Parasystole?

Abstract

The integration of smart watches into health care has heralded a new era in the diagnosis and monitoring of various medical conditions, including arrhythmias. However, it is imperative to acknowledge the limitations associated with smart watches in health care. We present a challenging tracing acquired from an Apple Watch.

Graphical abstract

History of Presentation

A 6-year-old girl was brought in by her mother owing to an irregular rhythm noted on an Apple Watch. She stated that while she was cuddling with her daughter, who was asleep at the time, the mother appreciated an irregular heart rhythm that was intermittently tachycardiac. The mother then placed her Apple Watch on her daughter and held her daughter. The patient was otherwise asymptomatic and sleeping comfortably at the time. The Apple Watch tracing is displayed in Figure 1. The tracing was displayed to her pediatrician and a referral was made to pediatric cardiology for a possible arrhythmia.

Learning Objectives

• •To gain familiarity with the strengths and weakness of smart watches in the diagnosis of arrhythmias.
• •To differentiate between normal and abnormal electrocardiographic tracings generated from smart watches.

Figure 1.

Patient ECG Tracing Acquired From an Apple Watch

This tracing represents a simultaneous recording of both the patient’s and mother’s ECG. In the tracing, there are 2 distinct QRS complex morphologies. The first (A), lower amplitude QRS complex is predominantly positive, regular, always preceded by a P wave, and with a rate of approximately 100 beats per minute representing the child’s rhythm. The second larger amplitude QRS complex (B) is predominantly negative, regular, with a rate of approximately 75 beats per minute. On occasion the maternal and child’s QRS complexes overlie each other. (C) Nonphysiological RR intervals. ECG = electrocardiogram.

In office, the patient had a blood pressure of 103/62 mm Hg and a pulse rate of 84 beats per minute. She was breathing at a rate of 22 breaths/min and had an oxygen saturation of 100% on pulse oximetry. On physical examination, the patient appeared well-developed and well-nourished. On auscultation, she had a regular rate and rhythm with a normal S1 and S2. There was a soft venous hum heard in the suprasternal notch when sitting that was not heard when supine. There was a 1-2/6 vibratory systolic murmur best appreciated at the left lower sternal border consistent with a benign flow murmur. There were no clicks, rubs, or gallops. The remainder of the examination was within normal limits.

Past Medical History

The patient has a past medical history of dermatomyositis diagnosed at age 4 years and treated with methotrexate, steroids, and intravenous immunoglobulin. Remission was achieved and all medications were discontinued after weaning about 6 months prior.

Differential Diagnosis

The differential diagnosis includes artifact or interference, atrial fibrillation, parasystole, sinus rhythm with premature atrial contractions, and atrial flutter with variable conduction.

Investigations

The electrocardiogram (ECG) demonstrates normal sinus rhythm and biventricular hypertrophy criteria. Echocardiography shows normal intracardiac anatomy and normal left ventricular size and function.

Management

A formal 12-lead ECG and echocardiogram were ordered and reviewed. Education was provided to the patient’s mother as to the cause of the ECG findings. Reassurance was provided on the benign nature of the findings, as well as the normal findings on subsequent testing. Guidance on proper ECG recording technique was provided to ensure accurate tracing acquisition in the future.

Discussion

The integration of smart watches into health care has heralded a new era in the diagnosis and monitoring of arrhythmias. Smart watches equipped with advanced sensors and algorithms have shown promising results in diagnosing and monitoring arrhythmias.1, 2, 3, 4, 5, 6, 7, 8, 9 Their ability to continuously track heart rate, detect irregularities, and provide real-time notifications to users has facilitated early detection and intervention, potentially preventing life-threatening cardiac events. However, it is imperative to acknowledge the limitations associated with smart watches in health care. One of the primary concerns is the accuracy of the data they generate. Despite significant advancements in sensor technology, these devices may still produce false positives or negatives, leading to unnecessary anxiety for patients or, conversely, missed diagnoses. Moreover, the reliability of smart watch data can be influenced by various factors, such as device placement, user compliance, and the presence of artifacts, highlighting the importance of careful interpretation by health care professionals.

In this case, the smartwatch tracing raises a diagnostic question, initially suggesting an arrhythmia. However, closer examination reveals key findings that help to narrow down the possibilities. First, consistent sinus P waves preceding each QRS complex rules out atrial fibrillation and flutter. Second, nonphysiological R-R intervals and the absence of a consistent compensatory pause make ectopy unlikely. Third, isolated QRS complexes without distinct fusion complexes, combined with the lack of consistent coupling intervals, make parasystole improbable. Considering the unique QRS morphologies and the context of the tracing acquisition, the most likely diagnosis is an artifact, stemming from simultaneous recording of maternal and patient ECGs.

Interference is a commonly encountered issue in the interpretation of ECGs and can result from a variety of internal and external causes. A few of the commonly encountered interference signals include loose lead artifact, wandering baseline artifact, muscle tremor artifact, electromagnetic interference, and neuromodulation artifact. Gaining familiarity with the types of interference allows for appropriate troubleshooting of the issue. However, there are occasional when artifacts may mimic ECG abnormalities that can lead to false diagnoses.

This case demonstrates the limitations that providers should be aware of, as the tracing generated represents both the patient’s and mother’s ECG recorded simultaneously owing to the method in which it was acquired, leading to its misinterpretation as an arrhythmia. Interestingly, fetal electrocardiographic monitoring in utero has previously been proposed¹⁰ and results in the acquisition of tracings with findings similar to our presented tracing (Figure 2).

Figure 2.

Indirect Fetal Electrocardiography Tracing

An example of a fetal electrocardiographic signal recorded on the maternal abdomen (M, F – QRS complexes, maternal and fetal, respectively). (This image is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution, and reproduction in any medium or format, as long as appropriate credit is given to the original author(s) and the source, a link to the Creative Commons license is provided, and any changes are indicated. Adapted from Matonia A, Jezewski J, Kupka T, et al. Fetal electrocardiograms, direct and abdominal with reference heartbeat annotations. Sci Data. 2020;7:200. https://doi.org/10.1038/s41597-020-0538-z. Image was cropped to display the tracing only. Link to license: http://creativecommons.org/licenses/by/4.0/.)

Follow-up

Given the lack of abnormal findings on history, examination, and investigation, routine pediatric cardiology follow-up was felt to be unnecessary. The patient was instructed to resume routine primary care and may follow-up with cardiology in the future on an as-needed basis as issues arise.

Conclusions

Smart watches have emerged as valuable assets in the diagnosis and monitoring of arrhythmias. However, health care providers must approach their integration with caution, critically evaluating the strengths and pitfalls associated with these devices, particularly the accuracy of the data they generate. The reliability of smart watch data can be influenced by various factors such as device placement, user compliance, and the presence of artifacts, highlighting the importance of careful interpretation by health care professionals.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.