Heart Rate Variability in Older Adults

Objectives What is HRV
 * 1) Define Heart Rate Variability
 * 2) Describe the relevant conditions and diseases associated with changes in HRV
 * 3) Provide sources on how to measure HRV
 * 4) Provide evidence for the use of physical exercise and breathing techniques on improving HRV

               The proper functioning of the autonomic nervous system (ANS) is vital for the performance of systems throughout the body. One specific target of the ANS is the heart with the sympathetic division being responsible for increased cardiac output and the parasympathetic division slowing the rate and force of contraction. A healthy heart is able to respond to increasing demands when necessary as well being able to return to baseline resting function when appropriate. One way to measure the functioning of the ANS is through Heart Rate Variability (HRV).

HRV is a measure of the variance in the heart beat intervals which are controlled via a balance between the sympathetic and parasympathetic divisions of the ANS. A high HRV is desirable because it indicates that the heart is dynamic and adaptable to physiologic and environmental changes 1,2. If an individual remains in a sympathetic state, then the attenuating effects of the parasympathetic division won’t be as pronounced.

Why is it important to measure?

               Because HRV provides a way to examine the functioning of the ANS and the heart, it can be a valuable tool in the analysis of a patient’s health. In older adults, cardiovascular conditions are increasingly common and are a major cause of death in the United States. Individuals with increased sympathetic and/or decreased parasympathetic activity are at a greater risk for sudden cardiac death, heart failure, ventricular arrhythmias and hypertension 3,4. In addition, a decreased HRV is associated with increased mortality in cardiac patients, as well as increased risk of developing coronary heart disease in a general population 5,6. In addition to cardiovascular health, a decreased HRV is associated with mental health diseases such as anxiety and PTSD 7,8. Because of the high prevalence of cardiovascular conditions in older adults as well as the possibility of mental health concerns, HRV should be considered an important measure for Physical Therapists treating this population.

'''How to measure it? '''

               The most accurate measure of HRV is done with EKG monitoring, but recent advances have made it much easier and cheaper to measure in more traditional clinical settings. Many companies offer the devices and software required to accurately measure HRV at home or in the clinic. Links to their websites are provided below. Usually, the standard deviation and root mean square of the beat to beat variability is the main indicator of HRV.

https://www.hrv4training.com/

https://elitehrv.com/

https://store.alivecor.com/products/kardiamobile

https://www.biohackerslab.com/reviews/best-hrv-monitor/

'''What is normal? '''

               In general, HRV decreases with age even when cardiovascular and metabolic conditions are taken into account 9. Published norms for age and gender are presented below:

Can HRV be Improved?

               Fortunately, HRV can be improved even in older adults. In a study by Earnest, HRV improved significantly after a low-moderate intensity exercise regimen in women over 60 who were previously sedentary, overweight and had high blood pressure11. In addition, greater leisure time activity as well as increased walking levels are shown to be associated with higher HRV 12. These studies, among others support the use of aerobic exercise to increase HRV. For older adults who may be struggling to find motivation to exercise and improve their health, the use of an objective, trackable measurement that is associated with better health could be a great way to increase the expectations of physical therapy.

 References   
 * 1) Jensen-Urstad K, Storck N, Bouvier F, Ericson M, Lindblad LE, Jensen-Urstad M. Heart rate variability in healthy subjects is related to age and gender. Acta Physiol Scand. 1997; 60: 235–241.
 * 2) Pikkujämsä S, Yliopisto O Heart Rate Variability and Baroreflex Sensitivity in Subjects Without Heart Disease: Effects of Age, Sex and Cardiovascular Risk Factors. Oulun Yliopisto.
 * 3) Vaseghi M, Shivkumar K. The role of the autonomic nervous system in sudden cardiac death. Prog Cardiovasc Dis. 2008;50:404–419.
 * 4) Olsson G, Wikstrand J, Warnold I, Manger Cats V, McBoyle D, Herlitz J, Hjalmarson A, Sonneblick EH. Metoprolol-induced reduction in postinfarction mortality: pooled results from five double-blind randomized trials. Eur Heart J. 1992;13:28–32.
 * 5) Dekker JM, Crow RS, Folsom AR, Hannan PJ, Liao D, Swenne CA, Schouten EG. Low heart rate variability in a 2-minute rhythm strip predicts risk of coronary heart disease and mortality from several causes: the ARIC Study. Atherosclerosis Risk in Communities. Circulation. 2000;102:1239–1244.
 * 6) Tsuji H, Larson MG, Venditti FJ, Manders ES, Evans JC, Feldman CL, Levy D. Impact of reduced heart rate variability on risk for cardiac events. The Framingham Heart Study. Circulation. 1996;94:2850–2855.
 * 7) Jönsson, P. "Respiratory sinus arrhythmia as a function of state anxiety in healthy individuals". International Journal of Psycho-physiology. 2007.
 * 8) Brosschot, J.F.; E. Van Dijk; J.F. Thayer. Daily worry is related to low heart rate variability during waking and the subsequent nocturnal sleep period. International Journal of Psychophysiology. 2007.
 * 9) Umetani, K, Singer DH, McCarty R, Atkinson M. Twenty-four hour time domain heart rate variability and heart rate: Relations to age and gender over nine decades. J American Coll Cardiology. 1998;31(3).
 * 10) Voss A, Schroeder R, Heitmann A, Peters A, Perz S. Short-term heart rate variability: influence of gender and age in healthy subjects. PLOS ONE. 2015.
 * 11) Earnest CP, Blair SN, Church TS. Heart rate variability and exercise in aging women. J Women's Health. 2012;21(3).
 * 12) Soares-Miranda L, Sattelmair J, Stein PK, Mozaffarian D. Physical activity and heart rate variability in older adults: the cardiovascular health study. Circulation. 2014;129(21).