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心率与年龄对照表

发布时间:2023-06-13 作者:admin 来源:文学

心率与年龄对照表

心率与年龄对照表

幼儿学习的特点-老公我想要

2023年3月18日发(作者:廉洁承诺一句话)

大连理工大学硕士学位论文

摘要

HRv是指逐次窦性心动周期之间的微小变异,反映心脏自主神经系统的功能状态。

这种心搏间的微小差异,可以被计算机心电检测系统记录、测量和计算出来,作为临床

应用指导。已经公认HRV是定量分析心脏自主神经系统张力的方法。频阈分析是近年

来受到重视的分析方法之~,即对心率变异的速度和幅度进行心率功率谱的分析,亦称

心率能谱分析。在频域分析指标中,HF主要反映迷走神经张力变化;LF主要反映交感

神经张力变化,与外周血管温度调节、肾素、血管紧张素系统活动和心脏泵血功能等多

种因素有关;LF/HF则可评估心脏交感神经和迷走神经活动均衡性。

在最近的二十年,自主神经系统与心血管衰竭率,包括心脏的突然衰竭之问的密切

关系已经得到了大家的公认。实验证明,心率不齐与增强的交感神经或者减弱的迷走神

经活动的并发,刺激了自律活动在数量上的里程碑式发展。对心率变化的研究已经成为

评定自主神经系统的常用的工具。心率变化分析是以“快速的波动必将影响交感神经和

迷走神经的变化”这一理论为基础的。该分析指出,结构生成的信号并不是简单的线性

变化,而是包含非线性的变化。在本文中,作者计算出了不同年龄段人群的ECG信号

的最大Lyaptmov指数,结果表明,随着年龄的增长,心率呈递减的趋势;在论文中,

作者还给出了常态下的四组不同年龄段人群的非线性参数的范围。

关键词;tlltV;自主神经系统;迷走神经;心宰;Lyapunov指数

大连理工大学硕士学位论文

Heart

rate

variationinnormalsubjectsamong

various

agegroups

Abstract

HRVis

negligible

variationbetlⅣ咖the

periods

ofsuccessivesinusheartrate.reflects

thestatusoffunctionofeardial

automaticilervoussystem.This

kindof

negligible

variation

betweentheheart

ratecanbe

record,measure

and

calculate

by

computer

ECGDetection

System

anduseasguides

forClinical

application.It

is

well-known

thatHRVisthemethod

about

quantitative

analysisofeardialautomaticnervoussystemtension.frequency

threshold

analysis

is

OBeoftheanalysismethods

have

been

given

moreattentionthese

years,It

is

analysis

the

heartratepowerspectnanofthe

speed

and

amplitudeofheartratevariation,that

isheartratepowerspectnananalysis.Infrequency

domam

analysis.HF

refects

thetension

vailation

ofvagus;LF

reflects

thetensionvariation

ofsympathetic

llorVe.Itrelateswithouter

bloodvessel

temperamreregulatiothrennin,an#otensinsystemand

cardiac

pumping

function

andSOon;LF/HF啪evaluatetheproportionalitybetween

cardiacsympatheticnerve

and

vagus

activity.

Thelasttwodecades

havewimessedthe

recognition

ofa

significantrclatiomMp

between

theautonomicIIejt'VOus

syStem

andcardiovascular

mortality,including

sudden

cardiacdeath.

Experimental

evidenceforallassociationbeCweellapropensity

forlethal

arrhythmias

and

signs

of

eitherin.easedsympatheticorreduced

vagal

activity

has

encouragedthe

development

of

quantitative

markers

ofautonomic

activity.Analysis

ofheart

rate

variation

(HRV)hasbecomeapopularnoninvasivetool

for

assessing

theactivitiesoftheautonomic

nervous

system(ANS).HRVanalysis

isbasedonthe

concept

that

fast

fluctuations

may

specifically

reflect

changes

ofsympatheticand

vagalactivity.It

showsthatthestructure

generating

the

signal

isnot

simply

linear,but

alsoinvolvesnonlinearcontributions.Inthis

paper

the

largestLyapunovexponentofECGsignalsfordifferent

age

groups

hasbeen

calculated,Theresultsshow

that,with

aging

theheartrate

variability

decreases.Inthis

work,

the

ranges

ofnonlinear

parameters

for

four

agegroup

normalsubjects

are

presented.

KeyWords:HRV;Autonomicnervous

system;vagal;Heartrate;LyapunovExponent

—-III—·

独创性说明

作者郑重声明:本硕士学位论文是我个人在导师指导下进行的研究工

作及取得研究成果.尽我所知,除了文中特别加以标注和致谢的地方外,

论文中不包含其他人已经发表或撰写的研究成果,也不包含为获得大连理

工大学或者其他单位的学位或证书所使用过的材料.与我一同工作的同志

对本研究所做的贡献均已在论文中做了明确的说明并表示了谢意.

作者签名:复妞日期:幽晕12日加日

人连理工人学硕士研究生学位论文

大连理工大学学位论文版权使用授权书

本学位论文作者及指导教师完全了解“大连理工大学硕士、博士学位

论文版权使用规定”,同意大连理工大学保留并向国家有关部门或机构送

交学位论文的复印件和电子版,允许论文被查阅和借阅。本人授权大连理

工大学可以将本学位论文的全部或部分内容编入有关数据库进行检索,也

可采用影印、缩印或扫描等复制手段保存和汇编学位论文。

作者签名:望纽

聊躲≥兰毛

幽年卫月掣日

ntroduction

ne1asttwodecades

havewimessedthe

recognition

ofa

significant

relationship

betweell

theautonomicnervoussystem

andcardiovascular

mortality,mcluding

suddencardiac

death.

Experimentalevidenceforan

associationbetweenapropensity

for

lethalarrhythmiasand

signs

of

eitherincreased

sympatheticorreduced

vagai

activity

hasencouragedthe

development

ofquantitative

markersofautonomic

activity.

Heartratevariability(HRV)repr髓%tsoneofthemostpromisingsuchmafkcrs.1f1犯

apparentlyeasy

derivationofthis

me,asurehas

popularized

itsuse.Asmany

commercial

devices

nOW

provide

automatedmeasurementof

HRV,the

cardiologist

hasbeen邮vided

withaseeminglysimple

toolforbothresearch

and

elinica]studies.However,the

significance

and

meaning

ofthe

many

differentmeas蝴ofHRVaremore

complex

thangenerally

appreciatedandthere

isapotemialforincorrectconclusions

andforexcessiveorunfounded

extrapolations.

In

thiswn出the

nodme盯parameter

evaluatedshowheartvadation

among

different

age

groups·

111e

paperarrangedin

following,the

first

chapter

has

introducedthe

background

of

this

paper,thenithasdescribedvariousmethodsfor

heartratemeasurements,theclinical

USeof

heartratevariability,In

the

later

chapters

ithasdescribed

LargerLyapunovexponent

and

laterthedatafrom

varioussubjectshasbeen

analyzed.

望竺璺墨坐!堂垫塑竺翌型墅堕竺垫竺些竖!竺塑竺垒壁塑

1Introduction

Thelasttwodecadeshavewitn髓sedthe

recogrlition

ofa

significant

relationship

between

theautonomicnervoussystem

andcardiovascular

mortality,including

suddencardiacdeath.

Experimental

evidenceforallassociationbetweenapropensity

for

lethalarrhythmias

and

signs

of

eitherInereesed

sympatheticorreducod

vagal

activity

hasencouragedthe

developmentofquantitative

markersofautonomic

activity.

Heartratevariability(HRV)representsoneofthemostpromisingsuchmark@l'S.ne

apparentlyeasy

derivationofthismeasurehas

popularized

its

use.Asmany

commercial

devicesnow芦odde

automated

measur9111ent

of

HRV,the

cardiologist

has

been

provided

withaseeminglysimple

toolforbomresearchandclinical

studies.However,thesignificance

and

meaning

ofthemany

differentmeasures

of

HRVare

more

complex

thangenerally

appreciated

andthereisapotentialforIncorrectconclusionsandforexcessiveorunfounded

extrapolations.

Recognition

ofthese

problems

ledthe

European

Society

of

Cardiology

andtheNorth

American

Society

of

Pacing

and

Eleetrophysiology

toconstituteaTaskForechargedwitlI

the

responsibility

of

developingappropriate

standards.The

specificgoals

ofthisTaskForce

wereto:standardizenomenclatureand

develop

definitions

ofterms;specify

standardmethods

of

measurement;define

physiological

and

pathophysiological

correlates;describe

currently

appropriate

clinical

applications,and

identify

areasforfutureresearch.

Inordertoachievethese

goals.the

membersofthe

T勰kForceworedrawn

from

the

fieldsofmathematics,engineering,physiology,andclinicalmedicine.Thestandardsand

proposals

off盯edinthistextshouldnotlimitfurtherdevelopmentbut,rather,should

allow

appropriatecomparisons,pronlotccircumspectInterpretations,andleadtofurther

progress

in

thefield.

一2一

大连理工大学硕士学位论文

Background

Theclinicalrelevanceofheartratevailabillty

wasfirst

appreciated

in1965whenHon

andLee【1】notedthatfetal

distresswasprecededby

alterationsininterbentintervalsbefore

anyappreciablechange

occurred

intheheartrateitself.Twenty

yearsago,Sayers

andothers

focusedattentionontheexiatenee

ofphysiologicalrhythms

imbeddedinthebeat-to-beatheart

ratesignat【2巧】.

During

the1970s,Ewingcta1.【6】devisedanumberof

simple

bedsidetestsof

short-termRRdifferencestodetect

autonomic

neuropathy

indiabeticpatients.The

associationof

higher

riskof

post-infarction

mortality

withreducedHRV

wasfirstshown

by

Wolfeta1.in1977【7】.In1981,Aksekodeta1.introducedpowerspectralanalysis

ofheart

ratefluctuationstoquantitativdy

evaluatebeat-to-beatcardiovascular

control【8】.

These

frequency-domainanalyses

contributedtothe

understanding

oftheautonomic

background

ofRR

intervalfluctuations

intheheartraterecord【9,lO].The

clinical

importanceofHRVb{N2a.iile

apparent

inthelate1980swhenitWasconfirmedthatHRVWasa

strong

and

independent

predictorofmortality

following

anacutemyocardialinfarction【1l,

12].Withtheavailabilityofnew,digital,highfrequency,24-h

multi-channelelectrocardio

graphicrecorders,HRV

hasthe

potential

to

provide

additionalvaluable

insight

into

physiological

and

pathological

conditions

andtoelhllanceriskstratification.

TheHeartratevariability(rmv)isanon-invasiveindexoftheneuralcontrolofthe

heart.HRV

Canbequantifiedby

the

simple

calculationofthestandarddeviationoftheRR

intervals.Furthermore,in

the

frequencydomain,spectralanalysis

ofHRVrevealsthree

distincttiequencyregionsinthemodulationofheartrateinhumans.The

typicalspectral

pattern,in

normalconditionsshowsthepresence

ofthree

frequency

bands:a

very

low

frequency(VLF)band

from0.00toO.03

Hz,a

low

frequency(LF)band

fromO.03to0.15Hz

anda11ighfrequency(HF)bandin

respiratoryrange

generally

morethanO.15Hz.

ThepowerofLFcomponentSeeInstoberelatedtothe

vagal

and

sympathetic

activities

(LF

componentincreaseswith

every

form

ofsympatheticstimulation),whereastheareaof

bighfrequencycomponent(HF)providesaquantitative

indexoftheinfluenceof

respiration

onECGsignal

and

may

beconnected

tothe

vagalactivity.Thus

LF,HFratioisan

important

markerofsympatheticmodulationorsympatho·vagalbalanceonheartratevariability

contr01.

Physiologicalsignals

often

vary

inacomplex

and

irregularmanner.Analysis

oflinear

statisticssuch弛mean

values,variabilitymeasures,andspectra

ofsuch

signalsgenerallydoes

not

address

directly

their

complexity

andthus

may

miss

potentiallyusefulinformation.Since

the

underlying

mechanismsinvolved

in

thecontrol

ofheartratearemainly

nonlinear,the

application

ofnonlineartechniques踮咖sappropriate【13-16].

3一

Recently,new

dynamicmethodsofHRV

quantification

havebeenused

tounoover

nonlinearfluctuationsinheartratethatarenototherwise

apparent.Several

methodshavebeen

proposed:Lyapunovexponents【17],l/fslope【18】,approximateentropy(ApEn)[19】and

detrendodfluctuation

analysis【20].Comparedtomen,womenareatlowerriskof

coronary

heartdisease[21】andofserious

arrhythmias【22],suggestingabeneficialdifferenc宅in

autonomiccon协olofheartrate.Previousstudieshaveassessedgenderand

age-telatod

diffcrencesintimeandfi-equencydomainindicesf23】and80menonlinearcomponentof

HRV【241.Therealsoseemedtobeasignificantdifferencebetween

day

and

night

hours

when

studying

HRVindicesusingspectral

andtime

domain

methods【25].Terryet

al,have

shownthatthemiddle.aged

womenandmenhaveadominant

parasympathetic

and

sympatheticregulation

oftheheartrate,respectively【26].Itisproved

that,theheartrate

v鲥abilitydependsonthes懿also.TheheartrateV撕abilityiSmoreiuthe

physically

active

young

and

oldwomen

f271.The

reduc,edHRV

rcsultsinnewcardiaceventsarestudied

by

Hisakoeta1.Itisprovedby

Emeseeta1.thatthealertnewboresheartratevailationislOWgr

in

thecaseof

boys

thanin

the

c笛eofgirls[281.TheHeartratevariationfor

healthys蛔cas

from20.70

yrs

isstudied

by

Hendriketa1.andfound

that

the

HRVdecreaseswith

age

and

vailatiOlliSmoreinthecaseoffemalethanmen.Galeeveta1.haveanalyzedtheheartrate

variationfor

healthysubjectsof

age

fi'om6to16

yrs

and

observed

the

statistical

and

fi'equency

domainvariation奶m

aging

and

gender【29].Inthis

work,we

have

analyzedthe

heartrate

variationofnormalsubjectsfrom

23-90

yrs

in

fourgroups(204-10,30士10,41

4-

29,71士19)by

nonlinearmethod.

一4一

大连理工大学硕士学位论文

3Measurementofheart

ratevar

iabiI

ity

3.1Tiritedomainmethods

Variationsinheartrate

may

be

evaluated

byanumber

ofmethods.Perhaps

the

simplest

toperformarethetimedomainmoasllrcs.Withthesemethodseither

the

heartrate

atany

∞intintimeortheintervalsbetween鞠-1.j嘲sivenormal

complexesaredetermined.Ina

continuous

electrocardiographic(ECG)record,eachQRScomplexis

detected,and

the

∞-called

normal-to-normal(NN)intervals(thatisallintervalsbetweenadjacentQRS

complexesresulting

fromsinus

node

depolarizations,or

the

instantaneoushea.qrateis

determined.Simoletime-domainvariablesthatcanbecalculatedincludethemeanNN

interval,the

meanheart

rate,the

differencebetween

the

longest

andshortestNN

interval,the

differencebetween

night

and

day

heart

rate.ete.Other

time-domainmeasurements

that眦be

usedarevariationsininstantaneousheartratesgcondarytorespiration,tilt,Valsalva

malloeuvre,orsecondaryto

Dheilylephrine

infusion.Thesedifferencescabbedescribed勰

eitherdifferencesinheartrateorcyclelengtlL

3.2StatisticaImethods

FromaseriesofinstanhalleoBsheartratesorcycleintervals,particularly

thoserecorded

over

longerperiods,traditionally

2411,more

complexstatisticaltime-domainmeasurescanbe

calculated.These

may

bedividedinto

twoclasses,①those

deriredfromdirect

measurementsoftheNNintervalsorinstantaneousheartrate,(Dthose

derived

from

the

differencesbetweenNNintervals.Thesevuriables

may

bederivedfrom

analysis

ofthetotal

electrocardiographicrecordingormay

becalculated

using

smaller

segmentsofthe

recording

period.The

latter

method

allowscomparisonofHRVtobemade

during

varymgactivities,e.g.

rest,sleep.etc.Thesimplest

vailabletocaleulateisthestandarddeviationof

meNNinterval

(SDNN),i.e。thesquare

rootof

variance.Since

varianceis

mathematicallyequal

lototal

power

of

spectralanalysis,SDNN

reflectsall

the

cycliccomponentsresponsiblefor

variabilityinthe

periodofrecording.Inmanystudies,SDNNiscalculatedovera24-h

period

andthus

encomp船ses

bothshort-term

highfrequencyvariations,as

wellasthelowest

frequency

componentsseen

ina24-h

period.As

theperiodof

monitoring

decreases,SDNN

estimatesshorterandshorter

cyclelengths,Itshould

alsobenotedthatthetotalvarianceof

HRVincreaseswiththelength

ofanalyzedrecording[30].Thus,onarbitrarily

selected

ECGs,

SDNN

isnotawelldefinedstatistical

quantity

becauseofitsdependenceon

thelengthof

recordingpaiod.Thus.inpractice,it

is

inappropriate

tocompareSDNNmeasuresobtained

from

recordings

ofdifferent

durations.However,durationsofthe

recordings

usedto

一5一

determineSDNNvalues(andsimilady

otherHRVmeasures)shouldbe

standardized.

Short—term5-min

recordings

andnominal24h

long-terrarecordings

senititobe

appropriate

options.Otherconm30nlY

usedstaffsticalvariablescalculatedfromsegments

ofthetotal

monitotingpedod

includeSDANN.thestandard

deviation

ofthe

average

NNinterval

calculatedOVershort

periods'usually

rain,which

iSanestimateofthechangesinheartrate

duet0

cycleslonger

than5min,and

theSDNN

index.the

moanofthe5·rainstandard

deviationoftheNNintervalcalculatedOVeI*2411.whichmeasures

the

variability

dueto

cycles

shotterthan5minutes.Themost

commonly

used

measures

derivedfTominterval

differencesincludeRMSSD.the

square

rootofthemean

squared

differencesofsuccessive

NN

intervals,NN50,the

number

ofintervaldifferances

of

successiveNNintervals

greater

than50ms.and

pNN50

the

proportion

derived

bydividing

NN50

by

thetotalnumberofNN

intervals.AII

thesemeasurementsofshort-term

variation

estimate

highfrequencyvariations

inheartrateandthusare

highlycorrelated(F嘻3.1).

3.3GeometricaImethods

ThesefiesofNNintervalscanalsobeconvertedintoageometricpattem,suchasthe

sampledeusitydistribution

ofNN

intervaldurations,sampledensity

distribufionof

differencesbetweenadjacentNN

intervals,Lorenz

plot

ofNNor

RRintervals,etc.,anda

simple

formulaisusedwhich

judgesthevariabilitybased

on

the

geometric

and/or

graphic

properties

of

the

resultingpattern.Threegeneralapproachesareusedin

geometric

methods:

①abasicmeasurementofthegeometricpattern(e.g.thewidthofthedistribution

histogram

atthe

specifiedlevel)is

convertedintothemeasureofHRV,②the

genmetriepaRem

iS

interpolatedbyamathematically

de丘ncdshape(e.昌approximationofthedistribution

histogram

byatriangle,orapproximationofthedifferentialhistogram

byallexponential

curve)and

thentheparametersofthismathematical

shape

areused,and③thegeometric

shapeis

一6一

大连理工大学硕士学位论文

F培3.1Relationship

bcIfwccntheRMSSD∞d

pNN50(a),andpNN50

andNN50(”m日日哪ofHRV

assessedfrom

857

nominal

24-hHolter

Pattern-basⅨl

categories

whichrepresent

different

classesofHRV(e.辱elliptic,2inear

and

triangularshapes

ofLorenzplots).Mostgeometric

methods

require

thcRR(orNN)

intervalsequeIlcetobemeasuredonorconvertedtoadiscrete

scalewhichiSnottoofineor

toocoarseand

whichpermitstheconstructionofsmoothed

histograms.Mostexperience

has

beenobtained

with

bins

approximately

8mslong(precisely7·8125ms=1/128S1which

corresponds

tothe

precision

ofcurreotcommcTcial

equipment.TheHRV

triangular

index

measurementiSthe

integral

ofthedeositydistribution亿e.thenumber

ofa11

NNintervals)

divided

by

themaximum

ofthe

density

distribution.UsingameasurementofNN

intervalson

adiscrete

scale,the

measureis

approximatedby

thevalue:(totalnumberof

NN

intcrvals)/(numbcr

ofNN

intervals

in

themodalbin)whichiSdependentOHthe

length

ofthe

bin,i.e.On

the

precision

ofthediscretescaleofmcasurcmont.Thus.ifthediscrete

一7一

墅坠!堂垫型型墅塑型!堂塑堕

approximation

ofthemeBsureisused、析tllNNintervalmeasuremefltona∞aledifferentto

themost

frequentsampling

of128H乙thesizeofthebinsshould

be

quoted.

Duratlma0fnormalRRtntervals

Fig.3.2

The

U'ia.gularinterpolation

ofNN

Tope触geometricalmeasures

ontheNN

intervalhistogrmn,the

sampledensity

distributionDis

constructed

which

assigns

thenumberof

ezluallylong

NNintervalstoench

valueoftheir

lengths.111e

most

frequent

NN

interval

length

is

established,thatisJr=D∞

isthemaximumofthe

sampledensity

distributionD.TheHRV

triangular

indexiSt11evalue

obtained

bydividing

theareaintegral

ofD

by

themaximum

y.When

constructing

the

distributionDwithadiscretescaleonthehorizontalaxis.thevalueisobtained

according

to

theformulaHRViadex=(totalnumberofallNNintervals)/Y.

ForthecomputationoftheTINNmeasure.thevalUesNandMareestablishedonthe

timeaxisandamultilinearfunction

constructedsuchthat4(f):Ofor匿Nandf≥Mand

ga产Eandsuchthatthe

integral

』(础)一g(f))2dt,M_<tgN,g(石)=y

istheminimum

anlong

allselections

ofallvaluesNandM.mTINNme.aSBl*e

is

expressed

inmsand

givenby

theformulaTINN=M.N.interval

histogram(TINN)is

the

baselinewidth

ofthedistributionmeasuredas

abaseofatriangle,approximatingthe

NN

intervaldistribution(the

minimum

square

differenceisusedtofindsuchatrian西e).Detailsof

computing

the

HRV

triangular

indexandTINNareshown

in

Fig.2.Both

these

measures

express

overallHRVmeasuredover24handaremoreinfluenced

by

thelOWer

than

by

the

higIlel"fi-equencies【31].Othergeometric

methodsarestill

inthe

phase

of

exploration

and

explanation.Themajoradvantageof

geometric

methodsliesintheirrelative

insensitivity

to

一8一

胃;Ⅳ髫

igl|o

大连理工大学硕士学位论文

the

analytical

quality

oftheseriesofNNintervals【32].The

majordisadvantage

istheneed

forareasonablenumberofNNintervalsto

constructthe

geometricpattern.Inpractice,

recordings

ofatleast20min(butpreferably

24h)should

beusedtoousurethecorrect

performanceofthe

geometric

methods,i.e.thecurrent

geometric

methodsageinappropriate

to

assessshort-term

changesinHRV.

3.4

Frequency

domeinmethods

Various

spectralmethods【33】for

theanalysisofthe

tachogram

have

been

applied

since

thelate1960s.Powerspectraldensity伊SD)analysisprovides

thebasicinformationofhow

power(i.e.variance)distributesasafunctionof呐uency.Mdcpendentofthemethod

employed,only

anestimateofthe

trim

PSDofthe

signalscanbeobtained

by

proper

mathematical

algorithms.

MethodsforthecalculationofPSD

may

be

generally

classifiedas

non-parametric

and

parametric.In

mostinstances.botllmethods

providecomparable

results.Theadvantagesof

the

non-parametric

methodsage."①the

simplicity

ofthe

algorithmemployed(Fast

Fourier

Transform—FFT-in

mostofthecases)and(萤melligh

processing

speed.whilst

the

advantagesofparametricmethodsare:smoother

spectralcomponentswhichcanbe

distinguishedindependently

ofpreselectedffequency

bands;easypost-processing

ofthe

spoctmmwithanautomaticcalculationoflowandhi曲呐uencypowercomponents

and

cosy

identificationofthecentralffequencyofeachcomponent;anaccurateestimationofPSD

evenonasmallnumberof

samplesonwhichthe

signal

issupposedtomaintain

stationarity.

Thebasic

disadvantageof

parametric

methodsistheneedtovmfythe

suitability

ofthe

chosenmodelandits

complexity“e.the

orderofthemodel).

Only

the

LFandHFcomponents

correspondto

peaks

ofthe

spcgtrum

whilethevLFand

ULFCanbeapproximatedbyalineinthis

plot

with

logarithmic

scalesonbothaxes.The

slope

ofsuchaline

isthemeasureofHRV.

Spectralcomponents

一9

墅墼!型竺兰型型塑壁咝!麴塑哑

Frequency砰酗

Fig.3.3

Example

ofaneatimate

ofpowerspectral

demityobtainedfrom

the

entire

24-hintervalofa

Ionsterm

Holter

recording.

Short-term

recordingsthreemain

spectralcomponentsaredistinguished

inasp戗:tnm

calculatedfrom

shortterm

recordings

of2to5mill:verylOWfrequency(VLF),lowfrequency

(LF),and

high厅equency(HF)components.Thedistributionofthe

power

andthecentral

丹equencyofLFandHFarenotfixedbut

mayvary

in

relationto

changes

inautonomic

modulationsoftheheartperiod.nephysiologicalexplanation

oftheVLF

component

is

muchlessdefinedandtheexistenceofaspecificphysiologicalprocess

attributabletothese

heart

period

changesmight

evenbe

questioned.The

non-harmonic

component

whichdoesnot

havecoherent

properties

andwhichisaffected

byalgorithmsofbaselineortrendrernovalis

commonlyaccepted笛amajorconstituentof

VLF.Thus

VLFassessedfromshort-term

recordings

fc.g.5

min)isadubiousmeasuleandshouldbeavoidedwhen

interpreting

the

PSDofshort-termECGs.MeasurementofVLF.ISandHF

powercomponentsiS

usually

madeinabsolutevaluesofpower(ms2),butLF

andHF

mayalsobemeasuredinnormalized

units(n.u.)which

represent

therelativevalue

of

each

powercomponentinproportiontothe

totalpower

minustheVLFcomponent.TherepresentationofLFandHFin

n.u.emphasizes

thecontrolledandbalancedbehaviourofthetwobranchesoftheautonomic

nervoussystem.

Moreover。normalizationtendstominimizethe

effectonthevaluesofLFandHFcomponents

ofthe

changesintotalpower.Nevertheless.n.u.shouldalways

bequotedwithabsolutevalues

of

LF

andHF

power

inordert0describeintotalthedistributionof

power

in

spectral

components.

Long-term

recordingsSpectral

analysismay

also

be

usedtoanalysethe

sequence

ofNN

intervalsintheentire24-h

period.The

resultthenincludesallultra-low台equencycomponent

(UL】哆,inadditionlo

v】LF,LF

andHFcomponents.1kslope

ofthe24-h

spectrum

Canalso

10一

大连理工大学硕士学位论文

be鹊g髂scdonalog-log

scale

by

linear

fitting

thespec嘲values.Table21istsselected

frequency-domain

measures.The

problemof‘stationarity'isfrequently

discussed

with

long-term

recordings.If

mechanisms

responsible

for

heart

period

modulationsofa

certain

frequency

remain

unchangedduring

thewhole

period

of

recording

the

corresponding

frequencycomponentofHRV

may

beusedasameasugeofthesemodulations.Ifthe

modulationsarenot

stable,interpretation

oftheresultsoffrequencyanalysis

islesswell

defined.In

particular,physiological

mechanismsofheartperiod

modulations

responsible

for

LFandHF

powercomponentscannotbeconsidered

stationaryduring

the24-h

period.Thus,

spectral

analysisperformedintheentire24-h

periodaswellasspectral

resultsobtainedfrom

shortersegments(e.g.5rain)averaged

OVertheentire2仙period(theLFandHFresultsof

thesetwocomputationsarenotdifferent)provideaverages

ofthemodulations

attributableto

theLFandHFcomponents(Fig.3.31.Suchaverages

obscuredetailedinformationabout

autonomicmodulationof

RR

intervalsavailablein

sbOrt盯recordings.It

should

be

rememberedthatthecomponentsofHRV

provide

measurementsofthe

degree

ofautonomic

modulationsratherthanofthelevelofautonomictoneand

averages

ofmodulationsdonot

repgesentallaveraged

leveloftone.

3.4.1Ieehni

cQI

roqu

irementsandreooemendations.

Becauseofthe

important

differencesinthe

interpretation

ofthe

results,thespectral

analyses

ofshortand

long-termeleetrocardiograms

should

always

be

strictlydistinguished

The强aIysedECG

signal

should

satisfy

several

requirementsinordertoobtainareliable

spectralestimation.Anydeparture

fromthe

followingrequirementsmay

leadto

unreproducible

resultsthataredifficultto

interpret.In

ordertoattributeindividual

spectral

componentstowell

definephysiologicalmechanisms,such

mechanismsmodulatingtheheart

rateshouldnotchangeduring

therecording.Transientphysiologicalphenomenamayperhaps

be

analysedby

specific

methodswhichcurrently

constituteachallengingresearch

topic,but

whichagenot

yetready

tobeusedinappliedresearch.Tocheckthe

stability

ofthe

signal

in

termsofcertain

spectral

components.traditionalstatistical

testsmaybe

employed.11坞

samplingrate

has

tobe

properly

chosen.Alow

samplingratemayproduceajitterin

the

estimationoftheRwavetiduciai

point

whichaltersthe

spectrumconsiderably.Theoptimal

rangeis250-500

Mz

orperhaps

even

higher,whilealowersamplingrate(in

any

case100Hz)

may

behave

satisfactorilyonly

ifanalgorithm

ofinterpolation(c.鲁parabolic)isusedto

refine

theRwave

fidudalpoint.Baseline

andtrendremoval(ifused)may

affectthe

lower

componentsin

the

spectrum.It

isad“sabletocheckthefrequencyresponseofthefilterorthe

behaviourofthe

regressionalgorithm

andtoveilfythatthe

spectralcomponentsofinterest

ale

notsignificantly

affected.

旦竺璺坠!堂垫婪竺型塾堕塑型!型竺坐鲤

ThechoiceofQRSfiducial

pointmay

becritical.Itis

neo晦sary

to

useawelltested

algorithm(i.e.derivative+threshold,template,correlationmethod,etc.)inordertolocatea

stableand

noise-independent

reference

point.A

fiducialpointlocaliz司farwithintheORS

complexmay

also

beinfluenced

byvarying

ventricularconduction

disturbances.Ectopic

beats.arrhythmic

events,missing

data

andnoiseeffects

may

alterthe

esfimationofthePSD

of

HRV.Properinterpolation(or

linear

recessionorsimilar

algorithms)Oil

preceding/successivebeatson

theHRV

signalsoron

itsautocorrelationfunctionmayreduce

this

error.Preferentially,short-termrecordings

whicharefleeof

ectopy,missing

data,and

noiseshouldbeused。Insomecircumstances,however,acceptanceof

orgyectopic-free

short·termrecordingsmayintroduce

significantselection

bias.Insuch

cas翩.proper

interpolation

shouldbeusedandthepossibilityoftheresults

being

influenced

byeetopy

shouldbeconsidered.Thetelativenumberandrelativedurationoflmintervalswhich、糯

omittedand

interpolated

shouldalsobequoted.

3.4.200rrelatlonanddifferencesbetweentimand

frequency

domalnmeasures

Ⅵm髓analysingstationary

short-term

recordings.moreexperienceandthenretical

knowledge

existsonthe

physiologicalinterpretation

oftlleffequenc州omainmeasures

comparcdtothetime-domain

measlesderivedfromthesame

recordings.However,many

timeandfrequency-domainvariablesmeasuredOVertheentire24-h

periodarestrongly

correlatedwitheachother.These

strong

correlationsexistbecanseof

bothmathematicaland

physiologicalrelationships,m

addition.thephysiologicalinterpretation

ofthe

spectral

components—ca—lculatedOVer24his

difficult,for

thereasonsmentioned(section

entitled

Long-term

recordings).Thus,tmlessspccial

investigations

areperformedwhichusethe24-h

HRV

signal

toextractInformationotherthanthe

usualfrequencycomponents(e.g.the

log—logslope

ofspectrogram),the

resultsof

frequency-domainanalysis

areequivalentto

thoseoftime,--domain

analysis,which

iseasierto

perform.

3。5

RhythmpatternanaIysiS

Asillustratedin

Fig.3.4,the

time-domainand

spectral

methodssharelimitations

imposedby

theirregnlantyoftheRR

series.Clearly

different

profilesanalysed

by

these

techniquesmaygive

identical

results.Trends

of

decreasingorincreasingcyclelength

arein

realitynotsymmetrical【34,35】勰heartrateaccelerationsareusually

followed

byafaster

decrease,In

spectralresults,this

tendstoreducethe

peak

atthefundamental丘equency,andto

enlarge

itSbasis.T1lisleads

to

theideaof

measuring

blocksof

RR

intervalsdetermined

by

properties

ofthe

rhythm

and

investigating

the

relationship

ofsuchblockswithoutconsidering

theintemal

variability.

一12一

大连理工大学硕士学位论文

Approaches

defiMedfromthetime-domainandthefrequency-domainhasbeen

proposed

inordertoreducethesedifficulties.Theintervalsp_cl锄嗍andsp_。ctmm

ofcoul怄methods

leadto

equivalentresults(Fig.3mandarewellsuitedtoinvestigate

the

relationship

betweeal

HRVandthe

variability

ofother

physiological

me&sures.Theinterval

spectrum

iswell

adapted

tolinkRRintervalstovariablesdefinedonabeat-to-beat

basis(e.g.bloodpressure).

11lc

spectrum

ofcountsis

preferable

ifRRintervalsarerelatedtoacontinuoussignal(e.吕

respiration),ortotheocculTeqllCeofspecial

eveuts(e.g.arrhythna曲.The‘peak-valley’

proceduresarebasedeitheron

the

detectionofthesummitandthenadirofoseillations『36,

37】orOllthedetectionoftrendsofhenrt

rate【38].Thedetection

may

belimitedtoshort-term

changes

butitcanbeextendedto

longer

variations:secondandthirdorder

peaks

and

troughs

orstcpwise

increaseofasequ黜ofconsecutiveincreasingordecreasingcycles

surro岫ded

byopposite

trends.11怆variousoscillationsoanbeeharaetcrizedonthebasisoftheheartrate

acceleratingorslowing,thewavelength

and/or

the

amplitude.Inamajorityofshort-to

mid-term

recordings,the

resultsarecorrelated丽th呐uencycomponentsofHRV【39].

nle

correlations.however,tendtodiminish勰the

wavelengthoftheoscillationsandthe

recording

duration

increase.Complex

demodulation

BSesthe

techniques

of

interpolation

and

detrending【40】andprovides

thetime

resolution

necessary

todetectshort-termheartrate

changes.as

wellastodescribetheamplitudeandphaseofparticular台equencycomponentsas

functionsoftime.At

present,thenon-linearmethods

representpotentiallypromising

toolsfor

HRVassessment,butstandardsare

lacking

andthefull

scope

ofthesemethodscannotbe

assessed.Advancesin

technology

andthe

interpretation

oftheresultsofnon-lineaxmethods

areneededbe如rethesemethodsare

ready

for

physiological

andclinical

smdies.

一13一

坚塑坠!墅墅垫型竺鲤坠墅壁螋!塑竺壁唑

(c)

05∞

Fig.3.4

Example

offour

synthesised

timeserieswith

identicalme卸s,standarddeviations。and

ranges.

Series(c)and(d)also

haveidenticalautocorrelationfenctionsandthereforeidentical

powerspec仃:a.

3.6Non-I.nearmethods

Non-linear

phenomenaalecortainlyinvolvedin

the

genesis

of

HRV.111cyare

determined

bycomplex

interactionsof

haemodynamic,electrophysiological

andhumoral

variables,aswellas

by

autonomic

andcentralneqt-vousregulations.It

has

beenspeculatedthat

analysis

ofHRVbasedonthemethodsofliOn—linear

dynamicsmight

elicitvaluable

informationforthe

physiological

interpretation

ofHRVandfortheassessmentoftheriskof

suddendeath.Theparameterswhichhavebeenusedtomeasurenon-linenr

properties

ofHRV

includel/f

scaling

ofFourierspectra【41,42],Hscaling

exponent,andCoarse

Graining

SpectralAnalysis(CGSA)Fordatarepresentation,Poincaresections,10W-dimensionattractor

plots,singularvalue

decomposition,and

attractortrajectorieshavebeenused.Forother

quantitativedcscriptiOIlS,the

D2correlation

dimension,Lyapunovexponents,and

Kohnogoroventropyhavebeenemployed[43].

Although

in

principle

these

techniques

havebeenshowntobepowerfultoolsfor

characterization

ofvariouscomplexsystems,nomajorbreakthrough

has

yet

beenachieved

by

their

application

tobio-medicaldata

including

HRV

analysis.It

ispossiblethat

integral

complexity

measuresalenot

adequate

to

analyzebiologicalsystems

and

thus,aretoo

insensitivetodetectthenon—linear

perturbations

of

RR

intervalwhichwouldbeof

physiologicalorpracticalimportanco.More

encouragingresultshavebeenobtained

using

differential,ratherthan

integralcomplexitym翩sur髓,e.g.thescaling

indexmethod

However;,

nosystematic

study

hasbeen

conducted

to

investigate

large

patientpopulationsusing

these

—14一

methods.At

present,the

liOn·linearmethods

represent

potentiallypromising

tools

for

HRV

assessment,but

standardsarclacking

andthefull

scope

ofthesemethods

cannotbeassessed.

Advancesintechnologyandtheinterpretationoft.he

resultsofnon-linearmethodsarcneeded

before

these

methodsaieready

for

physiological

andclinical

studies.

一15一

Physi0IogicaI

correIares

ofheartrateVariabi

ity

4.1AutonomioinfIuences

ofheartrate

Although

cardiac

automaticity

isintrinsictovarious

pacemakertissues,heart

rateand

rhythmarelargely

underthe

con订ol

oftheautonomicnervoussyst唧.

Thc

parasympathetic

influenceonheartrateismediatedviareleaseof

acctylcholineby

the

vagus

nerve.Muscarinic

acetylcholinereceptors

respondto

this

release

mostlyby

an

increaseincellmembrane

K+conductance.Acetyicholine

alsoinkibitsthe

hyperpolarization

activated‘pagemaker’current

IfThe‘lk

decay'hypothesisproposes

that

pacemaker

depolarization

resultsfromslowdeactivationofthedelayed

rectifier

current,m,which,dueto

atime-independent

backgroundinwardcurrent,causes

diastolic

depolarization.Conversely,

the‘Ifactivation’hypothesissuggest

that

following

actionpotentialtermination,Ifprovidesa

slowlyactivating

inwardcurrent

predominating

OVer

decaying

IL

thus

initiating

slow

diastolic

depolalization.

The

sympathetic

influenceOnheartrateismediated

by

releaseof

epinephrineand

norepinephrine.Activationofa-adrenergicreceptors

resultsin

cyclic

AMP

mediated

phosphorilatiOil

ofmembrane

proteins

andincreasesinICaLandinIf.n增endresultiSan

acceleration

oftheslow

diastolic

depolarization.Underrestingconditions,vagaltone

prevails

andvariationsinheart

periodarelargelydependentonvagal

modulation.111e

vagal

and

sympatheticaetivityconstantly

intcracts.Asthesinus

node

iSdchiIl

acetylcholinesterase,the

effectof

any

vagalimpulseis

briefbecausethe

acetylcholineis

rapidlyhydrolysed.

Parasympatheticinfluencesexceedsympatheticeffects

probably

viatwoindependent

mechanisms:a

cholincrgically

inducedreductionofnorepinepbrine

releasedin

responseto

sympatheticactivity,andacholinergic

attenuationofthe

responsetoaadrenergic

stimulus.

Thel浪iiltervalvariations

present

duringresting

conditionsrepresentafine

tuning

of

thebeat-to-beatcontrolmechanisms.Vagal

afferentstimulation1cadstoreflexexcitationof

vagal

efferent

activity

andinhibitionofsympatheticefferentacti“锣.nleopposite

reflex

effectsare

mediated

by

thestimulationofsympatheticafferent

activity.

Efferent

vagalactivity

also

appears

tobeunder‘tonic’restraint

by

cardiacafferent

sympatheticactivity.Efferentsympatheticand删activitiesdirec'tedtothesinusnodeale

characterized

bydischargelargelysynchronous

witheachcardiac

cycle

whichc强be

modulated

bycentral(e.g.vasomotor

and

respiratoryc_,cntres)andperipheral(e.g.oscillation

inarterial

pressure

and

respiratorymovements)oscillators【44].Theseoscillators

generate

—16一

大连理工大学硕士学位论文

rhythmic

fluctuationsinefferent

n伽'al

discharge

whichmanifestasshortand

long-term

oscillation

inthe

heart

period.Analysis

ofthese

rhythmsmaypermit

inferencesonthestate

andfunctionof①thecentraloscillators,②thesympathetic

and

vagal

eferentactivity,③

humoralfactors,and④thesinusnode.An

understanding

ofthemodulatoryeffects

ofneural

mechanisms011thesinusnodehasbeenenhanced

by

spectralanal)'sisofHRV.

111eefferent

vagal

activity

isamajorcontributortotheHF

component,asseeninclinical

and

experimental

observationsofautonomicmanoeuvr龆suchaselectrical

vagal

stimulation,

muscarinic

receptorblockade,and

vagotomy.More

conll"oversialisthe

interpretation

ofthe

LFcomponentwhichisconsidered

by

some嬲amarkerofsympatheticmodulation

(especially

when

expressing

it

innormalized

units)andby

othersasaparameter

thatincludes

bo血sympatheticand

vagal

influences.

Ⅲs

discrepancyisduetothefactthatin

someconditions.associatedwithsympathetic

excitation,a

decrease

intheabsolute

power

oftheLFcomponentisobserved.Itis

important

torecallthat

duringsympatheticactivationthe

resultingtachycardia

is

usuallyaccompanied

byamarkedreductionintotal

pOWer,whereas

thereverseoccursduringvagal

activation.

Whenthe

spectralcomponentsageexpressed

inabsolute

units(ms2),the

changesin

total

power

influenceLFandHFinthesame

direction

and

preventthe

appreciation

ofthe

fractionaldistributionoftheenergy.TIlis

explainswhy

in

supinesubjectsundercontrolled

respirationatropine

reducesbotllLFand

HF[14】andwhyduring

exerciseLFismarkedly

reduced.

Thisconceptisexemplifiedin

Fig.3.3

showing

the

spectralanalysisofHRV

in

anormal

subjectduring

control

supine

conditionsand90

head-up

tilt.Duetothereductionintotal

power.LFappears鹤unchangedifconsideredinabsolute

units.However,after

normalization

anincrease

inLFbecomesevident.Similar

results

apply

tothe

LF/HFratio.

Spectralanalysis

of24.h

recordings

showsthatinnormalsubjectsLFand

HI:%Vessed

innormalizedunitsexhibitacircadian

pattern

and

reciprocalfluctuations,withhJ曲Ca"VMUes

ofLF

inthe

daytime

andofHFat

night.

These

patterns

becomeundetectablewhenasinglespectrum

oftheentire24·h

period

is

usedorwhen

spectra

of

subsequent

shorter

segmentsAreaveraged.Inlong-termrecordings,

theHFandLFcomponentsaccountforapproximately5%oftotalpower.AlthoughtheULF

andVLF

componentsaccountforthe

remaining

95%oftotalpoWer,theirphysiological

correlaresarestillunimown.LFandHFcaninereaseunderdifferentconditions.Anin.eased

LF(expressedin

normalizedunits)isobserved

during

90tilt,standing,mentalstressand

moderateexercise

inhealthysubjects,andduring

moderate

hypotension,physical

activity

and

occlusionofacoronaryarteryorcommoncarotidarteriesinconscious

dcIgs.Conversely,an

—17一

塑墼!些垫望型塑壁婴!墅生唑

increase

inHFisinduc蝴bycontrolled

respiration,cold

stimulationofthefaceandrotational

stimuli.

4.3

Summary

andrecommendat

ons

fori

nterpretat

ion

of

HRV

Vagalactivity

isthemajorcontributortotheHFcomponent.Disagreementexists

in

respect

oftheLF

component.Some

studies

suggest

that

LF,when

expressed

in

normalized

units,isaquantitative

markerfor

sympathetic

modulations,other

stodicsviewLFas

reflexing

both

sympathetic

and

vagalactivity.Consequently,theLF/HFratioisconsidcrod

by

some

investigators

to111:Iil-1"01"sympatho/vagal

balanceortoreflect

sympathetic

modulations.

Physiological

interpretation

oflower

frequencycomponentsofHRV(thatisoftheVLFand

ULFcomponentslwarrants

fI】rⅡler

elucidation.ItisimportanttonotethatHRVmcasnr鼯

fluctuationsinautonomic

inputs

totheheartratherthanthemeanlevelofautonomic

inputs.

Thusbotllautonomicwithdrawalandasamratmglyhigh

levelof

sympathetic

inpm

leadsto

diminishedHRV.

一18—

大连理工大学硕士学位论文

Changes

ofHRVrelatedto

specific

pathoIogios

Areduction

ofHRVhasbeenrqmrtedin

several

cardiological

and

non-caxdiological

di剐鞫瞎韶.

5.1

gyocardial

infarotion

Dq’ressedHRVafterMI

may

reflexztadecDeasein

vagalactivity

dbectedtothehcan

whichleadstoprevalen∞of

sympathetic

mechanismsandtocaxdiacelectrical

instability.In

the

acute

phase

ofMLthereductionin24·hSDNNis

significantly

relatedtoleftventriculax

dysfunction,peak

creatine

kinase,andKillip

class.

The

mechanism

by

whichHRVis

transiently

reducedafterMIand

by

whichadepressed

HRVis

predictive

oftheneural

response

to

acuteMIisnot

yet

defined.butitis

likelyto

involve

derangements

intheneural

activity

ofcardiaconion.One

hypothesis

involves

cardio—cardiac

sympatho-sympathetic

and

sympatho—vagal

reflexesand

suggests

thatthe

changes

inthe

geometry

ofa

beating

heartduetonecroticandnon.eontractingsegmentsmay

abnormallyincrease

the

firing

of

sympathetic

afferentfibres

by

mechanicaldistortionofthe

sensoryending.

This

sympathetic

excitationattenuatesthe

activity

of

vagal

fibresdirectedtothesinus

node.Another

explanation,especially

applicabletomarkedreductionof

HRV,is

thereduced

responsivenessofsinusnodalcellstoneural

modulations.Spectralanalysis

of

HRVin

patientssurviving锄acute

MIrevealedareductionintotalandintheindividualpowerof

spectralcomponents.However,whenthepowerofLFandHFWascalculatedinnormalized

units.allincreasedLFandadiminishedHFwereobserved

during

botll

resting

controlled

conditionsand24-h

recordings

analysedovermultiple

5min

periods.These

changesmay

indicateashiftofsympatho-vagal

balancetowards

sympatheticpredominance

andreduced

vagal

tone.Similarconclusionswereobtained

byconsidering

the

changes

intheLF/HFratio.

The

presence

ofanalterationinneuralcontrolmechanismsWasalso

reflected

by

the

blunting

ofthe

day.Ilight

variationsoftheRRintervalandLFandHF

spectral

components

presentinaperiodrangingfrom

daystoafewweeksaftertheacuteevent.In

post

MI

patients

witllaverydepressed

HRV.mostof

the

residualenergy

isdistributedintheVLFfrequency

range

below0.03Hz,with

onlyasmall

respiration-related

HF.Thesecharacteristicsofthe

spectralprofilearesimilartothoseobservedinadvancedcardiacfailureoraider

cardiac

transplant,andaxelikely

toreflecteitherdiminished

responsiveness

ofthe

targetorgan

to

neural

modulatoryinputsorasaturating

influenceonthesinusnodeofapersistentlyhigh

sympathetictone.

一19一

堕坠!些垫婪型墅壁咝!螋塑堕

5.2Diabetic

neuropathy

neuropathy

aasociatedwithdiabet鹳mdlitus,characterizedby

alterationof锄all

nervefibres.areduetionintime-domain

parameters

ofHRV

sgemsnot

only

to

carrynegative

prognostic

valLiebutalsoto

precede

theelinical

expression

ofautonomicn帆ropathy.In

diabetic

patients

without

evidenceofautonomic

neuropathy,reductiOll

oftheabsolute

poWelt"

ofLFandHF

during

controlledconditionswas

als4)reportedHowever,when

theLFmFratio

wasconsideredorwhenLFandHFwereanalysedinnormalized

units。riosignificant

differencein

comparisontonormalswas

present.Thus.the

initialmanifestationof

this

neuropathy

is

likely

toinvolve

both

efferentlimbs

ofthe

autonomic

nervous

system.

5.30ardiao

transpIantation

very

reducedHRVwithnodefinite

spectralcomponents

was

reported

in

patients

wim

arecenthearttranspl锄.111eappearanceofdiscrete

spectralcomponentsinafewpatientsis

consideredtoreflectcardiacre-innervation.11畦sreAnnervation

mayoccur

asearly

as1to2

yearsposttransplantationandis

usually

of

sympatheticorigin,Indeed,the

correlation

betweenthe

respiratory

rateandtheHFcomponentofHRVobservedinsometransplanted

patients

indicatesthatanon-neuralmechanism

may

alsocontributeto

generate

respiration.relatedrhythmicoscillation.The

initialobservationofidentif弭ngpatients

developing

an

allograflrcjectionaccording

tochanges

in

HRV

couldbcofclinicalinterestbut

ng@dsfurtherconfirmation.

AreducedHRVhasbeenconsistentlyobservediu

patients

with

cardiacfailure.Inthis

conditioncharacterized

bysignsofsympathetic

activation,such勰faster

heartratesand

high

levelsof

circulatingcathe

colamines,a

relationship

between

changes

inHRVandtheextent

of1疆ventricular

dysfunction

was

controversiallyreported,Infact,whereas

thereduetionin

timedomainmeasuresofHRVs#ernedto

parallel

theseverityofthe

disease,therelationship

between

spectralcomponents

and

indicesofventrieular

dysfunction

appears

to

bemore

complex.Inparticular,in

most

patients

withavery

advanced

phase

ofthe

diseaseandwitha

drasticreductionin

HRV.a

LFcomponentcouldnotbedetected

despite

clinlcaI

signs

of

sympatheticactivation.Thus,inconditions

characterized

by

markedand

unopposed

persistent

sympatheticexcitation,the

sinusnodeseanstodrastically

diminishitsresponsivenessto

neural

inputs.

5.4

TetrapIegia

Patientswithc栅omc

completehigh

cervical

spinal

cordlesionshave

intactefferent

vagal

andsympatheticneural

pathways

directedtothesinusnode.However,spinal

sympatheticneuronsaledeprived

of

modulatory

controland

in

particular

ofbaroreflex

一20一

大连理工大学硕士学位论文

supraspinalinhibitoryinputs.For

this

reason,these

patients

representaunique

clinicalmodel

withwhichtoevaluatethecontributionof

supraspinal

mechanismsindetermining

the

sympatheticaetivity

responsible

forlowfrequencyoscillationsofHRV.Ithasbeenreported

thatnoLFcouldbedetected

in

tetraplegicpatients.thussuggesting

tlle

critical

roleof

supraspinal

mechanismsin

determining

the0.1Hz

rhythm.Tworecentstudies,however,have

indicatedthatan_LFcomponentcanalsobedetectedinHRVandarterial

pressure

variabilities

ofsome

tetraplegiepatients.WhileKoheta1.attributedtheLFcomponentof

HRVtovagal

modulations,Guzzettiet

al,attributedthesamecomponenttosympatheticactivity

beM:auseof

the

delay

withwhich

the

LFcomponent

appearedafter

spinalsection,suggestingallmerging

spinalrhythmicitycapableofmodulatingsympatheticdischarge.

一2l一

坚墅坐!些竺型堕!型塑驾!墅竺塑哑

6godificationsofHRV

byspecifiC

interventions

日壕rationalefor

tryingtomodify

HRVafterMIstemsfrom

multiple

oh∞rvatiom

indicating

thatcardiac

mortality

is

highcramongpost—MIpatientswhohaveamoredepressed

HRV.111einferenceisthatinterventionsthataugmentHRV

may

be

protectiveagainst

cardi∽

mortality

andsuddencardiac

death.Although

the

rationaleforchangingHRVis

sound,it

containsalsotheinhorent

danger

of

leading

totheunwarranted

assumption

thatmodification

ofHRVtranslates

directly

into

cardiac

protection,which

maynotbethecase.

Tk

target

iStheimprovementofcardiacelectrical

stability,and

HRViSinstamarkerof

autonomic

activity.Despite

the

growing

collSCIISllbthat

increases

in

vagalactivitycarlbe

beneficial,itisnot

yet

knownhowmuch

vagalactivity(oritsmarkers)hastoincreasein

ordertowo“deadequateprotcctioa.

6.1

Beta—adrenerg

iCbIockadeandHRV

T量ledataontheeffectofa-biockorsonHRVinpost-MIpatientsa糟surprisingly

scanty.

Despite

theobservationof

statisticallysignificantincreases,the

actual

changesagevery

modest.However,it

isofnotethata-blockade

prevents

therisein

theLFcomponent

observed

inthe

morning

hours.Inconscious

post-MIdogs,a-blockors

donotmodi移HRV.11le

unexpectedobservation

that,prior

toMI,a-blockade

increasesHRV

only

intheanimus

destinedtobeatlowriskforlethalarrhythmiaspost-MImaysuggest

novel

approachesto

post-MIriskstratifieation.

6.2

AntiarrhythmiCdrugs

andHRV

Dataexistforseveral

antiagrhythmicdrugs.Reeainide

and

propafenone,butnot

amiodarone,worereportedtodecrcasetime-domainmeasuresofHRV

inpatientswith

chomcventricular

arrhythmia.In

another

studypropafenone

reducedHRVanddecreasedLF

muchmorethan

HF.resulting

in

asignificantly

smaller

LFmFratio.A

largor

study

confirmedthat

flecainide,and

alSOencainideandmoricizine,decreasedHRV

inpost.MI

patientsbut

found

nocorrelationbetweenthechangein

HRVand

mortalityduring

follow-up.

Thus,¥omeantiarrhythmicdn{缪associatedwithincreased

mortalitycanreduce

HRV.

However,it

isnotknownwhetherthese

changes

inHRVhave

any

direct

prognostic

significance.

6.3

ScopolamiRe

andHRV

Lowdosemuscaginic

receptorblockers,such

as

atropine

andscopolamine,mayproduce

aparadoxical

increase

in

vagal

efferent

activity,as

suggested

byadecrease

inheartrate.

一22—

大连理工大学硕士学位论文

Differentstudiesexamined

the

effectsoftramdermal

scopolamineOnindices

ofvagal

activitv

in

patients

witharecentMIand

witll

congestive

heartfailure.Scopolaminemarkedly

increases

HRV.whichindicates

that

pharmacological

modulationofneural

aetivity

with

scopolaminemayeffectively

increase

vagalactivity.However,efficacyduringlong-term

treatment

hasnotbeenassessed.Furthermore.10Wdosescopolaminedoesnot

prevent

yentricular

fibrillationduetoacute

myocardial

ischaemiainpost—MIdo举.

6.4

lhromboIysiS

andHRV

Theeffect

of

thrombolysisO/IHRV(assessedbypNN50),Wasreportedin95patients

withacuteMI.HRVWas

higher

90minafter

thrombolysis

in

the

patients

with

patency

ofthe

infarct—related

artery.However,this

difference

wasnolonger

evidentwhentheentire24h

were

analysed.

6.5Exeroise

training

andHRV

Exercise

trainingmay

decreasecardiovascular

mortality

andsuddencardiacdeath.

Regular

exercise

training

isalso

thoughtcapable

of

modifying

theautonomic

balance.A

recentexperimentalstudy,designed

toassesstheeffectsofexercisetrainingonmarkersof

vagalactivity,has

simultaneouslyprovided

informationonchanges

incardiacelectrical

stability.Consciousdogs,documentedtobeat

high

risk

by

the

previous

OP.℃:UITanceof

veotricularfibrillationduringacutemyocardial

ischaemia,wererandomlyassignedto6

weeksofeither

daily

exercise

trainingorcage

restfollowed

by

exercise

training.After

training,HRV(SDNr0

inewased

by

74%andallanimalssurvivedanewischaemictest.

ExercisetrainingCallalsoaccelerate

recovery

ofthe

physiologicalsympatho-vagal

interaction,

asshowninpost-MIpatiants.

23—

堕些堕塑垫型墅堕咝燮塑鲤

70IinicaIuse

of

heartratevariabiI

ity

AlthoughHRVhasbeen

thesubjectofnun'lel"OU8clinicalstudies

mv璐figatmg

a州de

spectrum

of

cardiological

and

non-cardiological

diseasesandclinical

conditions,a

general

oonsalsusofthe

practicaluseofHRVinadultmedicinehasbeenreached

only

intwoclinical

scenarios.D印硝sedHRVcanbeused雒a

predictorofriskafteracuteMI

andasallearly

warningsignofdiabetic·neuropathy.Assessment

ofriskafteracutemyocardialinfarction

Fig.7-1

Cumulativesurvivalofpa6entsalk'rMI.(a)Showssurvivalofpa妇bstratified

according幻

24-hSDNNvaluesinthree

groups

wilh

ont-offpointsof50and100ms,(b)Showssimilarsurvivalcurves

0fp撕∞臼stratified

accordingto24-hHRVumgllJarindexvalueswith

cut-offpoints

of

15

and20

tlni扭.

respectively.(DataofSL

George’s

Post—infarctionResearch

SurveyProgrammed.)

Theobservationthatin

patients

withanacuteMItheabsenceof

respiratory

sinus

arrhythraias

is

associatcalwith锄increase

in‘in-hospital’mortalityrepresents

the

firstofa

large

numbcrof

reports

whichhavedemonstrated

the

prognostic

valueof

assessing

HRVto

idctl呖母hi曲riskpatients.DepressedHRVisapowerfulpredictor

of

mortality

andof

矾hytIlmic

cumplicafiom(e.g.symptomatic

sustainedvcntriculartachycardia)inpatients

一24一

大连理工大学硕士学位论文

following

aente

MI(Fig.7.11.Thepredictive

valueofHRVis

independent

ofother

factors

establishedfor

post-infarction

risk

stratification,suchasdepressed

leftventricularejection

fraction,increasedventrieular-eetopic

activity,endpresence

oflate

potentials.For

prediction

ofa11.causemortality,thevalueofHRVis

similartothatofleftventricularejectionfrac矗on,

butHRVis

superior

toleftventricular

ejection

fractionin

predictingarrhyttmaicevents

(suddencardiacdeathendventrieular

tachycardia).Thispermits

speculation

thatHRVisa

strongerpredictor

of

arrhythmicmortality

ratherthan

non-arrhythmicmortality.However,

cleardifferencesbetweenHRVinpatients

suffering

fromsuddenendnon·sudden

cardiac

deathafteracuteMIhavenot

beenobserved.Nevertheless,thismight

also

berelatedtothe

natul'eofthepresentlyuseddefinition

ofsuddencardiac

death,whiehisboundtoincludenot

onlypatients

suffering

fromarrhythmia-related

deathbutalsofatalfeinfhrdionsendother

cardiovascularevents.nevalueofbothconventionaltime-domainend

frequency-domain

parameters

have

been

fillly

assessed

in

severalindependentprospective

studies,butbecause

of

usingoptimized

cut-offvalues

defining

normaland

depressed

HRV.thesestudies

may

slightly

SensitivityI蛳

Fig.7.2Comparison

ofpositive

predictive

characteristics

ofHRV(solidlines)and

ofcombinations

of

HRVwithleftventrieular白瞅ionfraction(dashedlines)andofmⅣ谢Ih1eftv%tricular

ejecdonfraction

andentopic

countsoil“.hECGs(dottedHnes)usedforidenffication

ofpatientsatrisk

ofl-yearcardiac

mortality(a)and1-year

arrhytlunicevents(suddendeathand/or

symptomatic

sustainedventricular

tachycardia(b)afteracute

myocardial

infarction,(DataofSt.George’SPostinfarction

Research

Survey

Pm乎孤nmed)

龉一

塑堕堂垫塑型塑竺咝塑熊鱼型

Useofnominal24-h

recordingsmay

berecommendedforriskstratificationstudiesafter

MI.Ontheotherhand.theass锱smcntofHRVfrom

short-termrecordingscanbe

usedfor

initial

screening

ofsurvivorsofacuteMI.Suehallassessmenthassimilarsensitivitybut

lowerspodfieityfor

predictingpatients

athi曲riskcomparedto24.h

HRV.Spectral

analysis

ofHRV

ins眦-vivorsofMI

suggested

thattheULFandVLFcomponentscarry

thehi曲est

predictive

value.As

the

physiological

correlateofthese

componentsisunknownandasthese

compon伽【忸correspondto

up

tO95%ofthetotal

power

whichCallbe

easily

assessedinthe

time-domain.theBseofindividual

spectralcomponentsofHRVforriskstratificationafterMI

iSnotmore

powerful

than

theuseofthose

time

domainmethodswhiehassessoverallHRV.

7.1

DeveIopment

ofHfivaftoracutemyocardieIinfarctiorl

The

timeaideracuteMIatwhichthe

depressed

HRVreachesthehigh戚predictivevalue

hasnotbeen

investigatedcomprehensively.Nevertheless,thegenial

collsellsu8isthatHRV

shouldbeassessed

shortlyprior

to

hospitaldischarge,i.e.approximately

1weekafterindex

infarction.Sucharecommendationalsofitswellinto

the

common

practiceof

hospital

managementofsurvivors.

Heartrate

variability

isdecreased

early

aiteracuteMIand

begins

toroT,overwithinafew

weeks;itis

maximally

butnotfully

recovered

by

6to12

monthsafterMI[45,46].

Assessmentofheart

ratevariability

atboththe

earlystage

ofMI(2to3

days

afteracuteMI)

【47】andpre-discharge

fromhospital(1to3weeksafteracuteMI)offersimportantprognostic

information.Heartrate

variability

measured

late(1ye哪afteracuteMIalsopredictsfurther

mortalityf48].Data

fromanimalmodels

suggest

thatthe咧ofHRV

recovery

afterMI

correlateswith

subsequcut

risk【491.

7.2HRVusedformuItivariateriskstratificatiOn

11lepredictivevalueofheartratevariabilityalone

ismodest.butcombination

withother

techniquessubstantiallyimproves

itspositivepredictiveaccuracy

OVeraclinicallyimportant

rangeofsensitivity(25%to75%)forcardiac

mortality

and

arrhythmicevents(Fig.7.2).

improvementsin

the

positive

predietiveaccuracyoverthe

range

ofsensitivitieshavebeen

reportedforcombinationsofHRVwithmeanheart

rate,left

ventricular

ejectionfraction,

frequencyofventricular

entopieactivity,parameters

of

high

resolutionelectrocardiograms(c.

吕p懈∞∞orabsenceoflatepotentials),andclinicalassessment[50].However,itisnot

knownwhichotherstratificationfactorsarethemostpractical

andmostfeasibletobe

combinedwithHRVformultifactorriskstratification.Systematicmultivariatestudies

ofpost

MIfiskstratificationareneededbeforeaconscnsBscanbe

reachedandbeforeacombination

ofHRVwithothervariables

ofprovenprognosticimportanceCanberecommended.

一加一

大连理工大学硕士学位论文

Manyaspects

thatarenotrdevantforunivariateriskstratificationneedtobeexamined:

it

isnotobviouswhetherthe

optimmn

cut-offvaluesofindividual

riskfactorsknownfi,om

univariatestudi,'sare印弘邵d如inamultivariate

setting,Different

multivariate

combinationsarcprobably

neededfor

optimizingpredictiveaccuracy

atdifferent

rangesofsensifi哪.Stepwisestrategies

shouldbeexaminedto

i,k-ntifyoptimumsequences

of

performing

individualtestsusedin

multivariatestratification.

Predictivevalue

ofdepressed

HRV

afteracute

myocardial

infarctionThe

following

facts

shouldbenotedwhen

exploiting

HRVassessmentinclinicalstudiesand/ortrials

involving

survivorsofaci.Romyocardialinfarction.DepressedHRV

iSapredictorof

mortality

and

arrhythmiccomplicationsindependentofotherrecognizedriskfactors.Thereis

ageneral

colrL.qffBSUSthatHRV

should

bemeasured

approximately

weekafterindexinfarction.

Although

HRVassessedfromshort-term

reeordingsprovides

prognostic

information,

HRVmeasuredinnominal24-h

recordings

isastronger

riskpredictor.HRV

assessedfi'om

short-term

recoMmgs

may

beusedforinitialscreeningofallsurvivors

ofanacuteMI.

NocurrentlyrecognizedHRV

measure

provides

better

prognostic

information

thanthe

time-domainHRVmeasures

assessing

overallHRV

fe.g.SDNNorHRVtriangular

index).

Other

measures,e导ULF

ofentire24.h

spectralanalysis,performequally

well.Ahi曲risk

groupmay

be

selected

by

the

dichotomy

limitsofSDNN<50msorHRV

triangular

index<

15.For

clinicallymeaningfulranges

of

sensitivity,thepredictive

value

ofHRV

aloneis

modest,althoughitishigher

thanthatof

any

otherSO

farrecognizedriskfactor.To

improve

thepredictiVevalue,HRV

may

becombinedwithotherfactors,However,optimumsetofrisk

factorsandcorrespondingdichotomy

limitshavenot

yet

beenestablished.

7.3AssessmentofdiabetiCneuropathy

Asacomplicationofdiabetesmellitus.autonomic

neuropamy

ischaracterized

byearly

and

widespreadneuronal

degeneration

ofsmallIlCa"Vefibers

of

both

sympathetic

and

parasympathetictractsf511.Its

clinicaImanifestationsareubiquitouswith

functional

impairmentand

include

posturalhypotension,persistenttachycardia,gustatorysweating,

gastroparesis,bladderatony

andnocturnaldiarrhea.Onceclinicalmanifestationsofdiabetic

autonomicnmo咖y(DAN)supervene,theestimated

5-yearmortality

is

approximately

50%【s2].Thus,earlysubclinicaldetectionofautonomic

dysfunction

is

important

forrisk

stratificationand

subsequent

management.Analyses

ofshort-termand/or

long-tcrm

HRV

have

proven

nsefulin

detectingDAN『s3].

Forthepatientpresenting

witharealor

suspect

DANthereagethroeHRVmethodsfrom

whichtochoose:①simplebedsideRRintervalmethods,②long-term

time-domain

measBres,whicharcmoresensitiveand

more

reproducible

thantheshort-termtests,and③

一27—-

fiequency..domaln

analysisperformed

undershort-term

steadystateconditionsandwhich眦

usefulin

separatingsympathetic

from

parasympathetic

abnomaalities.

7.4

Long—term

timedomainmeasures

HRVcomputed

from

24.h

Holterrecordsaremoresensitivethan

simple

bedsidetests(e.

吕Valsavaiilanouvel-,orthostatie

test,and

deepbreathing【54])fordetecting

DAN.Most

expedeliCe

hasbeen

obtained

withtheNN50and

SDSD【55】methods.UsiIlg

theNNS0

count,

wheretheIOWer95%confidenceintervalfortotalcounts

rangefrom500to2000

depending

Oilthe

age,about

halfofdiaberic

patientswilldemonstrate

abnormally

lowcounts

per

24h.

Morcowr.thereisaslTong

correlationbetweenthe

percentage

of

patients

witllabnormal

countsandtheextentofautonomic

neuropathy

determinedfromconventionalmeasures.

Besidestheirincreased

sensitivity,these24-htimedomainmethodsare

strongly

correlatedwithotherestablishedHRVmeasurementsandhavebeenfoundtobe

reproducible

andstableOVertime.Similarto

survivorsofMI.patients

withDANarealSOpredisposedtO

13001"outcomessuchas翱也i鼬deathhutitremai整tobedeterminedwhetherthe

HRV

measuresconfer

prognostic

information

among

di西eties.

7.5

Frequenoy

domain

measures

The

following

abnormalitiesinfrequencyHRV

analysisareassociatedwithDAN:①

reduced

power

in

all

spcctral

bands

which

isthemostcommonfinding,②failuretoincrease

LFonstanding,which

isareflectionofimpairedsympatheticresponseordepressed

baroreeeptorsensitivity;,③abnormallyreducedtotalpowerwith

unchangedLF/HF

ratio,

and④aleftwardshiftintheLFcentral

frequency,thephysiologicalmeaning

ofwhich

needsfurtherelucidation[561.

Inadvanced

naturopathie

smtes,the

restingsupine

powerspectrum

oftenreveals

extremely

lowamplitudesofall

spectral

components

making

itdifficultto

separatesignal

fromnoise.Itis

thereforerecommendedthatanmterventionsuchasstandingortiltbe

included.Anothermethodtoovercomethelow

signal

to

noise

ratioistointroducea

coherencefunctionwhichutilizesthetotal

power

coherentwithoneortheother

frequency

band【57].

一28—

大连理工大学硕士学位论文

8MateriaIsandMethod

In

this

paper

ECGsalerecorded丘砌10

healthysubjectsf5maleand5femalelwith

ageranging丘om

23to89.mECG

datatakenisdividedintofour

groups.20

to30,30to40,

41to701and71to90.111edatahas

beencollectedfromMrr.Bm

Arrhythmia

Database.1k

recordings

weredigitizedat360

s=nples

per

second

per

channel、“ml1-bitresolutionoveTa

10mV

range.Twoormore

cardiologists

indqgendently

annotatedeach

record;disagreements

wereresolvedtoobtainthecompeer.readable

referenceannotationsforeachbeat

(approximatelyl

10.000annotationsina11)includedwith

thedatabase.11”numberof

subjectsin

eachgroupisshowntable8.1.

Tab.8.1Numberofsubjectsinvariousgroups

AgerangeNumberofsubjects

20.30

31.40

41.70

71.90

Theheartrateisanalyzedin

byusing

nonlinear

parameters.

8.1

LargestLyapunovExponent(LLE)

LyapunovExponent丑1Saquantitative

measureofthesensitivedependence011the

initialconditions.Itdefines

the

average

rateofdivergenceoftwo

neighboringtrajoratories.An

exponentialdivergenceof

initiallynearbytrajectories证phasespacecoupledwith

folding

of

trajectories,toensllrethatthesolutionswillremain

finite,is

thegeneralmechanismfor

generating

deterministicrandomnessandunpredictability.Therefore,theexistenceofa

positive五for

almost

allinitialconditionsinabounded

dynamicalsystem

is

widely

used

definition

ofdeterministic

chaos.Todiscriminatebetweall

chaotic

dynamics

and

periodic

signals

Lyapunov

Exponent五ale

oftenused.Itisameasureoftherateatwhichthe

trajectoriesseparateoile

fTorn

other.The

trajectoriesofchaotic

signals

in

phasespacefollow

typical

patterns.Closelyspacedtrajectoriescotlverge

and

diverge

exponentially,relativeto

each

other.Fordyrm捌systems,sensitivitytoinitialconditionsisquantifiedby

the

LyapunovExponent五Theycharacterize

the

average

rateof

divergence

ofthese

neighboring旬喇ed鲥鹤.Anegativeexponentimplies

thattheorbits

approachacommonfixed

point.AZeI'Oexponentmeanstheorbitsmaintaintheirrelativepositions;theyare

on

astable

attractor.Finally,apositiveexponent

implies

theorbits矾Oilachaoticattractor.

29—

旦塑堕!堂垫型型些塑婴!堂塑唑

The

algorithmproposedby

Wolfetalisusedto

Largestlyapunov

exponent(LLE)flora

EEGdata.Foragiven

thetimeseries

gt)for

dimensional

phasespace

with

delay

coordinate

t'thatisa

pointon

theattractorisgivenby

{工(f),x(t+f),x(t+(肌一l弘))

Welocate

nearest

neighbor

toinitialpoint

{X(to),X(to+f),…x(to+(m—I)0}.

Anddenotethedistancebgtwoenthesetwopoints∞诋).Atalater

timetI,initial

length

willevolvetolength三7(^).Themeanexponentialrateof

divergence

oftwo

initially

close

orbitsischar∞terized

by2=再1渺M器(tk10一fo智92三’一)

Inimplementation

ofthis

program,thefollowing

setofnummcal

parameters

hasto

be

chosen:

P;{m,f,正Smax,Smin,thmax}wherem

is

the

embeddingdimension,t

is

delay,T

beingevaluationtimeandSmax,Sminarethemaximumand

minimum

separations

of

replacementpointrespectively

andthllla,x.isthemaximumorientation

eTfor.According

toDas

etalanembeddingdimensionbetween5to20andadelay

of1shouldbeChOSenwhen

calculating

LEfor

EEG

data.Inouranalysis

wehavechosenallembeddingdimensionof10

anddelayofl.

Results:Theresultsofthenonlinear

param毗ers

for

four

different

ageyoupare

presented

in

table8.2.

Tab.8.2Varia60n

ofuonliaear

parameters

forvarious

agegroup

normalsubjcctB

Agerange

LLB一—————丽j万————————————西蕊丽.0545

31.400.0760-0.0732

41.700.0928-0.0668

71-90O.1122旬,0926

8.2ResuItforfirst

group

The

fi嘲group

containstwosubjects:

(1)Age23Female

一30一

大连理工大学硕士学位论文

Fig.8.1

ECG

ofsubjectI:age

23

Fig.8.2Largest

Lyapunov

graph

forsubject1:age

23

Fig.8.3

ECGofsubjvct2:age

24

Fig.8.4

Largest

Lyapunov

for

subject2:age

24

111:!::!垒!g堡磐些竺P粤!!壁翌!j!垒垡罂!竖

Age

LLE

22

24

0.2354

0.0545

8.3ResuItforsecond

group

Thesecond

group

contains

twosubjects:

(1)Age32Female

(2)Age39Female

一3l一

坐坚坠!型型竺鱼塑竺型墅堕塑型!塑竺壁唑

Fig.8.5

EC(3

ofsubject3:age

32

Fig.8.6LargestLyapunovofsubject3:age

32

Fig.8.7

ECG

ofsubject4:age

39

Fig.8.8LargestLyapunovofsubject4:age

39

Tab.8.4Variationofnonlinear

parameters

forsecond

group

32

39

O.0763

0.0732

8.4ResuItforthird

group

Thet11ird

group

containsthreesubjects:

(1)Age56Female

(2)Age68Male

(3)Age69Male

一32—

大连理工大学硕士学位论文

Fig.8.9

ECG

ofsubject5:age

56

Fig.8.10LargestLyapunov

ofsubject5:age

56

Fig.8.1

1ECGofsubject6:age68

Fig.8.12LargestLyapunovofsubject6:age

68

Fig.8.13

ECGofsubject

7:age

69

Fig.8.14LargestLyapunovofsubject7:age

69

堡竺坠!堂虫型竺型塑竺驾!塑竺熊堕

:!:21玺苎垒竺!!璺竺些竺鬯!堡翌堑!型墅!坚

Age

LLE

56

68

69

O.0928

0.0927

0.075l

8.5ResuItforfourth

group

Thefourth

group

containsthreesubjects:

(1)Age

73Male

(2)Age81Male

(3)Age

89Male

Fig.8.15ECGofsubject8:age

73

Fig.8.16LargestLyapunovofsubject8:age

73

Fig.8.17

ECG

ofsubject9:age

8l

Fig.8.18LargestLyapunovofsubject9:age

81

—34—

大连理工大学硕士学位论文

Fig.8.19

ECGofsu巧ect10:age

89

Fig.8.20Lm'g§tLyapuaovofsubj∞t10:age

89

Tab.8.6Variationofnonlinear

parameters

forfourth

group

LLE

73

8l

89

O.0926

O.1122

0.1122

Nikhil

Iyengar

et

al,haveapplicd

Recently,Echcverria

et

al,haveapplicd

Congestive

HeartFfilure(CHF)subjects.

DFAtothenormalheartrate

variability

signal.

dctrend既lfluctuation

analysis

tothenormaland

L盯gestLyapunovexponent's(LLE)quantifysensitivity

ofthe

system

toimfifl

conditionsandgivesameaslll'e

of

predictability.This

valuede唧ses、Ⅳitllthe

aging

indicating

thattheheartrate

variability

becomeslesschaoticasthe

healthysubjectgrows

old.

一35

塑坠型墅垫型些塑型些生唑

Heartrate

variability

has

considerable

potential

toa88锶¥theroleofautonomicna'voofl

system

fluctuationsinnormal

healthy

individualsandin

patients

with

variouscardiovascular

andnon-cardiovasculardisorders.HRVstudiesshouldenhanceourunderstanding

of

physiologicalphenomena,theactionsofmedications,anddisease

mechanisms.Large

prospectivelongitudinal

studiesareneededtodeterminethesensitivity,specificity,and

predictive

valueofHRVintheidenfificationofindividualsat

riskforsubsequentmorbidand

mortalevents.AfertileareaofresearchiStouseHRV

techniquesto

explore

theroleof

autonomicnervous

system

alterationsindiseasemechanisms,especiallythoseconditionsin

which

sympathovagal

factorsarethoughtto

play

an

important

role.Recentwork

suggests

that

alterationsinautonomicinnervationtothedevelopingheartmightbe

responsibleforsome

formsofthe

longQTsyndrome.FetalHRVstudiesin

pregnant

motherswiththisdisorderis

certainly

feasibleand

might

be

very

informative.Itwouldbeof

interesttoevaluateHRV

in

variouscircadian

patterns

suchasnormal

day-nightcycles,sustained

reversed

day-night

cycles(evening-night

shift

work),andtransiently

altered

day-nightcycles,suchasmight

occurwith

intemationaltravel.nmautonomicfluctuations

occurringduring

various

stages

of

sleepincludingrapideyemovement(REM)sleephavebeenstudiedin

onlyafewsubjects.In

normal

subjects,theHF

vagalcomponentof

thepowerspectrmn

isaugmentedonlyduring

non-REM

sleep.whereas

in

post.MIpatientswiththisincreaseinHFiSabsent.Heartrate

variability(HRⅥsignalcanbeUSedasareliable

indicaterofstateoftheheart.Itbecomes

lessrandomwiththe

aging(1esschaotic).T11isisevaluated

byusing

nonlinear

parameter

LargestLyapunovExponent.Asadiagnostictool:the

Lyapunovspectrumof

ECG

signals

couldbeconsideredasaf脚independenttooltoimprove

automatic

diagnosis

ofheart

disease.Inordertoallow

theiruseitisnecessaryto

repeat

the

analysisonalarge

ECGdata

set.

一36

大连理工大学硕士学位论文

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一39—

攻读硕士学位期间发表学术论文情况

【1】王兴元,安妮,海登.Heartratevariationinnormalsubjectsamong

various

age

刊物类型:网刊

主办单位:大连理工大学

论文章节:第一章到第八章

【2】马洪连,海登,安妮.IntelIPPforMPEG-4media

player

developmentinembedded

刊物类型:网刊

主办单位:大连理工大学

大连理工大学硕士学位论文

AcknowI

edgement

Firstoffll1want

tothank

mysuper

visorPmf器sorWangXing

Yuanf.orKs

g他athelp

in

allt11e∞yen.Rwouldbe嘶ssibleformet0finish

mythcsis

witlloutKs

hdp.hl

all

也器eyenhehas

hclped

metowalkⅡⅡou曲thepalllofk∞wledge'research.msbroadand

deep虹owledgci11

every

fidd

hasmade

my

r韶earcheasi盯.

Iflsow龇ttothanka11thed船smat鼯of

my

labspecify

Gulma.Shehas

helped

me

throughomtlle

year

to∞lVeV商。璐problcIIlsofmy

rese盯ch.Witllomhcr

hdp

itwofl血'tbe

posfible

formet0f.o皿at

my

tll器is.She

h勰al∞hclped

me、ⅣithChin锶e

l龃guage.

1wantt0thanktllisuniv呻forpro“ding

mechanccto

study

irI驰chaIli∞

aI“∞伽∞‘百Veme

oppommitytoenrich

mylmowlodge.

At

1ast1wanttomank

myfhther.mother,my

sistersand

b∞merfbflheir

con吐册d璐

support

throughout

mystudy.Whenev盯Igct

intomy仃oⅡbletheywe∞flways

thereto

help

me觚dextelldtlleir

loving

handstowards

me.Today

I'm

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mothersomuch

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worldbefore

seeing

herli砌edaught盯being鲫uated.Thisw嬲h盯dream.Sheis

the∞urcc

ofmyinspimtionforstIldyin孚

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myt髓chers,cl勰蛐at鼯,伍觚dsandfcla:civ铭fortlleirg僦helpin

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