Our clinical cases are drawn from the case report literature. The stories, names, and patient details are fictional, however the narratives are based on published patient cases that are available in the references.
Adele* was in for a shock when she went for her morning swim, in fact, three big shocks in quick succession that burst from her implanted cardiac defibrillator (ICD) [1,2]. Adele stopped swimming immediately, aware that the defibrillator only fired when her troubled heart was acting up and left the pool to call her Cardiologist. Adele had been under a cardiologist her whole life due to an anatomical problem with her heart that was discovered at birth - a congenital defect termed Transposition of the Great Arteries (TGA). The surgery she underwent as a child had saved her life, but similarly to many other patients who shared her condition, Adele continued to experience cardiac complications that eventually necessitated the implantation of an ICD to manage her heart rhythm [1-3]. The role of the ICD was to monitor the heart’s electrical activity and to respond with an electric shock to correct the rhythm if an anomaly was detected.
Adele and her Cardiologist discussed what could have caused the event. The electrograms that showed a recorded trace of the heart's activity demonstrated some atrial and ventricular noise preceding the electrical discharge from the device at the time of the event, however the cause of this was unclear. They discussed her exercise routine, given her cardiac disease it was possible that swimming in the pool was placing too much stress on the heart. Adele agreed to reduce her swimming activities but finished the consultation feeling perplexed. Since starting swimming a few months ago she'd felt her health was improving and had been walking increasing distances each day. Only since joining a new gym had she started to have these problems.
Adele returned to the pool the following week intent on taking the session easy but had not even finished her first length by the time the shocks arrived. Stood at the end of the pool Adele felt several thumps in her chest in quick succession that left her breathless. Feeling like she'd just finished a race, Adele cautiously left the pool and decided that perhaps swimming wasn't for her. She reported the incident to her Cardiologist, who again noted the disturbance on her heart trace at the time of the event however could not specify a reason for it. In the absence of a clear explanation, Adele opted to avoid the situation entirely and no longer swims on her Sunday afternoons.
Adele's story is based on two publications that describe several patients experiencing inappropriate ICD shocks from cardiac devices that coincided with the patient's swimming sessions [1,2]. In the first example, Wight and colleagues argue that the saline chlorination units of the swimming pools generated enough Electromagnetic Interference (EMI) that it affected the activity of the cardiac devices. The analysis of the device electrograms following the events demonstrated atrial and ventricular noise had been interpreted by the device as ventricular fibrillation, hence resulting in an inappropriate shock from the device. In other words, the device mistook the electric current in the water for a signal from the heart resulting in an electric discharge into the heart muscle.
Wight et al are not the only authors to describe the dangers of swimming pool currents for cardiac patients. Iskandar and colleagues have also described interference from electrical currents in standard swimming pools that originate from a range of sources such as underwater lighting [2]. In their case report, the authors tell the story of a 64-year-old male who experienced an ICD malfunction while sat in a swimming pool talking with his wife. In his case, the man was asymptomatic during the episode and unaware of the discharging current. Informing patients on potential environmental sources of interaction is therefore essential, given that inappropriate ICD shocks have been associated with adverse disease outcomes and reduced quality of life [3].
Malfunctions of ICDs and pacemakers due to Electromagnetic (EM) interference are particularly dangerous while swimming, and the widespread adoption of saline chlorination systems may pose a universal threat to those with implanted cardiac devices [4]. Furthermore, the staff present at the poolside are the responsible professionals who may need to assist these patients when they encounter a problem. Yet at present it appears Lifeguards do not receive training on EM interactions that can occur within the water. The widely used Lifeguarding Training Manual from the American Red Cross does not mention implanted medical technologies - an omission which may need addressing as more and more of the swimming pool population enter the water with embedded healthcare devices [5].
For patients such as Adele, digital-informed lifeguards are essential but so are digitally trained healthcare staff. Clinicians who will care for Adele over the course of her life, whether that’s in community or hospital settings, would benefit from understanding the specific digital risk factors related to EM interference that could impact her health. If we can improve awareness amongst the medical profession of the daily activities that may expose patients to EM interference, we can better counsel, safeguard, and provide effective care for patients dependent on these implanted devices.
References
1. Wight J, Lloyd MS. Swimming pool saline chlorination units and implantable cardiac devices: A source for potentially fatal electromagnetic interference. HeartRhythm Case Reports. 2019 May 1;5(5):260
2. Iskandar, Sandia, et al. ‘Electromagnetic Interference in a Private Swimming Pool’. Indian Pacing and Electrophysiology Journal, vol. 15, no. 6, Feb. 2016, pp. 293–95. PubMed Central, https://doi.org/10.1016/j.ipej.2016.02.008.
3. Grubb, Alex, et al. ‘Pacemaker and Defibrillation Implantation in Patients with Transposition of the Great Arteries’. Journal of Innovations in Cardiac Rhythm Management, vol. 8, no. 4, Apr. 2017, pp. 2658–64. DOI.org (Crossref), https://doi.org/10.19102/icrm.2017.080405.
4. Kulkarni N, Link MS. Causes and prevention of inappropriate implant- able cardioverter-defibrillator shocks. Card Electrophysiol Clin 2018; 10:67–74.
5. American Red Cross. Lifeguarding Manual. Accessed Jan 2022. Available at: https://media.wm.edu/content/wm/recsports/LG_PM_small.pdf
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