Biomedgrid (2024)

Mohammad Karimi Moridani*
Pargol Yousefi
Anahita Safavi Sohi

*Corresponding author: Mohammad Karimi Moridani, Department of Biomedical Engineering, Faculty of health, Tehran MedicalSciences, Islamic Azad University, Tehran, Iran.

Received: January 25, 2021; Published: March 16, 2021

DOI: 10.34297/AJBSR.2021.12.001736

Abstract

This study aimed to analyze the dynamics of heart rate before and during meditation to investigate the effect of meditation on heart rateregulation. For this purpose, heart rate signals from the Physiont database were used. Linear and nonlinear features were calculated in two data setsbefore and during meditation. The results show that the heart rate fluctuations decrease during meditation, and the heart rate rhythm becomes moreregular. In contrast, before meditation, the criteria for heart rate changes and heart rate fluctuations are high. Also, the result indicates a decrease inmean heart rate during meditation. It has been shown that the suggested features can be useful in evaluating the heart rate signal during meditation.

Meditation has been considered an adjunct therapy in managing psychiatric illnesses (such as anxiety and depression) and maintainingmental health. As a result, the use of meditation can be very effective in preventing cardiovascular disease due to its positive effect on heart rhythmregulation and relaxation.

Keywords: Heart rate; Meditation; Regulation; Detection; Nonlinear features

Introduction

Each year, patients with acute coronary syndrome symptomsand myocardial infarction account for 10% of emergency casesand up to 25% of all patient admissions [1,2]. This represents asignificant financial burden on health care resources, with thecost of treating these patients amounting to approximately $ 286billion annually, or negligibly 17% of health care costs [3], whichemphasizes that cardiovascular interventions such as meditationare needed to help. Over the past few decades, awareness of the useof meditation or other forms of mind-body therapy in health carehas increased.

The Effects of Meditation on Heart Rate Variability

Meditation has positive effects on cardiovascular function. Oneof the indicators of heart health is heart rate variability (HRV).HRV means the length of time between different heartbeats. If thetime interval between heartbeats is longer, the heart is healthier.Changes over time between consecutive heartbeats are mainlydependent on external HR regulation [20,21]. The HRV signalfrom electrocardiographic signals is strongly correlated withthe activity of the autonomic nervous system. HRV represents adynamic interaction and balance between the sympathetic andparasympathetic systems. The sympathetic system is responsiblefor raising the heart rate, raising blood pressure, and injectingglucose into the bloodstream to promote activity. In contrast, theparasympathetic nervous system reduces heart rate and nutrientstorage, effectively reducing everything [22,23]. HRV analysisis mainly divided into measurements in the time and frequencydomain. The pulse intervals’ changes to the pulses provided atrest indicate the RR control mechanisms’ precise adjustment.Because it helps to assess the balance between sympathetic andparasympathetic effects on heart rhythm. The sympathetic nervoussystem increases heart rate, which shortens stroke intervals. Whilethe parasympathetic system slows down the heart rhythm, causinglonger beats.

The degree of variability in HR provides information about thefunction of neural control over HR and the heart’s ability to respond[24]. HRV reflects the heart’s ability to adapt to changing conditionsby quickly tracking and responding to unpredictable stimuli. HRVanalysis is the ability to assess the overall health of the heart andthe state of the autonomic nervous system, which is responsiblefor regulating heart activity. HRV is a useful signal for studying theautonomic nervous system. HRV refers to changes in pulse intervalsand is accountable for balancing the branches of the sympatheticnervous system (SNS) and parasympathetic nervous system (PNS)in the ANS and controlling HR. Normal HR variability is due toautoimmune regulation of the heart and circulatory system [25].Increased SNS activity or decreased PNS activity leads to increasedheart rate. Conversely, a decrease in SNS activity or high PNS activitycauses a reduction in heart rate.

The Effect of Meditation on Blood Pressure andCardiovascular Diseases

Each year, patients with acute coronary syndrome symptomsand myocardial infarction account for 10% of emergency cases andup to 25% of all patient admissions [1,2]. These results representa significant financial burden on health care resources, with thecost of treating these patients being approximately $ 286 billionannually, or negligibly 17% of health care costs [3]. He emphasizesthat to help solve this problem, cardiovascular interventions suchas meditation are needed. Over the past few decades, awarenessof the use of meditation or other forms of mind-body therapy inhealth care has increased.

A meta-analysis of 1264 patients was performed to evaluatecognitive-behavioral therapies (such as biofeedback, relaxation,and meditation) on hypertension [26]. This study showed thatcognitive interventions for hypertension are better than notreatment. A meta-analysis reviewed randomized controlledtrials and compared blood pressure responses to transcendentalmeditation (TM) with a control group. This analysis, including 9randomized controlled trials, included patients from adolescents(mean age 16 years) to the elderly (mean 81 years) [27]. Andersonet al. [28] found that TM reduced systolic blood pressure by anaverage of 4.7 mm Hg and diastolic blood pressure by 3.2 mm Hgcompared with controls. Subgroup analyses of high blood pressuregroups and quality studies have shown similar reductions in bloodpressure in all groups. Gregowski et al. [29] evaluated the effectof breathing awareness meditation (BAM) on circulating bloodpressure and sodium excretion in African adolescents. They foundsignificant group differences in changes in systolic, diastolic, andnocturnal HR blood pressure over 24 hours and during schoolhours. Participants in the BAM treatment group showed the mostconsiderable overall reductions in these criteria (Benfroni adjustedP <0.05). The researchers concluded that BAM appears to improvehemodynamic function and may affect sodium transfer amongAfrican adolescents at increased risk of cardiovascular disease.

Another study also suggested that meditation was associatedwith beneficial effects on insulin resistance and fat profiles. Asurvey of 103 people with stable CHD examined the effectivenessof TM on the metabolic CHD syndrome [30]. The primary outcomemeasures included blood pressure, protein profiles, and insulinresistance. This study showed that the TM group had beneficialchanges in regulated systolic blood pressure, insulin resistance,and HRV compared to the control group. However, no significant increase in levels of total cholesterol, lipoproteins, and C-reactiveprotein was observed, which may be due to the high prevalence ofstatin use and low-density lipoprotein cholesterol levels [30].

Cooper & Aygen [31] compared 12 patients with hypercholesterolemiawith a history of regular meditation practice with 11 individualsin the control group without a history of meditation. Theyfound a 10% reduction in fasting cholesterol levels in those whomeditated over a 13-month period (P <0.005). A study publishedin 2010 evaluated the effects of meditation on 42 volunteers. Theparticipants were divided into two groups: one group participatedin one-hour meditation training sessions per week for 5 weeks,and one group formed the control group (normal heart care). After5 weeks, the meditation group showed a significant decrease indepression and an increase in attendance compared to the controlgroup [32]. Zidane et al. [33] evaluated the benefits of meditationsessions on mental health and cardiovascular variables such as HRand blood pressure. The study included 82 students (34 males and48 females) with no previous meditation experience. They participatedin 3 sessions of mindfulness meditation training. This studyshowed that meditation intervention was effective in reducingheart rate and negative mood, depression, fatigue, and confusioncompared to the control group. In 2012, Barnes and Eram-Johnsonproposed an updated model of a particular form of meditation[transcendental meditation] [34], which has been shown toreduce the sympathetic nervous system’s activation. Dilbeck andEram-Johnson reported severe decreases in respiration rate andplasma lactate during TM training, while controls with closed eyesexperienced an increase in basal skin resistance. In addition, TMparticipants had lower baseline HR and respiratory rate, lowerplasma lactate levels, and spontaneous reactions of skin resistanceoutside meditation [35]. Delui et al. [36] examined meditation inpatients with cardiovascular disease and depression. Forty-five patientswere randomly divided into three groups: relaxation, meditation,and control. After completing the beck depression scaleand anxiety self-assessment, patients participated in a series of 10sessions of Physical Muscle Rest (RMP) or Mental Meditation or receivedno intervention. Significant reductions in depression, systolicblood pressure, and RH were observed in the meditation groupcompared with the control group.

Kubious HRV Software

Kubious software was used to analyze the heartbeat signalbefore and during meditation. This software is capable of linearand nonlinear analysis of heart signals. The graphical environmentof this software is very simple and understandable and can be usedeasily. This software has the ability to read different formats of ECGsignals. In addition to displaying the ECG signal, this software canshow R-R intervals at any time by the user. This software is alsoused to show different time, frequency, and nonlinear analyzesof the cardiac signal. Figure 1 shows the image of Kubious HRVsoftware along with the results of various analyzes.

Non- Linear Analysis of Cardiac Signals before andDuring Meditation

Nowadays, it has been discovered that nonlinear analysis candescribe the processes produced by living biological systems.In recent years, nonlinear analysis methods have found manyapplications in the diagnosis of various conditions. Nonlinearanalysis of HRV signal has received a lot of attention for two mainreasons. The first reason is the nonlinear nature of the observedsignal from the heart, which acts as a nonlinear dynamic oscillator.The second reason is the need to acquire sufficient knowledgeabout this real phenomenon. Poincaré plot is a nonlinear methodfor extracting hidden information from the cardiac signal. In thismethod, each beat is considered in terms of the next beat and anelliptical shape is obtained that has short-term (SD1) and long-termchanges (SD2) [37]. Calculating the parameters SD1 and SD2 in thetwo previous states and during meditation using Kubius softwareare given in Tables 1 & 2.

Table 1 shows the nonlinear parameters’ values beforemeditation, and Table 2 shows the amounts of nonlinear parametersduring meditation. As the nonlinear parameters’ values show, whenthe person is during meditation, the heart signal is calmer andfluctuates less. So meditation can regulate your heart rate. Figure 2shows the changes in features introduced in the two states beforeand during meditation.

Figure 2: Boxplots of the most significant linear and nonlinear indices before and during meditation.

Table 1: Nonlinear features extracted from the cardiac signal before meditation.

Table 2: Nonlinear features extracted from the cardiac signal during meditation.

Discussion and Conclusion

Nowadays, anxiety is considered the most common psychiatricdisorder, and various medical and non-pharmacological techniquesand methods are used to relieve it and its stress. One of the mostuseful and common treatments for anxiety is meditation. Meditationis generally a technique of mastering the mind. According to theproponents of this method, the goal of meditation is to train andcontrol the mind by introspective techniques to achieve the joyof deep and long-lasting awareness and peace, independent ofothers. Meditation means focusing on the mind. This focus can beon a voice, phrase or prayer, object, image, self-awareness, howto breathe, religious duties, and so on. The goal is to be aware ofthe moment, achieve relaxation, and reduce stress. Meditationpromotes personality and spiritual growth [38]. It does not matterwhich meditation method you use because their effects on thebody are similar. Researchers have shown that meditation reducesstress hormone levels and contributes to the health of the immunesystem. Meditation has been shown to lower cholesterol levels inthe blood and help keep arteries open by reducing hormones suchas Epinephrine. Also, studies based on AJ have demonstrated thatthis technique increases alpha waves’ intensity, which indicatesa state of relaxation and acceptance, to an even higher level thansleep time [39]. Research has also shown that improving bloodflow, which protects the arteries, lowers blood lactic acid levels,which is associated with reduced anxiety and reduces heart rate,which reduces the need for pumping, giving the heart a chance torest. Another effect of meditation is slow breathing, as a result ofwhich the body consumes less oxygen.

Many studies have examined the effect of meditation on hearthealth. Regular meditation practice has been shown to help lowerhigh blood pressure in the long run. Among these studies, one studyshowed a sharp drop in blood pressure and heart rate in blackadults. Another study found that teens who meditate twice a dayfor 15 minutes each time for four months can lower their bloodpressure up to several digits [40]. The sympathetic nervous systemdilates the pupil and raises blood pressure and respiration rate.Meditation works the other way around, lowering blood pressureand muscle tension. This article shows that meditation is aninfluential factor in reducing heart rate, increasing concentration,and reducing anxiety and stress. Therefore, since meditation is asimple and low-cost method, meditation exercises can be one of themost common problems for people and Reduced heart disease. Asa result, using meditation by regulating heart rate reduces mentalfatigue and improves performance.

Biomedgrid (2024)

Mohammad Karimi Moridani*

Pargol Yousefi

Anahita Safavi Sohi