Lorenz plot (LP) method which gives a global view of long-time electrocardiogram signals, is an efficient simple visualization tool to analyze cardiac arrhythmias, and the morphologies and positions of the extracted attractors may reveal the underlying mechanisms of the onset and termination of arrhythmias. But automatic diagnosis is still impossible because it is lack of the method of extracting attractors by now. We presented here a methodology of attractor extraction and recognition based upon homogeneously statistical properties of the location parameters of scatter points in three dimensional LP (3DLP), which was constructed by three successive RR intervals as X, Y and Z axis in Cartesian coordinate system. Validation experiments were tested in a group of RR-interval time series and tags data with frequent unifocal premature complexes exported from a 24-hour Holter system. The results showed that this method had excellent effective not only on extraction of attractors, but also on automatic recognition of attractors by the location parameters such as the azimuth of the points peak frequency (APF) of eccentric attractors once stereographic projection of 3DLP along the space diagonal. Besides, APF was still a powerful index of differential diagnosis of atrial and ventricular extrasystole. Additional experiments proved that this method was also available on several other arrhythmias. Moreover, there were extremely relevant relationships between 3DLP and two dimensional LPs which indicate any conventional achievement of LPs could be implanted into 3DLP. It would have a broad application prospect to integrate this method into conventional long-time electrocardiogram monitoring and analysis system.
Heart rate variability (HRV) is the difference between the successive changes in the heartbeat cycle, and it is produced in the autonomic nervous system modulation of the sinus node of the heart. The HRV is a valuable indicator in predicting the sudden cardiac death and arrhythmic events. Traditional analysis of HRV is based on a multi-electrocardiogram (ECG), but the ECG signal acquisition is complex, so we have designed an HRV analysis system based on photoplethysmography (PPG). PPG signal is collected by a microcontroller from human’s finger, and it is sent to the terminal via USB-Serial module. The terminal software not only collects the data and plot waveforms, but also stores the data for future HRV analysis. The system is small in size, low in power consumption, and easy for operation. It is suitable for daily care no matter whether it is used at home or in a hospital.
ObjectiveTo explore the predictive value of systolic pulmonary artery pressure (SPAP) on autonomic nerve excitation in patients with valvular disease, so as to provide reference for the formulation of clinical intervention plans. Methods The clinical data of patients with valvular disease who received surgical treatment in the General Hospital of Northern Theater Command from August 28, 2020 to February 3, 2021 were prospectively collected. According to the standard deviation of normal-to-normal R-R intervals (SDNN) of the heart rate variability (HRV) of the long-range dynamic electrocardiogram (ECG) 7 days before the operation, the patients were divided into three groups: a sympathetic dominant (SE) group (SDNN≤50 ms), a balance group (50 ms<SDNN<100 ms) and a parasympathetic dominant (PSE) group (SDNN≥100 ms). The correlation between the changes of echocardiographic indexes and autonomic nerve excitation among the groups and the predictive values were analyzed. Results A total of 186 patients were enrolled, including 108 males and 78 females aged 55.92±11.99 years. There were 26 patients in the SE group, 104 patients in the balance group, and 56 patients in the PSE group. The left anteroposterior diameter (LAD), left ventricular end diastolic inner diameter, ratio of peak E to peak A of mitral valve (Em/Am), left ventricular end diastolic volume, left ventricular end systolic volume and SPAP in the SE group were higher than those in the balance group (P<0.05), while peak A of tricuspid valve (At) and left ventricular ejection fraction (LVEF) were lower than those in the balance group (P<0.05). The LAD and Em/Am in the balance group were significantly higher than those in the PSE group (P<0.05). Multivariate analysis showed that patients in the SE group had lower At (right atrial systolic function declines), lower LVEF and higher SPAP than those in the balance group (P=0.04, 0.04 and 0.00). When HRV increased and parasympathetic nerve was excited in patients with valvular disease, Em/Am decreased (left atrial function and/or left ventricular diastolic function declined) with a normal LAD. Pearson analysis showed that there was a linear negative correlation between SPAP and SDNN, with a coefficient of −0.348, indicating that the higher SPAP, the lower HRV and the more excited sympathetic nerve. Receiver operating characteristic curve showed that when SPAP≥45.50 mm Hg (1 mm Hg=0.133 kPa), the sensitivity and specificity of sympathetic excitation in patients with valvular disease were 84.60% and 63.70%, respectively. ConclusionParasympathetic excitation is an early manifestation of the disease, often accompanied by decreased left atrial function and/or left ventricular diastolic function. Sympathetic nerve excitation can be accompanied by the increase of SPAP and the decrease of left ventricular and right atrial systolic function. SPAP has a unique predictive value for the prediction of autonomic nerve excitation in patients with valvular disease.
Objective To systematically review the effect of percutaneous acupoint electrical stimulation (TEAS) on heart rate variability (HRV). Methods The PubMed, Embase, Ovid MEDLINE, Cochrane Library, CNKI, WanFang Data, VIP, and CBM databases were electronically searched to collect randomized controlled trials (RCTs) on the effects of percutaneous acupoint electrical stimulation on heart rate variability from inception to February 28, 2023. Two reviewers independently screened the literature, extracted data, and assessed the risk of bias of the included studies. Meta-analysis was then performed using RevMan 5.4 software. Results A total of 14 RCTs involving 719 patients were included. The results of meta-analysis showed that SDNN (MD=12.95, 95%CI 9.18 to 16.72, P<0.01), RMSSD (MD=1.81, 95%CI 0.10 to 3.53, P=0.04), pNN50 (MD=1.75, 95%CI 1.02 to 2.48, P<0.01), HF (SMD=0.27, 95%CI 0.01 to 0.52, P=0.04), LF/HF (MD=−0.07, 95%CI −0.12 to −0.03, P<0.01), ln-LF (MD=0.63, 95%CI 0.25 to 1.01, P<0.01), ln-HF (MD=1.05, 95%CI 0.60 to 1.49, P<0.01), mean RR (MD=−11.86, 95%CI −21.77 to −1.96, P=0.02), and HR (SMD=−0.43, 95%CI −0.66 to −0.20, P<0.01) all showed improvement compared with the control group. However, there were no significant differences between the two groups in LF (SMD=0.15, 95%CI −0.10 to 0.40, P=0.23), LF norm (SMD=0.24, 95%CI −0.10 to 0.58, P=0.16) or HF norm (SMD=0.25, 95%CI −0.47 to 0.97, P=0.5). TEAS on PC6: SDNN, pNN50, HF, LF/HF, LF norm, HF norm, ln-LF, ln-HF, and HR all showed improvement compared with the control group. However, there were no significant differences between the two groups in RMSSD, LF, or RR interval. Conclusion This study supports the improvement of heart rate variability by transcutaneous acupoint electrical stimulation and PC6 acupoint selection. Due to the limited quantity and quality of the included studies, more high-quality studies are needed to verify the above conclusion.
The purpose of this study is to discuss the feasibility of establishing capsaicin pain model and the possibility to evaluate different degrees of pain by the heart rate variability (HRV). It also aims to investigate the changes of autonomic nervous activity of volunteers during the process of pain caused by capsaicin. A total of 30 volunteers were selected, who were physically and mentally healthy, into the study. To assess the effects of capsaicin on the healthy volunteers, we recorded the Visual Analogue Scale (VAS) scores after the capsaicin stimulus. Additionally, the electrocardiogram signals and HRV analysis index before and after stimulating were also recorded, respectively. More specifically, the HRV analysis indexes included the time domain index, the frequency domain index, and the nonlinear analysis index. The results demonstrated that the activity of the autonomic nerves was enhanced in the process of capsaicin stimulus, especially for the sympathetic nerve, which exhibited a significantly differences in HRV. In conclusion, the degree of pain can be reflected by the HRV. It is feasible to establish a capsaicin pain model. And in further experiments, HRV analysis could be used as a reference index for quantitative evaluation of pain.
The linear analysis for heart rate variability (HRV), including time domain method, frequency domain method and timefrequency analysis, has reached a lot of consensus. The nonlinear analysis has also been widely applied in biomedical and clinical researches. However, for nonlinear HRV analysis, especially for shortterm nonlinear HRV analysis, controversy still exists, and a unified standard and conclusion has not been formed. This paper reviews and discusses three shortterm nonlinear HRV analysis methods (fractal dimension, entropy and complexity) and their principles, progresses and problems in clinical application in detail, in order to provide a reference for accurate application in clinical medicine.
The analysis parameters for the characterization of heart rate variability (HRV) within a very short time (＜1 min) usually exhibit complicate variation patterns over time, which may easily interfere the judgment to the status of the cardiovascular system. In this study, long-term HRV sequence of 41 cases of healthy people (control group) and 25 cases of congestive heart failure (CHF) patients (experimental group) was divided into multiple segments of very short time series. The variation coefficient of the same HRV parameter under multiple segments of very short time series and the testing proportion with statistically significant differences under multiple interclass t-test were calculated. On this account, part of HRV analysis parameters under very short time were discussed to reveal the stability of difference of the cardiovascular system function under different status. Furthermore, with analyzing the receiver operating characteristic (ROC) curve and modeling the artificial neural network (ANN), the classification effects of these parameters between the control group and the experimental group were assessed. The results demonstrated that ① the indices of entropy of degree distribution based on the complex network analysis had a lowest variation coefficient and was sensitive to the pathological status (in 79.75% cases, there has statistically significant differences between the control group and experimental group), which can be served as an auxiliary index for clinical doctor to diagnose for CHF patient; ② after conducting ellipse fitting to Poincare plot, in 98.5% cases, there had statistically significant differences for the ratio of ellipse short-long axis (SDratio) between the control group and the experimental group; when modeling the ANN and solely adopting SDratio, the classification accuracy to the control group and experimental group was 71.87%, which demonstrated that SDratio might be acted as the intelligent diagnosis index for CHF patients; ③ however, more sensitive and robust indices were still needed to find out for the very-short HRV analysis and for the diagnosis of CHF patients as well.
Heart rate variability (HRV) is an important point to judge a person’s state in modern medicine. This paper is aimed to research a person’s fatigue level connected with vagal nerve based on the HRV using the improved Welch method. The process of this method is that it firstly uses a time window function on the signal to be processed, then sets the length of time according to the requirement, and finally makes frequency domain analysis. Compared with classical periodogram method, the variance and consistency of the present method have been improved. We can set time span freely using this method (at present, the time of international standard to measure HRV is 5 minutes). This paper analyses the HRV’s characteristics of fatigue crowd based on the database provided by PhysioNet. We therefore draw the conclusion that the accuracy of Welch analyzing HRV combining with appropriate window function has been improved enormously, and when the person changes to fatigue, the vagal activity is diminished and sympathetic activity is raised.