion,it can increase the sensitivity of atrial fibrillation to 75%, specificity is increased to 90%, positive predictive accuracy increase to 92%. Right ventricular apical, which consists of abundant trabecular muscles, is a traditional right ventricular pacing electrode placement site. However, site is non-physiological pacing site. Modern pacing electrophysiological studies suggest that right ventricular apex pacing may exacerbate or precipitate the occurrence of atrial fibrillation in the future. However, the study is not so many about the right ventricular apex pacing and the occurrence of atrial fibrillation of time, the trend of right ventricular apical pacing with P wave dispersion change. The purpose of this study is by observing the right ventricular apex pacing in patients with P wave dispersion change in the near future to study the correlation of the right ventricular apex pacing and atrial fibrillation.Atrial fibrillation (AF) is a one of the most common and harmful arrhythmia in clinic, most of AF is occurred in patients with organic heart disease, a few can be no heart disease, and its incidence increased with age and cardiovascular disease, showing clearly increasing trend. In this century, atrial fibrillation has become one of the great challenges facing humanity, through the extension of surface ECG P wave duration(>110ms) and the P-wave dispersion increased(≥40ms) can be distinguished at high risk of atrial fibrillation, and there is a broad prospect in predicting atrial fibrillation.This study is by way of VVI (right ventricular apex pacing) pacemaker implantation in patients with preoperative and postoperative measurement of follow-up 12-lead simultaneous ECG P-wave dispersion to predict the occurrence of atrial fibrillation, and base on the results for the corresponding clinical interventions, to prevent or delay the occurrence of atrial fibrillation and improve the quality of life.Method: Choose from February, 2009 to November, 2009 in the Second Hospital affiliated Hebei Medical University, 47 cases of patients who is implanted VVI pacemaker at right ventricular apex, Male 25 cases, female 22 cases, age 64.40±9.45 years (49 ~ 77 years). 40 cases of coronary heart disease, hypertension in 35 cases. Sick sinus syndrome in 21 cases, of which 10 cases associated with paroxysmal atrial fibrillation and sinus arrest in 11 cases. 24 cases of third degree A-V block, second degreeⅡtype A-V block in 2 cases. All the patients is to be selected that they were not aware VVI pacemaker doctors choose the right ventricular apex pacing selected, retrospective analysis of pacemaker implantation before the body surface 12-lead ECG, tracing observed after 7 days, after 3 months the body surface 12-lead ECG. Also set up the control group, 21 cases is selected for the same period hospitalization in patients without implanted pacemakers, male 12 cases and 9 females, age 60.85±8.16 years (45 ~ 77 years), of which 19 patients with coronary heart disease, hypertension in 16 cases.Application of U.S. General Electric Company MAC1200ST type ECG records 12 electrocardiograms conductor, paper speed 50mm / s, gain 20mm/mV, and measures 12-lead simultaneous ECG in at least nine leads of P-wave maximum duration (Pmax) and P-wave minimum duration (Pmin), the difference between the two P-wave duration is P wave dispersion (Pd). Namely, Pd = Pmax– Pmin.Using Medtronic company 9790C-type program-controlled instrument, program pacemaker after 7 days and after 30 days of operation respectively, according to programmed pacing rate instrument display of pacing rate>50% are divided into pacing-dependent group (33 cases), pacing rate≤50% to establish pacing non-dependent group (14 cases).3 months follow-up of the incidence of atrial fibrillation is observated.Statistical analysis: Measurement data with the mean±standard deviation ( x±s), pacemaker group and control group use t-test to compare Pd and Pmax, and compare after 7 days and after 3 months of the Pd and Pmax between pacing-dependent group and non-dependent group. Pacemaker group are treated with repeated measure analysis of variance to compare Pd and Pmax at three different observation time points. To use the line of the relevant analysis and compare with the pacing ratios and Pd and Pmax. P<0.05 is statistically significant, all statistical analysis is done on the software SPSS16.0.Results:1. The preoperative pacemaker group and control group of Pd and Pmax comparison of the preoperative pacemaker group and control group of Pd, respectively 28.79±9.53 (ms) and 30.95±8.03 (ms), Pd of the two groups is no statistical difference (P>0.05); the preoperative pacemaker group and control group Pmax are 99.67±12.57 (ms) and 105.71±9.95 (ms), the two groups Pmax was no significant difference (P>0.05), it is no difference between the two groups of age , gender and type of disease. Pacemaker group of patients before and after 7 days, after 3 months, three observation time points Pd are 28.79±9.53 (ms), 31.20±7.21 (ms), 35.85±6.62 (ms). The results show at three time points of Pd there is significant difference (P<0.05), and further to do pairwise comparison of the results of variance analysis, it shows preoperative and postoperative 7-day comparison is no statistically significant difference(P>0.05), the result of preoperative and postoperative 3 months is statistically different compared of Pd(P<0.05), when postoperative 7 days group and postoperative 3 months group compared ,it is significant difference of Pd (P<0.05). Pacemaker group of patients before and after 7 days, after 3 months, three observation time points Pmax were 99.67±12.57 (ms), 101.04±11.87 (ms), 105.03±6.16 (ms). The results show three time points of Pmax are statistically different (P<0.05), and further to do pairwise comparison of the results of variance analysis, it shows preoperative and postoperative 7 days compared Pmax is no significant difference (P>0.05), the result of preoperative and postoperative 3 months is statistically difference of Pmax comparing(P<0.05), when postoperative 7 days and postoperative 3 months compared ,it is significant difference of Pmax (P<0.05).2. Pacemaker-dependent group and non-pacemaker dependent group comparison of Pd and Pmax pacemaker-dependent group and non-pacemaker dependent group after 7 days Pd are 31.58±6.78 (ms) and 30.31±8.35 ( ms), after 7 days Pd between the two groups show no significant difference (P>0.05). Pacemaker-dependent and non-dependent group after 3 months Pd are 36.17±5.92 (ms) and 35.09±8.24 (ms), between the two groups after 3 months Pd is no significant difference (P>0.05). Pacemaker-dependent group and non-pacemaker dependent group after 7 days Pmax are 101.38±10.59 (ms) and 100.24±14.87 (ms), Pmax between the two groups after 7 days is no significant difference (P>0.05). Pacemaker-dependent group and non-pacemaker dependent group after 3 months Pmax are 106.16±9.06 (ms) and 102.37±12.35 (ms), between the two groups after 3 months Pmax is no statistically significant difference (P>0.05). 3. The correlation between the pacing ratios and Pd of patients after 7 days and 3 months. The correlation coefficient of pacemaker ratio and Pd as 0.1 after 7 days, P>0.05, no statistics. The correlation coefficient of pacemaker ratio and Pd as 0.059 after 3 months, P>0.05, no statistics. The correlation coefficient of pacemaker ratio and Pmax as 0.105 after 7 days, P>0.05, no statistics. The correlation coefficient of pacemaker ratio and Pmax as 0.154 after 3 months, P>0.05, no statistics.4. The patients'3-month observation period for pacemaker group, founds no new cases of atrial fibrillation occurrence.Conclusion:1 Right ventricular apex VVI pacing in short-term there may be occur Pd and Pmax changes, with time extension, Pd and Pmax are increased.2 It is no significant effect for right ventricular apex VVI pacing ratios to Pd and Pmax, but the relatively small sample size of this study, according to pacing rate of 50% of the group, there may be some group deflexion.3 Right ventricular apex VVI pacing can lead to atrial electrophysiological disorder, leading to Pd and Pmax increases.4. There is no statistically correlation between pacing ratios and Pd and Pmax.
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