Urgent Implantable Cardioverter Defibrillator Deactivation by Unconventional Means

Transcription

1 Vol. 42 No. 6 December 2011 Journal of Pain and Symptom Management 941 Special Article Urgent Implantable Cardioverter Defibrillator Deactivation by Unconventional Means Michael Thomas Beets, MD, and Edward Forringer, PhD Hospice of East Texas (M.T.B.), Tyler, Texas; and LeTourneau University (E.F.), Longview, Texas, USA Abstract Increasing numbers of patients are receiving implantable cardioverter defibrillators (ICDs); the devices remain fully functional in most terminally ill patients at the time of death. We describe a case of a terminally ill patient with repeated defibrillations who requested urgent ICD deactivation. Nonmedical magnets available in the facility were used to deactivate the ICD and terminate the defibrillations. We then studied various magnetic field sources commonly available in homes, such as ceramic magnets, cell phones, computer hard drives, headsets, and earbuds that potentially may be used to temporarily deactivate an ICD until a device technician is available for reprogramming. We conclude that commonly available magnetic sources may potentially be used to deactivate an ICD. The clinical usefulness of this is speculative and limited to conditions when the need to turn off the device is urgent, and a delay in reprogramming is anticipated. J Pain Symptom Manage 2011;42:941e945. Ó 2011 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved. Key Words Implantable cardioverter defibrillator, automatic implantable cardioverter defibrillator, magnets, defibrillation, deactivation Introduction Hospice and palliative care professionals frequently encounter patients with an implantable cardioverter defibrillator (ICD). Although the need to address the goal of an ICD in endof-life care is recognized, many of these patients continue to have a fully functioning device. 1,2 On rare occasions, a patient in a home or nursing facility will have recurrent discharges of their device, often causing pain Address correspondence to: Michael Thomas Beets, MD, Hospice of East Texas, 4111 University Blvd., Tyler, TX 75701, USA. mtbeets@pol.net Accepted for publication: February 26, Ó 2011 U.S. Cancer Pain Relief Committee Published by Elsevier Inc. All rights reserved. and anxiety. Causes of recurrent shocks include ventricular arrhythmias, supraventricular tachycardias, oversensing, electromagnetic interference, and lead or device malfunction. 3 If a patient starts receiving multiple shocks in an out of the hospital setting and urgent deactivation is requested, is there any intervention that can be performed to emergently shut off the ICD? Optimally, an ICD technician could interrogate the device and deactivate it. Another alternative would be that a doughnut magnet, intended to be used for ICD deactivation, be placed over the unit until an ICD technician can arrive for formal permanent deactivation. In many cases, the recommended methods are not immediately available. In a crisis, while /$ - see front matter doi: /j.jpainsymman

2 942 Beets and Forringer Vol. 42 No. 6 December 2011 awaiting the ICD technician, is there anything a health care professional can do to urgently relieve the pain and suffering that occur with repeated unwanted shocks? We describe our experience with a request for urgent ICD deactivation and report on some investigations that reveal the potential for nonmedical household objects to deactivate an ICD. Case Mr. C. V., a 78-year-old male with severe ischemic cardiomyopathy with an ejection fraction of 10%e15%, had been transferred from an acute care hospital to our inpatient hospice unit for further management of dyspnea and associated end-of-life symptoms. In the hospital, he had vacillated between somnolence and lethargy. Because of his cardiomyopathy and dysrhythmias, an ICD with pacemaker had been placed two months earlier. On admission to hospice, the patient was told of the risk of repeated shocks as his condition progressed if his ICD was left operational; however, he declined deactivation, indicating that he felt better with the device on. The following morning, his ICD began discharging approximately every minute. Mr. C. V. was alert enough to talk. His pulse was difficult to palpate. He now requested that we turn off his ICD immediately. The patient could neither identify the brand of ICD he had nor did he carry a wallet card with ICD identification characteristics. The nurses set about to find a device technician to deactivate his ICD. Realizing that a magnet can be used to temporarily deactivate the ICD, we searched and found a flat business card-type magnet, which we applied over the device. The patient continued to be shocked. We placed a stack of 10 business card-type magnets over the ICD, and immediately the shocking ceased. Simultaneously, we located the manufacturer of his ICD and eventually a technician arrived and reprogrammed the device to the off mode while leaving his pacemaker on. After interrogation, we found that Mr. C. V. had been defibrillated 44 times with 36 J each time for ventricular and supraventricular tachycardias during a 35-minute period. This occurrence of three or more episodes of ventricular tachyarrhythmia within 24 hours is sometimes referred to as an electrical storm. 4 After reprogramming, the patient appeared to be in a sinus tachycardia, with a rate in the 120s. Propranolol was added but discontinued the next day because of hypotension. Mr. C. V. died peacefully three days later. Review of the Literature and Suggested Interventions The implantable or implanted cardioverter defibrillator also is known as an automatic ICD. Since the first placement of an ICD at Johns Hopkins Hospital in 1980, the device has increasingly been used in patients with life-threatening tachydysrhythmias. 1,5 The device has a small electric generator with a sensing and shocking function. Most ICDs also have a pacing function. When a dysrhythmia occurs, the ICD may pace the heart (antitachycardia pacing), cardiovert with a low energy synchronized shock, or defibrillate the heart with a higher energy shock. Most ICDs have a maximum delivery in the 30 J range. 6 If a shock is delivered and someone is touching the patient, some of the current may enter the bystander, causing mild discomfort; however, there has never been a reported case of bystander injury, and wearing gloves will prevent the conduction of energy to the person in contact with the patient. 7 For the cardiac patient with an ICD nearing the end of life, a discussion is in order to determine the goals of care. Although there is increasing recognition of the need to discuss and offer ICD deactivation at the time of hospice admission, a recent survey by Goldstein et al. 1 revealed that few hospices currently assess for an ICD as part of the hospice admission protocol. For a variety of reasons, most terminally ill patients with ICDs continue to have a fully functional device. 1,2 If the decision is made to leave the ICD on and later a request is made for urgent deactivation, then two issues need to be rapidly addressed. First, the manufacturer will need to be identified and contacted to request reprogramming to turn off the ICD. At the time of device placement, the patient is provided with a wallet card containing identifying characteristics of the device. If the patient does not have the wallet card, the cardiologist who

3 Vol. 42 No. 6 December 2011 ICD Deactivation by Unconventional Means 943 placed the device will have the required information. Another option is to obtain an overpenetrated anteroposterior chest radiograph. On the ICD, there will usually be a visible identifying code that indicates the manufacturer (e.g., the St. Jude Medical code begins with SJM). Another alternative is to call the three major ICD manufacturers in the U.S. and determine if the patient is enrolled in their database. The following are 24-hour contact numbers: Boston Scientific (formerly Guidant) 800-CARDIAC ( ); Medtronic 800-MEDTRON ( ); and St. Jude Medical Secondly, there may be a way to temporarily deactivate the ICD until the representative arrives to reprogram the device. A magnet of adequate strength placed directly over the ICD can disengage the tachycardia sensing and intervention ability of the device so that no shocks will be delivered. 3 The bradycardia pacing function will not be affected by a magnet. When the magnet is placed, there may be a beeping or other tone that is produced by the ICD depending on the specific device characteristics. Once the magnet is removed, the tachyarrhythmia detection and intervention ability may again be enabled. Discussions with the technical departments at the three major ICD manufacturers revealed that a magnetic field strength of 5e12 gauss or more is usually required at the level of the ICD for deactivation to occur. A gauss is a unit of magnetic field strength equal to 1/10,000 of a Tesla. For a typical dipole magnet, the magnetic field strength decays at a rate proportional to one/distance 3. The doughnuttype magnets that are used by the manufacturer to deactivate ICD units produce a magnetic field of more than 50 gauss at a distance of 7 cm; however, specialized magnets of this strength are not necessary to provide temporary relief for patients who are being repeatedly shocked. Because our patient was cachectic and the distance from his chest wall to the ICD was minimal, a stack of relatively weak business card magnets delivered enough magnetic flux to the ICD for temporary deactivation. As a performance improvement measure, our facility has subsequently obtained several of the stronger doughnut-shaped magnets and the staff is being trained on their use in case this type of event occurs again. Because we were able to disable the ICD with a stack of business card magnets, we wondered if there were other objects described in the literature that could deactivate an ICD. A PubMed literature search for alternative or accidental ICD deactivation found case reports of accidental deactivation from exposure to stereo speakers, magnets in the workplace, magnetic bingo wands, a 12-V starter for a model airplane engine, magnetized screws, and magnetic fields in the health care setting. 8e10 Empirical Observations The question then arose as to what other common household objects might be of benefit in turning off a device in an emergency. After further study, it was determined that many household items contain unrecognized forms of magnets. Speakers of any type typically have a permanent magnet as part of their assembly. Speakers are in traditional stereo speakers but are also present in telephones, headphones, and earbuds. A computer hard disk drive records data by magnetizing ferromagnetic material directionally, causing it to have a magnetic field. With this in mind, we devised two phases of experiments. In a physics laboratory at LeTourneau University, the authors measured the magnetic field strength of several magnets that might be found around home or office. Magnetic field measurements were performed with a Vernier magnetic field probe. The probe was calibrated using the Earth s magnetic field as a reference (0.496 gauss in Longview, TX). Magnetic fields were measured using a plastic barrier of 5.0 and 7.5 mm, for several magnets. For each magnet, the probe was positioned to find the maximum field produced by the device. For some devices, the location of the maximum field was small and not in an intuitively obvious place. The results are presented in Table 1. Next, in an attempt to move our findings from the bench to the bedside, a similar series of experiments were carried out using three different functioning ICDs: 1) Guidant Contak Renewal Ò 3RF DDDR Model H215, 2) Guidant Vitality Ò 2 EL Type DR Model T167, and 3) Guidant Ventak Prizm Ò 2 VR

4 944 Beets and Forringer Vol. 42 No. 6 December 2011 Device Table 1 Magnetic Field Strength of Various Devices Found in Homes Field 5 mm (Gauss) Field 7.5 mm (Gauss) Single business <0.5 <0.5 card-type magnet Stack of business cardtype magnets Motorola Bluetooth Ò earpiece Earbuds for cell phone Generic headset Computer speaker 16 9 Home telephone receiver Blackberry Ò CurveÔ cell phone Ceramic clip >80 >80 magnet Dell LatitudeÔ D830 laptop computer Type VR Model 1860 (Boston Scientific, Brussels, Belgium). Because these ICDs were not implanted at the time of our testing, the magnetic devices were held at a distance from the ICD in an attempt to replicate the skin and soft tissue distance in a patient. A 2 mm barrier of paper and a 4 mm plastic barrier were used to create a distance between the ICD and the magnetic device. Table 2 describes the results of these experiments. Some comments on our measurements are in order. If an ICD did not deactivate with a device held at a distance of 2 mm, then we assumed that it would not deactivate at 4 mm with the same device because of the decay of the magnetic field. The business card magnets are the size of a business card and are commonly placed on a refrigerator or other metal surface with an advertisement on the front. The earbuds were the standard ones supplied with a Blackberry Ò CurveÔ cell phone (Research In Motion, Ontario, Canada). The ceramic clip magnet used in Table 1 measured mm and was attached to a clip that was designed to hang notes from the refrigerator. For logistical reasons, a smaller ceramic clip magnet was used to test the three ICDs. The cell phones had the greatest magnetic field near the speakerphone, and the laptops measured strongest near the hard drive access door. Discussion Our measurements indicate that there are sources of magnets available in most homes potentially capable of temporarily deactivating an ICD, given that a magnetic field of 5e12 gauss is usually needed for deactivation. Most of these magnets are in devices that are often overlooked when one is searching for a magnet. Our studies indicate that doughnut and ceramic magnets appear to be most effective, followed by cell phones and computer hard drives. At close distances, a headset or an earbud may be successful. Business card magnets did not work well in our tests but did work on our patient. The magnet needs to be positioned over the ICD and, if available, gloves should Table 2 Effects of Various Magnetic Devices at Differing Distances on ICD Deactivation Devices and Distance #1 at 2 mm #1 at 4 mm #2 at 2 mm #2 at 4 mm #3 at 2 mm #3 at 4 mm Stack of 10 business card magnets NT NT NT Motorola Bluetooth Ò earpiece NT NT NT Earbuds for cell phone NT þþþ þþþ Generic headset NT þþþ þþþ Computer speaker NT NT NT Home telephone receiver NT NT þþþ þþþ Blackberry Ò CurveÔ Phone NT þþþ þþþ þþþ Blackberry Ò BoldÔ Phone NT NT þþþ þþþ þþþ þþþ iphone Ò NT NT NT NT Ceramic clip magnet þþþ þþþ IBM ThinkPad Ò NT þþþ þþþ Fujitsu LifeBook Ò NT þþþ þþþ þþþ #1 ¼ Guidant Contak Renewal 3RF DDDR Model H215; #2 ¼ Guidant Vitality 2 EL Type DR Model T167; #3 ¼ Guidant Ventak Prizm 2 VR Type VR Model 1860; ¼ ICD not deactivated; þþþ ¼ ICD effectively deactivated; NT ¼ not tested.

5 Vol. 42 No. 6 December 2011 ICD Deactivation by Unconventional Means 945 be worn when placing the magnet. Because of the magnetic field decay, a deeply implanted ICD in a patient with significant subcutaneous tissue over the device will require a strong magnet for deactivation. A patient who is cachectic with little body fat will be more likely to respond to a weak magnet. In many of the ICDs, the magnet will need to remain over the device in order for the deactivation to continue. The magnet strength, the distance between magnet and ICD, and the type of ICD all influence whether the device will be successfully deactivated. Health care professionals working in homes and facilities caring for patients at the end of life may benefit from obtaining one of the inexpensive but effective doughnut magnets for use in urgent ICD deactivation. Less than half of terminally ill patients at the end of life with ICDs have their devices deactivated. 1,2 Information contained in this article presents potential options for urgent unconventional deactivation of ICDs in homes and facilities while waiting for more conventional deactivation. Greater attention to addressing ICD deactivation early in a hospice admission should reduce the occurrence of unwanted electrical shocks in this population. We acknowledge that the observations described have not been rigorously tested and are of uncertain clinical relevance. We do not know if a cell phone or computer placed over an ICD but failing to deactivate it would be damaged by a shock. Additional studies and case reports would be beneficial to the understanding of how effective alternative means of ICD deactivation actually are in clinical practice. It is hoped that this information would in no way undermine attempts to proactively deal with anticipatory ICD deactivation in patients at the end of life. Conclusion Patients with a terminal illness can benefit from a discussion of the benefits and risks of maintaining a functional ICD. A decision to turn off the ICD will usually be implemented by a device technician. If a patient is having recurrent shocks and requests urgent deactivation, a doughnut-type magnet may be placed over the device to deactivate the sensing function and turn off the shocks while awaiting a technician. If no doughnut magnet is available, then other magnet-containing items available, such as ceramic magnets, cell phones, computer hard drives, desk telephones, headsets, earbuds, and perhaps a stack of business card magnets, may be able to temporarily deactivate the device. Disclosures and Acknowledgments The authors have no grants or financial support to disclose nor do they have any conflicts of interest. References 1. Goldstein N, Carlson M, Livote E, Kutner J. Brief communication: management of implantable cardioverter-defibrillators in hospice: a nationwide survey. Ann Intern Med 2010;152:296e Lewis WR, Luebke DL, Johnson NJ, et al. Withdrawing implantable defibrillator shock therapy in terminally ill patients. Am J Med 2006;119:892e McMullan J, Valento M, Attari M, Venkat A. Care of the pacemaker/implantable cardioverter defibrillator patient in the ED. Am J Emerg Med 2007;25:812e Gasparini M, Lunati M, Landolina M, et al. Electrical storm in patients with biventricular implantable cardioverter defibrillator: incidence, predictors, and prognostic implications. Am Heart J 2008;156:847e Mirowski M, Reid PR, Mower MM, et al. Termination of malignant ventricular arrhythmias with an implanted automatic defibrillator in human beings. N Engl J Med 1980;303:322e Roberts JR, Jedges JR. Clinical procedures in emergency medicine, 5th ed. Philadelphia, PA: Saunders Elsevier, Stevenson WG, Chaitman BR, Ellenbogen KA, et al. Clinical assessment and management of patients with implanted cardioverter-defibrillators presenting to nonelectrophysiologists. Circulation 2004;110:3866e Bonnet CA, Elson JJ, Fogoros RN. Accidental deactivation of the automatic implantable cardioverter defibrillator. Am Heart J 1990;120:696e Schmitt C, Brachmann J, Waldecker B, et al. Implantable cardioverter defibrillator: possible hazards of electromagnetic interference. Pacing Clin Electrophysiol 1991;14:982e Rasmussen MJ, Friedman PA, Hammill SC, Rea RF. Unintentional deactivation of implantable cardioverter-defibrillators in health care settings. Mayo Clin Proc 2002;77:855e859.