Cardiovascular-Main心血管-87-92

CardiovascularMain.87-92Q41A43-year-oldmancomestotheofficeduetofrequentepigastricburningnotrelievedbyantacidsforthepast4months.Thesensationistypicallybroughtonbyheavyliftingatworkandtakes10-15minutestogoaway.Thepatienthashadnoassociatedarmorneckpain,cough，shortnessofbreath,ordifficultyswallowing.Hismedicalhistoryissignificantforsystemiclupuserythematosusdiagnosed5yearsago,forwhichhetakeslow-doseprednisoneandhydroxychloroquine.Heisalifetimenonsmoker.Ayearago,thepatient'swifewasdiagnosedwithpepticulcerdiseasethatrequiredtreatmentwithantibiotics.Onphysicalexamination,bloodpressureis140/90mmHgandpulseis80/minandregular.Breathsoundsareequalonbothsides.Mowheezesorcracklesareheard.Firstandsecondheartsoundsarepresent.Noheartmurmursorrubsarenoted.Theabdomenissoftandnontendertodeeppalpation.Thereisnoskinrashorperipheraledema.EGGisnormal.Whichofthefollowingisthebestnextstepinmanagementofthispatient?A.AbdominalCTscanwsth/withoutcontrastB.AbdominalultrasoundC.ChestCTscanwithoutcontrastD.CoronaryangiographyE.EchocardiogramF.EsophagealmotilitystudiesG.ExerciseECGH.StoolHeHcobacterpyloriantigentestingLUppergastrointestinalendoscopyA41Correctanswer:GThispatient'sclinicalpresentation-epigastricburningprovokedbyexertion(heavylifting)andrelievedoverseveralminutesbyrest-isconcerningforatypicalangina(giventhelackoftypicalchestdiscomfort).SystemiclupuserythematosusIsaknownriskfactorforacceleratedatherosclerosisandprematurecoronaryheartdisease.Myocardialischemiainpatientswithstableanginaoccurswhenmyocardialoxygendemandexceedsoxygensupply.Symptomstypicallyhavegradualonsetwithexertionandarerelievedwithrestorterminationoftheprovokingactivity.ExerciseECGisrecommendedasaninitialstresstestfordiagnosisandriskstratificationofmostpatientswithsuspectedstableischemicheartdisease.Coronaryangiographyisperformedinpatientswithhigh-riskfindingsoninitialstresstesting.Itisalsoindicatedinpatientswithhighpretestprobabilityofischemicheartdisease(ChoiceD).Exercisestressechocardiogramisoccasionallyusedforthediagnosisofischemicheartdiseaseasitmayshowchangesassociatedwithischemiaonexertion;however,arestingechocardiogramalonemaybeunremarkable(ChoiceE).(ChoicesAandB)Thispatienthasanormalabdominalexaminationandnosymptomssuggestinganyacuteabdominalpathology.FurtherimagingwithabdominalCTscanorultrasoundisnotindicated.(ChoiceC)Therearenosymptomsorsignsofpulmonaryorthoracicpathology(cough,hemoptysis,dyspnea);therefore,chestCTimagingisnotindicated.(ChoicesF,H,andI)Thepresenceofepigastricdiscomfortonexertionthatisnotrelievedbyantacidsisconcerningforcardiacpathology.Evaluationforpossiblegastrointestinaletiology(eg,pepticulcerdisease,esophagealmotilitydisorders)shouldbeconsideredinpatientswithnoevidenceofmyocardialischemiaoninitialevaluation.Educationalobjective:ExercisestressECGisrecommendedasanInitialtestfordiagnosisandriskstratificationinmostpatientswithsuspectedstableischemicheartdisease.Q42A60-year-oidmancomestotheofficeforevaluationofa6-monthhistoryofintermittentchestpain.Hedescribessubsterna!tightnessandpainthatoccurwhenhewalksquicklyorclimbsstairs.Thesymptomslastabout10minutesandslowlyfadeawaywithrest.Theseepisodesdonothappenatrest.Thepatienthasaknownhistoryofcoronaryarterydiseasewithcoronaryarterybypassgraftingsurgery7yearsago.Othermedicalproblemsincludehypertensionandhyperlipidemia.BloodpressureIs140/78mmHgandpulseis78/minandregular.Therearenomurmursoncardiacauscultation.Lungsareclearbilaterally.Treadmillstresstestisperformed.Sevenminutesintothetest,thepatientdevelopschestpainandthetreadmillisstopped.Sublingualnitroglycerinisadministered,whichalmostimmediatelyrelievesthepatient'spain.Whatisthepredominantmechanismresponsiblefortherapidpainreliefinthispatient?A.CoronaryvasodilationB.DecreasedleftventricularcontractilityC.DecreasedleftventricularwallstressD.DilationofsmallarteriesE.NegativechronotropiceffectA42Correctanswer:CExplanation:Thispatientwithcoronaryarterydiseasehasaclassicpresentationofchronicstableangina(exertionalchestpainrelievedbyrest),withrapidreliefofhissymptomsfollowingtheadministrationofsublingualnitroglycerin.Nitratesexerttheireffectbydirectvascularsmoothmusclerelaxationcausingsystemicvenodilationandanincreaseinperipheralvenouscapacitance.Theirprimaryanti-ischemiceffectismediatedbysystemicvasodilationanddecreaseincardiacpreloadresultinginadecreaseinleftventricularend-diastolicandend-systolicvolume.This,inturn,leadstoareductioninleftventricularsystolicwallstress-whichreflectsafterloadandisproportionalto(pressure*radius/thickness)-andadecreaseinmyocardialoxygendemand,resultinginreliefofanginalsymptoms.Althoughnitratesactascoronaryvasodilators(viadirectrelaxationofcoronaryvascularsmoothmusclecells),thebeneficialeffectofthismechanismisuncertain(ChoiceA).Thecoronaryarteriolesintheareaofflow-limitingcoronarystenosisarealreadydilatedbyinnatemechanisms,allowingmaintenanceofrestingbloodflowacrossthestenoticlesion.Nitrate-inducedcoronaryvasodilationparadoxicallydecreasescoronaryperfusionpressureacrossthestenoticlesionbydivertingbloodflowtoarterioles