A Wireless and Context-Aware ECG
Monitor:An iMote2Based Portable
System
F Spadini1,F Vergari2,L Nachman3,C Lamberti2,T Salmon Cinotti1
1ARCES-University of Bologna,Bologna,Italy
2University of Bologna,Bologna,Italy
3Intel Corporation,USA
Abstract
This paper presents a portable monitoring system for ECG data.The system consists of an iMote2with its sen-sor board(a platform from Intel Research),a custom ECG board,and a Bluetooth module capable of transmitting information to a smart phone.The iMote2has the task of contextualizing the ECG data by adding not only ac-celerometer data,but ambient information as well.The integration of a subject’s activity from accelerometers and environmental data like temperature,humidity,and light intensity will give a better general picture of where the changes in ECG data come from.The system visualizes the information on a portable Windows Mobile handheld with the possibility of transmitting the information to a re-mote server for later use or re-use.The overall result is a system which provides a clean ECG signal for classi?ca-tion to be run on the iMote2,where further processing and visualization can be performed by add-on mobile devices.
1.Introduction
In the past,telemedicine has been predominantly fo-cused on gathering patient data and sending it to a remote terminal for processing or interpretation.With the contin-uing advancements in processor technology and machine learning,systems have progressed from their initial sam-ple and send counterparts to more active systems.Cur-rent research[1,2]has been progressively adding”‘intelli-gence”’to the local device by trying to provide user alarms as well as performing local processing and compression on captured ECG holter data.Thanks to the steady beat of Moore’s law,not only have processors become smaller and more powerful,but so have sensor technologies.With the advent of MEMS(Micro Electro-Mechanical Systems) sensors and their required signal conditioners,researchers have started adding contextual information to portable telemedicine systems as well[3].A great deal of research has gone into the combination of ECG and accelerometer data to provide a more complete understanding of the pa-tient’s conditions and the situations they occur in.
In the light of current research,a portable monitoring system is being developed which is in its prototype stages. The system is based on a custom ECG board,an iMote2[4] from Intel Research,a Bluetooth module and a UMTS en-abled smart phone.Unlike its predecessors,the system is designed to provide additional and more diverse kinds of context to the system.The initial design incorporates the sensors offered from the Intel sensorboard,including tri-axial accelerometer,temperature,humidity and light in-tensity as well as sensors not onboard,such as ECG data. The basis for offering environmental information is that by giving a more complete view of the patient’s situation, a private care physician can glean a better understanding of where the variations in ECG data come from.
This paper is organized into the following sections:Sec-tion II will cover the overall system,Section III provides an explanation of the context acquisition chain,Section IV provides insight into the ECG module as well the algo-rithms used,Section IV provides details as to the systems power consumption and other preliminary results,and Sec-tion V concludes this study.
2.System architecture
The system architecture can be seen in Figure1,of which the prototype encompasses the on-person platform. The overall goal is to have viable context information pro-cessed on the iMote2and then sent to a smart phone in or-der to be further aggregated and stored in a remote context management infrastructure[5].From a high level view-point,this system allows the re-use of context information gathered from multiple sources.As initial inputs,the sen-sors on the left of Figure1are fed into the iMote2for lo-cal processing.Local processing is performed in order to abstract the raw sensor data as well as reduce the over-
Smart Phone
Context Store
Server Side Context Store
BT connection
ECG_Sensor 500 Hz HR,QRS Duration
1 Hz
Activity
Bioclimatic Indexes (e.g. Discomfort Index)
On person Platform
Humidity 0.5 Hz Temperature 0.5 Hz
Light 5 Hz Accelerometer
50 Hz
Sensor level
Local Processing Level
Data Shaping Level
Context elements 1 Hz
iMote2 and external sensors
HRV
Context Aggregator
Context Consumer
Figure 1.System Overview
all wireless traf?c in the system.As shown in other re-search [6],this will decrease the possibility of congestion on both wireless links in addition to the overall power con-sumption of the system.
3.Context acquisition chain
The context acquisition chain is made up of four primary components:
?iMote2Platform
?Intel basic sensorboard for iMote2
?Bluetooth adapter carrying a Parani ESD200?ECG acquisition board
The iMote2is an advanced wireless sensor node orig-inally developed by Intel Research.The processor board carries a low-power XScale PXA271as well as an 802.15.4radio from Chipcon.Currently the data acqui-sition and processing software is run on top of TinyOS 2,a well known operating system for sensor network research.Sensor data is provided by a daughter board created in the Intel research labs known as the basic sensor-
board.This device carries an ST Micro LIS3L02DQ 3d ac-celerometer,Sensirion SHT15temperature/humidity sen-sor,TAOS TSL2651light sensor,a Maxim MAX1363A/D,and a TI TMP175temperature sensor.The current version of the application utilizes all sensors excluding the TI temperature sensor and the Maxim A/D converter,how-ever,due to the modularity of TinyOS programs they could be bound into the ?rmware in the future.
Since current off the shelf smart phones do not carry an 802.15.4interface,a custom Bluetooth board had to be fabricated.The need for a smart phone arises from the de-sire to be able to transmit the gathered and processed data to a remote data store for later use.A number of various modules exist for providing serial to Bluetooth interfaces,however,Parani offers an excellent module which is small and lightweight (Parani ESD200).In addition to providing Bluetooth,the custom board breaks out a number of vari-ous interfaces offered by the PXA271,including the serial interface necessary for interfacing with the ECG module developed.
Details of the ECG module are left for Section 4.
The software running on TinyOS 2provides data aggre-gation,control and some basic (for now)local processing.The current design is inspired by the well known pub-lish/subscribe abstraction.However,due to the static na-ture of TinyOS applications,this breaks down into a cen-tralized aggregation layer which handles storing and push-ing the incoming data to the various processing and storage components.The data is buffered in the internal SRAM of the PXA if the Bluetooth link is not active.Local pro-cessing is currently limited to converting temperature and humidity into a bioclimatic index value [7].
4.ECG acquisition chain
An ECG acquisition and processing board was devel-oped in-house and is one of the key components of this system.This particular design encompasses both an analog acquisition stage coupled with a TI MSP430for data ac-quisition and signal processing.The analog stage’s block diagram is shown in Figure 2.The electrode topology chosen for this design is based on a single lead with a third electrode which is switchable between ground and a right leg driven circuit.In order to reduce the effect of parasitic capacitances that appear between the cables and ground,the ground of the cable is driven by the common mode voltage signal buffered by a voltage follower.The input stage of the in-amp is based on an AC-coupled front-end [8]which provides a fully differential passive coupling network resulting in a high CMRR.A high cut off fre-quency low pass passive ?lter is used to abate RF inter-ference.The differential signal is then ampli?ed through a low-power,high CMRR instrumentation ampli?er from Analog Devices (AD623).
Figure2.Analog acquisition stage block diagram
In the second stage the signal is?ltered by a passive high-pass?lter with a cut-off frequency of0.5Hz and fur-ther ampli?ed in order to span the entire range of the A/D converter.Following this are5th-order switched-capacitor ?lters(SCF)from Maxim;a MAX7414is con?gured to obtain a notch?lter(for removing power-lines frequency); and a?nal MAX7413,in its standard con?guration,ap-plies a Bessel low-pass?lter at40Hz.SCF are accu-rate,require few external components,and maintain a pre-dictable response over the necessitated operation condi-tions.
Following the analog acquisition stage,a MSP430dig-itizes(at500Hz)and?lters the ECG signal.The design takes advantage of the onboard ADC,hardware multiplier and utilizes one of the micro’s UARTs to transmit data to the iMote2.The MSP is used to perform local process-ing on the ECG to extract HR and QRS wave duration. Real-time QRS detection is provided by a variant of the well known Pan and Tompkins[9]algorithm(PTA).The standard PTA?ow is used,however,instead of the typi-cal adaptive threshold stage,the algorithm uses a threshold similar to that proposed in[10].
In order to isolate the predominant QRS energy,a17-tap low-pass FIR?lter with a pass-band upper frequency of6Hz and stop-band lower frequency of30Hz and then a17-tap high-pass FIR?lter with a corner frequency of2 Hz was implemented.The?ltered signal is then differenti-ated(through a5-tap?lter),squared and passed through a moving window integrator of150ms.
Adaptive amplitude thresholding is?nally applied to the moving integration waveform for QRS detection;two in-dependent thresholds are used:steep slope threshold(M) and beat expectation threshold(R).A measurement algo-rithm calculates the QRS duration as each QRS complex is detected.Thus,two waveform features are available for subsequent arrhythmia analysis(RR interval and QRS du-ration).5.Results
The results cover three sections:robustness,power man-agement and?nally the data output by the system.
Initial concerns in this design stemmed from on-going problems with motion artifacts and capacitive coupling through our ECG module.The?rst iteration of the design had problems as people walked by the person under test which would cause the output to saturate.The problem seemed to be a capacitive coupling effect between the two individuals.An AC-coupled front-end was implemented to increase the system’s immunity to capacitive effects and to help balance the differential input stage[8].Following the initial hardware design phase,the system was unable to achieve the speci?ed behavior of the Parani ESD200mod-ule.As the iMote2was powered down,the Parani mod-ule would lose its con?guration.However,a solution was devised which involved placing a low-level component be-tween the TinyOS serial stack and the UART module so that whenever the Bluetooth device was powered on or off the system would recon?gure the necessary parameters.A placement issue regarding the light sensor was noted.As a user will typically prefer to keep the iMote2on their belt, the angle of incidence of the ambient light will be too large to achieve an accurate and consistent reading.Some pos-sible solutions are being considered such as creating an on body network and placing the light sensor in a more con-venient location.
Power management concerns were raised with the use of Bluetooth and how the software managed its connec-tions.Since the system has an extremely low data output rate,it seems appropriate to store some seconds worth of data and perform a burst transfer to the handheld in or-der to reduce the duty cycle of the Bluetooth controller. However,whenever the Parani is powered down the smart phone loses its connection.This leads to a complication in the software running on Windows Mobile.As the connec-tion would close the software would falter.The current so-lution is to disable power management and power cycling in the?rmware.Focus was placed on enabling appropriate power management to the MSP430.The MSP430has two listings,one in low power mode3and another for when the device is active.Pro?ling has shown that the device stays in its low power mode for80%of the time.This results in an average power consumption of16.5mW for the ECG module and MSP430.Table1lists the power consumption of the various components of the system.As seen in Table1,managing the power on the ECG acqui-sition board results in a power savings of approximately 30%.It is expected that extending power management to the iMote2and to the Bluetooth module would balance the energy consumption of the entire system,bringing the sys-tem energy requirements down into the range of50mW. After handling these and other minor issues,the sys-
Table1.Lists the power consumption of the different modules in the system
Current(mA)V oltage(V)Power(mW) Analog ECG Board 4.7314.1 MSP430LPM30.16 3.30.53 MSP430Active3 3.39.9 iMote2+Sensors38 4.5171 Bluetooth Board47 3.28154.16
Table2.System Output
ID Value Valid Accelerometer02d Int Array True/False Light Intensity116bit Int True/False Bioclimatic Index216bit Int True/False Heart Rate316bit Int True/False tem’s overall goal was achieved.It is able to collect,pro-cess and transmit ECG data over Bluetooth while contex-tualizing the signal with bioclimatic index,light intensity and accelerometer information,see Table2.The valid?ag is for future use,providing a mechanism to indicate if a sensor should be used,e.g.a patient removes the ECG but keeps the mote on the belt.
6.Conclusion and future works
This paper has presented preliminary work on an ECG platform which contextualizes raw ECG data with envi-ronmental variables as well as user activity data.A big stumbling block encountered is the wearability of this sys-tem.While each component is individually small,the sys-tem as a whole becomes cumbersome due to the ECG leads.Current research for wearable bio-systems moni-toring has been geared towards the application of textile sensors.These conductive polymers woven with standard cotton and blended clothing materials allow for good con-tact as well as a more comfortable experience.Future de-signs can implement available ECG devices utilizing these textile sensors in order to make data gathering a more plau-sible thought.
As the issue of wearability is resolved,the next step would be to enable client-server communication.If a smart phone were to be used which integrates GPS data,then user location could be integrated into the overall data set. This would put together all the pieces necessary for a small deployment in order to gain a semantically richer data set. Further study could be performed to understand if classi?-cation algorithms would have enough data to provide ap-propriate event detection and help further understand the user’s situation.Acknowledgements
We appreciate the support of Intel Corporation regarding this research.
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Address for correspondence:
ARCES-Federico Spadini
Via Toffano,2
Bologna,BO,40125
Italy
fspadini@arces.unibo.it
心电图基本知识及常见异常心电图表现特点 一、胸导联：??Ｖ1~V６导联的具体位置: ?V1:胸骨右缘第4肋间。?V2：胸骨左缘第4 肋间。 V３:V2与Ｖ4两点连线的中点。 V4：左锁骨中线与第5肋间相交处。 V5:左腋前线Ｖ４水平处。?V6:左腋中线V4水平处。? 二、心电图各波段的意义： ? ? P波：为心房除极波,反映左、右心房除极过程中的电位和时间变化。正常P波在aＶR导联倒置，Ⅰ、Ⅱ、aＶF、V3～V6导联直立，其余导联(Ⅲ、aＶL、V1、Ｖ2)可直立、低平、双向或倒置。正常Ｐ波的时间≤0．11s;电压在肢导联<0.２5mＶ,胸导联<0.２mV。 P-Ｒ段：是电激动过程在房室交界区以及希氏束、室内传导系统所产生的微弱电位变化,一般呈零电位，显示为等电位线(基线）。? P-R间期：自P波的起点至ＱRS波群的起点,反映激动从窦房结发出后经心房、房室交界、房室束、束支及普肯耶纤维网传到心室肌所需要的时间。正常成年P-R间期为0．12~0．20s。?
QＲS波群：为左、右心室除极的波,反映左、右心室除极过程中的电位和时间变化。正常成人QRＳ波群时间为０.06～0．10s。??S-Ｔ段:从ＱRS波群终点至Ｔ波起点的一段平线，反映心室早期缓慢复极的电位和时间变化。正常情况下,Ｓ-T段表现为一等电位线。在任何导联,Ｓ-T段下移不应超过0．05mV;Ｓ-T段抬高在V1-V3导联不超过０.３ｍV，其他导联均不应超过0.1 mＶ。 ?T波：为心室复极波，反映心室晚期快速复极的电位和时间变化。正常T波是一个不对称的宽大而光滑的波，前支较长,后支较短;Ｔ波的方向与QRS波群主波方向一致。 Q-T间期:从QRS波群的起点至T波终点，代表左、右心室除极与复极全过程的时间。Ｑ－Ｔ间期的正常范围为0.32~0．4４s。 ?三、常见异常心电图的表现:?1、心房肥大的心电图表现:?(1)左房肥大：心电图表现为P波增宽（>0.11ｓ),常呈双峰型，双峰间期≥0.０4s,以在V１导联上最为显著。多见于二尖瓣狭窄，故称“二尖瓣型P波”。 （2）右房肥大：心电图表现为P波尖而高耸,其幅度＞0.2５mV，以Ⅱ、Ⅲ、aVF导联表现最为突出,常见于慢性肺源性心脏病,故称“肺型P波”，也可见于某些先天性心脏病。?2、心室肥大心电图表现：?（1)左室肥大：心电图表现为①QRS波群电压增高:RV5或R Ｖ６>２.5mV，ＲV５或ＲV6+ＳV1>4．0mV（男）或>３.5mV（女)。②心电轴左偏。③ＱRS 波群时间延长到0．10~０.11s。④ＳＴ-T改变，以R波为主的导联中，ＳT段下移≥0.０5ｍＶ，Ｔ波低平、双向或倒置：左室肥大常见于高血压心脏病、二尖瓣关闭不全、主动脉瓣病变、心肌病等。其中QRＳ波群高电压最为重要，是诊断左室肥大的主要依据。 （2)右室肥大：心电图表现为①Ｖ1 R／S＞1,V5R／S<1,V1或Ｖ3 R的QRS波群呈RS、RSＲ’、R或ＱR型。②心电轴右偏，重症可＞+110°。③ＲＶ１＋SV５＞1.２mV,ａVR导联的R/Q或Ｒ/Ｓ＞1,RａVR>０．５mＶ。④V1或Ｖ3 R等右胸导联ＳT－T下移＞0.05mV，T波低平、双向或倒置。 ?3、心肌梗死心电图表现： （1)进展期:心肌梗死数分钟后出现T波高耸，Ｓ-T段斜行上移或弓背向上抬高,时间在6小时以内。?（2）急性期:心肌梗死后6小时至7天。Ｓ-T段逐渐升高呈弓背型，并可与T 波融合成单向曲线,此时可出现异常Ｑ波，继而Ｓ－T段逐渐下降至等电位线,直立的T波开始倒置，并逐渐加深。此期坏死型Q波、损伤型S-T段抬高及缺血性T波倒置可同时并存。?(3）愈合期：心肌梗死后7～28天,抬高的Ｓ-T段基本恢复至基线,坏死型Ｑ波持续存在,缺血型T波由倒置较深逐渐变浅。 (4)陈旧期:急性心肌梗死后29天及以后。S-Ｔ段和T波不再变化,常遗留下坏死的Ｑ波，常持续存在终生,亦可能逐渐缩小。 ?4、心肌缺血心电图表现:?（1)典型心绞痛:面对缺血区的导联上出现S-T段水平型或下垂型下移≥0．1mV,T波低平、双向或倒置，时间一般小于1５分钟。 （２)变异型心绞痛:常于休息或安静时发病，心电图可见S-T段抬高,常伴有T波高耸,对应导联S－T段下移。?（3）慢性冠状动脉供血不足:在R波占优势的导联上,S－T段呈水平型或下垂型压低≥1０.05mV；Ｔ波低平、双向或倒置。 5、心律失常心电图表现:?窦性心动过速的心电图表现：?(1)窦性P波,即P波在Ⅰ、Ⅱ、ａVＦ、V3~V6导联直立，aVＲ导联倒置。 (2）P-R间期0.１2～０.20s。?（3）心率100~1６0次/分钟。? 窦性心动过缓的心电图表现:?(1)窦性心律。 (2)心率在60次/分钟以下，通常不低于４0次/分钟。
心电图机 心电图机是指用来记录心脏活动时所产生的生理电信号的仪器。由于心电图机诊断技术成熟、可靠，操作简便，价格价格适中，对病人无损伤等优点，已成为各级医院中最普及的医用电子仪器之一。 基本简介 心电图机采用10.4英寸大型液晶显示屏，可以清晰地显示心电图波形。通过屏幕上的触摸键可以很容易的进行被检者信息输入、滤波器切换等操作各种以25mm/s记录速度采集的信息，能以50mm/s的记录速度快速打印输出（实时波形记录除外）。 基本特性 心电图机特别适合集体检查等需要快速进行操作的情况可任意选择3导联，记录长达3分钟的心率不齐分析检查。极大的提高了以一般记录时间难以捕捉到的心率不齐的能力可任意指定一个导联检测心电图波形的R-R间期变动（最长10分钟），通过定量分析，提高对自律神经紊乱判断的有效依据以经过经验总结的分析方法为基础的新十二导联分析程序提供更加完善的分析程序，提供了基于自动分析分类基准与分析结果的注释说明，该功能可以使自动分析的客观诊断结果与医生的主观诊断形成互补。 基本分类 按机器功能分类 心电图机按照机器的功能可分为图形描记普通式心电图机（模拟式心电图机）和图形描记与分析诊断功能心电图机（数字式智能化心电图机）。 按记录器的分类 1、动圈式记录器：动圈式记录器的结构原理是由磁钢组成的固定磁路和可转动的线圈。心 电图机功率放大器的输出信号加到记录器的线圈上，线圈上固定有记录笔。在有心电信号输出时，功率放大器向线圈输出电流，线圈转动。当线圈的偏转角度与盘状弹簧的回零力矩相
同时，停上偏转。这样，线圈带动的记录笔便在记录纸上描记出心电图波形。 心电图机 2、位置反馈记录器：位置反馈记录器是一种不用机械回零弹簧的记录器，特殊的电子电路 可起到回零弹簧的作用。机器断电时，位置反馈记录器的记录笔可任意拨动。 3、点阵热敏式记录器：热敏式记录器是利用加热烧结在陶瓷基片上的半导体加热点，在遇 热显色的热敏纸上烫出图形及字符的。 按供电方式分类 按供电方式来分，可分为直流式、交流式和交、直两用式心电图机。其中，交、直两用式居多。直流供电式多使用充电电池进行供电。交流供电式是采用交流-直流转换电路，先将交流变为直流，再经高稳定的稳压电路稳定后，供给心电图机工作。 信号导数来分类 按一次可记录的信号导数来分，心电图分为单导及多导式（如三导、六导、十二导）。单导心电图机的心电信号放大通道只有一路，各导联的心电波形要逐个描记。即它不能反映同一时刻各导心电的变化。多导心电图机的放大通道有多路，如六导心电图机就有六路放大器，可反映某一时刻六个导联的心电信号同时变化情况。 重要参数 输入电阻 即前级放大器的输入电阻。输入电阻越大，因电极接触电阻不同而引起的波形失真越小，共模抑制比越高。一般要求大于2MΩ，国际上大于50MΩ。 共模抑制 心电图机一般采用差动式放大电路，这种电路对于同相（又称共模信号，例如周围的电磁场所产生的干扰信号）有抑制作用，对异相信号（又称差模信号，需采集的心电信号就是差模信号）有放大作用。共模抑制比(CMRR)，指心电图机的差模信号（心电信号）放大倍数Ad与共模信号(干扰和噪声)放大倍数Ac之比，表示抗干扰能力的大小。要求大于80dB，国际上大于100dB。 极化电压
心电图的基本知识 （1）什么是心电图 心脏在机械收缩之前，先发生电激动而产生微小电流，这一电流可以经人体组织传到体表。若用心电图机连续记录全部心脏的电活动，就是心电图。 （2）心电图基本波形 P波：反映心房电激动的电压改变。 QRS波：反映心室电激动的电压改变。 PR间期：代表电激动由心房传到心室的时间。 T波：反映心室电激动恢复期的电压改变。 QT间期：代表心室电激动的全部时间。 正常心电图
心电图纸每小格横坐标表示时间0.04s（秒），纵坐标表示电压0.1mv（毫伏）。 （1）P波 形态：一般为钝图形，有时有轻度切迹担波峰间距小于0.03秒。V1V2导联顶部尖。 宽度：0.06～0.11秒。 高度：小于0.25毫伏。 方向：直立：Li、La、avF。V3～V6；倒置：avR；可以直立也可以倒置。V1、V2、Lm、avL。 （2）PR间期：0.12～0.20秒
（3）QRS综合波 正常时有些导联可出现小Q波，但其深度小于0.25R，宽度小于0.04秒。 宽度：0.06～0.10秒。 高度：V1的R波小于10毫伏，V5的R波小于25毫伏。 形态：V1V2avR主波向下，（R/S）<1，V5V6主波向上，（R/S）>1。 （4）ST段 正常人ST段下移不超过0.05毫伏，ST段上升不超过0.1毫伏。而V1～V3上升不超过0.3毫伏。 （5）T波 形态：波形平滑不对称，上升慢而下降快。 高度：QRS主波向上的导联，T波不应低于同导联R波的1/10。 方向：同P波的方向。 （6）QT间期： 正常人当心率在60～100次/分时，QT间期为0．32～0．44秒。 （7）心电轴 在每一个心动周期中，激动的方向是不断改变的。心电轴为一个心动周期中电激动总的方向正常心电轴为0～90度。小于0度为电轴左偏，大于90度为电轴右偏。
预激综合征 预激综合征是指病人除正常的房室传导途径外，还存在有附加的房室传导途径（旁路），引起心电图异常并可出现阵发性室上性心动过速。 诊断依据 1.典型预激综合征：(1)Ｐ-Ｒ间期＜０．１２秒，Ｐ波正常。 (2)ＱＲＳ时间＞０．１１秒。 (3)ＱＲＳ波群起始部分变粗钝，称为预激波或δ波。 (4)继发性ＳＴ-Ｔ改变。 临床上又分为三型：A型预激：预激波和ＱＲＳ波群在各胸导联均向上，其旁道位于左心室后基底部。 Ｂ型预激：预激波和ＱＲＳ波群的主波V１导联向下，在左胸导联V５向上，其旁道位于右室外侧壁。 Ｃ型预激：预激波和ＱＲＳ波群V１-V２导联向上，V３-V５导联向下。 为左室侧壁预激。 2.变异型预激：ＬＧＬ型预激：(1)Ｐ-Ｒ间期≤０．１１秒。 (2)ＱＲＳ波群时间正常。 (3)没有δ波ＭAｈAｉｍ型预激：(1)Ｐ-Ｒ间期≥０．１２秒。 (2)ＱＲＳ综合波起始波有δ波，但δ波小。 (3)ＱＲＳ时间≥０．１２秒，但增宽轻微。 完全性左束支传导阻滞 完全左束支传导阻滞的心电图特点有以下几点： ①QRS波群的时限≧0.12秒； ②QRS波群的形态的改变：V5导联呈宽大、平顶或有切迹的R波。凡是在v5或v6导联R波之前出现q波，则应排外完全性左束支传导阻滞。 ③V1、V2呈宽大、较深的S波，呈现QS或rS波。(Ⅱ、Ⅲ、aVF与V1相似)。 ④继发ST—T波改变，凡QRS波群向上的导联(如Ⅰ、aVL、V5等)ST段下降，T 波倒置。在QRS波群主波向下的导联(如Ⅱ、aVR、V1等)ST段抬高、T波直立。 不完全性左束支传导阻滞心电图形成的原理与完全性左束支传导阻滞的心电图形成原理相同，二者心电图形相似，只是不完全性左束支传导阻滞QRS时间小于0.12秒。但要注意，不完全性左束支阻滞的心电图与左心室肥厚的图型相似，必须结合临床其他资料进行区别。 完全性右束支阻滞 完全性右束支传导阻滞的心电图表现：①QRS波群时间≥0.12s；②V1或V2导联QRS呈rsR′型或M型，此为最具特征性的改变；Ⅰ、V5、V6导联S波增宽而有切迹，其时限≥0.04s；
心电图：一个小格为0.04秒，一个大格为0.2秒；一个小格为0.1mv，一个大格为0.5mv，两个大格为1mv。 标准电压：1mv=10mm。 P波：代表心房肌除级的电位变化。 P波时限一般小于0.12秒。振幅：P波振幅在肢体导联一般小于0.25mv，胸导联一般小于0.2mv。 P波方向: Ⅰ、Ⅱ、AVF、v4～v6导联向上，AVR导联向下，其余导联呈双向、倒置、低平均可。 PR间期：从P波的起点至QRS波群的起点，代表心房开始除级至心室开始除级的时间。 PR间期时限：0.12～0.20秒，老年人及心动过缓的情况下，PR间期可略延长，但一般不超过0.22秒。 QRS波群：代表心室肌除级的电位变化。 时间：正常人QRS时间一般不超过0.11秒。多数在0.06～0.10秒。 R峰时间：V1、V2导联一般不超过0.04秒，V5、V6导联不超过0.05秒。 Q波：正常人Q波时限一般不超过0.03秒(除Ⅲ和AVR导联外)。Ⅲ导联Q波的宽度可达0.04秒。 正常情况下，Q波深度不超过同导联R波振幅的四分之一。 正常人V1、V2导联不应出现Q波。但偶尔出现可呈QS波。 J波：QRS波群的终末与ST段起始之交接点称为J点。 ST段：自QRS波群的终点至T波的起点间的线段。代表心室缓慢的复级过程。 T波：代表心室快速复级时的电位变化。 方向：Ⅰ、Ⅱ、V4～V6导联向上，AVR导联向下，Ⅲ、AVL、AVF、V1～V3 导联可以向上，双向或向下。若v1的T波方向向上，则V3～V6导联就不应再 向下。 振幅：除Ⅲ、AVL、AVF、V1～V3导联外。其他导联T波振幅一般不应低于同 导联R波的10分之一。T波在胸导联有时可高达1.2～1.5mv尚属正常。 QT间期：指QRS波群得起点至T波终点的间距，代表心室肌除级和复级全过 程所需的时间。 QT间期：正常范围为0.32～0.44秒。 U波：在T波之后0.02～0.04秒。 早期复级：V3～V5导联、Ⅱ、Ⅲ、AVF导联ST段呈凹面向上抬高。 右心房肥大：P波高尖，其振幅≥0.12mv，以Ⅱ、Ⅲ、AVF导联表现最突出，又称“肺型P波”。
一、心电图产生原理 心脏机械收缩之前，先产生电激动，心房和心室的电激动可经人体组织传到体表。 心电图（electocardiogram,ECG）是利用心电图机从体表记录心脏每一心动周期所产生电活动变化的曲线图形。 心肌细胞在静息状态时，膜外排列阳离子带正电荷，膜内排列同等比例阴离子带负电荷，保持平衡的极化状态，不产生电位变化。当细胞一端的细胞膜受到刺激（阈刺激），其通透性发生改变，使细胞内外正、负离子的分布发生逆转，受刺激部位的细胞膜出现除极化，使该处细胞膜外正电荷消失而其前面尚未除极的细胞膜外仍带正电荷，从而形成一对电偶（dipole）。电源（正电荷）在前，电穴（负电荷）在后，电流自电深流入电穴，并沿着一定的方向迅速扩展，直到整个心肌细胞除极完毕。此时心肌细胞膜内带正电荷，膜外带负电荷，称为除极（depolarization ）状态。嗣后，由于细胞的代谢作用，使细胞膜又逐渐复原到极化状态，这种恢复过程称为复极（repolarization）过程，复极与除极先后程序一致,但复极化的电偶是电穴在前，电源在后，并较缓慢向前推进，直至整个细胞全部复极为止（图4-1-l）。 就单个细胞而言，在除极时，检测电极对向电源（即面对除极方向）产生向上的波形，背向电源（即背离除极方向）产生向下的波形，在细胞中部则记录出双向波形。复极过程与除极过程方向相同，但因复极化过程的电偶是电穴在前，电源在后，因此记录的复极波方向与除极波相反（图4-1-2）。 需要注意，在正常人的心电图中，记录到的复极波方向常与除极波主波方向一致，与单个
心肌细胞不同。这是因为正常人心室的除极从心内膜向心外膜，而复极则从心外膜开始，向心内膜方向推进，其机制尚不清楚。可能因心外膜下心肌的温度较心内膜下高，心室收缩时，心外膜承受的压力又比心内膜小，故心外膜处心肌复极过程发生较早。 由体表所采集到的心脏电位强度与下列因素有关：①与心肌细胞数量（心肌厚度）呈正比关系；②与探查电极位置和心肌细胞之间的距离呈反比关系；③与探查电极的方位和心肌除极的方向所构成的角度有关，夹角愈大，心电位在导联上的投影愈小，电位愈弱（图4-1-3）。 这种既其有强度，又具有方向性的电位幅度称为心电“向量”( vector ) ，通常用箭头表示其方向，而其长度表示其电位强度。心脏的电激动过程中产生许多心电向量。 由于心脏的解剖结构及其电活动相当错综复杂，致使诸心电向量间的关系亦较复杂，然而一般均按下列原理合成为“心电综合向量”( resullant vector ) ：同一轴的两个心电向量的方向相同者，其幅度相加；方向相反者则相减。两个心电向量的方向构成一定角度者,则可应用“合力”原理将二者按其角度及幅度构成一个平行四边形，而取其对角线为综合向量（图4-1-4）。可以认为，由体表所采集到的心电变化,乃是全部参与电活动心肌细胞的电位变化按上述原 理所综合的结果。 心电图各波段的组成和命名 心脏的特殊传导系统由窦房结、结间束（分为前、中、后结间束）、房间束（起自前结间束，称Bachmann束）、房室结、希氏束（His bundle）、束支（分为左、右束支，左束支又分为前分支和后分支）以及普肯耶纤维（Pukinje fiber）构成。心脏的传导系统与每一心动周期顺序出现的心电变化密切相关（图4-1-5）。
基本心電圖圖例 簡介 注意：本簡介僅供使用者瞭解心電圖基本病例與參數，本手冊從第一導程的心電圖角度，讓使用者可以認識正常心電圖與異常 心電圖之間的不同。 警告：本簡介之內容並非涵蓋所有心電圖異常病例。本簡介僅供參考，假如您發現您的心電圖波形與標準心電圖波形不一樣， 或是與文中所述異常心電圖病例相似，請儘速就醫尋求醫師 診斷。
目錄 認識心臟 (1) 1.1心臟的基本功能 (1) 1.2心臟的傳導系統 (2) 1.3心律不整(A RRHYTHMIA) (3) 認識心電圖 (4) 2.1瞭解心電圖參數 (4) 2.2心電圖波形與相關參數 (5) 心電圖圖例 (7) 3.1正常節律 (7) 3.2節律過緩 (7) 3.3節律過速 (8) 3.4上心室性頻脈(SVT) (8) 3.5心房顫動 (9) 3.6心房顫動 (9) 3.7心房撲動 (10) 3.8心室性節律 (10) 3.9心室性頻脈 (12) 3.10心室顫動 (12) 3.11竇性心律不整 (13) 3.12竇性節律暫停 (14) 3.13陣發性心房性頻脈(PAT) (15) 3.14N ODAL R HYTHM (15) 3.15左心室肥大 (16) 3.16第一級心房心室傳導阻滯 (17) 3.17第二級心房心室傳導阻滯 (17)
3.18第三級心房心室傳導阻滯 (18) 3.19右束枝傳導阻滯(RBBB) (18) 3.20左束枝傳導阻滯(LBBB) (20) 3.21早發性心房收縮(PAC) (20) 3.22P REMATURE N ODAL C ONTRACTION (PNC) (20) 3.23早發性心室收縮(PVC) (21) 3.24雙聯律B IGEMINY (22) 3.25三聯律T RIGEMINY (22) 3.26T WO PVC S TOGETHER (23) 其他不規律心電圖圖例 (24) 4.1不規律的ECG (24) 4.2電極倒置的訊號 (24) 4.3設置有心律調節器的ECG (25) 4.4訊號微弱 (26) 4.5雜訊 (27) 詞彙表 (28) 附錄 (30) 以RMH2.0模擬12導程心電圖量測圖解 (30) 第一導程L EAD I (30) 第二導程L EAD II (31) 第三導程L EAD III (32) 加強肢導L EAD A V R (33) 加強肢導L EAD A V L (34) 加強肢導L EAD A V F (35) 胸前導程V1-V6 (36)
以上是主页君在网上随意找到的正常的ＥＣG图示,可能很多人问,为什么很多时候正常的心电图看起来和上图不一样呢?其实，上图是一种理想的状态下的图示，只不过是为了说明心电图而画出的理论图示。正常的ECG在不同导联上有这完全不同的表现，我们学习的目标是认识正常的心电图,才有能力分辨异常心电图,发现其中的异常,从而得出判断，起到辅助诊断的目的。 一、心电图基本知识（这是额外要求,初学者了解,不懂也不影响学习） 心电图反映心脏兴奋的产生、传导和恢复过程中的生物电变化,和心脏的机械舒缩活动无直接关系。 (一)心电图各波段的意义 Ｐ波:反映左、右心房除极过程中的电位和时间变化。 P－R段:主要反映激动通过房室交接区所产生的电位变化。?Ｑ1lＳ波群:反映左、右心室除极过程中电位和时间的变化。 S-T段:代表心室早期复极(２期平台)的电位和时间的变化。?T波：反映心室晚期快速复极(3期）过程中的电位和时间的改变。 U波:一般认为是心室肌传导纤维(浦肯野纤维)的复极波所造成，也有人认为是心室的后电位所致。 (二）心电产生的原理?１．静息电位心肌细胞未受到刺激(处于静息状态）时存在于细胞膜内、外两侧的电位差，称为静息电位。以细胞膜为界,膜外呈正电位、膜内为负电位,并稳定于一定数值的静息电位状态,称为极化状态。?２.动作电位当细胞受到刺激时，其亚微结构就会发生改变，于是对钠离子的通透性加大，从而造成钠离子快速内流，此时可测得+３0ｍv 的电压,这就是动作电压。这时细胞膜上的Nａ+—K+AＴP泵逆浓度差把钾离子送回细胞内而排除钠离子，恢复原有的极化状态。3?. 除极和复极 １除极:指细胞由静息膜电位转变成动作电位的过程，不消耗能量,其速度较快。?２复极:指动作电位恢复到静息膜电位的过程,消耗ＡTＰ,逆浓度差进行，速度较慢。3?除极时正电荷在前,负电荷在后（指在细胞外）；人为地使对着正电荷描记向上的波、对着负电荷描记向下的波。(三)心电图电位强度与形态的决定因素 1．形态探查电极面对心肌除极的方向,可描记出一个向上的波。探查电极面对心肌复极的方向,则可描记出一个向下的波。 2.电位强度与下列因素有关：①与心肌细胞的数量成正比;②与探查电极和心脏的距离的平方成反比;③探查电极的方位和心脏除极的方向所构成的角度越大,电位越小。?(四)心电向量的概念 心脏是由无数心肌细胞所组成的，在除极与复极过程的每一瞬间都可以产生许多大小不—、方向不尽相同的心电向量，按平行四边形法或头尾相加法依次综合起来,这个最后综合起来的向量叫做瞬间综合心电向量。1．向量是一种既能表示方向又能表示力量大小的物理学名称,一般用“箭矢”表示。 2.心脏是由无数个心肌构成的，综合方向就是它的代数和。
心电图基础知识（一）正常心电图 心电图各波正常值及意义 心电图是由一系列的波组所构成，每个波组代表着每一个心动周期。一个波组包括P波、QRS波群、T波及U波。看心电图首先要了解每个波所代表的意义。 (1)P波：心脏的激动发源于窦房结，然后传导到达心房。P波由心房除极所产生，是每一波组中的第一波，它反映了左、右心房的除极过程。前半部分代表右房，后半部分代表左房。 (2)QRS波群：典型的QRS波群包括三个紧密相连的波，第一个向下的波称为Q波，继Q 波后的一个高尖的直立波称为R波，R波后向下的波称为S波。因其紧密相连，且反映了心室电激动过程，故统称为QRS波群。这个波群反映了左、右两心室的除极过程。 (3)T波：T波位于S-T段之后，是一个比较低而占时较长的波，它是心室复极所产生的。 (4)U波：U波位于T波之后，比较低小，其发生机理未完全明确。一般认为是心肌激动的“激后电位”。 正常心电图各波段的正常值及意义如下： (1)P波：呈钝圆形，可有轻微切迹。P波宽度不超过0.11秒，振幅不超过0.25毫伏。P波方向在Ⅰ、Ⅱ、aVF、V4-6导联直立，aVR导联倒置。在Ⅲ、aVL、V1-3导联可直立、倒置或双向。P波的振幅和宽度超过上述范围即为异常，常表示心房肥大。P波在aVR导联直立，Ⅱ、Ⅲ、aVF导联倒置者称为逆行型P波，表示激动自房室交界区向心房逆行传导，常见于房室交界性心律，这是一种异位心律。 (2)PR间期：即由P波起点到QRS波群起点间的时间。一般成人P-R间期为0.12～0.20秒。P-R间期随心率与年龄而变化，年龄越大或心率越慢，其PR间期越长。P-R间期延长常表示激动通过房室交界区的时间延长，说明有房室传导障碍，常见于房室传导阻滞等。 (3)QRS波群：代表两心室除极和最早期复极过程的电位和时间变化。 ①QRS波群时间：正常成人为0.06～0.10秒，儿童为0.04～0.08秒。V1、V2导联的室壁激动时间小于0.03秒，V5、V6的室壁激动时间小于0.05秒。QRS波群时间或室壁激动时间延长常见于心室肥大或心室内传导阻滞等。 ②QRS波群振幅：加压单极肢体导联aVL导联R波不超过1.2毫伏，aVF导联R波不超过 2.0毫伏。如超过此值，可能为左室肥大。aVR导联R波不应超过0 .5毫伏，超过此值，可能为右室肥大。如果六个肢体导联每个QRS波群电压(R+S或Q+R的算术和)均小于0.5毫伏或每个心前导联QRS电压的算术和均不超过0.8毫伏称为低电压，见于肺气肿、心包积液、全身浮肿、粘液水肿、心肌损害，但亦见于极少数的正常人等。个别导联QRS波群振幅很小，并无意义。 心前导联：V1、V2导联呈rS型、R/S＜1，RV1一般不超过1.0毫伏。V5、V6导联主波向上，呈qR、qRS、Rs或R型，R波不超过2.5毫伏，R/S＞1。在V3导联，R波同S波的振幅大致相等。正常人，自V1至V5，R波逐渐增高，S波逐渐减小。 (4)Q波：除aVR导联可呈QS或Qr型外，其他导联Q波的振幅不得超过同导联R波的1/4，时间不超过0.04秒，而且无切迹。正常V1、V2导联不应有Q波，但可呈QS 波型。超过正常范围的Q波称为异常Q波，常见于心肌梗塞等。 (5)S-T段：自QRS波群的终点(J点)至T波起点的一段水平线称为S-T段。正常任一导联S-T向下偏移都不应超过0.05 毫伏。超过正常范围的S-T段下移常见于心肌缺血或劳损。正常S-T段向上偏移，在肢体导联及心前导联V4—6 不应超过0.1毫伏，心前导联V1—3不超过0.3毫伏，S-T 上移超过正常范围多见于急性心肌梗塞、急性心包炎等。 (6)T波：T波钝圆，占时较长，从基线开始缓慢上升，然后较快下降，形成前肢较长、后肢