Dr. Ian Weisberg — Effects of Pulsed RF Energy Compared to Standard Electrocautery on Transvenous Lead Materials
Dr. Ian Weisberg, Shrojal M. Desai PhD, Paul O. Davison MS, Dipak P. Shah MD, Jose Baez-Escudero MD, John F. Beshai MD, Martin C. Burke DO and Bradley P. Knight MD.
University of Chicago Medical Center, Chicago IL, Boston Scientific CRM, St. Paul MN, Peak Surgical Incorporation, Palo Alto CA
Abstract
Introduction: Standard electrocautery can cause thermal injury to the insulation of transvenous pacing and defibrillation leads. There is a novel surgical cutting blade that uses pulsed radiofrequency (RF) to generate a plasma-mediated discharge along the exposed rim of an insulated blade, creating an effective cutting edge while minimizing collateral thermal damage. The purpose of this study was to determine the effects of electrocautery using the pulsed RF blade on transvenous lead insulation materials.
Methods : A preparation of chicken breasts at 37°C was used with transvenous leads tunneled superficially. Energy was delivered using a standard cautery blade and the pulsed RF blade (PEAK PlasmaBlade TM ) at outputs of 20 and 30W for 3 seconds. Parallel and perpendicular blade orientations were used on ten leads with outermost insulations of silicone rubber, polyurethane (PU55D), or silicone-polyurethane copolymer. Damage to each lead was classified after visual and microscopic analysis as no damage, minimal damage, significant damage without full breach and significant with full breach of insulation.
Results : Using standard electrocautery, significant insulation damage occurred to all polyurethane leads with more damage occurring at 30W vs. 20W (88% vs 42%), cut mode vs. coag (88% vs 46%), and perpendicular vs. parallel orientation (75% vs 54%). Silicone leads had less injury than polyurethane leads. The copolymer lead had the most thermal injury of all 10 leads. In contrast, the pulsed RF blade did not injure any of the leads in the coag mode at either perpendicular or parallel orientations except the copolymer lead. In the cut mode, only minimal damage was seen to 3 leads at the lower output and 4 leads at the higher output, all in the perpendicular orientation. There was no damage with the pulsed RF blade in cut mode with parallel blade orientation.
Conclusions : Consistent with prior findings, polyurethane and copolymer materials are highly
susceptible to thermal damage during standard cautery. In this study Pulsed RF blade technology caused less thermal injury to all lead insulation materials compared to standard electrocautery. This new technology may be useful during device upgrades and pulse generator replacements.
Background
Standard electrocautery can cause thermal injury to the insulation of transvenous pacing and defibrillation leads.
Thermal injury increases the incidence of lead failure.
Lim et al. previously demonstrated:
• Polyurethane (PU55D) insulated leads are extremely vulnerable to thermal damage from standard cautery.
• Silicone insulated leads are resistant to thermal damage but can be damaged mechanically by the blade if electrocautery is delivered perpendicularly to the lead.
There is a novel surgical cutting blade that uses pulsed
radiofrequency (RF) to generate a plasma-mediated
discharge along the exposed rim of an insulated blade.
• Minimizes collateral thermal damage.
• Creates an effective cutting edge.
Hypothesis
We hypothesized that using insulated planar electrodes to deliver pulsed electric waveforms of very short duration (<100 µs) from the exposed edges (12 µm wide) would result in less thermal injury to silicone, polyurethane and copolymer insulated leads.
Methods
A preparation of chicken breasts at 37°C was used with transvenous leads tunneled superficially.
Energy was delivered using a standard cautery blade and the pulsed RF blade (PEAK PlasmaBlade TM) at outputs of 20 and 30W for 3 seconds.
Parallel and perpendicular blade orientations were used on ten leads with outermost insulations of silicone rubber, polyurethane (PU55D), or silicone-polyurethane copolymer.
Damage to each lead was classified after visual and microscopic analysis as no damage, minimal damage, significant damage without full breach and significant with full breach of insulation.
Infrared temperature analysis was performed by Elastic Design, LLC (Redwood City, CA). Images were captured using a Thermavision SC600 camera (FLIR, Wilsonville, OR) in mid- infrared (3–5 mm) spectral range, using IR Control 4.5 capture software (Automation Technologies, Vienna, VA). Fifteen frames per second were captured over a five-second activation period for both cut and coagulation modes.
Results
Standard electrocautery
Significant insulation damage occurred to all PU55D leads with more damage occurring at 30W vs 20W (88% vs 42%, p<0.0001), cut vs coag mode (88% vs 46%, p=0.0037) and perpendicular vs parallel orientation (75% vs 54%, p=0.03).
Silicone leads had less injury than PU55D leads (p<0.0001).
The copolymer lead had the most thermal injury of all 10 leads (p<0.0001).
Pulsed RF blade:
• Less damage to all leads (p<0.0001)
• Coag mode: Did not injure any of the leads in
perpendicular or parallel orientations, except the copolymer lead.
• Cut mode: minimal damage was seen to 3 leads at the lower output and 4 leads at the higher output, all in the perpendicular orientation.
• There was no damage with the pulsed RF blade in cut mode with parallel blade orientation.
Results, continued
Conclusions
Consistent with prior findings, polyurethane and copolymer materials are highly susceptible to thermal damage during standard cautery. In this study, pulsed RF blade technology caused less thermal injury to all lead insulation materials compared to standard electrocautery. This new technology may be useful during device upgrades and pulse generator replacements.
References
1. Lim, K.K., et al., Effects of Electrocautery on Transvenous Lead Insulation Materials. J
Cardiovasc Electrophysiol, Vol. 20, pp. 429–435, April 2009
Disclosures: Paul Davison — Vice President of Research and Development at Peak Surgical, Inc.