Spectral Parameters Of Heart Rate Variability Research Articles

Spectral Analysis of Heart Rate Variability Based on the Hilbert-Huang Method.

Analysis of heart rate variability (HRV) is widely used for noninvasive assessment of the state of the regulation systems of the heart. The aim of this study was to evaluate the capabilities of the Hilbert-Huang method for calculating spectral parameters of HRV in comparison with the commonly used Fourier analysis. Fourier analysis allows estimation of averaged spectral amplitudes and power of HRV oscillations in fixed frequency intervals, which are associated with the activity of sympathetic, parasympathetic, and humoral regulation systems. Using the Hilbert-Huang method, we revealed four spectral components, described by Gaussian functions, in which HRV oscillations are concentrated, and showed the absence of fixed boundaries between them. The obtained energy quantitative characteristics of the spectral components of heart rhythm oscillations can serve as the basis for diagnostic methods of heart rhythm regulation, supplementing the commonly used ones.

SPECTRAL ANALYSIS OF HEART RATE VARIABILITY BASED ON THE HILBERT-HUANG METHOD

Analysis of heart rate variability (HRV) is widely used for noninvasive assessment of the state of its regulation systems. The aim of the research was to evaluate the capabilities of the Hilbert-Huang method for calculating spectral parameters of HRV in comparison with the commonly used Fourier analysis. Fourier analysis allows to estimate averaged spectral amplitudes and power of HRV oscillations in fixed frequency intervals, which are associated with the activity of sympathetic, parasympathetic and humoral regulation systems. Using the Hilbert-Huang method, we revealed 4 spectral components, described by Gauss functions, in which HRV oscillations are concentrated, and showed the absence of fixed boundaries between them. The obtained energy quantitative characteristics of the spectral components of heart rhythm oscillations can serve as the basis for diagnostic methods of its regulation, supplementing the commonly used ones.

Diabetic cardiac autonomic neuropathy: Omega-3 polyunsaturated fatty acids and heart rate variability

The aim of the study was to analyze the effect of ω-3 polyunsaturated fatty acids (ω-3 PUFAs) on the heart rate variability (HRV) parameters in patients with type 2 diabetes mellitus (T2DM) and advanced stage of cardiovascular autonomic neuropathy (CAN). We have examined 36 patients with T2DM and definite stage of CAN, aged between 50-59 years with disease duration 1-6 years and median glycated hemoglobin A1c 7.1%±0.12%. Patients were divided into 2 groups. The first group received traditional antihyperglycemic therapy (n=15, control) for three months; patients in group 2 (n=21) received in addition 1 g/day of the ω-3 PUFAs for three months. Results. Prescription of the ω-3 PUFAs to the patients with T2DM and definite stage of СAN was accompanied by a statistically significant increase of the time-domain HRV parameters; the spectral HRV parameters during the active and passive periods compared to the control group. Conclusion. Obtained results suggest that the efficacy of ω-3 PUFAs is the result of a direct effect of the ω-3 PUFAs on the investigated indexes.

A Shift of the Parameters of the Cardiovascular System in Adolescents during the Period from 2004 to 2020 as a Result of Modification of Educational Environment

The purpose of our study was to search for possible changes in the parameters of the cardiovascular system in adolescents during the period from 2004 to 2020 against the background of the introduction of digital technologies into the educational environment. Methods: A comparative analysis of the parameters of the cardiovascular system in female and male adolescents aged from 13.9 to 15.4 years was carried out (57 adolescents in 2004 and 53 adolescents in 2020). We used a spiroartheriocardiorythmograph allowing recording of heart rate (HR) and blood pressure (BP) and spectral parameters of HR variability and variability of systolic (sBP) and diastolic (dBP) BP. The parameters were recorded at rest in the sitting position for over two min. All studies were performed during school hours in February-March. Results: An increase in the mean sBP values and an increase in the proportion of adolescents with BP in the

Proposal of a pseudo‐electrocardiogram model incorporating heart rate variability and QT‐interval variability, and its application

In this work, we propose a model that incorporates QT‐interval variability (QTV) by extending the synthetic electrocardiogram (ECG) model including heart rate variability (HRV). The model consists of three modified coupled ordinary differential equations and an equation to incorporate QTV by shifting the position of the T‐wave; in addition, RR and QT tachograms that have frequency characteristics composed of multiple Gaussian distribution peaks are used. An ECG signal can be generated by adapting a certain ECG waveform and by giving the means, standard deviations, and power spectral density parameters of HRV and QTV. This proposed model may reveal the neurophysiological mechanisms underlying the relationship between QTV and HRV and/or the autonomic activity, and it may solve problems in the measurement of QT‐interval. In conclusion, this proposed model is a very useful tool in medical education and experimental simulation. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Heart Rate Variability Peculiarities in Adolescents with Psychopathology in the Educational Environment

Under conditions of inclusive education, students with health limitations, in particular, children with neurological and mental disorders, have the opportunity to study at a general school. The goal of this study was to assess the possibility of using analysis of heart rate variability (HRV) as a relatively simple tool for evaluation of the adaptive resources in students with mental disorders and for early detection of dysfunctions in the neuroregulatory mechanisms in healthy students. We compared the spectral parameters of HRV and peripheral blood pressure in healthy adolescents (n = 70) and adolescents with neuropsychiatric disorders (n = 58). Electrocardiogram was recorded for 2 minutes in a sitting posture, wearing a spirometric mask with voluntary breathing. Adolescents with mental disorders demonstrated a high total power of the HRV spectrum, an increased high-frequency power (0.15–0.4 Hz), a decreased low frequency / high-frequency ratio, and reduced total power and low frequency spectral power of systolic blood pressure variability. The revealed differences were observed mainly in males. The presented data demonstrate an increased vagal tone in adolescents with mental disabilities. Our findings support the idea that HRV can be used in schools to identify risk groups of vulnerability to mental disorders.

Evaluation of heart rate variability in patients with different forms of pulmonary hypertension

Pulmonary hypertension (PH) is a severe pathology of the cardiovascular system with extremely poor prognosis, if unreated. Early diagnosis of PH is difficult, due to the absence pathognomonic symptoms, and at the initial stage the disease may be asymptomatic. An increase in pulmonary vascular resistance and pressure in the pulmonary artery cause severe dysfunction of the right ventricle, which affects the functional status of patients. The assessment of heart rate variability (HRV) parameters is used to predict the increased risk of sudden death in various diseases of the cardiovascular system and the functional status of the body. HRV is mainly regulated by the sympathetic and parasympathetic divisions of the autonomic nervous system. It is noted that pulmonary arterial hypertension is associated with increasing of sympathetic activity. The review, based on the analysis of the pathophysiological mechanisms of pulmonary arterial hypertension and chronic thromboembolic PH, presents the results of studies assessing the time and spectral parameters of HRV in patients with PH of various etiologies.

Порівняльна характеристика впливу омега-3 поліненасичених жирних кислот, статинів та їх комбінування на показники ліпідного спектра крові, судинно-тромбоцитарного гомеостазу і варіативності ритму серця у хворих на цукровий діабет 2-го типу з кардіоваскуля

Актуальність. Особливу зацікавленість у лікуванні дисліпопротеїнемій (ДЛП) у хворих на цукровий діабет 2-го типу (ЦД-2) з кардіоваскулярною автономною нейропатією (КАН) викликає аналіз ефективності комбінування омега-3 поліненасичених жирних кислот (w-3 ПНЖК) і статинів, однак інформація про особливості їх використання неоднозначна, має фрагментарний характер, є предметом дискусії, а тому потребує подальшого уточнення. Мета. Проведення порівняльної характеристики впливу w-3 ПНЖК, статинів та їх комбінування на показники ліпідного спектра крові, судинно-тромбоцитарного гомеостазу і варіативності ритму серця (ВРС) у хворих на ЦД-2 з КАН. Матеріали та методи. Обстежено 75 хворих на ЦД-2 із функціональною стадією КАН. У крові визначали концентрацію глюкози, глікозильваного гемоглобіну, загального холестерину (ЗХС), тригліцеридів (ТГ), холестерину ліпопротеїнів високої (ХС ЛПВЩ) і низької щільності (ХС ЛПНЩ); вміст ендотеліну-1 (ЕТ-1), тромбоксану B2 (TXB2), 6-кетопростагландину F1a (6-ketoPGF1a), розраховували коефіцієнт атерогенності (КА), співвідношення TXB2/6-ketoPGF1a. З метою оцінки результатів короткотривалої ВРС використовували часові й спектральні параметри. Пацієнти з ЦД-2 та функціональною стадією КАН були стратифіковані на чотири групи і протягом трьох місяців, окрім цукрознижувальної терапії, отримували: 1-ша група (n = 21) — препарат w-3 ПНЖК 1 капс/добу; 2-га група (n = 22) — симвастатин 20 мг/добу; 3-тя група (n = 17) — препарат w-3-ПНЖК 1 г/добу і симвастатин 10 мг/добу; у контрольній (n = 15) — стандартну цукрознижувальну терапію протягом трьох місяців. Результати. Включення в лікувальні заходи препарату w-3 ПНЖК виявляло більш значуще порівняно з симвастатином зниження рівня ТГ, зменшення вмісту КА та збільшення концентрації ХС ЛПВЩ і не впливало на концентрацію ЗХС і ХС ЛПНЩ. Використання симвастатину супроводжувалось більш вірогідним зменшенням рівня ЗХС, ХС ЛПНЩ, КА, ТХВ2, TXB2/6-ketoPGF1a і зростанням вмісту ХС ЛПВЩ, ЕТ-1, 6-ketoPGF1a; часових і спектральних параметрів ВРС. Комбінація w-3 ПНЖК і симвастатину супроводжувалась найбільш вираженими, позитивними, вірогідними змінами ліпідного обміну, ендотеліальної функції, ТХВ2, TXB2/6-ketoPGF1a; часових і спектральних параметрів ВРС. Висновки. Отримані результати дозволяють вважати, що ефективність комбінованої терапії w-3 ПНЖК і симвастатином не пов’язана зі станом компенсації захворювання, а є результатом безпосереднього впливу цих фармакологічних агентів на досліджувані показники, що обґрунтовує доцільність її використання в лікуванні ДЛП у хворих на ЦД-2 і функціональну стадію КАН.

РОЛЬ ЭСТРОГЕНОВ В ВЕГЕТАТИВНОЙ РЕГУЛЯЦИИ СЕРДЕЧНО-СОСУДИСТОЙ СИСТЕМЫ В МЕНОПАУЗЕ

Hot flashes are known to be associated with a variety of cardiovascular risk factors. There is evidence of a close relationship between hot flashes and autonomic dysfunction, while the parameter - heart rate variability (HRV) - is a surrogate marker for assessing the activity of the autonomic nervous system (ANS). However, changes in HRV can be caused by both aging and hormonal changes. The purpose of this work is to consider the role of endogenous estrogens in the autonomic regulation of the cardiovascular system on the model of "acute estrogen deficiency" in cases of total oophorectomy and "partial estrogen deficiency" - in cases of hysterectomy with / without appendages. 44 women were included, mean age - 46.9 ± 2.2 years, whose HRV was assessed before surgery (1 week before surgery) and after (not less than 4 and not more than 5 weeks after surgery). According to the results obtained, there were no statistically significant changes in both temporal and spectral HRV parameters in patients after hysterectomy (p> 0.05). On the contrary, patients with total oophorectomy in the postoperative period showed decreased HRV parameters characterizing the parasympathetic activity of the ANS, namely SDRR, rMSSD, pNN50, HF and the LF index, reflecting both sympathetic and parasympathetic effects on heart rate. Patients with total oophorectomy have a higher ratio of the sympatovagal LF / HF index; the work shows that this fact is most likely due to the predominance of sympathetic nervous influences induced by "acute" withdrawal of ovarian hormones due to the performed volume of surgery, and not as a result of surgery. as such, or its psychological consequences. Thus, according to the above-described results of the study, patients in cases of total oophorectomy showed a decrease in the parameters of vagal HRV in the direction of sympathetic dominance, which may cause an increase in cardiovascular risk.

Assessment of Autonomic Nervous System Dysfunction in the Early Phase of Infection With SARS-CoV-2 Virus.

BackgroundWe are facing the outburst of coronavirus disease 2019 (COVID-19) defined as a serious, multisystem, disorder, including various neurological manifestations in its presentation. So far, autonomic dysfunction (AD) has not been reported in patients with COVID-19 infection.AimAssessment of AD in the early phase of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus).Patients and methodsWe analyzed 116 PCR positive COVID-19 patients. After the exclusion of 41 patients with associate diseases (CADG), partitioned to patients with diabetes mellitus, hypertension, and syncope, the remaining patients were included into a severe group (45 patients with confirmed interstitial pneumonia) and mild group (30 patients). Basic cardiovascular autonomic reflex tests (CART) were performed, followed by beat-to-beat heart rate variability (HRV) and systolic and diastolic blood pressure variability (BPV) analysis, along with baroreceptor sensitivity (BRS). Non-linear analysis of HRV was provided by Poincare Plot. Results were compared to 77 sex and age-matched controls.ResultsAD (sympathetic, parasympathetic, or both) in our study has been revealed in 51.5% of severe, 78.0% of mild COVID-19 patients, and the difference compared to healthy controls was significant (p = 0.018). Orthostatic hypotension has been established in 33.0% COVID-19 patients compared to 2.6% controls (p = 0.001). Most of the spectral parameters of HRV and BPV confirmed AD, most prominent in the severe COVID-19 group. BRS was significantly lower in all patients (severe, mild, CADG), indicating significant sudden cardiac death risk.ConclusionCardiovascular autonomic neuropathy should be taken into account in COVID-19 patients’ assessment. It can be an explanation for a variety of registered manifestations, enabling a comprehensive diagnostic approach and further treatment.

Is the heart rate variability monitoring using the analgesia nociception index a predictor of illness severity and mortality in critically ill patients with COVID-19? A pilot study.

IntroductionThe analysis of heart rate variability (HRV) has proven to be an important tool for the management of autonomous nerve system in both surgical and critically ill patients. We conducted this study to show the different spectral frequency and time domain parameters of HRV as a prospective predictor for critically ill patients, and in particular for COVID-19 patients who are on mechanical ventilation. The hypothesis is that most severely ill COVID-19 patients have a depletion of the sympathetic nervous system and a predominance of parasympathetic activity reflecting the remaining compensatory anti-inflammatory response.Materials and methodsA single-center, prospective, observational pilot study which included COVID-19 patients admitted to the Surgical Intensive Care Unit was conducted. The normalized high-frequency component (HFnu), i.e. ANIm, and the standard deviation of RR intervals (SDNN), i.e. Energy, were recorded using the analgesia nociception index monitor (ANI). To estimate the severity and mortality we used the SOFA score and the date of discharge or date of death.ResultsA total of fourteen patients were finally included in the study. ANIm were higher in the non-survivor group (p = 0.003) and were correlated with higher IL-6 levels (p = 0.020). Energy was inversely correlated with SOFA (p = 0.039) and fewer survival days (p = 0.046). A limit value at 80 of ANIm, predicted mortalities with a sensitivity of 100% and specificity of 85.7%. In the case of Energy, a limit value of 0.41 ms predicted mortality with all predictive values of 71.4%.ConclusionA low autonomic nervous system activity, i.e. low SDNN or Energy, and a predominance of the parasympathetic system, i.e. low HFnu or ANIm, due to the sympathetic depletion in COVID-19 patients are associated with a worse prognosis, higher mortality, and higher IL-6 levels.

Correlations between arrhythmogenic substrate and noninvasive risk stratification in ischemic heart disease patients modifications by radiofrequency ablation.

Several noninvasive risk factors for ventricular arrhythmias have been described in postmyocardial infarction (MI) patients, whose relationships with scar characteristics and modifications by ablation are unknown. Twenty-two patients with previous MI referred for ventricular tachycardia ablation were prospectively included. ECG, heart rate variability (HRV), signal-averaged ECG (SA-ECG), and T wave alternans (TWA) were performed before and after radiofrequency ablation. Scar areas were correlated to preablation parameters. Pre and postablation parameters were furthermore compared. Left ventricular ejection fraction and some spectral and time-domain HRV parameters were significantly correlated to the scar areas. QRS duration was larger after vs before ablation (120 ± 29 vs 105 ± 22 msec, P = .01). No significant modification in time or spectral domain of HRV was observed. There was no significant change in TWA and SA-ECG before and after ablation. Borderline decreases in quantitative TWA parameters were noted in patients with positive TWA and successful ablation procedure. Some noninvasive risk factors were linked to the scar areas, but few were significantly modified after ablation. Larger populations are needed to demonstrate significant differences or correlations.

Focal epileptic seizures anticipation based on patterns of heart rate variability parameters

Background and ObjectiveHeart rate variability parameters are studied by the research community as potential valuable indices for seizure detection and anticipation. This paper investigates heart activity abnormalities during focal epileptic seizures in childhood. MethodsSeizures affect both the sympathetic and parasympathetic system which is expressed as abnormal patterns of heart rate variability (HRV) parameters. In the present study, a clinical dataset containing 42 focal seizures in long-term electrocardiographic (ECG) recordings from drug-resistant pediatric epileptic patients (with age 8.2 ± 4.3 years) was analyzed. ResultsResults indicate that the time domain HRV parameters (heart rate, SDNN, standard deviation of heart rate, upper envelope) and spectral HRV parameters (LF/HF, normalized HF, normalized LF, total power) are significantly affected during ictal periods. The HRV features were ranked in terms of their relevance and efficacy to discriminate non-ictal/ictal periods and the top-ranked features were selected using the minimum Redundancy Maximum Relevance algorithm for further analysis. Then, a personalized anticipation algorithm based on multiple regression was introduced providing an “epileptic index” of imminent seizures. The performance of the system resulted in anticipation accuracy of 77.1% and an anticipation time of 21.8 s. ConclusionsThe results of this analysis could permit the anticipation of focal seizures only using electrocardiographic signals and the implementation of seizure anticipation strategies for a range of real-life clinical applications.

ANALYSIS AND FORECASTING OF RESERVE CAPABILITIES OF THE ORGANISM OF STUDENTS ACCORDING TO INDICES OF HEART RATE VARIABILITY

Introduction. Currently, there is a deterioration trend in the health of the younger generation, in particular, an increasing number of persons with functional disorders of the cardiovascular system. Regarding this it is important to develop an comprehensive approach to the study of the circulatory indices in the young age with informative clinical diagnostic techniques and new ways to analyze the data. Material and methods. Heart rate variability (HRV) indices in 200 students at rest and during exercise were studied. For a more complete assessment of the functional reserves of cardiovascular system after the load the index of the normal heart rhythm restoration (SDNN) was calculated. Moreover, we built logistic models and curves of the operating characteristics. Results. At rest, no significant differences in indices of both HRV and autonomic regulation of heart rate have been identified between boys and girls aged of 16-18 years. Students of the different gender, aged of 19-22 years showed significant differences in spectral parameters of HRV, there was noted the dominance of the sympathetic component of heart rate regulation in boys and parasympathetic - in girls. In terms of physical activity in undergraduate students there is observed mainly the activation of vagal influences on the heart, in senior students the vegetative balance shifted to the direction of the increased activity of mechanisms of the sympathetic regulation. The revealed decrease of NHRR reflects the low level of the reserve capacity of the cardiovascular system in 41% out of observed students. Part of students with an increased probability of the reduction of functional cardiac disorders accounted for 42% of boys and 39% of girls among students aged 16-18 years and 36% of boys and 44% of girls among students aged of 19-22 years. Conclusion. There is a change in the nature of autonomous regulation of heart rate in students of different gender and ages from 16-18 to 19-22 years. The optimal cardiac response to stress test is observed at low baseline values of heart rate and the prevalence of the parasympathetic part of the autonomic regulation of the heart rate at rest. To assess the functional reserve of the cardiovascular system in HRV indices we recommend the calculation of NHRR and the analysis of the SDNN coefficient for the effective prediction of heart rate recovery rate after exercise testing.

THE RELATIONSHIP OF THE RATIO TAURINE/ALANINE IN SERUM AND INDICATORS OF HEART RATE VARIABILITY IN PATIENTS WITH POSTINFARCTION CARDIOSCLEROSIS AND DIABETES MELLITUS TYPE 2

The aim of the article : to determine the relationship of the ratio taurine/alanine (Tau/Ala) serum indicators of heart rate variability (HRV) in patients with postinfarction cardiosclerosis (PICS) and diabetes mellitus type 2 (DM 2). Materials and methods: we examined 87 patients with PICS and DM 2 – 50 women and 37 men, median age of the patients was 65.2 years (microtile interval 61-69 years). Amino acids were determined and the ratio between them. According to the results of Holter ECG monitoring (of HMCG) evaluated HRV. Results: in patients with PICS compared with healthy individuals observed a significant decrease in the blood levels of Tau/Ala (at 51.01%, p<0.001). The presence of comorbid diabetes is accompanied by more significant decrease in Tau/Ala (for the accounting period 82.22%, p<0.001) compared to healthy individuals. Between Tau/Ala and SDNN, LF, TP, VLF power of communication has been high, between Tau/Ala and RMSSD, HF, pNN 50.%, ULF, – moderate strength. Conclusions: the lower values of Tau/Ala in the blood of patients Pxs diabetes compared with patients without disorders of carbohydrate metabolism, accompanied by a decrease in spectral and temporal parameters of HRV, but that does not mean a causal relationship, may be associated with pathogenetic mechanisms of disorders of carbohydrate metabolism and requires further research.

Doxorubicin treatments induce significant changes on the cardiac autonomic nervous system in childhood acute lymphoblastic leukemia long-term survivors.

Acute lymphoblastic leukemia (ALL) is one of the leading malignancies in children worldwide. The cardiotoxicity of anti-cancer treatments leads to a dysfunction of the cardiac autonomic nervous system. Protection strategies, with dexrazoxane treatments, were used to counter these adverse effects. The aim of this study was to investigate the effects of the treatments on the cardiac autonomic nervous system. A total of 203 cALL survivors were included in our analyses and were classified into 3 categories based on the prognostic risk group: standard risk, high risk with and without dexrazoxane. A 24-h Holter monitoring was performed to study the cardiac autonomic nervous system. The frequency domain heart rate variability (HRV) was used to validate the cardiac autonomic nervous system modifications. Other analyses were performed using linear HRV indexes in the time domain and non-linear indexes. A frequency domain HRV parameters analysis revealed significant differences on an overall time-period of 24h. A repeated measures ANOVA indicated a group-effect for the low frequency (p = 0.029), high frequency (p = 0.03) and LF/HF ratio (p = 0.029). Significant differences in the time domain and in the non-linear power spectral density HRV parameters were also observed. Anti-cancer treatments induced significant changes in the cardiac autonomic nervous system. The HRV was sensitive enough to detect cardiac autonomic nervous system alterations depending on the cALL risk category. Protection strategies (i.e., dexrazoxane treatments), which were used to counter the adverse effects of doxorubicin, could prevent changes observed in the cardiac autonomic nervous system.

PECULIARITIES OF HEART RATE VARIABILITY IN NEWBORNS

Heart rate variability values are potentially important for assessing vegetative dysfunction in children.The purpose of the research: a comparative study of spectral heart rate variability parameters and synchronization of low-frequency oscillations, characterizing baroreflex in the vegetative regulation of the cardiovascular system in healthy newborns and adults.15 healthy newborns and 60 healthy individuals in the age of 18-34 years old were included in the study. We performed synchronous recording of electrocardiograms and photoplethysmograms with 10 minutes duration, at rest. Were evaluated spectral heart rate variability indices and the index of synchronization of low-frequency oscillations in heart rate variability and photoplethysmograms (S index).Results. In newborns, the peak of low-frequency oscillations was predominantly in the range 0.07–0.09 Hz, and high frequency 0.40–0.50 Hz. Newborns had lower LF% values than adults: 22.8 (14.1, 29.4) vs 32.9 (25.1, 41.9) (p=0.009). The S index in newborns was 20.1 (16.9, 26.5)%, and 33.2 (21.2, 45.4)% in healthy adults (p=0.023).Conclusion. We have first demonstrated that the interaction of baroreflex regulation of heart rhythm and peripheral blood filling in healthy newborns is characterized by lower values of S index, than in healthy adults, which can be explained by the immaturity of the vegetative regulatory elements of the cardiovascular system.

EFFECTS OF OMEGA-3 POLYUNSATURATED FATTY ACIDS ON THE CIRCADIAN RHYTHM OF HEART RATE VARIABILITY PARAMETERS IN PATIENTS WITH TYPE 2 DIABETES MELLITUS AND CARDIOVASCULAR AUTONOMIC NEUROPATHY

Aim. The aim of the study was to analyze the effect of a-3 polyunsaturated fatty acids (a-3 PUFAs) on the heart rate variability (HRV) parameters in patients with type 2 diabetes mellitus (T2DM) and advanced stage of cardiovascular autonomic neuropathy (CAN). Material and methods. We have examined 36 patients with T2DM and advanced stage of CAN, aged between 50-59 years with disease duration 1-6 years and median glycated hemoglobin A1c 71%±0,12%. Patients with T2DM and advanced stage of CAN were divided into 2 groups. The first group received traditional antihyperglycemic therapy (n=15, control) for three mo; patients in group 2 (n=21) received in addition 1 g/day of the a-3 PUFAs for three months. Results. Prescription of the a-3 PUFAs to the patients with T2DM and advanced stage of CAN was accompanied by a statistically significant increase of the timedomain HRV parameters; the spectral HRV parameters during the active and passive periods compared to the control group. Conclusion. Obtained results suggest that the efficacy of a-3 PUFAs is the result of a direct effect of the a-3 PUFAs on the investigated indexes.

Comparative Evaluation of Heart Rate Variability Based on the Data of ECG and Blood Pressure Measurements

The development of new approaches to the assessment of heart rate variability (HRV) is an important problem, since HRV reflects the functioning of cardiovascular control and is affected by various diseases. The purpose of this study was to evaluate the informative value of statistical and spectral HRV parameters calculated from pulse interval (PI) data of blood pressure as compared with those calculated from RR-interval data of electrocardiograms (ECG). We recorded ECG in conscious rats using skin adhesive electrodes simultaneously with blood pressure signal obtained through a catheter in the femoral artery. It has been found that the PI sequence can be used to calculate the statistical HRV indices that describe the HRV at time intervals about 1 min or longer, but statistical indices of the PI and RR intervals may differ in the analysis of beat-tobeat variations. The power spectra of the RR intervals and PI coincide in the low-frequency region, including the band of baroreflex cardiac rhythm oscillation. However, they can differ in the high-frequency region (at respiration frequency and above).

The effect of level of injury and physical activity on heart rate variability following spinal cord injury

Objective/Background: To assess frequency domain heart rate variability (HRV) parameters at rest and in response to postural autonomic provocations in individuals with spinal cord injury (SCI) and investigate the autonomic influences on the heart of different physical activities.Design: Cross-sectional study.Methods: Ten subjects with complete cervical SCI and fourteen subjects with complete low thoracic SCI were prospectively recruited from the community and further divided in sedentary and physically active groups, the latter defined as regular weekly 4 hour physical activity for the preceding 3 months. Sixteen healthy individuals matched for sex and age were recruited to participate in the control group. The Low Frequency (LF), High Frequency (HF) powers and the LF/HF ratio of HRV were measured from continuous electrocardiogram (ECG) recordings at rest and after sitting using a fast Fourier transformation.Outcome measures: The LF,HF, and the LF/HF ratio at rest and after sitting.Results: A significant decrease in all HRV parameters in patients with SCI was found compared to controls. The change in HF, LF and LF/HF following sitting maneuver was significantly greater in controls as compared with the SCI group and greater in subjects with paraplegia as compared to subjects with tetraplegia. Better HRV values and enhanced vagal activity appears to be related to the type of physical activity in active subjects with paraplegia.Conclusion: In this cohort of subjects spectral parameters of HRV were associated with the level of the injury. Passive standing was associated with higher HRV values in subjects with paraplegia.