| Objective:The main objection of this study was to observe the changes in pacing parameters especially the pacing thresholds of active fixation leads at the time of implantation and within 3 months after implantation to evaluate whether the active fixation atrial leads were safe and effective or not.Methods:One hundred and nine patients who were implanted with new buried-type permanent artificial cardiac pacemaker from November 2015 to June 2016 in our Department of Cardiology in Ruijin hospital were enrolled.All the patients were subdivided into two group according to the type of atrial leads: Active fixation atrial leads group(68 patients)and Passive fixation atrial leads group(41 patients).Pacing parameters between the two groups at implantation,1 and 3 months after operation were compared.Furthermore,patients of active fixation atrial leads group were divided into high threshold group(>1 V)and low threshold group(?1 V)based on the initial pacing threshold when the atrial spiral electrode span out.Detailed analysis of pacing parameters especially pacing thresholds were collected after operation 1,3,6,24 hours and 1,3 months.Compare the differences between the pacing parameters particularly the pacing thresholds at the post-operation and intraoperation.Much attention was paid to the occurrence of intraoperative and postoperative complications such as chest tightness,chest pain,pericarditis and cardiac tamponade and so on.Results:For the passive fixation atrial leads group(41 patients),at the time of implantation and 1,3 months after operation,pacing thresholds were(0.67+0.28)V?(0.45+0.16)V?(0.41+0.15)V,senses were(3.20+1.34)mV?(3.15+1.42)mV?(3.03+1.31)mV,impedances were(526.51+93.06)??(533.63+89.64)??(535.17+90.64)? respectively.For the active fixation atrial leads group(68 patients),at the time of fixation and 1,3 months after operation,pacing thresholds were(1.12+0.40)V?(0.49+0.12)V?(0.42+0.13)V,senses were(2.84+1.17)mV?(2.75+1.36)mV?(2.61+1.27)mV,impedances were(454.56+82.51)??(370.53+87.86)??(371.07+86.14)? respectively.Pacing thresholds of active fixation atrial leads group at implantation were higher than passive fixation atrial leads group,the differences for pacing thresholds of the two groups postoperative 1 and 3 months had no statistical significances(all P >0.05);impedances of active fixation atrial leads group were lower when compared with passive fixation atrial leads group,the differences of impedances between the two groups had a remarkable statistical significances(all P<0.01).But the differences of senses between the two groups had no statistical significances(all P >0.05).For all the 68 patients,at the time of the fixation?after operation 1?3?6?24 hours?1 and 3 months,the pacing thresholds were(1.12+0.40)V?(0.77+0.33)V?(0.67+0.23)V?(0.61+0.19)V?(0.59+0.21)V?(0.49+0.12)V?(0.42+0.13)V;the senses were(2.84+1.17)mV?(2.45+1.01)mV?(2.46+0.96)mV?(2.56+0.97)mV?(2.55+1.03)mV?(2.75+1.36)mV?(2.61+1.27)mV;the impedances were(454.56+82.51)? ?(391.79+93.47)? ?(388.37+85.90)? ?(375.01+83.30)? ?(375.94+79.64)? ?(370.53+87.86)? ?(371.07+86.14)? respectively.The intraoperative pacing threshold was high,it decreased rapidly after operation 1 hour,and further declined after operation 24 hours,kept stable after 3 months.The postoperative pacing thresholds at different timepoints within 3 months were statistically significant when compared with the intraoperative pacing threshold(all P<0.01).The senses during the operation for all the patients were good,it went down 1 and 3 hours after operation and went up after operation 6 hours,kept stable 3 months after operation.The impedance during the operation was relatively high,but fell significantly at all the timepoints within postoperative 3 months.The impedances differences between postoperation and intraoperation were statistically significant(all P<0.01).Among the 68 patients,an initial threshold at implantation of ? 1 V [mean(0.79+0.20)V] was demonstrated in 35/68(51%)leads,falling to(0.69+0.34)V just 1 h after operation,at post-operation 3 h(0.61+0.21)V,6 h(0.59+0.19)V,24 h(0.58+0.18)V,1 month(0.50+0.10)V,3 months(0.42+0.13)V.The thresholds 3,6,24 h,1 and 3 months after operation had obvious statistical significances compared with the threshold at implantation(all P < 0.01);for the low threshold group,during operation and after operation,the senses were(2.93+1.08)mV?(2.56+1.11)mV?(2.53+0.99)mV?(2.54+0.96)mV?(2.51+1.00)mV?(2.87+1.40)mV?(2.55+1.16)mV,the impedances were(453.77+90.59)??(396.37+101.01)??(394.20+96.91)??(376.69+82.91)??(375.46+83.87)??(362.23+87.35)??(362.34+85.24)? respectively.An initial threshold at implantation of >1 V [mean(1.48+0.20)V] was demonstrated in 33/68(49%)leads falling significantly to(0.85+0.32)V just 1 h after operation,at postoperation 3 h(0.74+0.23)V,6 h(0.64+0.18)V,24 h(0.60+0.24)V,1 month(0.48+0.14)V,3 months(0.42+0.14)V.The differences between the threshold within 3 months and the threshold at implantation had obvious statistical significances(all P<0.01).For the high threshold group,at different timepoints during and after operation,the sense were(2.75+1.26)mV?(2.33+0.90)mV?(2.38+0.93)mV?(2.58+1.00)mV?(2.58+1.07)mV?(2.61+1.33)mV?(2.68+1.38)mV;the impedance were(455.40+74.40)??(386.94+86.04)??(382.18+73.45)??(373.24+84.96)??(376.45+76.19)?(379.33+88.87)??(380.33+87.42)? respectively.The differences of sense and impedance at different timepoints between the high and low pacing threshold groups all had no evident statistical significances(all P>0.05).Except for 3 hours after operation,the other postoperative pacing thresholds between the two groups had no statistical significances(all P>0.05).In this study,We didn't observe any complications of atrial active fixation leads and passive fixation leads for all the patients.Conclusions:1?At the time of implantation,the pacing thresholds of active fixation atrial leads group are higher than passive fixation atrial leads group,it decreased 1 and 3 months after operation and had no statistical significances when compared with passive fixation atrial leads group.2?Active fixation atrial leads are commonly associated with initially high thresholds at the time of implantation that fall rapidly after operation.The majority will have a threshold of <1 V the following day and keep stable within short time.The high thresholds at the time of implantation should not be considered as a standard to change the pacing site immediately.3?The sense of active fixation atrial leads is favorable both during and after operation,and the fluctuation range is permitted.The impedance of active fixation atrial leads is high at the moment of fixation,but falls remarkably after follow-up observation,and maintains in a more stable level 3 months later.The impedance of active fixation atrial leads group are lower when compared with passive fixation atrial leads group both at implantation and within 3 months after operation.4?The complications of the active fixation leads do not increase considerably.Therefore,the active fixation atrial leads are safe and effective after implanted,they can be applied in the clinical work broadly. |
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