Browsing by Author "Kazdagli, H"

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    Classical heart rate variability and non-linear heart rate analysis in mice under Na-Pentobarbital and Ketamine/Xylazine anesthesia
    Kazdagli, H; Özel, HF; Özbek, M; Alpay, S; Alenbey, M
    Background/aim: Anesthetics are often used in animal experiments to achieve immobilization and relieve pain. However, many anesthetics can alter the dynamics of cardiovascular systems. We aimed to compare the effects of two frequently used anesthetics agents on heart rate variability (HRV) parameters in mice. Materials and methods: This observational study was performed between May and June 2014 in 21 male BALB/c mice aged 16-20 weeks. The animals were divided into three groups: pentobarbital (P), (n = 7); pentobarbital+fentanyl (P+ F), (n = 7); and ketamine+xylazine (K+X), (n = 7). Surface electrocardiography (ECG) electrodes were placed in lead II configuration. 'the tachogram of RR intervals was obtained after R waves were detected using the Pan-Tompkins real-time QRS recognition algorithm. Frequency-domain, time-domain, and nonlinear HRV analyses were performed. Results: The bradycardia effect was higher in the K+X group (p < 0.01). Time-domain indices were higher in group K+X compared to group P (p < 0.01) and group P+F (p < 0.001). Very low frequency (VLF) power was significantly lower in group K+X compared to group P and group P+F (p < 0.01). Low frequency (LF) power, low frequency/high frequency (LF/HF) ratio, and total power (TP) were higher in group K+X compared to group P (p < 0.01) and group P+F (p < 0.001). The detrended fluctuation analysis short-term parameter (DFA alpha(1)) was significantly higher in group K+X compared to group P+F (p < 0.05) and the long-term parameter (DFA alpha(2)) was lower in group K+X compared to group P (p < 0.05). Standard deviations SD1 and SD2 were higher in group K+X compared to group P (p < 0.001) and group P+F (p < 0.001), SD2/SD1 ratio was lower in group K+X compared to group P (p < 0.05) and group P+F (p < 0.05). Entropy measures did not differ between groups. Conclusion: HRV analyses, including nonlinear methods, indicated that a K+X combination reduces imbalance and disorder in the regulation of the autonomic nervous system (ANS) in comparison to both P and the P+F combination.
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    Evaluation of differential effects of CDP-choline and choline on parasympathetic activity and changes in choline levels with heart rate variability
    Kazdagli, H; Alpay, S; Ozel, HF; Baris, E
    Objective: Heart rate variability (HRV) is used to evaluate the autonomic activity of heartbeat. This study aimed to investigate the effects of cholinomimetic drugs cytidine diphosphate-choline (CDP-choline) and choline, on short-term HRV parameters. Materials and Methods: Animals were randomized into three groups; control (0.9% NaCl), choline (100 mg/kg), CDP-choline (400 mg/kg). Electrocardiography recordings were obtained for 45-minutes after treatments with 15-minutes intervals. HRV analyses and total choline level measurements in serum and heart tissues were performed. Results: High frequency power and total power increased in treatment groups, while heart rates were decreased. Low frequency was decreased with choline while very low frequency power decreased with CDP-choline. Choline affected most of the HRV parameters in the first 15 minutes, while the effect of CDP-choline started within 30 minutes. Total choline levels were higher in both treatment groups than in the control while the levels were also higher in the choline group compared to CDP-choline group. Conclusion: This study showed that CDP-choline and choline treatments produced a rapid response to short-term HRV parameters, while increasing tissue choline levels. Moreover, the differences in effects and onset time between the drugs on HRV might be related to tissue choline concentration.
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    Right vagotomy alters heart rate variability temporarily and increases total choline levels in rats
    Kazdagli, H; Baris, E; Ozel, HF; Ozbek, M
    Objectives The variability in the time intervals between heartbeats, known as heart rate variability (HRV), serves as a reflection of the intricate interplay between the sympathetic and parasympathetic neural systems. While the potential asymmetric effects of the left and right branches of the vagus nerve remain uncertain, this study aims to investigate the impact of unilateral, bilateral, and atropine interventions on HRV parameters and choline levels within cardiac tissue.Methods 40 male adult Wistar albino rats were randomly assigned to the five groups (each n=8): sham-operated, atropine, right vagotomy, left vagotomy, and bilateral vagotomy. Heart rate variability (HRV) analyses were conducted, and the levels of total choline/acetylcholine in heart tissues were quantified. Statistical analyses were performed to assess the results.Results The bilateral vagotomy and atropine groups exhibited higher heart rates and high frequency power (HF), along with reduced low frequency power (LF). Total power (TP) remained relatively unchanged. In the bilateral vagotomy group, DFA alpha 1 was significantly elevated while DFA alpha 2 was reduced significantly. SD1 and SampEn were significantly lower in both the bilateral vagotomy and atropine groups. Notably, the right vagotomy group displayed significant changes primarily in the 15th minute, particularly in time-domain parameters, HF, TP, and SD1, with a significant increase observed in total choline levels.Conclusions Our results revealed that asymmetrical vagal innervation induces distinct effects on heart rate variability parameters and total choline/acetylcholine levels in heart tissues. Our findings suggest that compensatory hemodynamic recovery, possibly driven by contralateral vagal overactivity, may contribute to these observed results.
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    The effects of mechanical ventilation on heart rate variability and complexity in mice
    Kazdagli, H; Özel, H; Özbek, M
    In a variety of diseases, altered respiratory modulation is often as an early sign of autonomic dysfunc-tion. Therefore, understanding and evaluating the effects of mechanical ventilation on the autonomic nervous system is vital. The effects of mechanical ventilation on autonomic balance have been assessed by heart rate variability (HRV) using frequency domain and non-linear analysis including fractal complexity and entropy analysis in anesthetized mice. BALB/c mice (n=48) were divided into two groups: Spontaneous breathing and mechanical ventilation. The electrocardiograms were recorded. Four different types of analysis were employed: i. frequency domain analysis, ii. Poincare plots, iii. Detrended Fluctuation Analysis (DFA) and iv. Entropy analysis. An unpaired t-test was used for statistical analysis. In a ventilated group, very low frequency (VLF) and low frequency (LF) parameters were not changed, whereas the high frequency parameter was decreased compared to spontaneous breathing mice. DFA alpha 1 was significantly increased due to mechanical ventilation but DFA alpha 2 was unchanged. In Poincare plots analysis, standard deviation 2 (SD2) / standard deviation 1 (SD1) ratio was increased, however, SD1 and SD2 were not significantly affected. Also, Approximate Entropy and Sample Entropy remained unchanged. HF parameter, DFA alpha 1, and SD2/SD1 were affected by mechanical ventilation. Decreased HF and increased DFA alpha 1, further support the notion that HRV is dominated by respiratory sinus arrhythmia at high frequencies, this may be due to decreased vagal tone caused by me-chanical ventilation. This novel results of HRV analysis are important considering increased usage of HRV techniques day by day in animal models and other medical practices.
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    Which Measures and Parameters of Heart Rate Variability Analysis may be Useful for Early Detection and Predicting Prognosis of Sepsis? A Systematic Review
    Kazdagli, H; Özel, HF
    Sepsis causes a series of pathological changes, such as cardiovascular, respiratory, and thermoregulation. These changes alter heart rate variability (HRV). Even without any changes in the vital signs or clinical presentation of the disease, HRV may still be altered due to sympathetic nervous system activation caused by infection. Our aim in this review was to present sepsis-related HRV measures and parameters by examining the literature and their possible role in predicting the severity and mortality of sepsis. Databases were searched for original research articles reporting on human HRV-related sepsis published in the English language between April 1996 and May 2023. After completion of the article search, a total of 79 articles were selected for further evaluation where the full text of the articles was reviewed and 13 of the articles met the criteria for inclusion. The mean values of each HRV parameter were corrected to the sample size of each study, and the overall means were calculated accordingly. Statistical comparisons were performed after correcting for sample size using the Willcoxon signed-rank test. After the final evaluation, with a total of 1453 patients, 9 studies on sepsis in humans were included. The weighted mean age was 64.24 years, and 53.9% were male. Of the studies included, all underwent frequency domain analysis, and four underwent non-linear analysis. Seven of the nine studies were conducted in the emergency departments, and two were conducted in the intensive care units. 6 studies compared parameters between survivors and non-survivors, and 3 studies compared parameters between different severity levels of sepsis. SDNN, RMSSD, SDNN, HTI, LFnu, HFnu, LF/HF ratio, SD1, SD2, detrended fluctuation analysis (DFA)alpha 1, and DFA alpha 2 appear to be related to mortality in patients with sepsis outcome. Therefore, monitoring these parameters for the early detection of sepsis may be beneficial.
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    Exam Anxiety Evaluation by Heart Rate Variability in University Students
    Kazdagli, H; Özel, HF; Öztürk, S; Özalp, DCT; Erdeniz, B; Özbek, M; Semin, MI
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    Changes in total choline levels in heart tissues of vagotomized rats.
    Kazdagli, H; Özel, HF; Baris, E; Özbek, M
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    A simple approach to determine loss of physiological complexity in heart rate series
    Ozel, HF; Kazdagli, H
    There are several ways to assess complexity, but no method has yet been developed for quantitatively calculating the 'loss of fractal complexity' under pathological or physiological states. In this paper, we aimed to quantitatively evaluate fractal complexity loss using a novel approach and new variables developed from Detrended Fluctuation Analysis (DFA) log-log graphics. Three study groups were established to evaluate the new approach: one for normal sinus rhythm (NSR), one for congestive heart failure (CHF), and white noise signal (WNS). ECG recordings of the NSR and CHF groups were obtained from PhysioNET Database and were used for analysis. For all groups Detrended Fluctuation Analysis scaling exponents (DFA alpha (1), DFA alpha (2)) were determined. Scaling exponents were used to recreate the DFA log-log graph and lines. Then, the relative total logarithmic fluctuations for each sample were identified and new parameters were computed. To do this, we used a standard log-log plane to standardize the DFA log-log curves and calculated the differences between the standardized and expected areas. We quantified the total difference in standardized areas using parameters called dS1, dS2, and TdS. Our results showed that; compared to the NSR group, DFA alpha (1) was lower in both CHF and WNS groups. However, DFA alpha (2) was only reduced in the WNSgroup and not in the CHFgroup. Newly derived parameters: dS1, dS2, and TdS were significantly lowerin the NSR group compared to the CHF and WNS groups. The new parameters derived from the DFA log-log graphs are highly distinguishing for congestive heart failure and white noise signal. In addition, it may be concluded that a potential feature of our approach can be beneficial in classifying the severity of cardiac abnormalities.
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    Electrophysiological detection of exam stress in health schools' students
    Kazdagli, H; Ozel, HF; Ozturk, S; Ceylan, D; Erdeniz, B; Ozbek, M; Semin, MI
    Anxiety is a common issue among university students, many of them experience anxiety, depression, and stress during their school life. This study aimed to compare the acute physiological stress responses of students divided into two groups according to their perceived anxiety levels (positive test anxiety, PTA+, and negative test anxiety, PTA-). Heart rate variability (HRV) and electrodermal activity (EDA) were used to assess stress. Thirty-one healthy volunteers participated in the study. Participants completed anxiety assessments, including the Westside Test Anxiety Scale (WTAS), the State-Trait Anxiety Inventory (STAI), and the Test State Anxiety Inventory (TSAI). Based on their scores, participants were categorized into PTA+ + and PTA- groups. All participants underwent 24-h continuous recordings of pulse and electrodermal activity (EDA) on two separate occasions: one day prior to a written exam and during a designated exam-free day serving as a baseline control. We compared the HRV and EDA data obtained on a regular day and on an exam day between the two groups. Results showed that the PTA+ group had significantly higher heart rate, stress index, low frequency, and short-term detrended fluctuation analysis (DFA alpha 1) on the exam day. The tonic EDA component was also higher in the PTA+ group. Stress-related HRV and EDA parameters were negatively correlated with exam scores. In conclusion, the study found that physiological stress indicators obtained from HRV and EDA are associated with perceived exam anxiety in students.