Implantable Cardioverter Defibrillator Function Research Articles

Effects of Irradiation During Computed Tomography Scanning on the Function of Implantable Cardioverter-defibrillators.

The effect of irradiation during computed tomography (CT) imaging on implantable cardioverter-defibrillators (ICDs) has not been fully evaluated in various settings. The purposes of this study were to evaluate the occurrence of electromagnetic interference (EMI) during CT irradiation in various clinically available ICDs with phantom experiments and to determine the potential risks related to irradiation during CT imaging. Five types of clinically available ICDs from five manufacturers were tested. An ICD was combined with an electrocardiogram (ECG) simulator, mounted in a chest phantom, and subjected to CT imaging. Each ICD was irradiated at the maximal power level (tube voltage, 135 kVp; tube current, 510 mA; rotation time, 1.5 s). EMI was defined as oversensing, ventricular tachycardia/ventricular fibrillation (VT/VF) detection, noise, or shock delivery during CT imaging. For ICDs in which EMI was observed, EMI was then evaluated under 144 different irradiation conditions (tube voltage [four patterns from 80-135 kVp], tube current [six patterns from 50-550 mA], and rotation time [six patterns from 0.35-1.5 s]). Testing was also performed during irradiation at the typical doses in three clinical settings and in two settings with inappropriate irradiation of ICDs due to incorrect setup. Among the five ICDs, a shock was delivered by one ICD manufactured by Medtronic (Minneapolis, MN, USA) due to oversensing during irradiation, which occurred at the maximal power level. No oversensing was observed in other ICDs. In the malfunctioned ICD, oversensing was observed in 134 of 144 irradiation patterns, even at a low power in the ICD. The VF-detection criterion was fulfilled in 20 of 134 tests and was significantly associated with tube voltage, tube current, ration time, and tube voltage × rotation time interaction. Although oversensing was observed in three clinical settings (typical chest CT, CT coronary angiography after coronary artery bypass graft, and dynamic assessment for pleural tumors) and one situation during an incorrect scan range on the chest for head perfusion CT, they were not recognized as tachycardia beats. Oversensing was observed when scans were incorrectly set over the ICD during bolus tracking of contrast-enhanced CT. Maximal power CT imaging induced VT/VF detection and shock delivery in one model of ICD placed in a chest phantom. VT/VF detection was observed when tube voltages were high and irradiation times were longer. Oversensing can occur during inappropriate CT imaging, particularly when slices are positioned over the ICD.

Accuracy and Functionality of Select Continuous Glucose Monitoring Systems Are Not Impacted by Implantable Cardioverter Defibrillator Devices.

Increasing numbers of individuals with diabetes are adopting use of continuous glucose monitoring (CGM) in their daily self-management. Many of these individuals have advanced heart disease. Implantable cardioverter defibrillator (ICD) devices can effectively reduce arrhythmic death and all-cause mortality in individuals with advanced heart disease. However, the potential impact of ICD devices on CGM system accuracy and functionality has not been well studied. This evaluation assessed whether FreeStyle Libre (FL) CGM systems can coexist and function within the same patient in the presence of wireless interference devices, including current ICD devices. Interferer sources included Wi-Fi devices, Bluetooth devices, cellular mobile devices, implantable medical devices, Bluetooth Low-Energy (BLE) devices, BLE accessory devices and BLE mobile devices, and ICD-programmer interferers. Five testing methodologies were used to evaluate the accuracy and functionality of the CGM systems when exposed to ICD functions: high-energy emergency shocking, pacing modes, anti-tachycardia pacing mode (ATP), and DC Fibber mode. All acceptance criteria and testing requirements were met for the CGM and ICD system for wireless coexistence evaluation. Our findings demonstrated that coexisting ICD devices and FL CGM systems provide safe and effective wireless communications with functional and accurate transfer of data during scenarios expected in clinical use.

The Relevance of Preventive Implantable Cardioverter-Defibrillators (ICDs) in Non-Ischemic Cardiomyopathy in the Presence of Effective Quadruple Therapy for Heart Failure: A Review of Contemporary Medical Literature.

Cardiomyopathy is a disease of the cardiomyocytes that affects their structural function, leading to heart failure (HF). Non-ischemic cardiomyopathy (NICM) includes a subtype of dilated cardiomyopathy (DCM), restrictive cardiomyopathy (RCM), and hypertrophic cardiomyopathy (HCM). These types of cardiomyopathies have no coronary artery vessel involvement. The most common cause of NICM is DCM. In the ischemic cardiomyopathy (ICM) subtype, the utilization of implantable cardioverter-defibrillators (ICDs) has been effective in the prevention of sudden cardiac death (SCD). However, the relevance of ICDs in patients with NICM having an ejection fraction (EF) ≤35%, who are also receiving effective quadruple therapy (i.e., angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB), beta-blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter-2 (SGLT2) inhibitors)for HF has been a topic of debate.The purpose of this review is to analyze the benefits of preventive ICDs in NICM patients on adequate quadruple therapy for HF. The current guidelines recommend ICD implantation in patients with NICM who have a left ventricular ejection fraction of ≤35%, come under the New York Heart Association (NYHA) class II or III, andare in sinus rhythm with optimal medical therapy. The evidence supporting this recommendation islimited. Numerous clinical studies and meta-analyses have been conducted to look into this issue. While some have discovered a substantial decrease in mortality with the implantation of an ICD in patients with NICM, others have not found significant changes.Thereby, further investigations are required to define the function of ICDs in this population.

The use of a wearable cardioverter defibrillator during postmastectomy radiotherapy as an alternative for relocation of the pulse generator

We describe a case in which a breast cancer patient with an implantable cardioverter-defibrillator (ICD) was treated with postmastectomy followed by axillary radiation therapy. The ICD was partly within the target volume and according to the treatment planning system would receive a maximum dose of about 36 Gy. Postoperatively, the patient had a wound infection needing surgical intervention and 3 months of antibiotics. Therefore, it was decided not to relocate the ICD but instead to switch off the shock function of the ICD for the entire radiation therapy course. The ICD was successfully substituted with a wearable cardioverter defibrillator (WCD), which the patient wore during the 3-week radiation therapy period until 2 weeks after the end of treatment. The ICD function was monitored from the start of the treatment until 6 months after treatment. In situations in which an ICD needs to be switched off semipermanently, a WCD can be used as alternative. The patient in this report tolerated the WCD well. Despite the high dose received by the ICD, the device and its battery continued to function normally.

Annals for Hospitalists - March 2023

Annals for Hospitalists - March 2023

Implications of “slower” ventricular tachycardia on clinical management and detection and therapy function of implantable cardioverter defibrillators

Sophisticated dual-chamber atrioventricular and rate-responsive pacing therapies, cardiac resynchronization therapy (CRT), detection and therapies for ventricular tachycardia and fibrillation (VT/VF) form some major components of multitask functions of current implantable cardioverter defibrillators (ICDs). Appropriate programming of these devices is necessary for them to perform all such tasks precisely. In this report, we describe a case of a patient with Chagas cardiomyopathy with marked cardiomegaly, scarred ventricles, prior epicardial and endocardial ablations and on antiarrhythmic pharmacotherapy for VT, who presented with symptomatic wide complex tachycardia at a slower rate than definition of VT, and in whom programming for detection and therapy for "slow" VT could not be performed due to default technological limitation of the CRT-D.

Electromagnetic interference from left ventricular assist device in patients with transvenous implantable cardioverter-defibrillator.

Many advanced heart failure patients have both a left ventricular assist device (LVAD) and an implantable cardioverter-defibrillator (ICD). This study examines incidence, clinical impact, and management of LVAD-related EMI. We performed a three-center retrospective analysis of transvenous ICD implanted patients with LVAD implanted between January 1, 2005 and December 31, 2020. The primary outcome was EMI after LVAD implantation, categorized as LVAD-related noise or telemetry interference. The rate of LVAD-related EMI among the 737 patients (mean age 58.6 ± 12.8 years) studied was 5.0%. Telemetry interference (1.5%) compromised ICD interrogation in all patients. This was resolved successfully with use of a metal shield, encased wand, radiofrequency tower, different ICD programmer or by increasing distance between ICD programmer and LVAD (n=6). ICD replacement was required to reestablish successful communication in three patients. LVAD-related noise (3.5%) led to oversensing (n=4), inappropriate mode switches (n=4), noise reversion (n=3), inhibition of pacing (n=2), inappropriate detection as atrial fibrillation (AF) (n=2) and inappropriate detection as ventricular tachycardia (VT) and/or ventricular fibrillation (VF) (n=2). This noise interference persisted (n=3), resolved spontaneously (n=16), resolved with programming change (n=6) or required lead revision (n=1). EMI from LVAD impacts ICD function, although, the incidence rate is low. Physicians implanting both, LVAD in patients with ICD (more common) or ICD in patients with LVAD, should be aware of possible interferences. Telemetry failure not resolved by metal shielding was overcome by ICD generator replacement to a different manufacturer. In most cases, LVAD-related noise resolves spontaneously.

910Noise-related malfunctions in modern ICDs during oncologic radiotherapy: a multicentre, real-time, in-vitro observation

Abstract Funding Acknowledgements None Background Direct photon exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered not recommended, or even unsafe, by manufacturers and guidelines. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and electromagnetic interferences (EMIs) may present during exposure. Purpose To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy radiotherapy, 36 contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (E.R.I.) were evaluated in a realtime in-vitro session. Methods All ICDs had baseline interrogation. Single chamber devices were programmed in the VVI/40 mode and dual or triple chamber devices were programmed in the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still working. A centering computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was randomly assessed by an in-vivo dosimetry. During radiotherapy course, the devices were observed in a real-time session using manufacturer specific programmer, and ICD function (pacing, sensing, programmed parameters, detection) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure. Results During radiotherapy course, almost all ICDs (90.9%) recorded major or minor transient EMIs. On detail, 16 ICDs (44.4%) reported EMI-related atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. 16 ICDs (44.4%) recorded not clinically relevant minor EMIs, and no detections were observed. Only 4 ICDs (11.2%) reported neither transient malfunction nor minor EMIs, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. EMI-related malfunctions occurred regardless of either 2, 5 or 10 Gy photon beam exposure. Conclusions Transient EMIs were observed in most of the contemporary ICDs. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or reprogramming in the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure.

2410Oncologic radiotherapy-induced implantable cardioverter-defibrillator malfunctions: a real-time, in-vitro evaluation

Abstract Background Direct exposure of implantable cardioverter-defibrillators (ICDs) during radiotherapy is still considered not recommended, or even unsafe, by manufacturers and guidelines. The effects of photon beams on ICDs are unpredictable, depending on multiple factors, and malfunctions may occur during exposure. Purpose To evaluate transient ICD malfunctions by direct exposure to doses up to 10 Gy during low-energy radiotherapy, 33 contemporary wireless-enabled ICDs, with at least 4 months to elective replacement indicator (E.R.I.) were evaluated in a realtime in-vitro session. Methods All ICDs had baseline interrogation. Single chamber ICDs were programmed in the VVI/40 mode and dual or triple chamber ICDs were programmed in the DDD/40 mode. Rate response function and antitachycardia therapies were disabled, with the ventricular tachycardia (VT)/ventricular fibrillation (VF) detection windows still active. A centering computed tomography was performed to build the corresponding treatment plan and the ICDs were blinded randomized to receive either 2, 5 or 10 Gy exposure by a low photon-energy linear accelerator (6MV) in a homemade water phantom (600 MU/min). The effective dose received by the ICDs was assessed by an in-vivo dosimetry. During radiotherapy, the devices were observed in a real-time session using manufacturer specific programmer, and ICD function (pacing, sensing, programmed parameters, detection) was recorder by the video camera in the bunker throughout the entire photon exposure. All ICDs had an interrogation session immediately after exposure. Results During radiotherapy course, almost all ICDs (90.9%) recorded major or minor transient electromagnetic interferences. On detail, 13 ICDs (39.4%) reported atrial and/or ventricular oversensing, with base-rate-pacing inhibition and VT/VF detection. 16 ICDs (48.5%) recorded non clinically relevant noise, and no detections were observed. Only 4 ICDs (12.1%) reported neither transient malfunction nor minor noise, withstanding direct radiation exposure. At immediate post-exposure interrogation, the ICDs that recorded major real-time malfunctions had VT/VF detections stored in the device memory. In none of the ICDs spontaneous changes in parameter settings were reported. Malfunctions occurred regardless of either 2, 5 or 10 Gy photon beam exposure. Conclusions Transient electromagnetic interferences were observed in most of the contemporary ICDs during radiotherapy course, regardeless of photon dose. To avoid potentially life-threatening ICD malfunctions such as pacing inhibition or inappropriate shock delivery, magnet application on the pocket site or reprogramming devices in the asynchronous mode are still suggested in ICD patients ongoing even low energy radiotherapy exposure. Acknowledgement/Funding None

Inevitable high-dose irradiation to lead of implantable cardioverter defibrillator in small cell lung cancer: a\xa0case report

BackgroundRadiotherapy has been shown to cause malfunction of implantable cardioverter-defibrillators, and there are few studies of implantable cardioverter-defibrillators and radiotherapy. We report an unusual case of small cell lung cancer in a patient with an implantable cardioverter-defibrillator in whom direct irradiation to the electrode and lead could not be avoided.Case presentationWe report a case of radiotherapy in a 72-year-old Korean man with a limited stage of small cell lung cancer who had undergone insertion of an implantable cardioverter-defibrillator because of ventricular fibrillation. The radiation dose was 60 Gy in 30 fractions to the thorax. The mean dose and maximum dose estimated at the body of the implantable cardioverter-defibrillator were 0.89 Gy and 2.23 Gy, respectively. The mean and maximum doses of the lead and electrode were 17.12 Gy and 55.72 Gy in the lead and 1.81 Gy and 7.10 Gy in the electrode, respectively, because part of the lead and electrode was inevitably in the irradiated fields. The function of the patient’s implantable cardioverter-defibrillator was checked daily, and no change in implantable cardioverter-defibrillator function was observed for the duration of radiotherapy. The patient was tolerated the treatment well without severe complications. Computed tomography performed at 4 weeks after radiotherapy showed a good response with regression of the tumor. The patient was alive with complete remission of the tumor and without any implantable cardioverter-defibrillator dysfunction more than 36 months after the end of treatment.ConclusionsThis case demonstrates that radiotherapy may be a safe and effective treatment modality through careful monitoring of implantable cardioverter-defibrillators in patients with lung cancer who have implantable cardioverter-defibrillators.

Missed opportunities! End of life decision making and discussions in implantable cardioverter defibrillator recipients

BackgroundRecent guidelines highlight the need for clinician-patient discussions regarding end-of-life (EOL) choices prior to implantable cardioverter defibrillator (ICD) implantation. Health literacy could affect the quality and quantity of such discussions. ObjectiveOur objective was to determine the association of health literacy with experiences, attitudes, and knowledge of the ICD at EOL. MethodsIn this cross-sectional study, we used validated instruments to measure health literacy and patient experiences, attitudes, and knowledge of the ICD at EOL. ResultsOf the 240 ICD recipients, 76% of participants reported never having discussed the implications of a future withdrawal of defibrillation therapy with their healthcare provider. Increased odds of choosing to maintain defibrillation therapy were associated with female gender and lower ICD knowledge. ConclusionsFrom patients’ perspectives, EOL discussions with providers were minimal. Most patients hold misperceptions about ICD function that could interfere with optimal EOL care, particularly for those with inadequate health literacy.

Safety and interaction of patients with implantable cardiac defibrillators driving a hybrid vehicle

BackgroundElectromagnetic interference (EMI) can affect the function of implantable cardioverter defibrillators (ICD). Hybrid electric vehicles (HEV) have increased popularity and are a potential source of EMI. Little is known about the in vivo effects of EMI generated by HEV on ICD. ObjectiveThis study evaluated the in vivo interaction between EMI generated by HEV with ICD. Methods and resultsThirty patients (73±9 y/o; 80% male) with stable ICD function were exposed to EMI generated by a Toyota Prius Hybrid®. The vehicle was lifted above the ground, allowing safe changes in engine rotation and consequent variations in electromagnetic emission. EMI was measured (NARDA STS® model EHP-50C) and expressed in A/m (magnetic), Volts/m (electrical), and Hertz (frequency). Six positions were evaluated: driver, front passenger, right and left back seats, outside, at the back and front of the car. Each position was evaluated at idle, 30 mph, 60 mph and variable speeds (acceleration-deceleration-brake). All ICD devices were continuously monitored during the study.The levels of EMI generated were low (highest mean levels: 2.09A/m at right back seat at 30 mph; and 3.5V/m at driver seat at variable speeds). No episode of oversensing or inadvertent change in ICD programming was observed. ConclusionIt is safe for patients with ICD to interact with HEV. This is the first study to address this issue using an in vivo model. Further studies are necessary to evaluate the interaction of different models of HEV or electric engine with ICD or unipolar pacemakers.

Neuromuscular electrical stimulation of the thighs in cardiac patients with implantable cardioverter defibrillators.

SummaryBackgroundThe aim of this systematic review was to update scientific knowledge concerning the safety of neuromuscular electrical stimulation (NMES) to increase exercise capacity and prevent cardiac cachexia in patients with implantable cardioverter defibrillators (ICDs).MethodsA systematic review including the electronic databases PubMed, MEDLINE, and SCOPUS was conducted for the time period from 1966 to March 31, 2016.ResultsOnly four articles fulfilled the inclusion criteria (three original articles/safety studies and one case report). The three (safety) studies used NMES to increase muscle strength and/or endurance capacity of the thighs. NMES did not show electromagnetic interference (EMI) with ICD function. EMI was described in a case report of 2 patients with subpectoral ICDs and application of NMES on abdominal muscles.ConclusionThis review indicates that NMES may be applied in cardiac ICD patients if 1) individual risks (e. g., pacing dependency, acute heart failure, unstable angina, ventricular arrhythmic episode in the last 3 months) are excluded by performing a safety check before starting NMES treatment and 2) “passive” exercise using NMES is performed only for thighs and gluteal muscles in 3) compliant ICD patients (especially for home-based NMES) and 4) the treatment is regularly supervised by a physician and the device is examined after the first use of NMES to exclude EMI. Nevertheless, further studies including larger sample sizes are necessary to exclude any risk when NMES is used in this patient group.

Decision-Making of Patients With Implantable Cardioverter-Defibrillators at End of Life: Family Members' Experiences.

Many patients with advanced heart failure (HF) experience the life-extending benefits of implantable cardioverter-defibrillators (ICD), but at the end stage of HF, patients may experience shocks with increasing frequency and change the plan for end-of-life (EOL) care including the deactivation of the ICD. This report describes family members' experiences of patients with ICD making decisions at EOL. Understanding the decision-making of patients with ICD at EOL can promote informed decision-making and improve the quality of EOL care. This pilot study used a mixed methods approach to test the effects of a nurse-guided discussion in decision-making about ICD deactivation (turning off the defibrillation function) at the EOL. Interviews were conducted, audiotaped, and transcribed in 2012 to 2013 with 6 family members of patients with advanced HF and ICDs. Three researchers coded the data and identified themes in 2014. Three main themes described family members' experiences related to patients having HF with ICDs making health-care decision at EOL: decision-making preferences, patients' perception on ICD deactivation, and communication methods. Health-care providers need to have knowledge of patients' decision-making preferences. Preferences for decision-making include the allowing of appropriate people to involve and encourages direct conversation with family members even when advance directives is completed. Information of ICD function and the option of deactivation need to be clearly delivered to patients and family members. Education and guidelines will facilitate the communication of the preferences of EOL care.

Antiarrhythmic Drug Therapy to Avoid Implantable Cardioverter Defibrillator Shocks.

Implantable cardioverter defibrillators (ICDs) are effective in the prevention of arrhythmic sudden cardiac death. Many patients receiving an ICD are affected by heart failure and are at risk of ventricular arrhythmias, which may lead to appropriate shocks. On the other hand, in this population the incidence of atrial fibrillation, giving rise to inappropriate ICD shocks, is high. Accordingly, ICD discharges occur frequently and many patients with an ICD will need concomitant antiarrhythmic drug therapy to avoid or reduce the frequency of shocks. Therapeutic agents such as β-blockers, class I or class III antiarrhythmic drugs effectively suppress arrhythmias, but may have side-effects. Some drugs could eventually influence the function of ICDs by altering defibrillation or pacing threshold. Few prospective randomised trials are available, but current data suggest that amiodarone is most effective for prevention of appropriate or inappropriate ICD shocks. This review article summarises current knowledge regarding the antiarrhythmic management of patients with ICDs.

Abstract 11135: Missed Opportunities! End-Of-Life Discussions and Implantable Cardioverter Defibrillator Recipients

Introduction: Guidelines for device based therapy of cardiac rhythm abnormalities were updated by the ACC/AHA/HRS in 2008 to include discussions beginning at the time of implantation with implantable cardioverter defibrillator (ICD) recipients regarding end-of-life (EOL) choices and withdrawal of defibrillation therapy. The level of adherence to this guideline from the patients’ perspective is unknown. Methods: The purpose of this study was to determine (1) ICD patients’ perspectives about discussions held with their providers focused on EOL choices regarding the withdrawal of defibrillation therapy and (2) ICD recipients’ level of knowledge regarding ICD function at EOL. ICD recipients from outpatient cardiology clinics associated with an academic health center, a community hospital, or a suburban hospital located in Central Kentucky completed the EOL-ICD questionnaire. The EOL-ICD measures three domains: experiences of EOL issues, attitudes about EOL discussions and actions, and knowledge of the ICD in relation to EOL issues. This instrument is valid and reliable in the ICD population. Results: Of the 115 ICD recipients (mean age = 63 yrs., 22% non-white, 24% non-partnered, with a mean educational level = 13.6 yrs., a mean duration of therapy = 5yrs., and 34% reporting one or more ICD shocks) 71% reported that they have never had discussions with their health care provider regarding what withdrawal of defibrillation therapy implies. A total of 44% believed that turning off the ICD shocks was the same as active euthanasia and that to disable defibrillation therapy required surgical intervention; 43% believed that once defibrillation was disabled it could not be enabled again; and 24% of recipients believed that the heart would stop beating due to the withdrawal of defibrillation therapy. Conclusion: Adherence to the guidelines regarding EOL discussions with ICD recipients was minimal from the patients' perspective. Despite national and international guideline recommendations to discuss EOL issues with ICD recipients beginning at implant, most patients report not having these discussions and many hold alarming misperceptions that could interfere with optimal EOL care.

Nonhemodynamic parameters from implantable devices for heart failure risk stratification.

"Implantable devices are well suited to monitor and record several parameters that carry prognostic information. Specifically, the primary function of implantable cardioverter defibrillators (ICDs) is to monitor for changes in heart rhythm and treat both tachyarrhythmias and bradyarrhythmias. They are efficient in monitoring the heart rate, incidence of arrhythmias, and patient activity level, which provide prognostic information. Parameters such as thoracic impedance, heart sounds, and respiratory rate and patterns may further refine prognostic information available from ICDs. Combining parameters may provide a better way to interpret and use the available information."

Spinal cord stimulation is safe and feasible in patients with advanced heart failure: early clinical experience.

Pre-clinical work suggests that upper thoracic spinal cord stimulation (SCS) may have therapeutic effects in the treatment of heart failure (HF). We therefore aim to assess the safety and feasibility of SCS in HF patients. A prospective, randomized, double-blind, crossover pilot study was conducted in symptomatic HF patients receiving optimal medical therapy. Patients were implanted with an SCS system and randomized to an SCS-ACTIVE, delivered at 90% paraesthesia threshold, or an SCS-INACTIVE phase for 3 months, followed by a 1-month washout period and crossover to the alternative phase. The safety of SCS therapy was assessed by death and cardiac events. Implantable cardioverter defibrillator (ICD) function in the presence of SCS was tested by defibrillation testing during SCS system implant and review of real-time and stored electrograms during follow-up. The efficacy of SCS therapy was assessed by changes in patient symptoms, LV function, and BNP level. Nine patients were investigated. In all cases, ICD sensing, detection, and therapy delivery were unaffected by SCS. During follow-up, one patient died and one was hospitalized for HF while in the SCS-INACTIVE phase, and two patients had HF hospitalizations during the SCS-ACTIVE phase. Symptoms were improved in the majority of patients with SCS, while markers of cardiac structure and function were, in aggregate, unchanged. This study shows that an SCS system can be safely implanted in patients with advanced HF and that the SCS system does not interfere with ICD function.

ICD Recipients’ Understanding of Ethical Issues, ICD Function, and Practical Consequences of Withdrawing the ICD in the End‐of‐Life

The current international expert consensus statements recommend that clinicians should discuss elective implantable cardioverter defibrillator (ICD) deactivation before implantation of the device, and then consistently during the illness trajectory. However, no previous studies have investigated predictors of ICD patients' knowledge about end-of-life issues or whether knowledge influences patients' attitudes about deactivation. This nationwide survey study (n = 3,067) had a cross-sectional correlational design of self-reported data. Participants were recruited from the Swedish ICD and Pacemaker Registry and asked to complete a questionnaire about knowledge in relation to the ICD and end-of-life. Only 79 respondents (3%) scored correctly on all 11 questions. The mean sample score was 6.6 ± 2.7 out of a maximum score of 11. A total of 835 participants (29%) had an insufficient knowledge when using the 25th percentile as a cutoff. Younger ICD recipients, those cohabiting, male participants, and those who had received shocks, had a generator replacement, or who had discussed illness trajectory with their physician were more likely to have sufficient knowledge on the end-of-life issues. Insufficient knowledge was associated with indecisiveness to make decisions about ICD deactivation in the end-of-life situations, and with favorable attitudes about replacing the ICD even if seriously ill or have reached an advanced age, and keeping the shock therapy of the ICD even in a terminal phase of life when dying from cancer or other serious chronic illnesses. Insufficient knowledge is common among ICD recipients and is associated with attitudes and decisions that may result in a stressful and potentially painful end-of-life situation.

IMPLANTABLE CARDIOVERTER DEFIBRILLATORS IN MAGNETIC FIELDS OF A 400 KV SUBSTATION

Workers using an implantable cardioverter defibrillator (ICD) are classified by European Directive 2013/35/EU as being at particular risk because of the potential interference between implanted medical devices and electromagnetic fields. The aim of the study was to investigate ICD function using a human-shaped phantom in high magnetic fields of a shunt reactor at a 400 kV substation. We used the phantom in the following experiment periods: isolated from the ground, grounded by a foot, or grounded by a hand. We performed five ICD tests using five different ICD devices. In experiment place A, the magnetic field was over 1000µT, and in experiment place B, the exposure was over 600µT. We did not find any disturbances in the ICDs. However, we conducted only 5 ICD experiments in real exposure situations at 400 kV substations. Although it is not possible to draw a strong conclusion regarding risk level, the risk of such ICD disturbances from magnetic field exposure at 400 kV substations does not appear to be high.