the number of cardiovascular implantable electronic device ( cied ) implantation has increased over the past few years . the conventional access of lead implantation is the subclavian vein , which is often accompanied by high complication rate , including pneumothorax , hemopneumothorax , inadvertent artery puncture , local hematoma , subclavian crush syndrome , and difficulty in lead operating . thus , the axillary vein puncture has been proposed as an alternative technique to the conventional subclavian vein access . however , the comparison between subclavian and axillary vein access through large - size sampled and randomized clinical trial is still limited . here , we proposed a randomized , two - armed , open - label study to analyze the efficacy and safety of optimized axillary vein puncture versus conventional subclavian puncture in cied implantation . patients aged 18 years or older with the indication of permanent pacemakers , cardiac resynchronization therapy pacemakers / defibrillators ( crt - p / crt - d ) , and implantable cardioverter defibrillators ( icd ) were included in the study . all eligible patients were asked to sign and date an informed consent document in person before randomized into different groups . patients undergoing lead replacement were excluded from the study . the study was reviewed and approved by the clinical research ethics board at china - japan friendship hospital and was registered to www.clinicaltrials.gov with trial number nct02358551 . according to a computer - generated randomization list , patients were randomized to the optimized axillary vein puncture group or the conventional subclavian vein puncture group at a ratio of 1:1 using an 8-sized block . the pulse generators were implanted on the surface of pectoralis major on the same side . operated chest walls were locally strapped for 24 h and pressed with sandbags for 4 h. operations in both groups were performed consistently by one skilled electrophysiology physician . is usually fixed , we used the 21-g needle to search for the axillary vein with x - ray fluoroscopy at the point where the first rib meets the clavicle . the direction of needle was toward the first anterior rib , with an angle of about 4560 between the needle and the skin . after the venous blood was drawn , a 0.018 inch j - shaped guidewire was put into the 21-g needle , and the 5 fr sheath ( cook group incorporated , bloomington , indiana , usa ) was inserted into the vein [ figure 1 ] . subsequently , both the 0.018 inch guidewire and 5 fr sheath were replaced by the standard 0.035 inch j - shaped guidewire and the peel - away electrode lead sheath ( biotronik , berlin , germany ) . if five attempts of puncture failed , an ipsilateral cubital vein angiography will be performed to observe the passage of axillary vein [ figure 2 ] and subsequently the same method of vein puncture should be used as stated above . the left arrow indicates the axillary vein and the right arrow indicates the subclavian vein . subclavian vein puncture ipsilateral cubital vein trocar was retained before the procedure . pacemaker pocket was created below the clavicle . we used the 18-g needle to search for the subclavian vein with x - ray fluoroscopy at the point of clavicle . the entry point of the needle was a one - third point to the sternoclavicular joint , and direction of the needle was toward the suprasternal fossa , with an angle of about 1530 between the needle and the skin . after the venous blood was drawn , a standard 0.035 inch j - shaped guidewire and the peel - away electrode lead sheath were inserted into the vein . if five attempts of puncture failed , an ipsilateral cubital vein angiography will be performed to observe the passage of subclavian vein and the same method of vein puncture should be used as stated above . success of puncture was defined as drawing of venous blood and insertion of guidewire and sheath . one - time success was defined as minor adjustment of needle direction and point of puncture , without withdrawing the needle . number of puncture needed , length of time in puncture and x - ray exposure , parameters of pacemakers including threshold , impedance , and p / r wave amplitude were recorded . patients were followed up at 1 , 3 , 6 , and 12 months after the operation and for every 12 months afterward . continuous variables were used to compare between groups by t - test for normally distributed values ; otherwise , mann - whitney u - test should be used . patients aged 18 years or older with the indication of permanent pacemakers , cardiac resynchronization therapy pacemakers / defibrillators ( crt - p / crt - d ) , and implantable cardioverter defibrillators ( icd ) were included in the study . all eligible patients were asked to sign and date an informed consent document in person before randomized into different groups . patients undergoing lead replacement were excluded from the study . the study was reviewed and approved by the clinical research ethics board at china - japan friendship hospital and was registered to www.clinicaltrials.gov with trial number nct02358551 . according to a computer - generated randomization list , patients were randomized to the optimized axillary vein puncture group or the conventional subclavian vein puncture group at a ratio of 1:1 using an 8-sized block . the pulse generators were implanted on the surface of pectoralis major on the same side . operated chest walls were locally strapped for 24 h and pressed with sandbags for 4 h. operations in both groups were performed consistently by one skilled electrophysiology physician . is usually fixed , we used the 21-g needle to search for the axillary vein with x - ray fluoroscopy at the point where the first rib meets the clavicle . the direction of needle was toward the first anterior rib , with an angle of about 4560 between the needle and the skin . after the venous blood was drawn , a 0.018 inch j - shaped guidewire was put into the 21-g needle , and the 5 fr sheath ( cook group incorporated , bloomington , indiana , usa ) was inserted into the vein [ figure 1 ] . subsequently , both the 0.018 inch guidewire and 5 fr sheath were replaced by the standard 0.035 inch j - shaped guidewire and the peel - away electrode lead sheath ( biotronik , berlin , germany ) . if five attempts of puncture failed , an ipsilateral cubital vein angiography will be performed to observe the passage of axillary vein [ figure 2 ] and subsequently the same method of vein puncture should be used as stated above . the left arrow indicates the axillary vein and the right arrow indicates the subclavian vein . subclavian vein puncture ipsilateral cubital vein trocar was retained before the procedure . pacemaker pocket was created below the clavicle . we used the 18-g needle to search for the subclavian vein with x - ray fluoroscopy at the point of clavicle . the entry point of the needle was a one - third point to the sternoclavicular joint , and direction of the needle was toward the suprasternal fossa , with an angle of about 1530 between the needle and the skin . after the venous blood was drawn , a standard 0.035 inch j - shaped guidewire and the peel - away electrode lead sheath were inserted into the vein . if five attempts of puncture failed , an ipsilateral cubital vein angiography will be performed to observe the passage of subclavian vein and the same method of vein puncture should be used as stated above . success of puncture was defined as drawing of venous blood and insertion of guidewire and sheath . one - time success was defined as minor adjustment of needle direction and point of puncture , without withdrawing the needle . number of puncture needed , length of time in puncture and x - ray exposure , parameters of pacemakers including threshold , impedance , and p / r wave amplitude were recorded . patients were followed up at 1 , 3 , 6 , and 12 months after the operation and for every 12 months afterward . continuous variables were used to compare between groups by t - test for normally distributed values ; otherwise , mann - whitney u - test should be used . a total of 247 patients were enrolled in this study between january 2013 and november 2015 , with no loss during follow - ups . among all the patients , 125 were randomized into the axillary vein group and 122 were randomized into the subclavian vein group . the sex and age distribution , body mass index , and types of cied were similar between the two groups . baseline characteristics of the study population * normally distributed continuous variables are presented as mean  sd . :  value ; : t value . cied : cardiovascular implantable electronic device ; crt - p / crt - d : cardiac resynchronization therapy pacemakers / defibrillators ; icd : implantable cardioverter defibrillator ; sd : standard deviation . patients in the axillary vein group were implanted with 231 pacing / defibrillation electrode leads , of which 221 punctures succeeded . patients in the subclavian vein group were implanted with 227 pacing / defibrillation electrode leads , of which 218 punctures succeeded . one - time success rate of both groups was 68.4% ( 158/231 ) and 66.1% ( 150/227 ) , respectively . the mean time spent in puncture of the axillary vein group was 45.9  14.1 s , whereas in the subclavian vein group , it was 28.7  13.9 s ( t = 9.679 , p < 0.001 ) . the duration of x - ray exposure was 150.1  33.6 s and 145.5  34.9 s , respectively [ table 2 ] . success rate and duration of the procedure * normally distributed continuous variables are presented as mean  sd . the vein punctures failed in 11 patients , who all received cubital vein angiographies to observe the passage of axillary veins or subclavian veins . among them , three patients in the axillary vein group had total occlusion of veins and two had shifting veins ; two patients in the subclavian vein group had total occlusion of veins , one had vein stenosis , and three had shifting veins . we successfully performed the puncture under the guidance of angiography or performed the procedure on the opposite side . in the subclavian vein group , pneumothorax occurred in three patients . three patients subclavian gaps were too tight to allow operation of the electrode lead ( all of them had puncture repeated once to complete the operation ) . there were no puncture - associated complications in the axillary vein group . in either group , none had pocket hematoma or other severe complications . in a mean follow - up of 24.1  7.4 months , lead dislocations occurred in one patient in both groups , both of whom underwent lead replacements . pocket infection occurred in one patient in both groups , both of whom underwent pocket debridement and later were implanted with the cieds in the opposite side . two patients in the subclavian vein group had subclavian crush syndrome , both of whom underwent lead replacements . the remaining patients had no complications , and threshold , p / r wave amplitude , and impedance of their cieds were all in the normal range during the follow - ups . the complication rate in perioperative period and follow - ups of the axillary and subclavian vein group was 1.6% ( 2/125 ) and 8.2% ( 10/122 ) , respectively (  = 5.813 , p = 0.016 ) [ table 3 ] . complications in perioperative period and follow - ups a total of 247 patients were enrolled in this study between january 2013 and november 2015 , with no loss during follow - ups . among all the patients , 125 were randomized into the axillary vein group and 122 were randomized into the subclavian vein group . the sex and age distribution , body mass index , and types of cied were similar between the two groups . baseline characteristics of the study population * normally distributed continuous variables are presented as mean  sd . :  value ; : t value . cied : cardiovascular implantable electronic device ; crt - p / crt - d : cardiac resynchronization therapy pacemakers / defibrillators ; icd : implantable cardioverter defibrillator ; sd : standard deviation . patients in the axillary vein group were implanted with 231 pacing / defibrillation electrode leads , of which 221 punctures succeeded . the overall success rate was 95.7% . patients in the subclavian vein group were implanted with 227 pacing / defibrillation electrode leads , of which 218 punctures succeeded . one - time success rate of both groups was 68.4% ( 158/231 ) and 66.1% ( 150/227 ) , respectively . the mean time spent in puncture of the axillary vein group was 45.9  14.1 s , whereas in the subclavian vein group , it was 28.7  13.9 s ( t = 9.679 , p < 0.001 ) . the duration of x - ray exposure was 150.1  33.6 s and 145.5  34.9 s , respectively [ table 2 ] . success rate and duration of the procedure * normally distributed continuous variables are presented as mean  sd . : the vein punctures failed in 11 patients , who all received cubital vein angiographies to observe the passage of axillary veins or subclavian veins . among them , three patients in the axillary vein group had total occlusion of veins and two had shifting veins ; two patients in the subclavian vein group had total occlusion of veins , one had vein stenosis , and three had shifting veins . we successfully performed the puncture under the guidance of angiography or performed the procedure on the opposite side . three patients subclavian gaps were too tight to allow operation of the electrode lead ( all of them had puncture repeated once to complete the operation ) . group , none had pocket hematoma or other severe complications . in a mean follow - up of 24.1  7.4 months , lead dislocations occurred in one patient in both groups , both of whom underwent lead replacements . pocket infection occurred in one patient in both groups , both of whom underwent pocket debridement and later were implanted with the cieds in the opposite side . two patients in the subclavian vein group had subclavian crush syndrome , both of whom underwent lead replacements . the remaining patients had no complications , and threshold , p / r wave amplitude , and impedance of their cieds were all in the normal range during the follow - ups . the complication rate in perioperative period and follow - ups of the axillary and subclavian vein group was 1.6% ( 2/125 ) and 8.2% ( 10/122 ) , respectively (  = 5.813 , p = 0.016 ) [ table 3 ] . common vein access for cied lead implantation was cephalic , subclavian , and axillary veins . subclavian vein puncture has faster learning curve , and the success rate is generally high . however , due to its anatomic characteristics , complications are relatively common , including pneumothorax , hemopneumothorax , inadvertent subclavian artery puncture , brachial nerve plexus injury , subclavian crush syndrome , and electrode lead fracture . a large - scale retrospective study found that cephalic vein access was related with lower rate of lead failure . however , it requires vein incision which renders the operation more complicated and time consuming . moreover , the size of the axillary vein is relatively small , thus it often suffers from a high failure rate , especially with multiple leads . the number of implantations of icds and crt - ps / crt - ds has increased in the past few years , and cephalic vein puncture may not be an optimal procedure . anatomically , the axillary vein terminates at the lateral margin of the first rib and becomes the subclavian vein . its passage is outside the clavicle and far from the cupula pleurae , and the diameter is larger compared with the cephalic vein with little variation . therefore , the axillary vein puncture avoids nerve or pleura injury and subclavian crush syndrome , which ensures a high success rate . however , these maneuvers are complicated and have steep learning curves , which limit the clinical application . belott reported an approach based on anatomic landmark on body surface and radiograph , where the axillary vein terminates and becomes the subclavian vein with little variation . overall , axillary vein punctures guided by fluoroscopic landmark , contrast venography , or ultrasound have shown high success rate and low complication rate . in this trial , furthermore , we used the 21-g needle instead of the routine 18-g needle , which reduced tissue injury as well as the risk of artery injury and pneumothorax . in this study , the overall success rate and one - time success rate of axillary and subclavian vein puncture were similar . no pneumothorax or difficulty on lead operating occurred in the operation and no subclavian crush syndrome occurred in the follow - ups , which confirmed the efficacy and safety of this technique . no pocket hematoma or other severe complications occurred in either group , probably due to the operator 's experience and the use of electrotome . the duration of procedure in the axillary vein group is longer than the subclavian group , probably because the axillary vein puncture requires more fluoroscopy guidance and searching in local area . in addition , the axillary vein puncture included an extra procedure : exchange of guidewire and sheath , which was time consuming . the relatively steep learning curve of axillary vein puncture is an issue , and innovations in the axillary vein puncture have been proposed recently , such as using the cephalic vein as anatomic landmark , introducing guidewire retrogradely from the femoral vein up to the left axillary vein as roadmap , and utilizing the caudal fluoroscopic view . first , the relatively short follow - up period is not sufficient to evaluate long - term efficacy . second , it was a single - centered trial and all the procedures were performed by one operator , thus interpretation and extrapolation of the results should be cautious . a multi - centered trial with larger scale and longer follow - ups is necessary to present more evidence of the advantage of the axillary vein puncture technique . in conclusion , optimized axillary venous approach may be superior to conventional subclavian vein approach for cied lead placement . this work was supported by grants from fund for clinical study of capital characteristic ( no . this work was supported by grants from fund for clinical study of capital characteristic ( no .
background : the conventional venous access for cardiovascular implantable electronic device ( cied ) is the subclavian vein , which is often accompanied by high complication rate . the aim of this study was to assess the efficacy and safety of optimized axillary vein technique.methods:a total of 247 patients undergoing cied implantation were included and assigned to the axillary vein group or the subclavian vein group randomly . 
 success rate of puncture and complications in the perioperative period and follow - ups were recorded.results:the overall success rate ( 95.7% vs. 96.0% ) and one - time success rate ( 68.4% vs. 66.1% ) of punctures were similar between the two groups . in the subclavian vein group , 
 pneumothorax occurred in three patients . 
 the subclavian gaps of three patients were too tight to allow operation of the electrode lead . 
 in contrast , there were no puncture - associated complications in the axillary vein group . in the patient follow - ups , 
 two patients in the subclavian vein group had subclavian crush syndrome and both of them received lead replacement . 
 the incidence of complications during the perioperative period and follow - ups of the axillary vein group and the subclavian vein group was 1.6% ( 2/125 ) and 8.2% ( 10/122 ) , respectively ( 2 = 5.813 , p = 0.016).conclusion : optimized axillary vein technique may be superior to the conventional subclavian vein technique for cied lead placement.trial registration : www.clinicaltrials.gov , nct02358551 ; https://clinicaltrials.gov/ct2/show/nct02358551?term=nct02358551 & rank=1 .