除草剂草甘膦异丙胺盐水剂对中华大蟾蜍心电活动的影响

采用生物信号采集处理系统对草甘膦异丙胺盐胁迫条件下中华大蟾蜍(BufogargarizansCantor)的心率和心电活动的相关指标进行了测定和分析。不同浓度的草甘膦异丙胺盐溶液被喷施到中华大蟾蜍的体表,由皮肤进入体内而作用于心脏。试验结果表明:随着草甘膦异丙胺盐处理浓度的增大,中华大蟾蜍的心率减慢,心电图中P波、R波和T波的电压峰值降低,而P-R间期、QRS期和Q-T间期的时值延长。草甘膦异丙胺盐胁迫条件下,蟾蜍心率与心电图的各项指标有显著相关性,可用多元线性回归模型分别对蟾蜍心率与心电图中P、R、T波和P-R、QRS、Q-T间期的相关关系进行拟合。多元回归分析结果表明,蟾蜍心电图中Q-T间期值对心率的影响最大,可以推断草甘膦异丙胺盐主要是通过延长蟾蜍心电活动周期中Q-T间期时值即心室收缩期而延长心动周期,导致蟾蜍心率减慢。由此可见草甘膦异丙胺盐水剂的喷施对中华大蟾蜍心脏的电活动周期和机械活动周期均造成了一定影响。     

温度对花背蟾蜍心电活动影响的多元回归分析模型

运用多元回归分析方法对花背蟾蜍(Buforaddei)在4个不同实验温度条件下描记的心电图实验数据,利用SPSS/PC 统计分析的软件包进行处理分析,结果表明蟾蜍的心率和心电图各指标有显著相关性;温度对蟾蜍的心电活动影响较明显;随着温度的升高,蟾蜍心率,P波、R波、T波电压值升高;P-T间期,Q-T间期,QRS间期值均显下降趋势。     

几种脊椎动物宽频带心电图波形与心电向量环特点的比较

对小鼠、家鸽、蟾蜍、鲫鱼4种脊椎动物宽频带心电图Ⅱ导联的波形特点及QRS额面心电向量环的位置、形态特点进行了比较研究。结果发现,(1)宽频带心电图Ⅱ导联QRS波群小鼠、蟾蜍、鲫鱼QRS波群的主波均向上,而家鸽的主波向下;(2)QRS波群时程(ms)小鼠88±09,家鸽365±14,蟾蜍790±110,鲫鱼283±57;(3)QRS心电向量环的位置家鸽的位于-90°～-180°象限内,这是家鸽心电图Ⅱ导联QRS波群主波向下的根本原因;小鼠、蟾蜍、鲫鱼的均位于0°～90°象限内,与它们的QRS波群主波向上相一致;(4)QRS心电向量环的形状;小鼠的QRS向量环较其它3种动物的要大,蟾蜍的最小。鲫鱼的不规则,有的呈三角形,有的呈“8”字形,还有的呈半圆形,这是导致鲫鱼的QRS波群出现较多切迹和扭挫的原因。     

心脏性猝死心电学预测方法研究新进展

心脏性猝死是一个严重的公共问题.如果能对其进行早期救治,抢救的成功率将会大大提高.经过心血管医生的多年来的探索,心脏性猝死的预测以日趋成熟.本文阐述通过心电图的一些新指标对心脏性猝死进行预测.而将心电图分为静息心电图,信号平均心电图,动态心电图.虽然静息心电图能为预测心脏性提供一些有用的信息,但由于敏感性及特异性均较低,目前常用动态心电图的相应指标.动态心电图可记录24小时甚至更长时间的心电信息,能够提供更多有价值的预测指标和参数,例如心率变异性、窦性心律震荡、T波电交替及心率减速力等.心率减速力的能对迷走神经张力的高低进行定量评估,是预测心脏性猝死一种动态心电新指标.现在仍没有任何单一指标能够准确预测SCD的发生.研究表明心电图可以提供有价值信息,我们已经在心电图预测SCD方面取得了很大进步.然而目前仍然有许多问题尚未解决,这些问题恰恰给我们提供了广泛的机遇与挑战.     

鸡胚发育后期心电图的无损测定及心率变化

目的：测量鸣胚发育后期心电图,测定鸡胚发育后期心率及其变化.方法：利用壳膜外电极测量鸡胚心电图,根据RR间期计算鸡胚心率。结果：引出了具有较为清晰Q波、R波（振幅在8—20μV波动）、S波的鸡胚心电图。鸡胚的QRs间期在发育后期无明显变化,心率在D14～D20早期的心率变化较小,在D20后期和D21显著增加（P〈0．01）。结论：建立了壳膜外记录鸡胚心电图的方法,鸡胚在啄壳期心率显著增加.     

电刺激迷走神经对蟾蜍心率和心率变异的影响

目的:观察不同频率迷走神经刺激对蟾蜍离体心脏的心率及心率变异的影响。方法:将蟾蜍心脏和右侧迷走交感干离体后,以不同频率电刺激神经,记录心电图曲线并作心率变异性(HRV)分析。结果:交感神经阻断后,电刺激迷走交感干,心率(HR)显著下降(P0.01),全部正常心动周期的标准差(SDNN)和相邻正常心动周期差值的均方根(RMSSD)显著升高(P0.01),不同频率刺激组之间没有明显差异;与对照组相比,各指标变化较大;给药组0.2Hz时高频(HF)显著升高(P0.01),低频/高频比值(LF/HF)明显降低(P0.05),0.8Hz时HF和LF/HF接近刺激前水平。结论:一定范围内增加刺激频率,迷走神经降低心率的作用增强;没有交感神经调节条件下的迷走神经对心率和心率变异的调节可能存在不同的机制。     

心率变异性信号的分析处理:现状与展望

一、概述 从1903年Einthoven第一次记录下人体的心电图至今已近一百年。这期间心电信号的分析处理取得了长足进展,已由对常规心电图的自动分析发展到体表多导心电图的描记及其逆向求解以及心电图中微小电位变化(如希氏束图、晚电位、高频变化等)的分析。近年来心率变异性Heart Rate Variability(HRV)成为心电信号处理中又一个前沿热点。 HRV是指连续心跳间瞬时心率的微小涨落或逐拍心跳R-R间期的微小涨落。人们发现,健康人的心率即使在静息状态下也非恒定不变,而是有起伏的。心率变异过小反而     

基于遥测技术对巴马小型猪部分生理指标的观测

目的：应用遥测技术观察巴马小型猪在清醒自由状态下心电、血压、呼吸、活动等指标昼夜波动变化。方法取雄性6月龄巴马小型猪6只,行浅表股动脉VAP血管通路植入手术,恢复7 d后,用EMAK遥测系统进行24 h连续清醒自由状态下心电、血压、呼吸、活动指标监测,并用EMAK分析软件对上述指标进行分析。结果6月龄巴马小型猪心电、血压、呼吸、活动都有昼夜节律变化,白昼心率显著高于黑夜心率（ P ＜0.01）,且白昼PR间期、QRS间期与QT间期均显著低于黑夜（P ＜0.05,P ＜0.01）,白昼平均心率为76.22次/分,黑夜平均心率为67.03次/分,白昼平均PR间期、QRS间期和QT间期分别为109.97 ms、42.72 ms、380.37 ms,黑夜平均PR间期、QRS间期和QT间期为112.32 ms、44.01 ms、389.24 ms。巴马小型猪白昼收缩压、舒张压、平均压都显著高于夜间（ P ＜0.01）,白昼平均收缩压、舒张压、平均压分别为129.57 mmHg、96.75 mmHg、111.73 mmHg,夜间平均收缩压、舒张压、平均压分别为122.81 mmHg、92.65 mmHg、106.19 mmHg,且黑夜收缩压、舒张压、平均压下降率分别为19.89％、19.05％、19.35％。另外,巴马小型猪在白昼的活动情况与呼吸频率都要显著高于夜间（ P ＜0.01）。结论利用遥测技术可以对清醒自由状态下巴马小型猪心电、血压、呼吸、活动等进行连续监测,能真实的反应小型猪在24 h内上述生理指标的变化规律,为巴马小型猪在药理毒理研究中的应用提供参考。     

MIJ和HFJ近交系大鼠心电图表现

目的 测定近交系MIJ、HFJ大鼠心电图,并与Wistar大鼠比较分析,观察MIJ和HFJ大鼠心电图表现.方法 大鼠麻醉后,仰卧位固定于大鼠固定板上,用短针电极刺入皮下2～3 mm位置,麻醉5 min后,用福田青岛FX-102B心电图机做心电图,并对心电图进行分析.结果 三种大鼠均为窦性心律,心律齐整,雄性HFJ、MIJ心率均高于同性别Wistar.HFJ和MIJ品系、性别间心率差异均无显著性.HFJ和MIJ心电轴与Wistar相同,主要在0°～90°间.三种大鼠的P波方向及QRS波群基本相同,但各波振幅和各波时限,在不同品系和性别之间存在较明显的差异.结论 近交系MIJ和HFJ大鼠各有其独特的心电图表现.     

草原兔尾鼠心电图的分析

本文采用标准双极导联（Ⅰ、Ⅱ、Ⅲ）、加压单极肢导联（ａＶＲ、ａＶＬ、ａＶＦ）和单极胸导联（Ｖａ、Ｖｂ、Ｖｃ）,对经１０％乌拉坦麻醉状态下的１１９只成体草原兔尾鼠进行心电图测定,同时对２０只昆明系小白鼠作为对照比较。结果表明,草原兔尾鼠的平均心率为５５８．５４±５４．５９次／ｍｉｎ,均为窦性心率,额面心电轴平均５９．６１±１２．６３度。ＰＤ－Ｒ、ＱＲＳ波、Ｑ－Ｔ、Ｐ波平均间期分别为３８．２９±６．４８、１２．７０±０．４６、２７．６２±７．３７、１２．３４±４．０９毫秒。Ｐ波和Ｔ波的方向与主波Ｒ波一致。在Ⅰ、Ⅱ、ⅢａＶＬ、ａＶＦ和Ｖａ导联为正,在ａＶＲ导联均为负向。无典型的Ｓ－Ｔ段,ＱＲＳ波群与Ｔ波部分重叠,Ｑ－Ｔ间期较短。     

Electrocardiogram and heart rate in response to temperature acclimation in three representative vertebrates

Comparisons of electrocardiogram (ECG) and heart rate characteristics of three representative species in response to temperature acclimation were studied. In toad (Bufo raddei), T wave had positive, negative and flat patterns, which was different from positive in lizard (Eremias multiocellata), blunt and broad in bird (Alectories magna). The duration of P-R interval, Q-T interval and QRS complex interval reduced with increasing temperature in toad, but the P-R and T-P intervals were affected mostly, the QRS and R-T intervals were relatively less affected in lizard. In the bird, the voltage of P, S and T wave scarcely changed, R wave increased slightly with temperature going up in the thermal neutral zone (20-35 degrees C), T and S waves tended to increase and P-S and S-T intervals shortened when temperature went below the neutral zone. Heart rate was high and relatively steady in bird, but changed linearly in relation to temperature in toad and lizard. The increasing of heart rate with temperature was mainly caused by the T-P interval shortened in lizard, but P-S and S-T intervals shortened in bird. Comparisons of ECG and heart rate characteristics of three representative species in response to temperature acclimation reflected phylogenetically based constraints on pacemaker rates, oxygen supply and modulatory mechanisms.     

超声波清洗器对大鼠心电图的影响

目的考察超声波清洗器对大鼠的影响。方法用RM6240多道生理信号采集处理系统,采用标准肢体二导联法测量正常状态和超声波清洗器工作时麻醉大鼠的心电图。结果超声波清洗器打开后2 min、15 min和30 min时,麻醉大鼠的心率显著增加,心电图的QRS波群间期显著缩短。而超声波清洗器停止工作后30 min时,大鼠心率和QRS波群间期基本恢复至正常。结论超声波清洗器工作时对大鼠心脏可产生一过性的不良影响。因此,在动物饲养或实验区内,超声波清洗器的放置应远离大鼠饲养室。     

Assessment of pulse rate variability by the method of pulse frequency demodulation

Background  

Due to its easy applicability, pulse wave has been proposed as a surrogate of electrocardiogram (ECG) for the analysis of heart rate variability (HRV). However, its smoother waveform precludes accurate measurement of pulse-to-pulse interval by fiducial-point algorithms. Here we report a pulse frequency demodulation (PFDM) technique as a method for extracting instantaneous pulse rate function directly from pulse wave signal and its usefulness for assessing pulse rate variability (PRV).     

Hypocapnia reduces the T wave of the electrocardiogram in normal human subjects

During voluntary hyperventilation in unanesthetized humans, hypocapnia causes coronary vasoconstriction and decreased oxygen (O(2)) supply and availability to the heart. This can induce local epicardial coronary artery spasm in susceptible patients. Its diagnostic potential for detection of early heart disease is unclear. This is because such hypocapnia produces an inconsistent and irreproducible effect on electrocardiogram (ECG) in healthy subjects. To resolve this inconsistency, we have applied two new experimental techniques in normal, healthy subjects to measure the effects of hypocapnia on their ECG: mechanical hyperventilation and averaging of multiple ECG cycles. In 15 normal subjects, we show that hypocapnia (20 +/- 1 mmHg) significantly reduced mean T wave amplitude by 0.1 +/- 0.0 mV. Hypocapnia also increased mean heart rate by 4 beats/min without significantly altering blood pressure, ionized calcium or potassium levels, or the R wave or other features of the ECG. We therefore provide the first unequivocal demonstration that hypocapnia does consistently reduce T wave amplitude in normal, healthy subjects.     

The significance of heart rate in free swimming cod,Gadus morhua: Some observations with ultra‐sonic tags

Ultra sonic transmitters (cylindrical, 1.5 cm diameter × 7 cm long) with three‐week battery life were used to examine the heart rate and electrocardiogram (ECG) of cod in swimming experiments. The maximum heart rate was observed when the period between the recovery (T) wave and the initial wave (P) of the ECG was zero and was limited by the P to T period which was not observed to vary in an individual. Low heart rates were observed in resting fish and maximum rates were associated with exhaustion and cruising swimming. Maximum rates continued during periods of oxygen debt repayment and during anaesthesia as long as oxygen was supplied to the gills. Brief inhibition of heart rate was associated with sudden stimuli and during maximum swimming exertion. The significance of rate change and its relation to the aerobic and anaerobic states is discussed.     

The electrocardiogram of the Beagle dog: reference values and effect of sex, genetic strain, body position and heart rate

The aim of the study was to establish a database for electrocardiographic parameters of Beagle dogs used for toxicological studies and to evaluate the influence of supplier, sex, heart rate (HR) and body position for electrocardiogram (ECG) recording on ECG parameters. Peripheral ECG leads were recorded from 934 female and 946 male dogs from Marshall Farms and 27 females and 30 males from Harlan, either standing on a table or restrained in a hammock. HR, RR, PQ and QT intervals, P and QRS duration and P-wave amplitude were measured. There were no major differences between sexes for ECG parameters. The axis of the heart was shifted to the left when the animals were restrained in a hammock compared to when they were standing on a table. The PQ interval was higher (about 9%) in Harlan than in Marshall dogs. HR was negatively correlated with QT (coefficient of linear correlation: r=-0.61 to -0.74), which emphasizes the need for a formula correcting QT interval for HR when interpreting changes in QT interval. HR was also negatively correlated with PQ intervals (r=-0.26 to -0.11), whereas a positive correlation was found between HR and the amplitude of the P wave (r=0.21-0.34). The level of the respiratory sinus arrhythmia (SA) was quantified by calculating the ratio of maximum to minimum RR interval measured over a 10 s period. This ratio was negatively correlated with HR (r =-0.49 to -0.33). Therefore, at high HRs, SA was less marked than at low HRs, but it did not completely disappear. Analysis of beat-to-beat variation indicated that QT and PQ intervals and the amplitude of P wave fluctuated over time and the degree of this variability was positively correlated with the level of SA. In conclusion, we have established reference values for the duration and/or amplitude of some ECG parameters both in terms of means and variability over the recording period, and we have evaluated the influence of body position, genetic strain and HR on the ECG parameters. These data can be used as baseline for the interpretation of the ECG of Beagle dogs.     

Sudden unexpected improvement in the atrioventricular conduction. What is the mechanism?

The 12-lead electrocardiogram (ECG) of a 79-year-old male patient with recurrent pre-syncope showed irregular sinus rhythm with constant PR interval and left bundle branch block (LBBB) with intermittently blocked P waves. The beat following the blocked P wave had a narrower QRS with a shorter PR interval. The phenomenon of bilateral bundle branch block explains the sudden improvement in the atrioventricular conduction.