Reducing the Risk of Transvenous Lead Damage During Pacemaker and ICD Generator Replacement

The PEAK PlasmaBlade (PEAK Surgical, Inc., Palo Alto, CA) is a novel, low-temperature electrosurgical device originally designed for precision dissection with minimal thermal injury to adjacent tissue. However, there is an additional benefit for cardiologists and electrophysiologists: decreased potential for thermal damage to the insulation of indwelling leads. In this article, we will discuss the differences between conventional electrosurgical systems and the PlasmaBlade, with a focus on thermal damage to indwelling pacer/defibrillator leads. We also summarize in vitro data regarding the differential effects of these instruments on transvenous lead insulation materials. Indwelling Lead Damage: A Dangerous and Expensive Problem Silicone rubber, polyurethane, and silicone-urethane copolymers are widely used in the production of transvenous pacing and defibrillator leads due to their favorable flexibility, insulative and tunneling characteristics. Though widely available and cost effective, they are susceptible to damage from high-temperature electrosurgical instruments.1,2 Clinically, this is of greatest concern during pacemaker and implantable defibrillator generator changes and replacements, where sufficient healing has occurred since the initial implantation so as to render the device and leads effectively embedded in the tissue. In such a situation, dissection using a conventional electrosurgical instrument simplifies device and lead removal compared to the use of surgical scissors; however, surgeons are routinely advised by generator and lead manufacturers to maintain operative vigilance and use low-power settings to avoid thermal damage.3 Unfortunately, this is not always practical or possible. Damage to transvenous leads from high-temperature electrosurgical devices during generator replacement may be significantly underreported, despite having important consequences, as much of the damage may be microscopic. There are limited options for handling a damaged lead. One solution, lead extraction with reimplantation, carries significant morbidity and mortality and requires expertise and special equipment to carry out. Reimplantation alone is complicated by the frequent incidence of chronic venous occlusion in patients with indwelling pacer/defibrillator leads. Overall, the need for additional surgical intervention involves significant risk, including increased length of stay and death, as well as serious financial implications, averaging between $5,000 and $20,000 per incident.8 Expanding indications for defibrillator implantation, the growing market for pacemakers due to the overall aging population, and the fact that people are living longer with these indwelling devices mean that generator replacement procedures comprise an increasing portion of many electrophysiologists’ practices. Proficiency with appropriate repair and replacement techniques is necessary and critical, but technology that can decrease the potential for thermal damage to transvenous leads in the first place is even more desirable and of obvious benefit to both patient and electrophysiologist. In the remainder of this article, we will discuss the fundamentals of electrosurgery and key elements of the PlasmaBlade and conventional electrosurgical instruments. We will then summarize the recent work of Weisberg et al, which evaluated the potential for damage between these two technologies in an in vitro transvenous lead extraction model. Finally, we will briefly report on our personal, in vivo clinical experience with this technology in patients undergoing generator replacement procedures. Low-Temperature Tissue Dissection with Pulsed Radiofrequency Energy Electrosurgical instruments have been the mainstay of subcutaneous dissection and hemostatic control since their introduction by Bovie and Cushing in the 1920s.9 Central to their design is the use of continuous-waveform radiofrequency energy (RF) delivered via an uninsulated electrode to cut tissue by thermal ablation, thus producing a simultaneous hemostatic effect. While prized for their hemostatic control, these devices are associated with significant thermal necrosis to incised tissue, poor surgical precision, and delayed wound healing.10,11 In addition to their undesirable effects on living tissue, these instruments operate at temperatures known to be detrimental to transvenous pacing and defibrillator lead coating materials.8 The PEAK PlasmaBlade is a novel surgical device that uses very brief (40µs range), high-frequency pulses of RF energy to induce electrical plasma along the edge of a thin (12.5µm), 99.5% insulated electrode12 (Figure 1). Due to the low duty cycle from the RF pulsing and the proprietary Thermal Protection Shield (TPS) insulating technology, the PEAK PlasmaBlade uses less total energy than traditional electrosurgical technology and functions at significantly lower operating temperatures (40-90°C vs. 200-350°C) (Figures 2 and 3). Comparatively, PlasmaBlade incisions demonstrate 60 to 90% less thermal injury depth than traditional devices, with near-equivalence to the crush injury zone of the standard scalpel10 (Figure 4). Hemostatic control, meanwhile, remains equivalent to that of traditional electrosurgical devices.10 Preclinical animal and human clinical studies with this technology have demonstrated that the improved thermal injury profile of the device results in equivalent healed-wound strength and skin scarring to the scalpel; decreased inflammatory cell counts and serous drainage; lower narcotic consumption; and improved post-operative activity and diet levels compared to traditional electrosurgery.10,13 The Effect of Pulsed RF on Transvenous Lead Insulation Expanding on prior work examining transvenous lead damage with respect to power setting and time of exposure, Cut vs. Coagulation (Coag) mode, insulation type and dissection orientation, a collaborative research group from the University of Chicago and Boston Scientific hypothesized that the PlasmaBlade’s lower operating temperature would cause less insulation damage during simulated lead extraction when compared to conventional electrosurgical instruments.2 To test their hypothesis, the investigators superficially tunneled a series of ten polyurethane, silicone, and silicone-urethane copolymer transvenous leads into chicken breasts maintained at 37°C. These leads were then subjected to simulated extraction using traditional electrosurgery (i.e., the “Bovie”) or the PlasmaBlade. Extraction was performed with either a parallel or perpendicular-to-lead technique using purely Cut or Coag mode at three-second power outputs of either 20 or 30W. Lead damage was scored numerically (0 to 3 scale, by severity) in a blinded manner by visual and microscopic inspection. With traditional electrosurgery, significant lead damage was noted in all polyurethane leads, with more damage occurring at 30W vs. 20W, Cut vs. Coag mode, and perpendicular vs. parallel orientation (Figure 5). Silicone leads demonstrated less damage than polyurethane. Of the three insulating materials, copolymer-coated leads sustained the greatest amount of damage from traditional electrosurgical technology. In contrast, the PlasmaBlade did not damage the silicone or polyurethane leads in Coag mode with either parallel or perpendicular technique (Figure 5). Using Cut mode, only minimal damage was demonstrated with perpendicular technique in the polyurethane and copolymer leads. Of the three insulation materials, silicone demonstrated the highest tolerance to electrosurgery, regardless of technique or energy mode. Discussion While Weisberg and colleagues’ approach used a simulated, in vitro model to compare the effects of different dissection instruments on lead coating materials, we believe the comparison and methodology to be directly relevant to current clinical practice. Their results confirm prior findings that polyurethane and copolymer materials are highly susceptible to thermal damage when subjected to exposure from a conventional electrosurgical instrument. These results further demonstrate that the lower operating temperature of the PlasmaBlade greatly reduces the risk of thermal damage to these materials regardless of mode or orientation of approach (Figure 6). In addition, the experience from the Yale University School of Medicine has confirmed that the operational and handling characteristics of the PEAK PlasmaBlade handpiece during tissue dissection are equally easy and effective as a conventional electrosurgical system. To date, we have encountered no detectable lead damage during these procedures, and have noted less tissue charring, and an associated reduction in surgical smoke released during dissection. It has also been suggested that this technology’s ability to cut skin in a scalpel-like manner yet simultaneously remain cool without any inherent sharpness may reduce the risk of inadvertent scalpel injuries or electrosurgery burns to operating room personnel.10,13,14 Summary In conclusion, preliminary work shows that the PlasmaBlade carries a decreased risk of thermal damage to the insulative coating of indwelling leads compared to conventional electrosurgical devices, and our personal experience has demonstrated other potential benefits. Although the overall risk of transvenous lead injury during pacemaker and implantable defibrillator generator replacement is relatively low, the patient and financial consequences are serious. Therefore, the use of additional safety measures, including this advanced dissection technology, should be considered in the electrophysiology practice. Disclosures: Joshua G. Vose, MD discloses that he is Director of Clinical Affairs at PEAK Surgical, Inc. Mark A. Marieb, MD discloses that he is a consultant to PEAK Surgical, Inc. Editor’s Note: This article underwent peer review by one or more members of EP Lab Digest’s editorial board.