The peak period of cardiovascular disease (CVD) is around the time of awakening in the morning, which may be related to the surge of sympathetic activity at the end of nocturnal sleep. This paper chose 140 participants as study object, 70 of which had occurred CVD events while the rest hadn’t during a two-year follow-up period. A two-layer model was proposed to investigate whether hypnopompic heart rate variability (HRV) was informative to distinguish these two types of participants. In the proposed model, the extreme gradient boosting algorithm (XGBoost) was used to construct a classifier in the first layer. By evaluating the feature importance of the classifier, those features with larger importance were fed into the second layer to construct the final classifier. Three machine learning algorithms, i.e., XGBoost, random forest and support vector machine were employed and compared in the second layer to find out which one can achieve the highest performance. The results showed that, with the analysis of hypnopompic HRV, the XGBoost+XGBoost model achieved the best performance with an accuracy of 84.3%. Compared with conventional time-domain and frequency-domain features, those features derived from nonlinear dynamic analysis were more important to the model. Especially, modified permutation entropy at scale 1 and sample entropy at scale 3 were relatively important. This study might have significance for the prevention and diagnosis of CVD, as well as for the design of CVD-risk assessment system.
On the basis of Poincare scatter plot and first order difference scatter plot, a novel heart rate variability (HRV) analysis method based on scatter plots of RR intervals and first order difference of RR intervals (namely, RdR) was proposed. The abscissa of the RdR scatter plot, the x-axis, is RR intervals and the ordinate, y-axis, is the difference between successive RR intervals. The RdR scatter plot includes the information of RR intervals and the difference between successive RR intervals, which captures more HRV information. By RdR scatter plot analysis of some records of MIT-BIH arrhythmias database, we found that the scatter plot of uncoupled premature ventricular contraction (PVC), coupled ventricular bigeminy and ventricular trigeminy PVC had specific graphic characteristics. The RdR scatter plot method has higher detecting performance than the Poincare scatter plot method, and simpler and more intuitive than the first order difference method.
Based on the imaging photoplethysmography (iPPG) and blind source separation (BSS) theory the author put forward a method for non-contact heartbeat frequency estimation. Using the recorded video images of the human face in the ambient light with Webcam, we detected the human face through software, separated the detected facial image into three channels RGB components. And then preprocesses i.e. normalization, whitening, etc. were carried out to a certain number of RGB data. After the independent component analysis (ICA) theory and joint approximate diagonalization of eigenmatrices (JADE) algorithm were applied, we estimated the frequency of heart rate through spectrum analysis. Taking advantage of the consistency of Bland-Altman theory analysis and the commercial Pulse Oximetry Sensor test results, the root mean square error of the algorithm result was calculated as 2.06 beat/min. It indicated that the algorithm could realize the non-contact measurement of heart rate and lay the foundation for the remote and non-contact measurement of multi-parameter physiological measurements.
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.
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.
ObjectiveTo investigate the correlation between intima-media thickness (IMT) of carotid artery in color ultrasonography and the heart rate variability. MethodsA retrospective analysis was performed in 64 patients from West China Hospital of Sichuan University between March and May 2013. Carotid intima-media thickness was measured with color ultrasonography and dynamic electrocardiogram, and the heart rate variability was assayed at the same time. ResultsIMT in the cardiovascular disease group, combination group, coronary heart disease group and hypertension group was significantly thicker than the control group (P<0.05). The differences of SDNN and SDANN were statistically significant (P<0.05) between the combination group and the control group. There were 23 cases with IMT ≥ 1.0 mm in the cardiovascular disease group including 8 cases in the combination group, 10 cases in the coronary heart disease group and 5 cases in the hypertension group. IMT in those groups were all significantly higher than that in the control group with only 2 cases having IMT ≥ 1.0 mm (P<0.05). There were 18 cases with SDNN<100 ms in the cardiovascular disease group including 7 cases in the combination group, 6 cases in the coronary heart disease group and 5 cases in the hypertension group, but there was no statistically significant difference compared with that in the control group with only 11 cases (P>0.05). Negative correlation was found between IMT and SDNN, SDANN in the cardiovascular diseases group (r=-0.574, -0.544; P<0.01) and negative correlation was found between IMT and SDANN in the control group (r=-0.392, P<0.05). ConclusionThe carotid artery lesions and autonomic nerve especially sympathetic nerve dysfunction are obvious in patients with cardiovascular diseases and there is a negative correlation between them.
Heart rate is the most common index to directly monitor the level of physical stress by comparing the subject's heart rate with an appropriate "target heart rate" during exercise. However, heart rate only reveals the cardiac rhythm of the complex cardiovascular changes that take place during exercise. It is essential to get the dynamic response of the heart to exercise with various indices instead of only one single measurement. Based on the rest-workload alternating pattern, this paper screens the sensitive indices of exercise load from electrocardiogram (ECG) rhythm and waveform, including 4 time domain indices and 4 frequency domain indices of heart rate variability (HRV), 3 indices of waveform similarity and 2 indices of high frequency noise. In conclusion, RR interval (heart rate) is a reliable index for the realtime monitoring of exercise intensity, which has strong linear correlation with load intensity. The ECG waveform similarity and HRV indices are useful for the evaluation of exercise load.
Objective To investigate the changes and clinical relationship of plasma adrenomedullin( ADM) , atrial natriuretic polypeptide( ANP) , and heart rate variability( HRV) in patients with obstructive sleep apnea-hypopnea syndrome ( OSAHS) . Methods Seventy-five inpatients with OSAHS were enrolled in this study. According to the apnea hypopnea index ( AHI) by polysomnography, the subjects were divided into a mild group, a moderate group, and a severe group. Meanwhile, HRV was screened bydynamic electrocardiogram in sleep laboratory. HRV parameters were obtained including LF ( low frequency power) , HF( high frequency power) , pNN50( percentage of NN50 in the total number of N-N intervals) ,SDNN( standard deviation of the N-N intervals) , rMSSD( square root of the mean squared differences of successive N-N intervals ) . Plasma levels of ADM/ANP were measured by radioimmunoassay. Results The levels of SDNN ( P lt;0. 05) , rMSSD, pNN50, LF ( P lt; 0. 05) and HF were gradually reduced, and the levels of ADM ( P lt;0. 05) and ANP ( P lt; 0. 05) were increased with increasing severity of OSAHS. Linear correlation analysis demonstrated that SDNN was negatively correlated with ADM( r = - 0. 423, P lt;0. 05)and ANP( r = - 0. 452, P lt; 0. 05) , and LF was also negatively correlated with ADM( r = - 0. 348, P lt;0. 05) . Conclusion Lower HRV is associated with more sever OSAHS, and it may be modulated neurohumorally by ADM and ANP.
目的:探讨64层螺旋CT冠状动脉成像(64-slice CTA)检查中护理工作的重要性及获得最佳图像的影响因素。材料与方法:对462例行64-slice CTA检查的患者进行有效的护理措施和细致的前期准备工作。结果:462例检查者中96%的病例达到诊断标准。结论:经过细致准备和护理,可以提高图像质量和冠脉疾病的诊断率。