Correlation Between QRS Duration And Cardiac Function After Cardiac Pacing

Objective:To study the correlation between QRS time limit of ECG and cardiac function in patients after implantation of dual-chamber pacemakers,and to analyze the long-term changes of cardiac cardiac size and left ventricular function in patients with dual chamber pacemaker.Methods:Patients with permanent dual chamber pacemaker implanted at the outpatient clinic of Shanxi Baiqiuen Hospital from November 2011 to January 2020 were enrolled.Pacemakers were implanted to treat Sick sinus syndrome(SSS)and Atrioventricular block(AVB).At the time of pacemaker implantation,patients showed no serious heart diseases or cardiac dilatation and had normal cardiac functions,who could provide complete preoperative and postoperative information related to the pacemaker;The pacing rate was higher than 40%.Left atrial diameter(LAD),left ventricular end diastolic dimension(LVEDD),left ventricular end systolic dimension(LVESD)and left ventricular ejection fraction(LVEF)were measured by ultrasound cardiogranm at pre-operation,the 1st month,3rd month,6th month,1st year,2nd year and 3rd year after pacemaker implantation,and QRS time limit of ECG.To investigate the effects of long-term pacemaker implantation on cardiac size and left ventricular function through a before-and-after self-controlled design,and to analyse the correlation between QRS time limit of ECG and cardiac function in patients after implantation of dual-chamber pacemakers.Results:(1)According to the results of the relevant indicator of echocardiography after dual chamber pacemaker implantation,LVEF 、 LAD 、 LVESD and LVEDD had statistical significance at different time points before and after treatment(P<0.05).Among them,LAD is lower than before implantation 1st month,3rd month after pacemaker implantation[(27.80±3.00)mm vs(26.26±2.97)mm、(26.10±2.60)mm],and LAD is greater than before implantation 1st,2nd or 3rd year after operation[(27.80±3.00)mm vs(28.70±3.16)mm、(29.23±2.98)mm、(29.60±3.37)mm].LAD had no difference before the pacemaker implantation and 6th month after dual chamber pacemaker implantation(P=0.163).LVESD had no difference before the pacemaker implantation and 2nd year after dual chamber pacemaker implantation(P>0.05).LVESD is lower than before implantation 1st month,3rd month,6th month and 1st year after surgery[(30.60±3.51)mm vs(29.60±3.09)mm、(28.90±3.72)mm、(28.42±4.00)mm、(29.99±4.21)mm],and increases2 nd 、 3rd year after pacemaker implantation,which is larger than before implantation[(30.60±3.51)mm vs(31.39±3.28)mm].The difference is statistically significant(P<0.05).LVEDD is statistically significant when it is lower than before implantation 1st month,3rd month,6th month and 1st year after implantation[(44.27±4.48)mm vs(43.18±3.89)mm、(43.58±3.45)mm、(43.57±3.55)mm、(43.69±3.25)mm],and 2nd and 3rd year after operation than before implantation[(44.27±4.48)mm vs(44.78.±3.11)mm 、(45.65±3.55)mm,(P<0.05)].The LVEF at 1st month,3rd month,6th month and 1st year after implantation of the pacemaker increased compared with that before implantation(59.04%±4.69% vs 60.31%±5.49% 、61.36%±5.56%、62.47%±5.67%、60.83%±5.44%),and the LVEF decreased at 2nd year and 3nd year after implantation,which was lower than the LVEF before implantation(59.04%±4.69% vs 58.16%±4.92% 、 57.85%±5.64).The difference is statistically significant(P<0.05).(2)The overall trend of LAD,LVESD and LVEDD was first reduced and then increased.Within 6 months after dual chamber pacemaker implantation,LAD,LVESD and LVEDD gradually shrinks,and then gradually increased,.The overall trend of LVEF is to rise first and then decrease,and LVEF peaked at 6th month after dual chamber pacemaker operation and gradually decreased.(3)Spearman correlation analysis indicated that ECG QRS duration was significant inversely correlated with LVEF(r =-0.4643,P=0.000),and significant positively correlated with LVESD and LVEDD(r =0.133 ～ 0.151,P < 0.05)in patients after pacemaker implantation,there was no significant correlation with LAD.Conclusion:(1)After implanting a double-chamber pacemaker in a short time,it can improve cardiac function,enhance left ventricular contraction,and improve ventricular structure;However,long-term dual chamber pacing will reduce cardiac function,reduce ejection fraction and enlarge the heart size.This change is more obvious in patients implanted with dual chamber pacemaker for more than 2 years;(2)QRS duration may be used as an objective index to evaluate the patients’ cardiac structure and left ventricular function after implantation of dual chamber pacemaker.The longer the QRS duration,the larger the patient’s heart size and the worse the left ventricular function.