Electromagnetic interference by transcutaneous neuromuscular electrical stimulation in patients with bipolar sensing implantable cardioverter defibrillators: a pilot safety study

Risk of occurrence of electromagnetic interference from the application of transcutaneous electrical nerve stimulation on the sensing function of implantable defibrillators

BACKGROUND

Transcutaneous electrical nerve stimulation (TENS) is an established method for pain relief. But electrical TENS currents are also a source of electromagnetic interference (EMI). Thus, TENS is considered to be contraindicated in implantable cardioverter-defibrillator (ICD) patients. However, data might be outdated due to considerable advances in ICD and cardiac resynchronization therapy (CRT) filtering and noise protection algorithm technologies. The aim of this pilot safety study was to re-evaluate the safety of TENS in patients with modern ICDs.

METHODS AND RESULTS

One hundred and seven patients equipped with 55 different models of ICD/CRT with defibrillators from 4 manufacturers underwent a standardized test protocol including TENS at the cervical spine and the thorax, at 2 stimulation modes-high-frequency TENS (80 Hz) and burst-mode TENS (2 Hz). Potential interference monitoring included continuous documentation of ECG Lead II, intracardiac electrograms and the marker channel. Electromagnetic interference was detected in 17 of 107 patients (15.9%). Most frequent were: interpretations as a premature ventricular beats (VS/S) in 15 patients (14%), noise reversion in 5 (4.6%) which resulted in temporary asynchronous pacing in 3 (2.8%), interpretation as ventricular tachycardia/ventricular fibrillation in 2 (1.9%), and premature atrial beat in 2 (1.9%) patients. Electromagnetic interference occurrence was influenced by position (chest, P < 0.01), higher current intensity (P < 0.01), and manufacturer (P = 0.012).

CONCLUSION

Overall, only intermittent and minor EMI were detected. Prior to the use of TENS in patients with ICDs, they should undergo testing under the supervision of a cardiac device specialist.

Influence of electrical stimulation therapy on permanent pacemaker function

BACKGROUND

Electrical stimulation therapy (EST) and transcutaneous electrical neuromuscular stimulation (TENS), a modality of EST, have become widely applied, accepted and effective methods for the treatment of musculoskeletal and other pain conditions. According to the rising number of permanent pacemaker (PM) wearers the number of potential candidates for EST with concomitant device implantation is growing. Contradictory recommendations exist regarding the application of EST or TENS on PM wearers.

AIM

The study was carried out to evaluate the impact of EST on PM function.

METHODS

A full size model mimicking the electrical characteristics of the human body was used to evaluate the application of EST on permanent PM devices. Various configurations with respect to energy modality, position of the stimulation electrodes and PM device models were evaluated. Intracardiac PM electrogram tracings (iEGM) were analyzed for the interference of EST with PM function.

RESULTS

Unilateral EST application did not cause interference with PM function in any of the configurations (0%; n = 700). On the contrary, bilateral stimulation (350 configurations in total) caused either ventricular inhibition or switch to V00 back-up pacing due to electrical interference in 165 cases (47.1%) depending on the applied stimulation parameters.

CONCLUSION

The use of EST potentially interferes with PM therapy, especially if the electrodes are positioned bilaterally; however, unilateral EST application appeared to be safe in all tested configurations.

The safety of electrical stimulation in patients with pacemakers and implantable cardioverter defibrillators: A systematic review

Introduction

A number of patients are excluded from electrical stimulation treatment because there is concern that electrical stimulation could cause electromagnetic interference with pacemakers and implanted cardioverter defibrillators. The decision to use electrical stimulation in these patients needs to be supported by an assessment of benefit and harm.

Methods

We conducted a systematic review of the risk of electromagnetic interference between electrical stimulation and pacemakers or implanted cardioverter defibrillators. We included the electronic databases MEDLINE and EMBASE in the time period between 1966 and 26 August 2016.

Results

18 papers fulfilled the inclusion criteria (eight safety studies and ten case studies). Although we were unable to accurately estimate the risk of electromagnetic interference, the studies revealed that patients having electrical stimulation of the lower limb are less susceptible to electromagnetic interference.

Conclusions

The results suggest that electrical stimulation could be used safely to help drop foot in patients with pacemakers or implanted cardioverter defibrillators. However, in order to obtain an accurate estimate of the risk of electromagnetic interference, a large, long-term, and intervention-specific safety study is required. Until such a study is undertaken, electrical stimulation should be used with caution in patients with pacemakers and implanted cardioverter defibrillators.

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

Background

The 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).

Methods

A systematic review including the electronic databases PubMed, MEDLINE, and SCOPUS was conducted for the time period from 1966 to March 31, 2016.

Results

Only 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.

Conclusion

This 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.

Lack of maintenance of shortwave diathermy equipment has a negative impact on power output

Although shortwave diathermy has been widely used by physiotherapists, there are a few studies assessing the performance of the equipment in use. The aim of the present study was to evaluate the procedures adopted by physiotherapists as users of shortwave diathermy continuous (CSWD), as well as to measure the power output and frequency of CSWD equipment. [Subjects and Methods] Twenty-three physical therapists were interviewed and 23 CSWD equipment were evaluated. Admeasurement was carried out by using a standard phantom to simulate the electrode-skin distance, which ranged from 0.5 to 3.0 cm. Data analysis was performed by using descriptive statistics, ANOVA, and a post-hoc Tukey's test or Pearson's correlation coefficient. [Results] The questionnaires showed that 48% of the interviewees use the correct electrode-skin distance, 70% use a single electrical outlet, and 35% use a grounded electrical outlet, and that 48% of the physiotherapy tables and 61% of the plinths were made of wood. However, only 13% of the interviewees perform yearly preventive maintenance. The highest power (95.56 W) was achieved at electrode-skin distances ranging from 1.0 to 1.5 cm, with distances of 2.5 cm and 3.0 cm being null in four and eight equipment, respectively. There was a negative correlation between power output and electrode-skin distance as well as between power output and purchase date. [Conclusion] The physiotherapists involved in this study had inadequate knowledge about the correct use of CSWD equipment, which may adversely affect its performance and patient safety.

Safety of nerve conduction studies in patients with implantable cardioverter-defibrillators

OBJECTIVE

A patient with an implantable cardioverter-defibrillator (ICD) may suffer from neuromuscular disorders and may need to undergo a nerve conduction study (NCS). However, a NCS may be a source of electromagnetic interference (EMI). The aim of the present study was to investigate whether the interference from NCS used in a standardised test protocol affects ICD function.

METHODS

Twenty patients (19 males; mean age of 59.8±9.9 years) with implantable ICDs (eight with integrated and 12 with true bipolar leads), treated with amiodarone and with symptoms suggesting neuropathy were included. NCS were conducted using repetitive stimulation with frequency of 2 Hz and single, rectangular pulses of intensity up to 100 mA. Stimulation was performed in standard sites including proximal sites in the arm.

RESULTS

The impulses generated NCS were not detected by the ICD, irrespective of the site, rate or stimulus intensity.

CONCLUSIONS

Standardised test protocol for an NCS is safe in patients with an ICD regardless of the leads type.

SIGNIFICANCE

Current guidelines which limitate the NCS in patients with ICD may be the subject of revision.

Low-frequency electromyostimulation and chronic heart failure

Low-frequency electromyostimulation (EMS) acts on the skeletal muscle abnormalities that aggravate intolerance to effort in patients with chronic heart failure (CHF). It improves the oxidative capacity of muscles and thus enhances aerobic performance and physical capacity to almost the same degree, as does conventional physical training. No local or hemodynamic intolerance has been reported, even in cases of severe CHF. However, the presence of a pacemaker is one of the relative contra-indications (prior evaluation of tolerance is required), while that of an implanted defibrillator is one of the absolute contra-indications. EMS is an alternative to physical effort training when the latter is impossible due to a high degree of deconditioning or because there is a contra-indication, which may be temporary, due to the risk of acute decompensation and/or rhythm troubles. EMS can also be used in patients waiting for a heart transplant or in CHF patients who are unwilling to engage in physical activities. As EMS is not expensive and easy to set up, its use is likely to develop in the future.

Risk of interference from transcutaneous electrical nerve stimulation on the sensing function of implantable defibrillators

BACKGROUND

The use of transcutaneous electrical nerve stimulation (TENS) for pain relief is increasing. At the same time the implantable cardioverter defibrillator (ICD) is a routine treatment for malignant tachyarrhythmias. Today patients often need devices for more than one condition, and consideration must be given to the interaction between them. We studied the risk of interference between TENS and the ICD function.

METHODS AND RESULTS

Thirty patients who had received an ICD underwent a test protocol including TENS at the mammilla and hip levels, at two energy levels, and at the highest comfortable stimulation level. The effects of TENS on the electrocardiogram lead II, intracardiac electrograms, and the ICD marker channels were analyzed. Disturbance from TENS on the sensing function was seen at all stimulation attempts. Interference between the systems was observed in 16 patients. In eight patients (27%) the interpretation was VT/VF and in 14 patients (47%) as ventricular premature extra beats. Other kinds of interactions were seen in five patients (16%). Each patient could have more than one kind of interference.

CONCLUSIONS

Noise reversion and undersensing might prevent the ICD from delivering shock when it should and the interpretation as VT/VF could result in inappropriate shocks. Because of the potentially serious consequences of interference we do not recommend the use of TENS in patients with ICD.

Investigation of practices and procedures in the use of therapeutic diathermy: a study from the physiotherapists' health and safety perspective

BACKGROUND AND PURPOSE

The safe use of therapeutic diathermy requires practices and procedures that ensure compliance to professional guidelines and clinical evidence. Inappropriate use may expose physiotherapists and other people in the vicinity of operating diathermy devices to stray radiofrequency electromagnetic fields, which can be a source of risk and may lead to adverse health effects. The aim of the present study was to investigate practices and procedures for therapeutic diathermy from a health and safety perspective.

METHOD

A cross-sectional research design was used, this included a postal survey using a self-administered questionnaire and semi-structured observational visits to 46 physiotherapy departments in National Health Service (NHS) hospitals located in the south-east and south-west of England, including Greater London.

RESULTS

Microwave diathermy was not available in the departments surveyed. Pulsed shortwave diathermy was available and was used more commonly than continuous shortwave diathermy. There were metallic objects in treatment cubicles used for pulsed shortwave diathermy and continuous shortwave diathermy. Shortwave diathermy devices created electromagnetic interference with a variety of electrical and medical devices. Physiotherapists reported that they did not stay in the treatment cubicle during the entire period of electrotherapy with pulsed shortwave diathermy or continous shortwave diathermy; pregnant physiotherapists reported that they did not use these devices. Electrotherapy with pulsed shortwave diathermy and continuous shortwave diathermy was not always administered on a wooden couch or chair. Electrotherapy was highest in those departments with the fewest physiotherapists.

CONCLUSIONS

Departments report good practices and procedures regarding the use of therapeutic diathermy devices. However, field observations of practices and procedures, and the working environment, have identified issues with a potential to create health and safety problems, and these should be addressed.

Sonic and ultrasonic scalers in periodontal treatment: a review

Periodontal therapy aims at arresting periodontal infection and maintaining a healthy periodontium. The periodic mechanical removal of subgingival microbial biofilms is essential for controlling inflammatory periodontal disease. Mechanical periodontal therapy consists of scaling, root planing and gingival curettage. The sonic and ultrasonic scalers are valuable tools in the prevention of periodontal disease. The vibration of scaler tips is the main effect to remove the deposits from the dental surface, such as bacterial plaque, calculus and endotoxin. However, constant flushing activity of the lavage used to cool the tips and cavitational activity result in disruption of the weak and unattached subgingival plaque. The aim of the study was to review the safety, efficacy, role and deleterious side-effects of sonic and ultrasonic scalers in mechanical periodontal therapy.

Inappropriate implantable cardioverter-defibrillator discharges unrelated to supraventricular tachyarrhythmias

AIMS

The development of implantable cardioverter-defibrillators (ICDs) with QRS morphology discrimination and dual-chamber sensing capabilities has improved the differentiation of supraventricular from ventricular tachycardias (VTs). Inappropriate ICD discharges may result from extracardiac signals caused by electromagnetic interference (EMI), because of electric fields and leakage currents from domestic or medical electrical devices, damaged sensing leads, and various cardiac and extracardiac signals that mimic VT and/or ventricular fibrillation. The aim of our study was to determine retrospectively the incidence and clinical relevance of these ICD behaviours and offer possible therapeutic solutions.

METHODS AND RESULTS

We have observed inappropriate discharges unrelated to supraventricular arrhythmias in 13 (3.9%) of the 336 patients implanted with ICDs in our centre from 1989 to 2005. Seven patients received inappropriate shocks following exposure to external EMI: improperly grounded electric stove, electrically powered watering system, hydro-massage bath, electrical pruner, electrocautery current during cardiac surgery, transcutaneous electric nerve stimulation. In four patients, spurious discharges were related to internal noise of the ICD system from inappropriate lead connections. In two cases, erroneous antitachycardia therapy was delivered following different body signals oversensing (T-wave oversensing, wide QRS double-counting and myopotentials). In nine patients, non-invasive solutions prevented further inappropriate therapies (avoidance of EMI, malfunctioning atrial lead exclusion, ventricular sensing reprogramming). In four patients, surgical revision of the system was required (lead connections or position revision).

CONCLUSION

In our experience, inappropriate ICD discharges unrelated to supraventricular arrhythmias occurred in about 4% of ICD patients. A careful evaluation of clinical data and telemetric information (lead impedance, sensed R-wave, stored electrograms) is essential in order to understand the nature of inappropriate ICD discharges and to select the most appropriate solution.

Effects of mobile telephones on the function of implantable cardioverter defibrillators

OBJECTIVE

We investigated whether mobile telephones affect the function of implantable cardioverter defibrillators (ICDs).

BACKGROUND

It is well known that electromagnetic fields can affect medical devices.

METHODS

The study included 43 patients with ventricular tachycardia and/or fibrillation treated with transvenous pectoral ICDs. Testing was done under continuous electrocardiograph monitoring under supervision of an ICD programmer. Initially, each patient was tested during spontaneous rhythm. Then the ICD was programmed to a pace rhythm higher than the patient's heart rate, and the tests were repeated at paced rhythm. In 7 patients, tests were performed during the implantation procedure as well. In 3 of the patients, only a single defibrillation zone was active. The other 40 patients had one or more active ventricular tachycardia zones. Two mobile phones (both GSM 900 MHz) were positioned 50 cm away from the implanted device in opposite directions and switched on. Communication was established between these phones, two investigators had a 20-second conversation, and then the phones were switched off. The same procedure was repeated at 30, 20, and 10 cm away from the implantation site, respectively. Finally, the procedure was performed with the antennae of both phones touching the device pocket. In the above-mentioned 7 cases where testing was done during implantation of the ICD, a call was made from one phone to the other, ringing occurred for 5 seconds, and then two investigators conversed while the device was implanted.

RESULTS

There was no change in the function of the ICDs during any of the phone testing procedures. In 5 cases, artifacts were noted on the surface electrocardiographic (ECG) screen of the programmer during the tests, but no such changes were observed on the simultaneous intracardiac ECGs.

CONCLUSION

The results of the study suggest that mobile phones have no effects on ICD function.

Inappropriate implantable cardioverter defibrillator shock from a transcutaneous muscle stimulation device therapy

Inappropriate shock from implantable cardioverter defibrillator (ICD) may result from external electromagnetic interference (EMI), especially for unipolar ventricle sensing. Previous case reports and small in-vitro safety study suggested that endocardial bipolar lead system may be immune from EMI resulting from transcutaneous electrical neuromuscle stimulation (TENS) therapy. This report presents an unusual case of inappropriate discharge in a patient with ICD of endocardial bipolar lead system, receiving TENS from a commercially available device.

Long-term Transcutaneous Neuromuscular Electrical Stimulation in Patients with Bipolar Sensing Implantable Cardioverter Defibrillators: A Pilot Safety Study

Neuromuscular electrical stimulation (NMES) is an option for increasing thigh muscle strength and endurance capacity in patients with chronic heart failure. Electromagnetic interference (EMI) by the signals with sensing of implantable cardioverter defibrillators (ICDs) is possible. The aim of the present pilot safety study was to test the safety of a long-term NMES in patients with ICDs. Six patients with subpectoral ICDs were subjected to long-term NMES of thigh muscles. Four inpatients received NMES to increase muscle strength, and two outpatients performed NMES as a home treatment to increase endurance capacity. During long-term NMES, all patients together received 14 139 799 biphasic electrical pulses and 412 425 on-phases without adverse events. ICD function after the stimulation period revealed no abnormalities in any patient. These results indicate that long-term NMES of thigh muscles seems to be safe in patients with ICDs, providing that an individual risk is excluded before.