现代心脏病学2.docx

现代心脏病学2.docx

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现代心脏病学2

ClinicalFindings

A.HISTORY

Theevaluationofheartdiseaseinpregnancymaybecomedifficultduetothenormalanatomicandphysiologicchangesofpregnancy.Acarefulhistorytakingthereforebecomesmoreimportantandshouldincludeahistoryofrheumaticfever,valvulardisorder,arrhythmia,congenitalheartdisease,coronaryriskfactorsorestablishedcoronaryarterydisease,andcardiacsurgery.

Reducedexercisetoleranceandfatiguearethemostcommonsymptomsreportedinpregnantwomen,probablyduetoincreasedbodyweightandanemia.Dizziness,light-headedness,orevensyncopalepisodesmayoccurduringthelatterpartofpregnancybecausemechanicalcompressionoftheuterusontheinferiorvenacavadecreasesvenousreturn,andthusthecardiacoutput.Palpitationsarealsoafrequentcomplaintbutusuallyarenotassociatedwithasignificantarrhythmia.Dyspneaandorthopnea,probablyduetohyperventilation,arealsoreported.

B.PHYSICALEXAMINATION

Thephysicalexaminationofpregnantpatientswithnormalcardiovascularsystemschangesbecauseoftheincreasedhemodynamicburden.Theevaluationofpatientswithsuspectedheartdiseaseduringpregnancyrequiresathoroughknowledgeofthenormalphysiologicchanges.

Anormalpregnantpatienthasaslightlyfastrestingheartrate,largepulse,slightlywidenedpulsepressure,andwarmextremities.Thejugularvenousdistentionisseenfromthetwentiethweek.Edemaoftheanklesandlegsiscommonlyencounteredinlatepregnancy.Aprominentbutunsustainedleftventricularimpulsemaybepalpatedinlatepregnancyandmaysimulatethevolumeoverloadseeninaorticormitralregurgitation.Theauscultatoryfindingsofnormalpregnancybeginlateinthefirsttrimesterandusuallydisappear2–4weeksafterdelivery.Duringcardiacauscultation,thefirstheartsoundisloudandexhibitsanexaggeratedsplitting.Thesecondheartsoundduringlatepregnancyisoftenincreasedandmayexhibitpersistentexpiratorysplitting,especiallywiththepatientintheleftlateralposition.Athirdheartsoundhasbeenreportedtobefrequentinlatepregnancy.However,becauseofitsassociationwithheartfailure,thepresenceofathirdheartsoundshouldleadtofurtherinvestigationofunderlyingheartdisease,especiallyinwomenwithsymptomsandothersignssuggestiveofheartdisease.Afourthheartsoundisrarelyheardduringanormalpregnancy.

Systolicmurmursarecommonduringpregnancyandresultfromtheincreasedbloodvolumeandhyperkineticstate.Mostfrequentlytheyareinnocentmidsystolicmurmurs,grade1–2/6,thatarebestheardatthelowerleftsternalborderandoverthepulmonaryarea,radiatingtothesuprasternalnotchortotheleftoftheneck.Theyusuallyrepresentvibrationscreatedbyejectionofbloodintothepulmonarytrunk.Acervicalvenoushumormammarysouffléheardbestintherightsupraclavicularareainasupinepositionisabenignsystolic,oracontinuous,murmuroccurringinlatepregnancy.Diastolicheartmurmursareunusualandusuallyrepresentvalvularabnormalities（Table31–5）.

Table31–5.Cardiovascularsignsandsymptomsinnormalpregnancy.

1.Diagnosticdifficulties—Problemsindiagnosisencounteredduringphysicalexaminationsareoftenduetothenormalphysiologicchangesofpregnancy.Cardiacauscultationmaybeparticularlyconfusinginpregnantpatients.Alongwithinnocentsystolicmurmursheardinmanynormalpregnantwomen,benignvascularmurmursarealsoheard.Thesemurmurscanbedifferentiatedfromthoseofcardiacoriginbytheirdisappearancewhenpressureisappliedwiththestethoscopeorwhenthepatientsitsupright,buttheycanbeeasilymisinterpreted.

Althoughsystolicmurmursarecommon,thefindingofadiastolicmurmurisrareduringanormalpregnancyandshouldwarrantfurtherdiagnosticevaluation.Bothsystolicanddiastolicmurmursassociatedwithcardiacdiseasecanincreaseordecreaseinintensityduringpregnancy.Thesystolicmurmursofaorticorpulmonicstenosisusuallyincreaseinintensitybecauseoftheincreasedcardiacoutputandbloodvolume.Thediastolicmurmurofmitralstenosisisalsoincreasedandmayevenbefirstdetectedduringpregnancy.Theaugmentedbloodvolumeandtheincreasedheartrateofpregnancyshortenthediastolicfillingperiodandincreasetherateofbloodflowacrossthemitralvalve.Incontrast,murmursofmitraloraorticregurgitationmaysoftenorevendisappearduringpregnancyasaresultofthedecreaseinperipheralvascularresistance.Thecirculatorychangesofpregnancyalsoaffecttheauscultatoryfindingsincardiacabnormalities,suchasmitralvalveprolapseandhypertrophiccardiomyopathy,whicharedependentonvolume.Theincreaseinleftventricularvolumeduringpregnancymayattenuateorabolishtheclickandlatesystolicmurmurtypicalofmitralvalveprolapse.Thesystolicmurmurofhypertrophicobstructivecardiomyopathymayalsodecreaseordisappearastheleftventricularvolumeincreasesduringpregnancy.Thediagnosisofinfectiveendocarditisduringpregnancymaybedifficult.Feverispresentinmorethan95%ofpatientswithendocarditis;however,thehemodynamicchangesassociatedwithpregnancymakecardiacmurmurscommon,andpreviouslyexistingmurmursmaydiminishinintensity.Ahighindexofsuspicionisthereforenecessarytomakethediagnosisofinfectiveendocarditisinpregnantpatients.Themostusefulclinicalfindingsarefever,murmur,evidenceofpreexistingcardiacdisease,andpositivebloodcultures.

C.DIAGNOSTICSTUDIES

1.Chestradiography—Theusefulnessofchestfilmsduringpregnancyislimitedbecauseofthepotentialhazardtothefetusfromradiationexposure.Wheneverachestfilmisbelievednecessary,theabdominopelvicareashouldbeshieldedwithleadtominimizeexposure.Thenormalcardiacchangesofpregnancy,suchaschamberenlargementandthehorizontalpositionoftheheartbecauseoftheelevationofthediaphragm,shouldnotbemisinterpretedascardiacdisease.NewerandmoreaccuratetechniquessuchasDopplerechocardiographyhavelargelyreplacedchestfilmsintheevaluationofcardiacstructureandfunction.

2.Electrocardiography—Theelectrocardiogramisanimportantdiagnostictechniquethatcanindicatethepresenceofunderlyingcardiacabnormalities.Cardiacchamberhypertrophy,myocardialischemiaandinfarction,pericarditis,myocarditis,conductionabnormalities,andthepresenceofatrialandventriculararrhythmiasmaybedetectedbyelectrocardiography.Inpatientswithsuspectedcardiacarrhythmias,ambulatoryHoltermonitoringmaybeindicated.Duringnormalpregnancy,sinustachycardia,ashiftoftheaxistotheleftorrightmaybeobserved,andtransientSTabnormalitiesarecommon.

3.Echocardiography—Transthoracicechocardiographyisanimportantdiagnosticnoninvasivestudy,whichcanbeperformedsafelyinpregnancy.Theintracardiacstructurescanbeevaluatedforabnormalitiesofthegreatvessels,cardiacchambers,andheartvalves.Chambersizesandventricularfunctioncanalsobemeasured.

Duringtheechocardiographicexamination,thenormalphysiologicchangesthatoccurwithpregnancyshouldbekeptinmind.Whenthepatientisevaluatedintheleftlateralposition,anincreaseinthediastolicdimensionsoftherightandleftventriclesiscommonbecauseofvolumeincreasesthatoccurwithanormalpregnancy.Becauseoftheincreaseintheleftventriculardimensions,mitralvalveprolapsemayimproveordisappearduringpregnancy.Rightandleftatrialdimensionsmayalsoincreaseslightly;thesechangesincreaseasthepregnancyprogresses.Smallpericardialeffusionshavebeennotedinlatepregnancyinhealthywomen.

Two-dimensionalechocardiographygivesdiagnosticinformationaboutthecauseofthevalvularabnormalityanditsassociatedeffectsonventricularsizeandfunction.Dopplerechocardiographyprovidesreliablequantitativeandqualitativeinformationregardingthepresenceandseverityofvalvularstenosisandregurgitation.Dopplerechocardiographycanmeasurethevalveareaandgradientsacrossstenoticvalves.Smalldegreesofpulmonary,tricuspid,andmitralregurgitationhavefrequentlybeenfoundinnormalindividuals,whetherpregnantornot.Inpatientswithcongenitalheartdisease（correctedoruncorrected）Dopplerechocardiographycandetectthepresenceofintracardiacshuntsandestimatetheshuntratiosbydeterminingtherightandleftcardiacoutputs.Itcanmeasurepulmonaryarterysystolicpressuretoassesstheeffectsofthevalvularlesionsandintracardiacshuntsonthepulmonarycirculation.

Transesophagealechocardiography（TEE）providessuperiorimagesoftheintracardiacstructuresandgreatvessels,providingthesamedetailedanalysisofcardiacstructure,function,andhemodynamicassessmentpossiblewithtransthoracicechocardiography.TEEcanbeusedforpatientsinwhomthetransthoracicexaminationistechnicallysuboptimalandforthosewithsuspectedprostheticornativevalvedysfunction,infectiveendocarditis,congenitalheartdisease,oraorticdissection.AlthoughexperiencewithTEEduringpregnancyhasbeenlimited,theprocedureshouldbeconsideredinpregnantpatientsforwhomtherisksarelessthanthepossiblebenefit.Theprocedureshouldbeperformedbyanexperiencedechocardiographer,andfetalmonitoring,inadditiontotheroutinemonitoringofthepatient,shouldbeavailable（Table31–6）.

Table31–6.Diagnostictestfindingsinpregnancy.

4.Exercisetolerancetest—Littleisknownaboutthesafetyofanexercisetesttoestablishischemicheartdiseaseinpregnancy.Fetalbradycardia,markedhypoxia,acidosis,andseverehypothermiaatpeakexercisehavebeenreported.Inlightofthesefacts,theus