Electrocautery is commonly employed during surgical implantation and explantation of pacemakers and implantable cardioverter-defibrillators (ICDs). Four cases of electrocautery-induced ventricular tachyarrhythmias including ventricular tachycardia (VT) or ventricular fibrillation (VF) during device implantation or explantation are described. Methods. The incidence of electrocautery-induced VT or VF at Winthrop University Hospital was analyzed over a 5-year period (November 2000 to March 2006). Specific devices, indications for device implantation or explantation, electrocautery configuration, and grounding patch placement were analyzed. Results. Between November 2000 to March 2006, 4,698 devices were implanted and/or explanted at Winthrop University Hospital, of which 4 patients developed electrocautery-induced ventricular tachyarrhythmias. The patients had a mean age of 64 ± 16 years, and mean left ventricular ejection fraction of 34 ± 9 percent. Three patients (75%) had severe coronary artery disease with prior myocardial infarction. Three patients (66%) had clinical hypertension. Three patients developed ventricular tachycardia during elective explantation of a malfunctioning device. One patient developed ventricular fibrillation during pacemaker implantation. Prior to each explant, the ICD was programmed off. Patients underwent explantation of a Medtronic Marquis model #7230CX ICD, Medtronic Marquis DR #7274 and Guidant Ventak Prizm 2 model #1861. The mean age of explanted devices was 35 ± 13 months. Conclusions. This study demonstrates a 0.09% incidence of provoked sustained ventricular tachycardia or ventricular fibrillation requiring external defibrillation during device implantation or explantation. This occurred despite programming off the ICD prior to device replacement, positioning the grounding pad far from the pulse generator and the use of bipolar electrocautery. We hypothesize that direct current energy is delivered to the pulse generator, lead and/or connector and then to the myocardium. Staff should be aware of electrocautery-induced VT or VF during device procedures and be prepared to promptly cardiovert and/or defibrillate VT/VF should this scenario occur.

Figure 1.

Electrocautery-induced ventricular tachycardia.

       Electrocautery has long been described to generate electromagnetic interference (EMI) and oversensing by implanted pacemakers and defibrillators. Electrocautery is commonly used during surgical procedures involving implantation and explantation of pacemakers and implantable cardioverters-defibrillator (ICDs). However, ventricular tachycardia (VT) or ventricular fibrillation (VF) occurring as a result of electrocautery has only been sporadically reported. We present 4 cases of electrocautery-associated VT or VF during either implantation or explantation of ICDs and pacemakers. The etiology of VT/VF is unclear in these circumstances.

Methods
       This retrospective study was approved by the Institutional Review Board at Winthrop University Hospital. During the period of November 2000 to March 2006, 4,698 pacemakers and implantable defibrillators were implanted and/or explanted at Winthrop University Hospital. Of these, 1,069 of these procedures (433 pacemakers and 636 ICDs) involved explantation of devices. A retrospective chart review was performed on the patients with electocautery-induced VT or VF, looking for specific devices, indications for implantation and explantation, electocautery configuration and grounding patch configurations. Specifically, we analyzed the incidence of electrocautery-induced VT or VF in new implants and explants/reimplants and compared the pacemaker group to the ICD group. A Chi-square statistical analysis was performed to determine whether any statistical difference was present in any patient subgroup. Odds ratios were calculated for de novo implants versus explants/reimplants as well as the pacemaker versus ICD group. All data are reported as mean ± standard deviation. A p-value < 0.05 was considered statistically significant.

Figure 2.

Electrocautery-induced ventricular fibrillation.

       The United States National Library of Medicine’s Pubmed database was queried from 1976 to the present using the keywords “electocautery-associated ventricular arrhythmia”, “electrocautery” and “arrhythmia”, “electocautery” and “ventricular”, and “electocautery” and “tachycardia” to identify any large series of device implantations or explantations with electrocautery-induced VT or VF as a phenomenon or complication.
       Operative procedure. The chest wall was prepped in the usual sterile manner. A lidocaine/bupivacaine mixture was injected subcutaneously around the pocket of the old ICD or at the site for the new implant. An incision was made approximately 2 fingerbreadths below the left clavicle in the midclavicular line or directly over the old device site for explant/implant procedures. All electrocautery was performed utilizing a standard Force 2 F2-2PCH (Valleylab, Boulder Colorado) bipolar electrocautery machine set at 30 Watts for cutting and 40 Watts for coagulation. Dissection to the level of the prepectoral fascia was performed using bipolar electocautery. Patients were monitored continuously for any arrhythmia. All sustained ventricular arrhythmias were defibrillated with a Lifepak 12 (Medtronic, Inc., Minneapolis, Minnesota) at 200 Joules. The old ICD was explanted, the remaining leads were tested for pacing sensitivities, thresholds and lead impedances prior to implanting a new device.

Table 2. Incidence of VT/VF During New Implants and Explants with Reimplantation

- New Implants: 1,868 PPM 1,761 ICD 3,629 (ALL) VT/VF during case 1 (0.05%) PPM 0 (0%) ICD 1 (0.027%) (ALL) 0.33 (p-value) Explants and Reimplants: 433 PPM 636 ICD 1,069 (ALL) VT/VF during case: 0 (0%) PPM 3 (0.5%) ICD 3 (0.28%) (ALL) 0.20 (p-value) All procedures: 2,301 PPM 2,397 ICD 4,698 (ALL) VT/VF during case: 1 (0.04%) PPM 3 (0.13%) ICD 4 (0.09%) (ALL) 0.33 (p-value) Number of procedures: 1,868 PPM Implant 636 ICD Explant and Reimplant VT/VF during case: 1 (0.05%) PPM Implant 3 (0.5%) ICD Explant and Reimplant 0.02 (p-value)

Results
       Four patients (0.09%), 3 men and 1 woman, developed VT/VF during device implantation or explantation procedures. Three patients underwent elective explantation of a malfunctioning ICD secondary to manufacturer recall. One patient underwent a de novo implantation of a permanent pacemaker. The mean age was 64 ± 16 years. The ejection fraction was 34 ± 9%. Three patients had prior coronary artery disease.
       Table 1 shows the clinical characteristics of all 4 patients who developed electrocautery-induced VT/VF. In each of the ICD explants, contact was made with the electrocautery knife and the old pulse generator (prior to lead disconnection), resulting in VT/VF. In each case a single biphasic 200 Joule shock terminated the arrhythmia. Figure 1 shows sustained VT induced in a 70-year-old male with a history of diabetes, hypertension, ischemic cardiomyopathy with a left ventricular ejection fraction of 25%. One pacemaker procedure resulted in sustained VF. This patient was an 84-year-old female with a history of paroxysmal atrial fibrillation, preserved left ventricular systolic function with a history of significant bradycardia. She underwent an electrophysiology study prior to device placement and did not have inducible VT/VF during programmed electrical stimulation. She underwent implantation of a dual-chamber pacemaker using a cephalic vein cutdown method. Atrial and ventricular leads were placed using active fixation. Additional electrocautery was performed in the pacemaker pocket to obtain hemostasis, and the patient went into VF (Figure 2) and promptly defibrillated. The patient then received a dual-chamber pacemaker without any further clinical events.
       Duration of electocautery causing VT/VF was minimal in these 4 patients. The timing in all 4 cases appears to be approximately 2 seconds each.
       The incidence of VT during ICD explantation in our series was 0.5%. VF during pacemaker implantation was 0.05%. There was a statistically significant difference in the incidence of VT/VF in new pacemaker implants when compared to device explants/reimplants (0.03% vs. 0.3%, x²; p = 0.02).
       A query of the United States National Library of Medicine’s PubMed database failed to identify any large-scale trials or databases reporting electocautery-induced or electocautery-associated ventricular arrhythmias as a complication.

Discussion
       Associations between electrocautery and ventricular arrhythmias with pacemakers and ICDs have largely been limited to atrial and ventricular oversensing. However, electocautery-associated VT and VF has also been described as isolated infrequent case reports,^2–4 but not as part of any large-scale clinical trials or published registries.
       Aggarwal and colleagues reported on a case where electrocautery was used to ensure hemostasis in a patient undergoing revision of a nonfunctioning pacemaker. They postulated that electrical current may have conducted down the implanted lead system as the potential cause of VF. Stimulation of the myocardium with direct current may occur with direct application of electrocautery to the pulse generator, lead connector and/or lead. The essential component is the entry of direct current energy by a direct or circuitous pathway down the pacing or defibrillation leads.

Table 4. Odds Ratio Comparing Pacemaker Procedures to ICD Procedures

- PPM: ICD OR: 95% CI: (n = 3,629) (n = 1,069) VT/VF: 1 (0.043%) 3 (0.125%) 2.88 0.31–27.18

       On further review of the 4 cases with ventricular arrhythmias, they were all performed by the same operator. At the time, our institution had 4 electrophysiologists with varying degrees of experience. It was interesting to note that all 4 cases occurred with our most senior operator with over 14 years of procedural experience. The 3 cases involving elective explantation secondary to device advisories were routine and had no additional complexities. The single case involving a new pacemaker implant occurred towards the end of a routine case during electrocautery for pocket hemostasis.
       Electrocautery, which uses radiofrequency energy to cut or coagulate tissues, is a significant source of EMI during these procedures. Circuitry inside current devices is typically shielded inside a hermetically-sealed titanium or stainless-steel case. The use of bipolar leads and bandpass filters also has decreased the susceptibility of devices to EMI. EMI has been well described as causing noise reversion to fixed pacing and device inhibition due to oversensing of outside signals.⁵ Whether this is a definite cause of the induction of VT or VF is uncertain.

Table 1. Summary Data

- Patient Number: 1 Age: 53M EF: 30% Cardiac Substrate: Ischemic cardiomyopathy Indications for Procedure: Elective explant due to device advisory Device Explanted: Medtronic Marquis 7230CX Result: Ventricular tachycardia requiring external cardioversion to normal sinus rhythm Patient Number: 2 Age: 49M EF: 25% Cardiac Substrate: Hypertension, ischemic cardiomyopathy Indications for Procedure: Elective explant due to device advisory Device Explanted: Medtronic Marquis DR #7274 Result: Ventricular tachycardia requiring external cardioversion to normal sinus rhythm Patient Number: 3 Age: 70M EF: 25% Cardiac Substrate: CABG, ischemic cardiomyopathy, diabetes, hypertension Indications for Procedure: Elective explant due to device advisory Device Explanted: Guidant Ventak Prizm 2 Model 1861 Result: Ventricular tachycardia requiring external cardioversion to normal sinus rhythm Patient Number: 4 Age: 80F EF: 55% Cardiac Substrate: Normal LV function, paroxysmal atrial fibrillation Indications for Procedure: Sick Sinus Syndrome, new pacemaker implantation Device Explanted: No device. Right atrial and right ventricular leads in place at time of VF Result: Ventricular fibrillation requiring external cardioversion to normal sinus rhythm EF = ejection fraction; LV = left ventricular; VF = ventricular fibrillation; CABG = coronary artery bypass graft surgery; M = males; F = females

       More recently, there appears to be a correlation between the recording systems, pacing stimulators and radiofrequency generators used in electrophysiology laboratories. Boston Scientific’s in-house research and development laboratory recently detailed interactions between several combinations of devices located in electrophysiology laboratories. There is the creation of direct current voltage across pairs of catheter electrodes during radiofrequency delivery in certain device combinations. Whether this specific condition caused the ventricular arrhythmias in our study patients is also unknown.
       It is our recommendation that minimal power settings for electrocautery be utilized during device-related procedures. Appropriate placement of grounding pads will also move the electrocautery-associated electrical current away from the device. A potential solution would be the use of an ultrasonic scalpel which uses harmonic energy to cut and coagulate tissue. This system would reduce potential EMI and has been used successfully in patients with pacemakers and ICDs.

Conclusions
       These 4 patients demonstrate that electrocautery-induced VT and VF can occur during implantable pacemakers (0.05%) or ICD (0.5%) procedures. There was an increased incidence of VT/VF during device explant/implant (0.3%) procedures as compared to new implant procedures (0.03%) Appropriate precautions include the use of minimal power settings, distant grounding patch placement and vigilant patient monitoring with immediate access to external cardioverters-defibrillators.

Table 3. Odds Ratio Comparing Implant Procedures to Explant Procedures

- Implants: Explants: OR: 95% CI: (n = 3,629) (n = 1,069) VT/VF: 1 (0.027%) 3 (0.28%) 10.2 0.26–398.26

This article was reprinted from the Journal of Invasive Cardiology 2007;19:12–15.