Safety of Pacemakers and Defibrillators in Electromagnetic Navigation Bronchoscopy

Transcription

1 CHEST Original Research INTERVENTIONAL PULMONOLOGY Safety of Pacemakers and Defibrillators in Electromagnetic Navigation Bronchoscopy Ahmed Y. Khan, MD ; David Berkowitz, MD ; William S. Krimsky, MD, FCCP; D. Kyle Hogarth, MD, FCCP; Christopher Parks, MD ; and Rabih Bechara, MD, FCCP Background: Electromagnetic Navigation Bronchoscopy (ENB) (InReach ilogic system; superdimension Inc) is a relatively new discipline, with promising diagnostic and therapeutic applications in patients with lung lesions. Navigation is performed in a magnetic field and, therefore, has been considered relatively contraindicated in patients with pacemakers and automated implantable cardioverter-defibrillators (AICDs). Potential risks include altering the function and shutting off the device, device damage, lead displacement, and potential overheating. Over the past decade, there has been extensive literature about the safety of pacemakers in either the 1.5-T or 3-T magnetic fields used in current MRI scanners. Although the magnetic field used in ENB is significantly weaker, T or approximately equal to the earth s gravity, its safety in patients with pacemakers is yet to be elucidated. We present our initial experience with ENB in patients with cardiac implanted electrical devices. Methods: Twenty-four procedures in 24 patients with lung lesions and permanent pacemakers were performed. A cardiac electrophysiologist and programmer were present during the procedure. At baseline, the pacers were interrogated, and ECG was recorded. Continuous cardiac monitoring was performed during the procedure, and at the end, the pacer settings and function were reinterrogated to check for any changes. Results: The procedures were all successfully concluded. None of the patients suffered any arrhythmias or disruption to their pacemakers function. Conclusion: ENB appears to be safe when performed in patients with pacemakers and AICDs. Larger multicenter studies are needed to prove the final safety in this patient population. CHEST 2013; 143(1):75 81 Abbreviations: 3-D 5 three-dimensional; AICD 5 automated implantable cardioverter-defibrillator; CIED 5 cardiovascular implantable electronic device; ENB 5 Electromagnetic Navigation Bronchoscopy; PPM 5 permanent pacemaker Despite significant advances in the treatment and diagnosis of lung cancer over the past decades, it remains the leading cause of cancer deaths. 1 Fortunately, detection of lung cancer in earlier stages affords improved prognosis, response to treatment, and survival in patients. 2,3 This is reflected in recently published Manuscript received March 15, 2012; revision accepted June 8, Affiliations: From the Interventional Pulmonology Program (Drs Khan, Berkowitz, Parks, and Bechara), Emory University School of Medicine, Atlanta, GA; the Interventional Pulmonary Program (Dr Bechara), Cancer Treatment Centers of America at Southeastern Regional Medical Center, Atlanta, GA; the Interventional Pulmonology Program (Dr Krimsky), Medstar Franklin Square Medical Center, Baltimore, MD; and the Department of Pulmonary and Critical Care Medicine (Dr Hogarth), University of Chicago, Chicago, IL. Funding/Support: The authors have reported to CHEST that no funding was received for this study. data from the National Lung Screening Trial that shows a clear 20% reduction in mortality of high lung cancer risk patients undergoing low-dose CT screening. 3 The assessment of peripheral lung lesions has previously been performed surgically or with CT scanguided transthoracic needle tissue sampling. Both methods afford much higher sensitivity than conventional bronchoscopy with transbronchial biopsy. 4 Recently, Electromagnetic Navigation Bronchoscopy (ENB) and radial endobronchial ultrasound with guide Correspondence to: Rabih Bechara, MD, FCCP, Emory University Department of Pulmonary and Critical Care Medicine, 1365 Clifton Rd NE, Atlanta, GA 30322; rbechar@emory.edu 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: /chest journal.publications.chestnet.org CHEST / 143 / 1 / JANUARY

2 sheaths have become suitable alternatives, specifically in peripheral lesions involving the upper lobes that are less amenable to CT scan-guided biopsy ( Fig 1 ). ENB affords diagnostic sensitivity ranging from 59% to 74% while remaining less invasive, more comfortable, and with minimal complications. 4-6 The patient population at highest risk for a neoplastic etiology of lung mass/nodules tends to be at higher risk for postoperative pulmonary complications from surgical procedures. As such, ENB allows a way to decrease procedural risk and allows these patients to obtain a definitive diagnosis of their lesions. The population of patients with severe heart failure and cardiac implantable electronic devices (CIEDs) is growing. Patients with automated implanted cardiac defibrillators (ACIDs) or permanent pacemakers (PPMs) may also require evaluation of peripheral lung lesions. Since 85% of all pacemaker patients have one or more comorbidities, 7 the need for less-invasive means of diagnosis to reduce procedural risk in this population favors evaluation with ENB. Currently, ENB is considered to be relatively contraindicated in patients with pacemaker or defibrillator implants because of the electromagnetic field generated by ENB for the guidance of the steerable probe. Over the past decade, there has been extensive literature published about the safety of CIEDs in either the 1.5-T or 3-T magnetic fields used in current MRI scanners. 8,9 Issues with the generated magnetic fields include concerns of lead heating causing damage to the heart or an alteration in lead function that could contribute to alteration of the pacing threshold. 7,10 Stimulation from the magnetic field can cause the device to unintentionally shut off or induce voltage within the lead resulting in the delivery of unintended therapy that may be arrhythmogenic. 11 Furthermore, device interactions, such as inhibition of device function due to sensed magnetic energy, battery depletion, and magnetic switch deactivation can occur. 7,10 In comparison with MRI, the magnetic field used in ENB is significantly weaker,, T or approximately equivalent to the earth s gravity. 12 In vitro studies to evaluate possible interference of AICD function by the ENB magnetic field have not shown any device dysfunction. 12 The in vitro studies, however, were in a static substitutive human model and not predictive of clinical performance either of CIED function or effects on diagnostic accuracy. Prospective studies looking at the safety of implanted cardiac devices with reduced force of 0.5 T MRI have shown no significant adverse events once reprogramming to an asynchronous mode. 13 Thus, it is reasonable to assume that the magnetic field used in ENB should pose even less risk. However, the safety of ENB in patients with CIEDs is yet to be elucidated. This article is the first, to our knowledge, to describe the safety of ENB in patients with implanted cardiac devices. Materials and Methods The study was approved by the Institutional Review Board committee (IRB approval # ), and all patients gave written informed consent to the ENB procedure. The study was conducted prospectively. Study Population We performed ENB on 24 patients with peripheral lung lesions who had implanted cardiac devices. The flow of patients through the study is shown in Figure 2. Patient demographics, characteristics, and the types of implanted cardiac devices are shown in Table 1. The location of the target lesions in relation to the patient s hemithorax are shown in Table 2. The lesions varied in size from 1.5 cm to 3 cm. No patients who were evaluated were excluded based on our existing institutional protocol for patients with CIEDs exposure to a magnetic field. Initially, CT imaging of the patient was obtained to determine suitability for ENB. All patients were discussed at multidisciplinary thoracic tumor board meetings, and the decision to proceed with ENB was made with board consensus. Subsequently, in congruence with our institution s electrophysiology department Figure 1. A, B, Chest radiographs showing lung lesion and implanted cardiac device. C, CT scan showing peripheral lung mass that is not candidate for CT scan-guided biopsy. Pacing leads are also shown. 76 Original Research

3 Table 2 Location of the Target Lesions in Relation to the Patient s Hemithorax Location of Target Lesions No. Central third 4 Middle third 8 Peripheral third 12 chest pain, discomfort, heating, or vibration of the CIED also excluded patients from the procedure. Last, interrogation either in advance of the procedure or immediately preprocedure verified that capture thresholds were, 2.00 V at a pulse width of 0.40 milliseconds and that the leads were electrically intact, with impedance values that were between 200 and 1,500. Importantly, all the patients were medically stable prior to the procedure. As the procedures were diagnostic, none were performed emergently. ENB Procedure Figure 2. Flow of patients during the study. AICD 5 automated implantable cardioverter-defibrillator. protocol for patients with CIEDs requiring MRI, patients were screened for exclusion criteria to exposure to the magnetic field. Implantation of the device, myocardial infarction, or cardiothoracic surgery within the previous 3 months prevented patients from receiving ENB. In addition, unstable angina, the presence of abandoned leads, or the inability to communicate symptoms of Table 1 Patient Demographics, Characteristics of Implanted Devices in Study Patients, and Results Patient Age, y Sex Type of Device Symptoms Reported Diagnostic Tissue Obtained 1 66 M PPM/AICD No Yes 2 64 M PPM/AICD No Yes 3 65 F PPM No Yes 4 82 F PPM No No 5 58 M PPM No Yes 6 72 M AICD No Yes 7 80 F PPM No Yes 8 68 M PPM/AICD No Yes 9 76 F PPM No Yes M PPM No No F PPM No No F PPM No Yes M PPM No Yes M PPM/AICD No Yes M PPM No Yes F PPM No Yes M PPM/AICD No No M PPM No Yes M PPM No Yes M AICD No Yes F PPM No No F PPM No Yes M PPM/AICD No Yes M PPM No No ACID 5 automated implantable cardioverter-defibrillator; F 5 female; M 5 male; PPM 5 permanent pacemaker. Peripheral navigation was performed using the superdimension system. During the procedure, a T electromagnetic field was generated around the patient s thorax ( Fig 3 ). 12,14 This electromagnetic field allowed the guidance of a steerable probe into the nonendoscopically visible lung parenchyma toward the target lesion. In brief, the three-dimensional (3-D) virtual rendering of the patient s airways and the target lesion was constructed using the inreach ilogic system (superdimension Inc), superdimension software, and obtained CT images. A very important initial phase of the procedure involves the registration of preset landmarks within the patient s airways to allow linking the CT imaging and 3-D-rendered virtual air ways to the position of a steerable probe ( Figs 4, 5 ). A pathway via the airways to the target lesion was chosen using the 3-D model, and navigation was performed to the target. Once the target was reached, the location was verified with realtime biplanar fluoroscopy, and tissue sampling was performed ( Figs 6, 7 ). Any pulmonary mass or nodule obscured by the pacemaker, leads, or other foreign object on one view of fluoroscopy was visualized in a different view by manipulation of the c-arm of the fluoroscope. ENB was performed as per standard of care. Patients were screened for symptoms of device heating, chest pain, discomfort, movement, or vibration of their CIED. Monitoring and Pacemaker Interrogation A cardiac electrophysiologist and programmer were present throughout each procedure. The programmer then interrogated the CIED to ensure adequate functioning of the device and determine pacemaker dependence. Capture thresholds were reevaluated and lead impedance measured if this had not been done within the prior 3 months. A 12-lead ECG was obtained. No change was made to the pacing mode or to device programming. Interrogation either in advance of the procedure or immediately preprocedure Figure 3. Magnetic field generated around the patient s thorax to create the sensing volume to allow probe navigation. journal.publications.chestnet.org CHEST / 143 / 1 / JANUARY

4 Figure 4. Initial registration phase of Electromagnetic Navigation Bronchoscopy (ENB) to link three-dimensional (3-D) reconstructed airways and CT scan to probe position within the patient. This image shows automatic registration to link the images to probe position. verified that capture thresholds were, 2.00 V at a pulse width of 0.40 milliseconds and that the leads were electrically intact with impedance values that were between 200 and 1,500. Continuous cardiac monitoring, continuous pulse oximetry, and BP measurements every 5 min were obtained immediately prior to and throughout the procedure. The patients were screened for symptoms of cardiac ischemia, arrhythmias, chest discomfort, and device vibration or heating. Immediately postprocedure another 12-lead ECG was obtained, and the CIED was interrogated to assess and correlate with the continuous cardiac monitoring during the procedure and evaluate for occult arrhythmia, programming changes, or other device malfunction. All patients were monitored postprocedure per protocol and symptoms were assessed. Results The procedures were all successfully concluded. None of the patients suffered any arrhythmias or disruption to their pacemakers function either during the procedure or afterward. The concern expressed in earlier studies, even with reduced-energy MRI, related to the activation of the reed switch causing a change to asynchronous pacing mode 10 was not noted in our study patients within the T field. Furthermore, the presence of the CIED in the magnetic field did not appear to cause any disruption to the guidance provided to the steerable probe in locating the target lesion. This can be verified by the diagnostic yield of 75% in the patients reported in this article in comparison with that reported elsewhere in the literature. None of the patients reported any symptoms related to effects of the magnetic field on their CIEDs. No pneumothoraces were identified during or postprocedure. All procedures were performed on an outpatient status, and no hospital admissions occurred postprocedurally except in the five patients with nondiagnostic biopsies. These patients were subsequently admitted to the thoracic surgical service for more invasive tissue diagnosis. Discussion This study is unique and is the first, to our knowledge, to evaluate the safety of ENB in patients with CIEDs. We have shown that in all of our patients with CIEDs the magnetic field generated during the ENB 78 Original Research

5 Figure 5. Initial registration phase of ENB to link 3-D reconstructed airways and CT scan to probe position within the patient. This image shows the manual registration to link the images to probe position, the steerable probe, and 3-D reconstruction of bronchial airways. The tip of the probe is depicted by the purple dot. See Figure 4 legend for expansion of other abbreviations. did not affect the function of their cardiac devices. In addition, the presence of the CIEDs did not affect guidance to the target site and hence diagnostic yield of the ENB. During the study period, 24 patients required ENB. The patient demographics seen in our study population parallel other patients with lung lesions and neoplasms noted in literature. 1,3,15-18 The similarity of demographics should theoretically mean that our study population is not different from patients without CIEDs who would otherwise require similar evaluation with ENB. Intraprocedural monitoring of the cardiac waveform and rhythm can be affected due to the induction of voltage along monitoring or pacing system leads by strong gradient or radiofrequency magnetic fields. 7 This is a phenomenon than can be seen in MRI requiring correlation of the pulse oximetry waveform as a surrogate to monitor adequate perfusion. 19 In the weaker magnetic field of ENB a similar disruption from sensed energy was not seen either, in relation to cardiac monitoring nor the pacing leads with resultant arrhythmias. In addition, cardiac monitoring revealed the absence of arrhythmias or delivery of therapy by the CIEDs. Furthermore, the patients did not report any symptom related to device movement, vibration, heating, or chest pain/discomfort. Interrogation of the devices postprocedure failed to reveal variation in any of the parameters screened. The magnetic field generated for ENB guidance is integral to the precise positioning of the extended working channel to ensure biopsy of the target lesion. The potential effect of placing a CIED within the magnetic field on the accuracy of the spatial positioning of the probe is not known. As seen on MRI scanning of patients with CIEDs, significant artifact from the electromagnetic effects of the device causes loss of image acquisition in the immediate proximity. 20 Theoretically, a similar artifact and disruption of the magnetic field can alter the registration of the patient airways that allow correlation of the constructed airway model with the real-time spatial positioning of the probe within the patient. This would manifest as inaccurate positioning of the biopsy, thereby missing the target lesion. However, during our experience such issues did not arise. On assessment, the diagnostic yield of 75% was in keeping with the yield quoted for ENB in literature. 5,6 As there was no prior experience with patients with CIEDs undergoing ENB, we extrapolated from the literature pertaining to other diagnostic modalities using magnetic fields, the most common of which is MRI. The extensive literature and assessment of the safety of CIEDs within magnetic fields stem from a few initial experiences that led to fatal outcomes for such patients while being scanned with MRI. 10 Although the specific electrophysiologic details of these fatalities were not elucidated, the number of fatalities, in addition to the unknown dynamics of device and lead function in a magnetic field, prompted appropriate caution and investigation. Since these initial reports, a number of issues that may result from the interaction of the ferrous materials of the CIED within the magnetic field of the MRI scanners had been evaluated. In addition, recent advances in technology have permitted the incorporation of nonferromagnetic materials into both the leads and the CIEDs, thereby limiting the potential for any adverse effects. Initial studies evaluating the safety of CIEDs in magnetic fields sought to describe the effects of the field on the implanted system. Figure 6. Fluoroscopy image showing the ENB-guided catheter; pacing and defibrillator wires from the implanted devices can be seen in the foreground. See Figure 4 legend for expansion of abbreviation. journal.publications.chestnet.org CHEST / 143 / 1 / JANUARY

6 However, the much weaker magnetic field used in ENB is, T, thereby making such interactions unlikely. As such, it was believed that during our study changes to the programming of the devices was not warranted. In fact, our results show that no such interaction occurred. This is the first study, to our knowledge, that describes the safety of ENB in patients with CIEDs. The electromagnetic fields generated and required for navigation to the target lesion do not appear to pose a risk to this study population, based on our observations. Conclusion Figure 7. Fluoroscopy image showing the ENB-guided catheter; pacing and defibrillator wires from the implanted devices can be seen in the foreground. See Figure 4 legend for expansion of abbreviation. An initial significant concern was the direct force of the magnetic field causing movement or displacement of the leads from their anchor points within the heart or the device from the chest wall. This has fortunately not been seen in studies looking at the performance of CIEDs in 0.5- and 1.5-T MRI scans. 13 The lack of change noted in our study of changes in lead impedance or pacing capture threshold due to movement or dislodgment of the anchor point of the leads is in keeping with these findings. The resonance of the component particles required for imaging invariably leads to heating of the CIEDs, which has the potential for causing damage to the heart and resultant deterioration of the pacing capture threshold due to scar tissue formation at the anchor point of the leads. 7 This resonance is created by radiofrequency pulses needed in MRIs for image acquisition and is not required for the electromagnetic guidance in ENB; as such, similar issues with heating do not arise during the procedure.7,14 Remaining issues with battery depletion with exposure to magnetic fields have also been shown to be clinically insignificant. 10,13 CIEDs use reed switches to enable and disable functions within the device. These reed switches are activated by magnetic forces and have been documented to be affected by fields as low as T. 10 Activation of the switch causes the device to switch to asynchronous mode, leading to delivery of inappropriate therapy and causing potentially lifethreatening arrhythmias. This is a significant problem for patients with CIEDs requiring MRIs that range from 0.5 to 3 T. 7,10 This necessitates that most patients be switched to a predictable and predetermined asynchronous mode prior to scanning, subsequently reverting to the baseline programming of the device postscan. ENB appears to be safe when performed in patients with implanted pacemakers and defibrillators. Since the magnetic field in ENB is much weaker than that used in MRI, it was believed that reprogramming of the implanted cardiac devices was not required. Although we encountered no complications, we would still recommend close cardiac monitoring of patients during and post procedure. Larger multicenter studies are needed to prove the final safety in this patient population. Acknowledgments Author contributions: Dr Bechara is the guarantor of the paper, taking responsibility for the integrity of the work as a whole, from inception to published article. Dr Khan: contributed to all aspects of this publication and Dr Berkowitz: contributed to all aspects of this publication and Dr Krimsky: contributed to all aspects of this publication and Dr Hogarth: contributed to all aspects of this publication and Dr Parks: contributed to all aspects of this publication and Dr Bechara: contributed to all aspects of this publication and Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. References 1. Jemal A, Siegel R, Xu J, Ward E. Cancer statistics, 2010 [published correction appears in CA Cancer J Clin. 2011; 61(2): ]. CA Cancer J Clin ;60(5): Doria-Rose VP, Szabo E. Screening and prevention of lung cancer. In: Kernstine KH, Reckamp KL, eds. Lung Cancer: A Multidisciplinary Approach to Diagnosis and Management. New York, NY : Demos Medical Publishing ; 2010 : Aberle DR, Adams AM, Berg CD, et al ; National Lung Screening Trial Research Team. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med ;365(5): Ernst A, Anantham D. Update on interventional bronchoscopy for the thoracic radiologist. J Thorac Imaging ;26(4): Original Research

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