血压变异与心率变异及心电异常相关性分析

目的：研究血压变异(BPV)与心率变异(HRV)及心电图(ECG)异常相关性，方法：对157例未经治疗的早期高血压患者及167例未服过影响血压及心率药物的正常人，进行BPV、HRV及ECG异常的相关分析，各种数据在同一时刻得到，结果：当血压昼夜节律消失(非杓型)，BPV及HRV不正常，ECG异常明显高于其他组，当高血压患者血压昼夜节律存在时HRV各项指标接近正常，ECG异常率较低，HRV降低与血压负荷升高呈明显正相关，与心电异常也呈明显正相关，结论：对高血压治疗的目的。不仅仅是降压，还应尽量恢复昼夜血压的规律性，降低夜间血压负荷，调节植物神经功能，对于血压正常的患者。血压昼夜节律消失也应投以关照给予植物神经功能调节，达到或降低靶器官损伤或延缓靶器官损害的目的，提高患者的生活质量。     

Effects of gender,age, and heart rate on QT intervals in children

The objective of this study was to determine if gender, age, and heart rate affect corrected QT intervals in children. Electrocardiograms were obtained from 781 healthy children 10–18 years of age. Corrected QT intervals were significantly (p < 0.0005) greater for girls than for boys in the entire population and for each age group over 14 years. The corrected QT interval varied inversely with age and directly with heart rate. Hence gender, age, and heart rate should be considered when diagnosing long QT syndrome.     

A Field-Compatible Method for Interpolating Biopotentials

Mapping of bioelectric potentials over a given surface (e.g., the torso surface, the scalp) often requires interpolation of potentials into regions of missing data. Existing interpolation methods introduce significant errors when interpolating into large regions of high potential gradients, due mostly to their incompatibility with the properties of the three-dimensional (3D) potential field. In this paper, an interpolation method, inverse-forward (IF) interpolation, was developed to be consistent with Laplace's equation that governs the 3D field in the volume conductor bounded by the mapped surface. This method is evaluated in an experimental heart–torso preparation in the context of electrocardiographic body surface potential mapping. Results demonstrate that IF interpolation is able to recreate major potential features such as a potential minimum and high potential gradients within a large region of missing data. Other commonly used interpolation methods failed to reconstruct major potential features or preserve high potential gradients. An example of IF interpolation with patient data is provided to illustrate its applicability in the actual clinical setting. Application of IF interpolation in the context of noninvasive reconstruction of epicardial potentials (the inverse problem) is also examined. © 1998 Biomedical Engineering Society. PAC98: 8710+e, 0260Ed     

Filter properties of root mean square successive difference (RMSSD) for heart rate

The root mean square successive difference (RMSSD) in heart period series is a time domain measure of heart period variability. The RMSSD is sensitive to high-frequency heart period fluctuations in the respiratory frequency range and has been used as an index of vagal cardiac control. By transfer function simulations, the RMSSD statistic is shown to represent a high-pass filter that effectively captures respiratory sinus arrhythmia but also passes lower frequency fluctuations that can include sympathetic influences. These simulations, together with analysis of actual heart period series, reveal that the RMSSD is biased by basal heart period. Although between-subjects levels of RMSSD covary highly with spectral estimates of high-frequency variability, within-subject RMSSD change scores account for only 50-60% of the variance in spectral estimates. The present findings raise caveats in the applications and interpretation of the RMSSD statistic.     

Evaluation of telephone transmission for computer electrocardiographic interpretation in Japan

The reliability of the Japanese public telephone facilities to transmit electrocardiograms (e.c.g.) for computer interpretation was assessed. The International Business Machine's (IBM) e.c.g. computer program by Bonner was used. No appreciable distortion of e.c.g. was observed following repeated transmission from hospitals separated by 1000 km. Thirty-four normal and 66 abnormal e.c.g.s. were transmitted twice. Identical results were observed in 97% of normals and 92% of abnormals. Following these fundamental experiments, 1236 patients' e.c.g.s. were transmitted for computer intepretation. The study showed that 98·6% (1219 cases) were technically satisfactory and 1·4% (17 cases) were not. The 17 unsatisfactory cases were classified into ten unreceivable data formats, six inconsistent measurements and one unacceptable noise level. The authors concluded that the Japanese public telephone facilities were acceptable for the transmission of e.c.g.s. for computer interpretation.     

Delineation of the QRS complex using the envelope of the e.c.g.

A new algorithm for QRS delineation has been developed. Based on the envelope of the e.c.g. signal a delineation function is defined, which yields a single positive pulse for each complex. From this function the onset and end of the QRS or, alternatively, a fiducial point is determined. To remove low-frequency component such as S-T abnormalities without distortion of the QRS complex, a filter with time-varying characteristics is used. The accuracy of the method has been evaluated in a test set of different QRS complexes obtained from coronary care patients. For QRS onset, the standard deviation of the difference between automated and manual determination was 7 ms in normal beats and 14 ms in ectopic beats. With simulated noise added to each waveform an average dispersion of 7 ms was observed in the recognition of the QRS onset at a signal-to-noise ratio of 15 dB. The corresponding dispersion in the location of a fiducial point was 2 ms. Using simulated e.c.g. data, the stability of the method is demonstrated for transitions between different waveform morphologies. Presented in part at ‘Computers in cardiology’, Florence, 23rd–25th September 1981     

微机心电场仿真模型与仿真研究

心电场仿真是心电理论研究的前沿课题。本文讨论首次在IBM-PC/AT微机上实现的一个完整的心电场仿真模型。其中,人体和心脏的单元分割精度与国外最近的研究相同,采用边界元法求解心电场电位,并提出一种新的心脏兴奋传播仿真算法,提高了仿真速度。应用该模型对正常心脏和病变心脏进行了仿真研究,仿真结果与临床测量结果是一致的。     

一种心电数据压缩算法的研究

利用心电信号的相关性，对ECG进行预处理，再进行差值运算，将得到的差值序列进行DCT变换，从而实现心电数据的压缩。     

深呼吸时P—R间期,P—P间期变化的临床意义

目的：通过深呼吸心电图试验,探讨观察心脏自主神经功能的无创性方法。方法：１０９名健康成人,描记１２导联心电图,在Ⅱ导联上分别描记平卧平静呼吸、深呼吸时心电图。分析Ｐ－Ｒ间期、Ｐ－Ｐ间期的变化。结果：深吸气时Ｐ－Ｒ间期、Ｐ－Ｐ间期均较平静呼吸缩短,深呼气时Ｐ－Ｒ间期、Ｐ－Ｐ间期均较平静呼吸时延长,均Ｐ〈０．０１。结论：呼吸时Ｐ－Ｒ间期、Ｐ－Ｐ间期的变化可为评价心脏自主神经功能提供参考依据。     

海洛因依赖者心电图改变及相关因素分析

目的:探讨海洛因依赖者的心电图(ECG)变化及其危险因素.方法:对122例海洛因依赖者的心电图进行分析,并调查患者的海洛因滥用情况、肝功能及心肌酶等资料.结果:36例(29.5%)患者有ECG异常,且ST-T改变最为常见.海洛因滥用时间、滥用量、多药滥用情况以及血清丙氨酸氨基转移酶(ALT)和血清肌酸激酶(CK)等在ECG异常与正常组间有显著差异.Logistic回归分析,海洛因滥用时间、滥用量和CK 3个变量进入回归方程.结论:海洛因依赖者ECG异常较多见,患者滥用时间和滥用量、CK异常为危险因素.脱毒治疗时应注意躯体情况.