The incidence of venous stenosis following transvenous lead implant documented by contrast venogram is ranging from 25 to 64% (6–11); this variability is mainly related to the degree of stenosis adopted as inclusion criteria among the different series. In a study by Morani et al. (11), severe stenosis (>75%) have been found in 27% of patients referred for CIED revision after a median time from first implantation of 66.7 ± 46.4 months. Total venous occlusions are also relatively common and have been reported in 6% of patients 6 months after pacemaker (PM) implantation (8) and in up to 26% of patients requiring CIED revision 6.2 years after the first implant (6).

Total venous occlusions are more frequently located at the level of the brachiocephalic vein (7), whereas the most common site of stenosis is the subclavian vein followed by the brachiocephalic trunk, even though both subclavian and brachiocephalic vein are often involved together (11).

Patients' demographics, implant techniques and lead characteristics have been analyzed by several studies to assess the risk for venous stenosis after CIED implantation. While prolonged implantation time (>60 min), perioperative complications, previous use of temporary PM and left ventricular ejection fraction (LVEF) ≤ 40% are associated with an increased risk of venous stenosis or occlusion (8, 10, 12), the role of the number of implanted leads and lead characteristics including lead type (PM and implantable cardiac defibrillator (ICD) leads), diameter and insulation (silicone, polyurethane and Optim™) still remains controversial (6, 10, 11, 13–18). Interestingly, Haija et al. (6) found that not only the number of implanted leads, but also the total lead diameter as the sum of all implanted lead diameters, is a risk factor for venous stenosis or occlusion. Furthermore, they described an association between multiple lead implant procedures and venous stenosis, as confirmed also by Morani et al. and Czajkowski et al. (11, 12) corroborating the hypothesis of the endothelium trauma as “primum movens” of a cascade where the inflammatory reaction may result in venous stenosis promoting development of granulation tissue development and fibrous capsule formation around the transvenous lead (8, 10). This hypothesis supports the role of anticoagulant therapy in reducing the risk of venous thrombosis after CIED implant (16, 17), but not the risk of venous stenosis itself (13).

Venous stenoses are often asymptomatic because of venous collateral formation ensuring venous drainage (7, 8, 13, 14, 16, 17) so that they are usually discovered accidentally at the time of CIED revision. The extension of the collateral circulation increases proportionally with the degree of venous stenosis (7) and the development of collateral superficial veins across the clavicle has been shown to be a sensitive marker of severe venous obstruction (9).

SVC syndrome is the manifestation of severe obstruction or occlusion of the SVC and has been documented in 0.1–3.3% of patients implanted with transvenous leads (19, 20). Typical signs and symptoms consist of facial and neck oedema, non-pulsatile distended neck and chest veins, dyspnea and cough, arm oedema and dizziness (19, 21). The severity of clinical presentation depends on the level of obstruction (upper SVC proximal to the azygos vein, azygos vein, and distal to the azygos vein), onset of obstruction and establishment of venous collaterals (19). After transvenous lead implant, symptoms of SVC syndrome might occur months to years later, as documented in a meta-analysis by Riley et al. (22) where the median time between PM implantation and development of SVC syndrome was 48 months (range several hours to 396 months).

Chronic venous stenoses related to transvenous leads usually do not need specific treatments unless in case of SVC syndrome or CIED upgrade requiring new transvenous lead implant. Figure 1 illustrates the current therapeutic approach to treat or to overcome venous stenosis in these cases.

Currently the adopted definition of CIED lead extraction is “any lead removal procedure in which at least one lead requires the assistance of equipment not typically required during implantation or at least one lead was implanted for longer than 1 year” (1, 2). CIED infections (including pocket infections with or without bacteriemia, CIED endocarditis and occult bacteriemia with suspected CIED infection) represent the main indication for CIED extractions amounting to 46–56.9% in the largest series on TLE procedures (ELECTRa, LExICon and PROMET study) (30–32). The second most frequent reason for lead extraction is lead dysfunction [38.1% of cases in the ELECTRa study (30)] followed by abandoned leads. In this case, as for lead dysfunction, the rational for extraction would be to reduce the intravascular lead burden especially in young patients (1, 33). Other indications for lead extraction are: lead complications such as SVC syndrome; venous stenosis, preventing new lead implantation; access to MRI in case of abandoned or dysfunctional lead; chronic pain due to periosteal reaction at the lead insertion site (1). An emerging indication for lead extraction is severe tricuspid regurgitation caused by a lead interfering with tricuspid valve leaflet mobility or coaptation in absence of right ventricular or tricuspid valve annulus dilatation and damage of tricuspid valve leaflets (5, 34, 35). However, given the absence of data on large series, this approach should be reserved to very selected patients.

Percutaneous techniques represent the first line approach for TLEs. Open surgical extractions are associated to an increased risk of major complications and mortality compared to percutaneous extractions (36, 37), therefore they are currently indicated for patients with systemic infection and large lead vegetations (>20 mm) (38). However, also in these cases, a percutaneous approach associated to the aspiration of the lead vegetations has been recently proposed and preliminary results seem encouraging (39, 40).

Tools and techniques for percutaneous TLEs are illustrated in Figure 2. Additional tools (not shown in Figure 2) are grasping devices, like myocardial biopsy forceps or endoscopic graspers, mostly employed to retrieve lead fragments and occlusion balloons able to control bleeding in case of vascular tear. Figure 3 shows two examples of transvenous leads extracted using mechanical sheaths in our center. Usually, the percutaneous TLEs are performed by using the same venous access as the one of the original implant procedure, even though a femoral or a jugular access may be used as alternative or in case of bailout procedure (1). Furthermore, a “stepwise” approach is normally adopted so that the operator moves from simple (e.g., gentle traction using a locking stylet) to more complex strategies and tools (e.g., powered extraction sheaths) during the procedure according to the success of each single step (1). A pre-procedural contrast venography is also helpful to identify regions of venous stenosis/occlusion and adhesion sites (1, 2, 42).

Percutaneous TLEs have been shown to be safe and effective in several large series of extraction procedures. In the ELECTRa study (30) 3,510 patients underwent TLEs in 73 centers across Europe between 2012 and 2014. Complete removal of the target leads was obtained in 95.7% of cases, whereas the clinical success rate (defined as the achievement of the clinical outcome for which the TLE was scheduled without the occurrence of major complications) was 96.7%. Procedure-related major complications, including death, occurred in 1.7% of patients. The more frequent procedure related complications were cardiovascular requiring pericardiocentesis, chest drainage and/or surgical repair in 1.4% of patients. Powered and non-powered sheaths were used in the majority of the procedures (63.6%) with laser sheaths accounting for 19.3%. In LExICon study (31) all TLE procedures were performed using laser methods only. The procedural and clinical results were similar to the ELECTRa study with a procedure success rate of 96.5% and a clinical success rate of 97.7%. Procedural complications occurred in 1.4% of patients, including 4 deaths (0.28%). More recently the PROMET study (32) showed similar efficacy and safety of laser methods when using mechanical and rotational sheaths with a procedural success rate of 96.5%, major complication rate of 1% and peri-operative or procedure-related mortality rate of 0.18%.

As previously discussed, TLE has been proposed as a part of therapeutical approach in case of venous disorder related to transvenous leads.

Retrospective data from relatively small series and case reports (23–25) documented the safety and the feasibility of TLE as a part of percutaneous management of the SVC syndrome, even though symptom recurrences may occur several months or even years later, requiring additional venoplasties mostly because of intrastent stenosis. Extraction techniques, procedural results and clinical outcomes of the largest studies available in the literature on TLEs in patients with SVC syndrome are reported in Table 1.

TLE of abandoned leads has also been confirmed to be a safe and effective solution to overcome venous stenosis at the time of CIED revision or upgrade. Furthermore, the presence of venous obstruction itself seems to have no impact on procedural major complications (42). In the series from Barakat et al. (28) 503 patients underwent abandoned lead extraction because of lead dysfunction, lead recall or venous stenosis (37 patients). Powered sheaths were used in 75% of the TLEs and the overall success rate was 96.6%. Major complications occurred in 1% of patients and damage to pre-existing leads related to the extraction procedure was documented in 3.8% of cases. Sohal et al. (29) evaluated 71 patients who underwent lead extraction because of venous occlusion preventing CIED revision. All leads (129 in total, mean dwelling time 80 ± 62 months) were completely extracted using laser sheaths, and the new leads were successfully implanted across the obstruction in 94% of cases. There were two major complications consisting in infection of previously sterile sites but no peri-procedural mortality. Post-procedural device checks were satisfactory in 92% of cases with a mean follow-up of 26 ± 19 months. However, these data (28, 29) reflect the experience of high-volume centers and suggest that the adoption of these strategies should be limited to experienced operators only. Finally, post-extraction venous occlusion and embolization of collateral veins have been described following TLE procedures using laser sheaths, because of vessel injuries promoting thrombus formation (43). The impact of this phenomenon is particularly relevant in case of TLEs performed for symptomatic venous obstructions and should be taken into account when defining the TLE strategy. Anticoagulation therapy seems to prevent post-operative thrombosis but more evidence are required to support its use in this specific context.