Illustrations and references can be found in my book.
The second edition has been published and can be downloaded here .
The following text is a short excerpt from the detailed chapter on TENS in the book.
First off: LLLT and ultrasound are permitted. Using ultrasound directly over the pacemaker is, of course, reckless nonsense due to reflections, not because the implanted device could be triggered. NMES, TENS, and medium-frequency currents (IFC) should only be used after consultation with a cardiologist and with the utmost caution. High-frequency applications (like short wave diathermia) are absolutely contraindicated !
The frequently mentioned 50 cm distance between electrodes and the pacemaker does not make the applications any safer.
What does the literature say?
• Weitz et al. described in 1997 how a postoperative parasternal TENS application in a 24-hour ECG mimicked atrial fibrillation in a patient. The authors point out that misinterpretation could have led to over-diagnosis and incorrect treatment.
• Vlay described a case in 1998 where a patient with an implanted pacemaker and cardioverter-defibrillator (ICD) received an electric shock during TENS treatment. The electrodes were placed on the sacrum, more than 50 cm from the pulse generator. Vlay notes that patients must be instructed to avoid these sources of electromagnetic interference.
• Crevenna et al. noted in 2003 that during muscle stimulation of the quadriceps with TENS-like parameters, three out of eight patients with so-called DDD-R pacemakers experienced pacemaker interference. Here too, there was certainly more than 50 cm of safety distance between the electrodes and the pacemaker.
• Pyatt et al. described a patient in 2003 with angina pectoris symptoms after bypass surgery and ICD implantation. Burst TENS was used for pain management. The electrodes were placed on the ventral thorax in the painful area. At a follow-up after six months, the patient reported having received one shock during TENS application and feeling dizzy during each application. He also became bradycardic (hence the dizziness). The symptoms disappeared as soon as he switched the device off. An ICD check showed that the TENS device interfered with the ICD's function. The treatment was discontinued. The authors point out that problems can develop even after initially uneventful use and that patients must therefore be thoroughly informed in this regard.
• Occhetta et al. investigated in 2006 the incidence and clinical relevance of ICD interference due to external electromagnetic interference. In 13 out of 336 patients, unwanted shocks had occurred between 1989 and 2005. In two patients, this was due to a TENS treatment not described in detail. The patients were advised to avoid this type of therapy, and no further interference occurred.
• Nägele and Azizi reported a case in 2006 where a patient was treated with TENS in the upper lumbar region (50 Hz, 40 mA). Almost immediately after the start of treatment, he felt several shocks from his ICD. The treatment was stopped immediately, and the patient was transferred to cardiology.
• Engelhardt et al. described a case in 2007 where, after shoulder joint replacement surgery, stimulation of the right brachial plexus with 1 ms, 1.4 mA led to the complete temporary deactivation of the (also right-sided) pacemaker.
• Holmgren et al. investigated the influence of TENS on ICDs in 2008. TENS was applied at two different sites on 30 patients with an ICD under medical supervision. The electrodes were first placed proximal to the nipples. In the second attempt, they were placed over the anterior superior iliac spines (ASIS). Low Frequency TENS and High Frequency TENS were used. Placement proximal to the nipples triggered interference with the ICD in 16 out of 30 patients; placement over the ASIS did so in seven out of 30 (more than 50 cm!). The applications differed only minimally in terms of interference. The authors recommend not using TENS on patients with an ICD.
• Carlson et al. investigated the influence of TENS on implanted pacemakers in 2009. TENS at 2 Hz and 80 Hz was used on 29 patients under medical supervision. The electrodes were placed proximal to the nipples. In the first attempt, both TENS applications were performed with normal pacemaker sensitivity. Then the pacemaker was set to maximum sensitivity. Only five out of the 29 patients experienced no interference. With normal sensitivity, interference occurred in nine patients at 80 Hz and in 14 patients at 2 Hz. With maximum sensitivity, interference occurred in 17 patients at 80 Hz and in 22 patients at 2 Hz. The authors advocate for a controlled trial use before issuing a TENS device to pacemaker patients and for subsequent monitoring of the treatment. They suggest setting the pacemaker to the lowest clinically justifiable sensitivity.
• Cenik et al. (2016) recommend clear precautions when using Neuromuscular Electrical Stimulation (NMES) (with TENS-like parameters). Individual risks (pacemaker dependency, acute heart failure, unstable angina pectoris, ventricular arrhythmias in the last 3 months) must be ruled out, NMES should only be used for thigh and gluteal muscles, patient compliance, especially at home, must be ensured, and regular monitoring by the treating cardiologist is required.
• Badger et al. (2017) write in their review that the use of electrical stimulation on the lower limb in pacemaker patients is probably safe. However, as there is insufficient reliable information, caution should still be exercised when using electrical stimulation on patients with a pacemaker or an ICD.
• Egger et al. conducted measurements in 2019 on a pyjama-like model consisting of several towels soaked in NaCl solution. They found that unilateral stimulation on the thigh
and upper arm
of the model caused no interference with the tested pacemakers, but bilateral applications certainly did. Their parameters are not comprehensible but were typical for electrical stimulation
and were performed at the maximum possible intensity. Their conclusion: Electrical stimulation can interfere with pacemakers, especially bilateral applications. Unilateral applications appear to be safe.
• … and there is much more …
Pacemakers and implanted cardioverter defibrillators (ICDs) can thus demonstrably be interfered with by TENS and medium-frequency applications. SWD machines are very strong transmitters and will even make hearing aids start to loudly bleep
so please do not allow patients with pacemakers or ICD's in the same room with a switched-on SWD or a MW machine.
For patients with ICDs, this means they can receive one or several quite severe shocks while awake, despite adhering to the recommended safety distance of 50 cm between the electrodes and the ICD.
The demand pacemaker measures and monitors heart activity via an electrode and only delivers impulses when intrinsic stimulation fails. Nowadays, almost exclusively multiprogrammable demand pacemakers are implanted.
Exogenous electrical stimuli (electrotherapy) and strong electromagnetic fields (high-frequency electrotherapy, for example, SWD, and microwave) demonstrably interfere with the function of such a device. So-called permanent pacemakers
are not disturbed by such external stimuli and therefore do not represent a contraindication, except relatively for local application. These pacemakers constantly deliver stimulation impulses, but this type is only used exceptionally today.
Given this situation, the pacemaker and the implanted cardioverter defibrillator must be considered an absolute contraindication for any treatment with low-frequency stimulating current, TENS, and interferential current. This also applies to high-frequency applications; more on this in Chap. 9.
The author himself has a state of the art
ICD and can confirm that a Low TENS application on the left elbow with a high-quality TENS device leads to rapid activation of the ICD. This is not the case on the right elbow. The ICD is located on the upper left thorax, about two finger-widths distal to the clavicle.
ICD Activation
What actually happens during such an interaction?
Let's say the patient is using TENS and, quite by chance, becomes bradycardic at that very moment, and the heart rate falls below the threshold set on the device.
Normally, the demand pacemaker would now intervene and deliver its extra impulses so that the pump keeps working.
However, the device can be misled by the TENS device and think
that the patient's heart is already beating more or less regularly and does not need additional support.
Due to reduced blood flow to the brain, the patient will quickly become dizzy and, if lucky, will only lose consciousness.
A well-informed patient knows this and switches off the TENS device at the first sign of dizziness. Nothing happens.
With ICDs, it's different. ICDs are designed to deliver series of impulses during arrhythmias intended to make the heart return to sinus rhythm (your doctor does not refer to these as shocks but rather euphemistically as stimulations).
These shocks gradually increase in strength depending on whether the disturbed rhythm normalises or not. The first stimulations feel like a series of quite strong, dull blows to the thorax. If the ICD detects no change, the intensity of these stimulations increases. Usually, the patient is already unconscious by then and does not perceive the stimulations. Not so during TENS application, as one remains awake. Ouch.
TENS is sometimes used for pain relief in patients with angina pectoris symptoms. The electrodes are placed ventrally on the thorax for this purpose. Cardiologists recommend trying this treatment under close supervision for such patients before issuing them a device.
Patients must, of course, be very thoroughly informed about possible symptoms (bradycardia, dizziness) and be monitored regularly.