| Background:In our country,the incidence rate of arrhythmia is high.Artificial cardiac pacing has become the only valid way to cure bradycardia.Traditional right ventricular apex(RVA) pacing is very popular,because the electrode can be located easily and rarely dislocated.However,it's may induce pacemaker syndrome or pacemaker induced cardiomyopathy.Recently,right ventricular outflow tract(RVOT) pacing has been found having more advantages,it can maintain better cardiac conduction sequence and get better hemodynamic effects than right ventricular apex pacing.But we haven't gold index to evaluate the effects after different ventricular sites pacing with DDD pacing mode.Purpose:research cardiac synchronization motion and cardiac function after right ventricular apex pacing and right ventricular outflow tract pacing with DDD pacing mode in sick sinus syndrome patients.Subjects and methods:forty-one patients with sick sinus syndrome had been randomly divided into two groups:Group A(n=22) would be implanted in RVA;Group B(n=19) would be implanted in RVOT.Two groups were examined by echocardiography before and the second day and 3 months,6 months after the operation on left ventricular end diastolic diameter(LVEDD),E/A,left ventricular ejection fraction(EF),myocardial performance index(Tei index),Left-right ventricle pre-ejection time delay(PET_d),Standard deviation of the time to peak of systolic velocity(Ts-SD), incidence rate of post systolic shortening(PSS).Meanwhile,plasma NT-proBNP were measured.Finally,compared the above data use SPSS 16.0.Results:1.After 2 days,3 months,6 months of pacemaker treatment,the LVEDD, E/A,EF didn't change against those before treatment(P＞0.05).There were no difference over the same period in the two groups(P＞0.05).2.In the next day of operation,PET_d reflected interventricular desynchronization(Group A t=12.361,P＜0.01;Group B t=11.112,P＜0.01).Group A was more evident(t=2.292,P=0.03).3.On the second day after operation Ts-SD reflected intraventricular desynchronization(A group t=33.426,P＜0.01;B group t=30,853,P＜0.01) Compared group B,group A were more asynchronous(t=4.041,P＜0.01).4.After 6 months,the incidence of PSS increased more significantly in group A than group B(χ~2=8.63,P＜0.01).The incidence of PSS was also markedly increased after 6 months than before in group A(χ~2=23.48,P＜0.01). Group B had no significant change before and after treatment(χ~2=2.80,P＞0.05).5. After 6 months,the Tei index were significantly higher than that before treatment both in A and B groups(A t=33.328,P＜0.01,B t=32.118,P＜0.01).It increased more significantly in A than that of B(t=2.231,P=0.03).6.After 6 months,the NT-proBNP increased significantly in group A(t=3.562,P＜0.01),but there was no change in group B(t=0.221,P=0.82) when compared with those before operation.At the same time,the level of NT-proBNP was more higher in group A than group B(t=2.727,P=0.01).Conclusion:After DDD pacing,whether apex or outflow tract pacing affect interventricular and intraventricular cardiac synchronization motion.Apex pacing influence more significantly on cardiac motion than outflow tract pacing.
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