What is Heart Rate Variability (HRV) and Why is it Important?
Heart rate variability (or “HRV”) is the variation in time intervals between consecutive heart beats averaged over time. Your heart rate speeds up during inhalation and slows down during exhalation. Variability in your heart rate is good and desirable.
Large heart rate increases during inhalation and large heart rate decreases during exhalation will generate greater heart rate variability and flexibility of the cardiac autonomic nervous system, which offers multiple health benefits. The greater the magnitude of your heart rate fluctuations or changes between beats, the more sensitive and capable the physiological reflexes are that help to control your autonomic nervous system. Thus, enabling your autonomic nervous system to control your body processes more effectively, including, most importantly, regulating your blood pressure.
HRV is an indicator of vulnerability to stress and disease as well as one's capacity to adapt and recover from stress. A person with higher HRV is better protected from the negative consequences of stress. Low heart rate variability increases your vulnerability to stress and susceptibility to disease, and is a predictor of mortality from all causes. Research has shown that an increase from low to moderate heart rate variability decreases mortality by 400%.
How is Heart Rate Variability Measured?
Heart rate variability is measured with instrumentation (Procomp Infiniti biofeedback instrument-Thought Technology; Montreal, Canada) that simultaneously records the patient’s heart rate changes with respiratory frequency, with duration of inhalation and exhalation, etc. The instrument identifies the optimal breathing pattern to maximize heart rate variability.
Heart rate variability measurement provides a “special window” and very effective method to measure how balanced your autonomic nervous system is functioning. The autonomic nervous system influences important contributors to your overall health, regulating processes like heart rate, blood pressure, digestion, metabolism and immune system functioning. Our autonomic nervous system's nerves stimulate and regulate our internal organs, so it’s extremely important that the system is operating at an optimum balance.
An imbalance in the autonomic nervous system, resulting in a reduced heart rate variability due to the presence of an overstimulated sympathetic nervous system (fight or flight response) and/or an underactive parasympathetic nervous system (conserve and restore), may increase your risk for cardiovascular diseases and other disorders. It is also seen in anxiety and depression.
What does that mean in layman’s terms? Reduced heart rate variability is a marker for cardiovascular disorders including hypertension and heart disease, and is associated with vulnerability to stress and disease. You are more vulnerable if you suffer a myocardial infarction (heart attack).
Treatment for Low Heart Rate Variability
A patient can increase/improve their heart rate variability through biofeedback training, a process referred to as “HRV Biofeedback Treatment/Training”, which helps synchronize respiratory and heart rate to a measured individualized breathing frequency pattern, maximizing heart rate variability.
But HRV Biofeedback therapy is far more involved than simply learning to slow your breathing and relax. In fact, heart rate variability biofeedback training/treatments are a clinical process requiring sensitive and sophisticated testing instrumentation, including a heart rate variability monitor to display your HRV and provide instantaneous feedback to the patient.
By increasing your HRV you are not only improving your autonomic nervous system functioning, but you may also be reducing high blood pressure, anxiety, or depression and developing improved cardiac protection.
How Does HRV Biofeedback Work?
Heart rate variability biofeedback training targets the baroreceptors located in the walls of our aorta and carotid arteries. The baroreceptors are sensors in the artery walls that respond rapidly to changes in blood pressure to keep blood pressure stable and protect the heart from problems or dysregulations such as arrhythmias. The mechanism whereby the baroreceptors regulate blood pressure is called the "baroreflex.”
Heart rate variability biofeedback treatment strengthens and improves the sensitivity/efficiency of our baroreceptors (baroreflex), helping to more efficiently control blood pressure. By increasing heart rate variability through biofeedback, the patient is improving the baroreflex which would translate into having "a more sensitive thermostat" to regulate your blood pressure more effectively and safely. A more sensitive "baroreflex" has strong positive prognostic value.
Physicians used to believe that a patient could not improve their baroreflex, and while they felt that this would be extremely useful to the patient, they felt it to be a pipe dream. Fortunately, with the development of HRV biofeedback, today we know that it can be improved without drugs or invasive procedures. In essence, the core purposes for heart rate variability biofeedback are to optimize autonomic nervous system regulation, improve the baroreflex, potentially decrease risk for cardiovascular events, and increase our capacity to handle day to day stress better.
Stress, Heart Disease, and Heart Rate Variability
Your heart is not just a mechanical pump in the body. It is a vital organ that is being affected continuously by autonomic nervous system impulses and hormonal changes triggered by stress, which can significantly contribute to cardiovascular disease. Chronic stress can cause essential hypertension (high blood pressure), as well as a variety of other negative health problems. It’s a proven fact that men with high levels of anxiety and anger are more likely to have coronary heart disease and heart attacks.
A new study from Harvard Medical School's Massachusetts’s General Hospital has recently confirmed a link between stress reactivity in the region of the brain involved in processing emotions (the Amygdala) and having an increased risk of heart attacks or strokes (https://www.nlm.nih.gov/medlineplus/news/fullstory_157945.html).
In fact, the study found a 14-fold increase in the risk of a cardiovascular event after having increased stress activation in the brain. What’s that mean? It means that reducing your stress reactivity should be at least as important a priority as nutrition and exercise, and that heart rate variability needs to be on your radar, especially if you have a history of cardiac issues.
Heart Rate Variability and Mortality
Heart rate variability is not only a marker of vulnerability to stress and a measure of one's capability for adapting to and recovering from stressors, but also an independent predictor of all-cause mortality.
People with a higher heart rate variability have more capacity to adapt and recover from stress more effectively, and they are also certainly more protected health wise, especially from stress related disorders and diseases.
Low heart rate variability is a marker for cardiovascular disorders such as coronary heart disease, hypertension, ventricular arrhythmia, and heart failure. In fact, lowered heart rate variability has been associated with increased risks for ventricular fibrillation, ventricular tachycardia, and even sudden cardiac death following a heart attack.
Evidence for HRV’s Influence on Cardiac Issues & General Health Outcomes
Like smoking, diabetes and elevated lipids, low HRV is a risk factor for mortality in all patients. For several decades it has been known that low heart rate variability predicts sudden cardiac death from arrhythmias after a heart attack and that it also predicts post-heart attack survival (Circulation,1992,85,164-171 and Biofeedback,DOI:10.5298/1081-5937-41.1.05).
Low HRV is also associated with depression, anxiety disorders, and post-traumatic stress disorder (PTSD). Low HRV is an index of compromised health overall, but especially important in coronary artery disease. Thus, for patients with a history of cardiac issues or risks, increasing heart rate variability is highly recommended.
As far back as 1996, it was known that reduced heart rate variability predicted increased risk for subsequent cardiac events such as coronary heart disease, congestive heart failure, and myocardial infarction (heart attack) in both men and women who had no clinical symptoms of heart disease (American Heart Association/Circulation. 1996; 94: 2850-2855 doi: 10.1161/01.CIR.94.11.2850). Previous research has already shown that lowered Heart Rate Variability predicted increased risk for all-cause mortality.
In 2013, a European study showed that low HRV is associated with an increased risk of a first cardiovascular event in populations without known cardiovascular disease (doi: 10.1093/europace/eus341). On the positive side, increasing HRV may result in a lower risk of fatal or non-fatal cardiovascular disease.
Improving Heart Rate Variability and Decreasing Cardiovascular Risks
Since reduced heart rate variability is associated with coronary artery disease, increasing heart rate variability should be a part of the patient's overall treatment regimen to improve prognosis in patients with coronary artery disease.
HRV biofeedback treatment/training can increase heart rate variability and thereby may reduce cardiovascular risk in coronary heart disease patients by improving vagal tone (increasing parasympathetic activity which increases heart rate variability). Back in 2004, a breakthrough study showed that Heart Rate Variability biofeedback training along with abdominal breathing retraining increased heart rate variability in patients with coronary artery disease. (Am Heart J. 2004 Mar;147(3):E11).
It is well documented that patients with cardiovascular disease with low heart rate variability (HRV) do worse clinically as low heart rate variability is linked to both increased cardiac mortality and morbidity.
In 2009, an important study demonstrated that Heart Failure patients undergoing heart rate variability biofeedback treatment/training were able to significantly improve their exercise tolerance (Appl Psychophysiol Biofeedback. 2009 Jun;34(2):71-91. doi: 10.1007/s10484-009-9077-2. Epub 2009 Feb 10). The significance of this finding is that improving exercise tolerance in Heart Failure patients is a positive prognostic indicator.
Finally, a landmark study from the Cleveland Heart Clinic (rated the number 1 heart clinic in the United States since the year 2000) showed that biofeedback training to reduce psychophysiologic stress and learning breath training increased heart rate variability in most of the patients with end-stage heart failure in their study. There were actually biologic improvements in the heart muscle in these failing hearts. Quite remarkably, the biofeedback training /treatment and breathing retraining produced a reversal of some of the biologic abnormal heart muscle changes that are seen in progression to heart failure (doi: http://dx.doi.org/10.5298/1081-5937-41.1.04). It was shown that increasing heart rate variability with noninvasive biofeedback and breath training produced similar improvements in the heart that surgically implanted Left Ventricular Assist Devices have done.
In conclusion, biofeedback heart rate variability treatment is a major non-drug breakthrough for improving cardiac autonomic nervous system functioning and may reduce cardiovascular risks. This reduction in cardiovascular risks is achieved by increasing parasympathetic activity, decreasing sympathetic activity, and improving the baroreflex. These improvements give patients an increased sense of self-control over their cardiovascular functioning and health. The benefits of HRV biofeedback are many, but it should not be overlooked that it is a noninvasive process without the potential negative side effects related to drug treatments and surgery.
Contact Us Today
If you or a loved one has been diagnosed with low heart rate variability, or a history of cardiovascular disease or cardiac issues, please call the Drake Institute today to find out how we can help. Call us now to schedule your no-cost screening consultation.