心肌梗死全球统一定义与影像学诊断  内容预览： 

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心肌梗死全球统一定义与影像学诊断  内容简介：

心肌梗死全球统一定义与影像学诊断
心肌梗死全球统一定义与影像学诊断何作祥
中国医学科学院阜外心血管病医院

BiomarkerEvaluation
Thepreferredbiomarkerformyocardialnecrosisiscardiactroponin(IorT),whichhasnearlyabsolutemyocardialtissuespecificityaswellashighclinicalsensitivity,therebyreflectingevenmicroscopiczonesofmyocardialnecrosis.
Iftroponinassaysarenotavailable,thebestalternativeisCKMB(measuredbymassassay).

ElectrocardiographicDetectionof
MyocardialInfarction
TheECGisanintegralpartofthediagnosticwork-upofpatientswithsuspectedmyocardialinfarction.
TheacuteorevolvingchangesintheST-TwaveformsandtheQ-waveswhenpresentpotentiallyallowthecliniciantodatetheevent,tosuggesttheinfarct-relatedartery,andtoestimatetheamountofmyocardiumatrisk.

ElectrocardiographicDetectionof
MyocardialInfarction
Coronaryarterydominance,sizeanddistributionofarterialsegments,collateralvessels,andlocation,extent,andseverityofcoronarystenosesc**soimpactECGmanifestationsofmyocardialischemia.


ElectrocardiographicDetectionof
MyocardialInfarction
TheECGbyitselfisofteninsufficienttodiagnoseacutemyocardialischemiaorinfarctionsinceSTdeviationmaybeobservedinotherconditionssuchasacutepericarditis,LVhypertrophy,LBBB,Brugadasyndrome,andearlyrepolarizationpatterns.AlsoQ-wavesmayoccurduetomyocardialfibrosisintheabsenceofcoronaryarterydisease,asin,forexample,cardiomyopathy.

ImagingTechniques
Theunderlyingrationaleisthatregionalmyocardialhypoperfusionandischemialeadtoacascadeofeventsincludingmyocardialdysfunction,celldeath,andhealingbyfibrosis.
Importantimagingparametersarethereforeperfusion,myocyteviability,myocardialthickness,thickening,andmotion,andtheeffectsoffibrosisonthekineticsofradiolabeledandparamagneticcontrastagents.

Echocardiography
Echocardiographyisanexcellentreal-timeimagingtechniquewithmoderatespatialandtemporalresolution.Itsstrengthistheassessmentofmyocardialthickness,thickening,andmotionatrest.ThiscanbeaidedbytissueDopplerimaging.Echocardiographiccontrastagentscanimproveendocardialvisualization,butcontraststudiesarenotyetfullyvalidatedforthedetectionofmyocardialnecrosis,althoughearlyworkisencouraging.

RadionuclideImaging
Severalradionuclidetracersallowviablemyocytestobeimageddirectly,includingthallium-201,technetium-99mMIBI,tetrofosmin,and[18F]2-fluorodeoxyglucose(FDG).
Thestrengthofthetechniquesarethattheyaretheonlycommonlyavailabledirectmethodsofassessingviability,althoughtherelativelylowresolutionoftheimagesdisadvantagesthemfordetectingsmallareasofinfarction.

RadionuclideImaging
Thecommonsinglephoton-emittingradio-pharmaceuticalsarealsotracersofmyocardialperfusionandsothetechniquesreadilydetectareasofinfarctionandinducibleperfusionabnormalities.
ECG-gatedimagingprovidesareliableassessmentofmyocardialmotion,thickening,andglobalfunction.

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