Correlation Analysis of Heart Rate Variability and Respiratory Frequency Under Sinus Arrhythmia Condition

Abstract

The heart is not just a muscular organ that serves to pump and make blood flow in the whole body, the heart, being connected to the brain and the autonomic nervous system, is emotional in its feelings and expression. The heart rate variability (HRV) test is designed to give an indication of the state of the biological systems that regulate cardiac activity. The cardiac system functions best when it is regulated by the autonomic circuit. When homeostasis is broken i.e. the natural balance is disturbed, higher levels of the central regulatory system dominate cardiac activity. These changes in regulation are reflected in the variability of the heart rhythm. Beatto- beat changes in cardiac signals or heart rate variability is controlled by the two branches of autonomic nervous system (ANS) in a very complex manner. It is clear that HRV analysis with and without respiratory information provides different results. The differences become more obvious when respiration rate is low. Furthermore, many standard ANS tests include deep breathing test, which is to stimulate parasympathetic branch of ANS. Therefore for accurate assessment of the ANS activity, one must include the effect of respiration in HRV analysis. This kind of a change is only observed when respiratory peak is used in HRV analysis to locate high frequency area then estimating the power. Employing respiratory signal in HRV analysis provides more accurate isolation of sympathetic and parasympathetic activity, which provides a better diagnostic tool in assessing human ANS. Power spectral analysis of HRV measure changes in total ANS power and sympathetic and parasympathetic balance that occur during different emotional states. There are many situations where heart rate changes rapidly over time, and the control of those changes is of considerable interest. Our thesis work focuses on analyzing the correlation between heart rate variability and respiratory frequency using MATLAB software tool. Pearson correlation coefficient is used for this purpose. Thereafter, various parameters like noise, high frequency component are varied to find the effect of respiration on heart rate variability. Hence, a better understanding is attained about autonomic control of rapidly changing signals. As a result of this methodology, pathophysiological conditions of paramount importance, such as arterial hypertension, myocardial ischemia, sudden cardiac death, and heart failure might soon undergo a novel scrutiny with practical implications. It is generally accepted that RSA amplitude is a noninvasive marker of the activity of the parasympathetic nervous system, and it can therefore be used to infer relative changes in parasympathetic cardiac tone.