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Predictors of venous obstruction following pacemaker or implantable cardioverter-defibrillator implantation: a contrast venographic study on 100 patients admitted for generator change, lead revision, or device upgrade

Majid Haghjoo, Mohammad Hossein Nikoo, Amir Farjam Fazelifar, Abolfath Alizadeh, Zahra Emkanjoo, Mohammad Ali Sadr-Ameli
DOI: http://dx.doi.org/10.1093/europace/eum019 328-332 First published online: 16 March 2007


Aim Venous obstruction following transvenous device implantation rarely cause immediate clinical problems. When lead revision or device upgrade is indicated, venous obstruction become a significant challenge. The aim of this study was to determine the predictors of venous obstruction after transvenous device implantation, and to asess likely effects of antiplatelet/anticoagulant drugs in preventing venous thrombosis.

Methods and results Between March 2005 and July 2006, contrast venography was performed in 100 patients who were candidates for generator change, lead revision, or device upgrade. Vessel patency was graded as either completely obstructed, partially obstructed (>70%), or patent. The incidence of venous obstruction was 26%, with 9% of patients having total obstruction and 17% of patients exhibiting partial obstruction. No statistically significant differences between obstructed and non-obstructed patients were seen for age, sex, indication for device implantation, atrial fibrillation, cardiothoracic ratio, insulation material, operative technique, device type, and manufacturer (all Ps > 0.05). In a univariate analysis, multiple leads (P = 0.033), and presence of dilated cardiomyopathy (P = 0.036) were associated with higher risk of venous obstruction, whereas anticoagulant/antiplatelet therapy (P = 0.047) significantly reduced incidence of venous obstruction. Multivariate logistic regression analysis showed that only number of the leads (P = 0.039, OR: 2.22, and 95% CI: 1.03–4.76) and antiplatelet/anticoagulant therapy (P = 0.044, OR: 2.79, and 95% CI: 0.98–7.96) were predictors of venous obstruction.

Conclusion Total or partial obstruction of the access veins occurs relatively frequently after pacemaker or ICD implantation. Multiple pacing or ICD leads are associated with an increased risk of venous obstruction, whereas antiplatelet/anticoagulant therapy appears to have a preventive effect on development of access vein thrombosis.

  • Venous obstruction
  • Predictors
  • Pacemaker
  • Implantable cardioverter-defibrillator
  • Venography


There are growing numbers of follow-up procedures, such as generator change, lead revision, and device upgrade in patients with pacemakers and implantable cardioverter-defibrillators (ICD). Obstruction of the access vein is a well-known complication of both permanent pacemaker and ICD implantation.14 These obstructions are most commonly asymptomatic (with incidence of 30–50%) and symptomatic cases are seen infrequently (1–3%).5 Presence of obstruction in the access vein can make follow-up procedures difficult or impossible.

Although numerous studies have tried to determine predictors of venous obstruction following transvenous device implantation, no risk factors were defined.3,4,69 In addition, protective effects of antiplatelet/anticoagulant drugs on venous obstruction have not been demonstrated.10 Therefore, to determine predictors of venous obstruction after transvenous device implantation and to asess likely effects of antiplatelet/anticoagulant drugs in preventing venous thrombosis, the preoperative venography of patients referred for pacemaker or ICD generator change, lead revision, and device upgrade were reviewed.


Study population

Between March 2005 and July 2006, 100 consecutive patients admitted to our institution for their first pulse generator replacement, lead revision, or device upgrade were enrolled in the study. The study was approved by the local Ethics Committee, and written informed consent was obtained from all the patients. Included were 53 men and 47 women with a mean age of 62.76 ± 19.40 years (range 10–89 years). Three patients were not included in the study because of prior history of contrast medium hypersensitivity (n = 2) and renal dysfunction (Cr = 2.5 mg/dL,=1). Contrast venography was performed in all patients. No patient had a history of hypercoagulable state or exhibited symptoms or clinical signs of venous obstruction at the time of study. Indication for original device implantation was complete atrioventricular (AV) block in 61%, second-degree AV block in 3%, sick sinus syndrome in 18%, ventricular tachycardia or fibrillation in 13%, and refractory heart failure in 5%. Underlying diseases were coronary artery disease (35%), dilated cardiomyopathy (4%), hypertrophic cardiomyopathy (3%), hypertension (10%), diabetes (1%), valvular heart disease (5%), and congenital heart disease (10%). History of aspirin and warfarin therapy was present in 50 and 11 patients, respectively. No other antiplatelet drugs including clopidogrel, ticlopidine, and dipyridamole were taken by the patients. At the time of study, baseline rhythm was sinus in 87 patients and the remainder (n = 13) had atrial fibrillation. There were 83 patients with pacemakers and 17 with an implantable cardioverter-defibrillators (ICD). Subclavian vein puncture technique was used for lead insertion in 59 patients and cephalic vein cutdown in 41 patients. All leads were in place for an average of 8.09 ± 4.48 years. Lead insulation material consisted of silicone rubber in 92 patients and polyurethane in eight patients. Patient characteristics are summarized in Table 1.

View this table:
Table 1

Patient characteristics


From March 2005, contrast venography was performed for all patients before generator change, lead revision, and device upgrade in our institution. Venography was performed by placing a 16-gauge canulla in a peripheral arm vein on the side to be studied, and 20–30 mL of a contrast medium (Urografin 76%, Schering AG, Berlin, Germany) was injected. Contrast medium flow in the cephalic, axillary, subclavian and brachiocephalic veins, as well as the superior vena cava was observed and recorded by cineangiography.

The venograms were reviewed by two electrophysiologists, and vessel patency was graded as either completely obstructed (clear interruption of contrast flow), partially obstructed (>70% compared with the distal site of the vessel in association with venous collateral),4,7 or patent (Figure 1). Of 100 patients, transvenous leads were implanted from the right pectoral side in 61 patients, and from the left pectoral side in the remaining 39 patients.

Figure 1

(A) Partial obstruction of right subclavian vein (white arrow) with extensive collateral circulation. (B) Complete obstruction of left subclavian vein (white arrow). Note that there is well-developed cervical collateral formation bypassing the site of obstruction.

Statistical analysis

Continuous data are presented as mean ± SD and ranged when appropriate. Continuous variables were compared by Student's t-test in case of normal distribution. Otherwise, the non-parametric test Mann–Whitney U was used. For categorical data, χ2 analysis was used, and the Fisher exact test for cell count less than five. We used binary logistic regression analysis with forward selection method to find the potential predictors of venous obstruction after transvenous device implantation. We included all the parameters which showed a P value <0.1 during bivariable correlation into our binary logistic regression analysis model. Hosmer–Lemeshow statistics where used to confirm model fitness for the data. A P value <0.05 was defined as statistically significant. The software SPSS version 13.0 (SPSS Inc., Chicago, IL, USA) was used for statistical analysis.


A total of 100 patients (53 men, mean age 62.76 ± 19.40 years) was included in this study (Table 1). Device systems, which were in place before obtaining contrast venography, comprised single-chamber pacemakers (n = 55), dual-chamber pacemakers (n = 22), biventricular pacemakers (n = 6), single-chamber ICDs (n = 7), dual-chamber ICDs (n = 5), and biventricular ICDs with an atrial lead (n = 5). All ICD leads were dual-coils. Procedures performed after venography consisted of generator change (n = 70), lead revision (n = 17), and system upgrade (n = 11). Change to an epicardial system was necessary only in the remaining two patients.

Findings of contrast venography

No abnormality was found in 74% of patients. The remaining 26% exhibited venous obstruction of various degrees. Of 100 patients with venography, 9 (9%) had complete venous obstruction and another 17 (17%) had partial obstruction. Well-developed collateral circulation was observed in all patients with complete or partial obstruction. All patients were asymptomatic and no abnormalities were found on physical examination. The locations of venous obstruction (Figure 2) were left brachiocephalic vein in one patient (partial obstruction), left subclavian vein in 13 patients (complete obstruction in seven patients and partial obstruction in six patients), right subclavian vein in 10 patients (complete obstruction in two patients and partial obstruction in eight patients), right cephalic vein in one patient (complete obstruction), and superior vena cava in one patient (partial obstruction). Side effects of contrast venography were not observed in any of the 100 patients.

Figure 2

Schematic representation demonstrating locations of venous obstruction. RSCV, right subclavian vein; LSCV, left subclavian vein; RCV, right cephalic vein; RBCV, right brachiocephalic vein; LBCV, left brachiocephalic vein; RIJV, right internal jugular vein; LIJV, left internal jugular vein; SVC, sperior vena cava.

Predictors for venous obstruction

Numerous patient-related and device-related risk factors were investigated and compared between patients with venous obstruction (Group I) and those with patent venous anatomy (Group II). There were no statistically significant differences in terms of age (P = 0.90), sex (P = 0.42), baseline rhythm (P = 0.79), indication for endovenous device implantation (P = 0.17), left ventricular ejection fraction (P = 0.24), cardiothoracic ratio (P = 0.81), and hypertension (P = 0.08). Also, no significant differences between Group I and Group II were seen for type of device (pacemaker vs. ICD, P = 0.13), total lead duration (P = 0.14), insulation material (P = 0.44), site of implantation (left vs. right, P = 0.07), route of entry (cephalic vs. subclavian approach, P = 0.53), and device manufacturer (P = 0.94). Furthermore, the univariate analysis showed statistically significant differences in the incidence of venous obstruction in terms of number of leads (Group I: mean 1.9, range 1–4 vs. Group II: mean 1.1, range 1–2, P = 0.033), history of antiplatelet/anticoagulant therapy (P = 0.047), and presence of dilated cardiomyopathy (P = 0.036) (Table 2). There was no statistically significant difference between those on aspirin and those on warfarin, in terms of protection from venous obstruction (P = 0.48). However, the numbers were not adequate to permit any definite conclusions. In multivariate logistic regression analysis, only the number of leads (P = 0.039, OR: 2.22, and 95% CI: 1.03–4.76) and antiplatelet/anticoagulant therapy (P = 0.044, OR: 2.79, and 95% CI: 0.98–7.96) were predictors of venous obstruction after transvenous device implantation (Table 3). Subgroup analysis in patients with pacemakers indicated that both the number of the leads (P = 0.046, OR: 2.01, and 95% CI: 0.97–3.65) and antiplatelet/anticoagulant therapy (P = 0.038, OR: 3.30, and 95% CI: 0.98–11.06) were predictors, whereas the number of the leads was the only predictor of venous obstruction after ICD implantation (P = 0.019, OR: 4.89, and 95% CI:1.06–22.55) (Table 3).

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Table 2

Univariate comparison of risk factors for venous obstruction after long-term pacemaker or ICD

View this table:
Table 3

Multivariate comparison of risk factors for venous obstruction after pacemaker or ICD


Main findings

The present study evaluates the predictors of venous obstruction following long-term transvenous pacemaker or ICD implantation. The main findings of our study include: (i) Multiple leads (both pacemaker and ICD lead) are associated with an increased risk of venous obstruction. (ii) Antiplatelet/anticoagulant therapy for other reasons than transvenous lead is associated with significant preventive effect on development of the access vein thrombosis. (iii) Total or partial obstruction of the access veins occurs relatively frequently after pacemaker or ICD implantation. The incidence of total obstruction and partial obstruction was 9 and 17%, respectively. (iv) This study demonstrates that pacemaker and ICD patients have a similar risk of lead-related venous obstruction.

Predictors of venous obstruction after transvenous pacemaker or ICD implantation

Despite many years of experience with transvenous pacing or defibrillator systems, no studies have been able to identify clear risk factors that lead to venous stenosis.3,4,69 Neither the hardware (total lead duration, lead size, number, and insulation material) nor the operative technique (cephalic vs. subclavian approach or right vs. left pectoral implantation) appears to affect the rate of venous complications in previous studies.6 The same is true of underlying disease, age, sex, smoking, and history of atrial fibrillation.3

Among the multiple patient-related (age, sex, underlying disease, indication of pacemaker or ICD implantation, baseline rhythm, and cardiothoracic ratio) and device-related factors (pacemaker vs. ICD, total lead duration, insulation material, site of implantation, route of entry, and device manufacturer) entered in our study, only two predictors (number of the implanted leads and antiplatelet/anticoagulant therapy) were identified for the occurrence of venous obstruction.

Although it has been stated that if too many leads are present the resultant reaction has a high probability of obstructing the vein, this has not been well substantiated in the literature.11,12 None of the published studies (clinical venographic and clinical only) described a higher incidence of occlusion with multiple leads.3,710,1317 Only Pauletti et al.,18 in an isotope study, reported a significantly higher incidence of occlusion in a population with multiple leads compared with single lead (26 vs. 8%, P < 0.05). In this study, obstruction was not directly visualized but its presence derived from the presence of collaterals and progressive increasing isotope activity locally. To the best of our knowledge, the present study is the only venographic study in which there is a significant correlation between number of leads and venous thrombosis after endovenous pacemaker or ICD implantation both in univariate and multivariate analyses (Table 3). These controversial results may be explained by differences in number of patients, mean time from implant, definition of venous obstruction, and characteristics of study population.

In view of endothelial trauma caused by lead insertion, extension of thrombus from ligated vein, and post-operative hypercoagulable state,1 it is expected that antiplatelet/anticoagulant therapy could be useful to prevent thrombus formation following transvenous device implantation. This issue had been investigated by Goto et al. in a retrospective study.10 However, these investigators could not find the efficacy of prophylactic administration of anticoagulant and antiaggregant drugs to prevent venous thrombosis after transvenous pacemaker implantation. Our data demonstrate that antiplatelet/anticoagulant therapy (for other reasons than pacemaker lead) had a significant antithrombotic effect in patients with endovenous pacemakers. Similarly, Seeger et al. described the beneficial effects of post-operative prophylactic heparin in their prospective study.19 Number of patients receiving antiplatelet/anticoagulant drugs (42 vs. 61%) and type of the administered drug (mainly dipyridamole in the Goto study vs. aspirin in our cases) may explain dicrepancies between the results of Goto et al. study and the present study. We could not demonstrate efficacy of antiplatelet/anticoagulant drugs in preventing venous thrombosis after ICD implantation. We think that small number of patients with ICD is responsible for this observation.

Among the patients who were candidate for transvenous device implantation, Oginosawa et al. showed that cardiothoracic ratio was significantly greater in patients with venous occlusions than patients with patent venous anatomy.20 However, the predictive role of cardiothoracic ratio was not assessed in a multivariate analysis. We could not confirm this finding in our study. These discrepancies may be explained by the fact that Oginosawa et al.20 evaluated the patients at the time of their first device implantations, whereas our study investigated the venous obstruction among the patients who were candidates for repeat device procedures.

Study limitations

The present study must be interpreted in the face of certain limitations. This study was a retrospective analysis and a selection bias was introduced by evaluating a population of patients at the time of repeat device procedures. However, prospective data acqusition limited untoward effects of retrospective analysis. The present study was also limited by the fact that the incidence of venous obstruction prior to implanting the leads was not been investigated. Some previous reports have shown that the incidence of venous obstruction before pacing lead implantation is not rare.3 However, in view of successful initial implantation of all transvenous leads, no preexisting complete obstructions should be expected in the present study. Among the patients in whom results of pre-procedure venography were available (n = 32), no partial obstruction was reported. Another limitation is that the study is a single centre experience.

Conclusions and clinical implications

Various degrees of venous obstruction are relatively frequent following permanent pacemaker or ICD implantation, occurring in nearly one-fourth of patients who are candidate for generator change, lead revision, or device upgrade. However, venous access is possible in most cases either for lead revision or implantation of additional leads, with the goal of upgrading a preexisting system. On the basis of our findings, we recommend venography in all patients who present for pacemaker or ICD generator change associated with signs of lead injury or who need implantation of additional leads for upgrading to dual-chamber or biventricular systems.

Before any recommendation regarding the administration of antiplatelet/anticoagulant therapy in patients with endovenous device implantation, confirmation of antithrombotic effects of aspirin and warfarin in a prospective and randomized study is reasonable to determine practice guidelines. The role of superfluous lead extraction in preventing venous thrombosis should also be further studied.


We would like to thank Mr Nikpoor and Mr Lotfi for performing contrast venography and storage of data.


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