Effects of Pulsed RF Energy Compared to Standard Electrocautery on Transvenous Lead Materials

. Ian L. Weisberg† MD, 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 PlasmaBladeTM) 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.

  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.

  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 PlasmaBladeTM) at outputs of 20 and 30W for 3 seconds.

  Parallel and perpendicular blade orientations were used on 10 leads with outermost insulations of silicone, polyurethane (PU55D), or silicone-polyurethane copolymer.

  Damage to each lead was classified after visual and microscopic analysis as no damage, minimal damage, significant damage and 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.

1. Lim, K.K., et al., Effects of Electrocautery on Transvenous Lead Insulation Materials. J Cardiovasc Electrophysiol, Vol. 20, pp. 429-435, April 2009.

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.

  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:1

•  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.

Background

Hypothesis

Methods

Results

Results, continued

Conclusions

References (A) Blade electrode. (B) Plasma discharge along the exposed edge. (C) High magnification of the blade with the 12.5 µm edge of the metal foil and 10 µm layers of glass insulation. (D) Plasma discharge along the metal edge extending approximately twice the width of the electrode

  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.

A - 30 Watts, Bovie, Parallel B - 30 Watts, Bovie, Perpendicular C - Energy Dissipation, Bovie 30 W

D - 30 W, Pulsed RF, Parallel E - 30 W, Pulsed RF, Perpendicular F - Energy Dissipation, Pulsed

0

1

2

3

Z1 2

0W/3

sec

C1

20W

/3se

c

Z2 2

0W/3

sec

C2

20W

/3se

c

Z3 3

0W/3

sec

C3

30W

/3se

c

Z4 3

0W/3

sec

C4

30W

/3se

c

Z5 3

/3se

c

C5

2/3s

ec

Z6 3

/3se

c

C6

2/3s

ec

Z7 5

/3se

c

C7

4/se

c

Z8 5

/3se

c

C8

4/3s

ec

Dam

age

Cla

ss

Thermal Injury Ratings I--------Electrocautery-------I-------Pulsed RF Blade------I

BSC 0175 Silicone

BSC 4088 Silicone

MDT 5076 Silicone

SJM 1688T Silicone

SJM 7120 Copolymer

MDT 4194 PU

MDT 4076 PU

MDT 6947 PU

BSC 4543 PU

BSC 4471 PU

SJM 1056T PU

Cautery Modes: Z=Cut C=Coag Blade Orientation: Parallel=1,3,5,7 Perpendicular=2,4,6,8

0 = no damage 1 = minimal damage 2 = significant damage 3 = full breach of insulation

Disclosures: Paul Davison - Vice President of Research and Development at Peak Surgical, Inc.

A B C

D E F