Thank you to Megan L. Jester and Emily J. Jones for this article on heart rate variability measurement. You can read the first article in this series here.

Using Heart Rate Variability Measurements for Prevention and Treatment of Cardiovascular Disease Across the Lifespan

In the first article in the series, heart rate variability was introduced as an easily accessible, non-invasive approach to understanding autonomic innervation and function of the heart in childhood diseases and their progression to adult-onset diseases including cardiovascular disease (CVD). This second article introduces how heart rate variability is measured for the prevention and treatment of cardiovascular disease across the lifespan, and how nurse scientists and clinicians may contribute to this body of knowledge.

Ways to Measure Heart Rate Variability

As described in the first article, heart rate variability measurement may help guide prevention and treatment strategies for CVD. Data to measure heart rate variability are collected through the noninvasive methods of electrocardiograph (ECG) recordings and photoplethysmography. Photoplethysmography is an optical process of recording electrical signals that represent blood volume changes (i.e., pulse rate) via skin exposure to LED-emitted light.^1-3 These noninvasive approaches are beneficial for children or adults who may have a fear of uncomfortable or painful procedures and allows them the opportunity to view real-time recordings of their heart rate variability data.

Photoplethysmography is best measured through a wearable technology device, which have increased in popularity in recent years. Many individuals already sport the needed technology through commercial wearables that include, but are not limited to, the following:

• Fitness tracker (e.g., Polar® , Fitbit®)
• Smartwatch (e.g., Apple Inc. watch)
• Smart jewelry (e.g., Oura Ring) or clothing (e.g., Hexoskin shirt) (Note- the Hexoskin used a 3-lead ECG for heart rate variability data collection)

Watches and wrist-worn fitness trackers are the most-purchased wearables because they are unobtrusive and often incorporated into an individual’s daily activities (e.g., recording of physical activity, daily step count, sleep).^2-4 Not only are these devices telling time, tracking steps, and measuring how far and how quickly the wearer is moving, but the information they gather may be utilized for patients and providers to track individual cardiovascular and pulmonary data, and even support clinical research studies. Of importance, the Food and Drug Administration regulates these commercial wearables; therefore, they have met a series of requirements and are deemed safe for the intended use.³ Before purchase, individuals should determine if a wearable device is designed to collect heart rate variability data and review the company’s safety data sheets.

Heart Rate Variability and CVD Prevention and Management

The data collected from appropriate wearable devices may be shared with a health care provider to guide clinical decision-making for an individual patient. With approval from users of the devices, the data may also be used on a more global scale. Therefore, measuring heart rate variability should be considered as part of larger studies⁵ and clinical recommendations. Recent studies have evaluated heart rate variability and arrhythmias, cardiovascular fitness, cardiovascular events, cardiovascular risk factors, cardiovascular rehab, congenital heart disease, coronary artery disease, and stroke, to name a few. Despite the abundance of heart rate variability literature in adults, there is a gap in understanding heart rate variability’s influence in CVD research and practice in infants, children, and adolescents.⁶ Future considerations may include establishing psychometric properties for children⁷ to evaluate for changes in cardiac regulation,⁶ and using heart rate variability to stratify patients for the best course of treatment.⁵

Limitations of Heart Rate Variability Measurement

Even though the use of wearables for collecting heart rate variability data is convenient, there are limitations to measuring heart rate variability individually. Variances in heart rate variability recording and measurement may affect the integrity of a study or clinical outcome. Miscellaneous electrocardiogram or wearable device issues may be related to incorrect use of monitors (e.g., mobile health), electrodes, and devices,^4,8 technical concerns (e.g., battery failure), participants’ refusal to wear the monitor,⁹ and variations among the types of equipment used. Therefore, the choice of heart rate variability collection method must be identified a priori, appropriately match the aim of the study or clinical outcome, and evaluated for reliability.^7,10 Recordings of heart rate variability may be affected by type, duration, or intensity of physical activity, food and drink consumption including caffeine intake, or testing environment. Potential environmental influences, such as testing participants in a similar environment at the same time of day, must be accounted for and controlled.¹⁰ Unstable recordings contribute to inaccurate analyses and interpretations.¹⁰ Ectopic beats, arrhythmias,^7,10 missing data, and other extraneous “noise” may alter results. It is recommended that the recordings used be free of artifact that may lead to biased results,^10-11 and can be accomplished through a combination of manual and computer-based artifact visualization and adjustment (e.g., Kubios Oy heart rate variability analysis software).^10-11

Implications for Cardiovascular Nurses

Nurses can contribute to health promotion and disease prevention through school-based and primary care screenings, including the potential to collect heart rate variability measurements and provide necessary referrals for treatment. The collection and interpretation of an individual’s heart rate variability results offer opportunities for real-time education about the impact of lifestyle choices on cardiovascular health. Additionally, advanced providers may review heart rate variability data to determine elevated risk factors for CVD, alongside personalizing prevention and management strategies.³ This information may empower children, adults, and families to incorporate lifestyle behaviors and actions into practice. It is recommended that heart rate variability is measured across the lifespan to indirectly identify potential underlying changes in autonomic function before irreversible changes develop. Early identification of autonomic dysfunction leads to earlier implementation of interventions that may slow or prevent the onset of CVD.

Key Takeaways

1. Measuring heart rate variability is noninvasive and may help identify early signs of autonomic dysfunction.
2. Appropriate device placement and the recording of heart rate variability data will mitigate limitations.
3. Nurses should advocate for heart rate variability measurement as part of primary screenings beginning in early childhood.

References

1. Nelson BW, Low CA, Jacobson N, et al. Guidelines for wrist-worn consumer wearable assessment of heart rate in biobehavioral research. NPJ Digit Med. 2020;26(3):90. doi: 10.1038/s41746-020-0297-4
2. Nuuttila OP, Korhonen E, Laukkanen J, Kyröläinen H. Validity of the wrist-worn polar vantage V2 to measure heart rate and heart rate variability at rest. Biosensors. 2022; 22(1):137. doi: 10.3390/s22010137
3. Prieto-Avalos G, Cruz-Ramos NA, Alor-Hernández G, et al. Wearable devices for physical monitoring of the heart: A Review. Biosensors. 2022;12(5):292. doi: 10.3390/bios12050292
4. Ashur C, Cascino T, Lewis C, Townsend W, et al. Do wearable activity trackers increase physical activity among cardiac rehabilitation participants? A systematic review and meta-analysis. J Cardiopulm Rehabil Prev. 2021;41:249-256. doi: 10.1097/HCR.0000000000000592
5. Ernst G. Heart Rate Variability. Springer-Verlag London; 2014.
6. Billman GE, Sacha J, Werner B, Jelen PJ, Gąsior JS. Editorial: Heart rate variability and other autonomic markers in children and adolescents. Front Physiol. 2019;10:1265. doi: 10.3389/fphys.2019.01265
7. Weiner OM, McGrath JJ. Test-retest reliability of pediatric heart rate variability: A meta-analysis. J Psychophysiol. 2017;31(1):6-28. doi:10.1027/0269-8803/a000161
8. Dobbs WC, Fedewa MV, MacDonald HV, et al. The accuracy of acquiring heart rate variability from portable devices: A systematic review and meta-analysis. Sports Med. 2019;49(3):417-435. doi: 10.1007/s40279-019-01061-5
9. Jarrin DC, McGrath, JJ, Poirier, P., & Quality Cohort Collaborative Group. Autonomic dysfunction: A possible pathophysiological pathway underlying the association between sleep and obesity in children at-risk for obesity. J Youth Adolesc 2015;44:285-297. doi:10.1007/s10964-014-0235-3
10. Electrophysiology TF. Heart rate variability. Circulation. 1996;93(5):1043-1065. doi:10.1161/01.cir.93.5.1043
11. Berntson GG, Thomas Bigger J, Eckberg DL, et al. Heart rate variability: Origins, methods, and interpretive caveats. Psychophysiology. 1997;34(6):623-648. doi:10.1111/j.1469-8986.1997.tb02140.x