室上性心动过速课件.pptx

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1、IntroductionPathophysiologyDiagnosisTreatmentAcuteChronicExcluding Atrial Fibrillation and Flutter第1页/共37页EpidemiologyCommon problem presenting EDsOrejarena,J AM Coll Card.1998;31:150-7Mean age of onset 57 yearsRanging from infancy to 90 years oldIn this study,younger patients(mean of 37)were more l

2、ikely to present to the ED and less likely to have structural heart disease(69%)第2页/共37页MechanismsTwo basic mechanisms leading to all TachyarrhythmiasImpaired impulse initiationproblems of abnormal automaticityAbnormal impulse conductionRe-entrant impulses第3页/共37页Location of disorderSVT is any arrhy

3、thmia arising from AV node or aboveImpulses can be transmitted from several loci Sinus NodeAtriumAV NodePoint of origin has implications for treatment第4页/共37页AV NodeThere are two basic forms of SVTs arising from the AV nodeAtrioventricular Node Reciprocating Tachycardia(AVNRT)Atrioventricular Recipr

4、ocating Tachycardia(AVRT)Both are dependent on the AV node for maintenance of the Reentry circuit第5页/共37页Reentry CircuitsMines in 1913 first described reentry as a mechanism of cardiac arrhythmiasNeed a ring of conduction with unidirectional block in one branch第6页/共37页AVNRTAccounts for more than hal

5、f of the cases of PSVTsFast and slow conducting fibers from the atrium to the AV node make up reentry circuitFast fibers have a long refractory periodSlow fibers have a shorter refractory period第7页/共37页AVNRT(cont)Cycle is started by a PACFast fibers are still refractory from previous impulseImpulse

6、conducted down Slow fibers and retrogradely up fast fibersThis slow-fast mechanism accounts for 90%of AVNRTs第8页/共37页AVNRT(cont.)From Schilling,From Schilling,Heart 2002;87:299304第9页/共37页AVRTDependent on an accessory pathwayWolf-Parkinson-White syndromeCan have either Orthodromic or Antidromic conduc

7、tion through the AV nodeMost common is Orthodromic with retrograde conduction through the accessory pathway第10页/共37页AVRT(cont.)From Schilling,From Schilling,Heart 2002;87:299304第11页/共37页AVRT(cont.)Reentry is precipitated by a PAC or PVCDependent on AV node for continued reentry第12页/共37页Both AVNRT an

8、d AVRT arise due to reentrant mechanismBoth are dependent on the AV node for their maintenanceDrugs that work on the AV node should break the circuit第13页/共37页Atrial TachycardiasUnifocal atrial tachycardiaSingle P wave morphologyMay be due to either abnormal automaticity or reentry mechanismsSometime

9、s mistaken for Flutter although rate is usually less than 250Rare第14页/共37页Atrial Tachycardias(cont.)Multifocal atrial tachycardiaDue to increased automaticityMultiple atrial sites of impulse initiationUsually not ParoxysmalMore common than unifocal第15页/共37页Atrial Tachycardias(cont.)Atrial tachycardi

10、as are not dependent on the AV node for their propagationAV blocking agents will slow conduction through the AV node but not break them第16页/共37页Sinus TachycardiasPhysiologic Sinus TachycardiaInappropriate Sinus TachycardiaReentrant Sinus TachycardiaMicro reentry circuit within the SA node第17页/共37页Di

11、agnosisHistoryPhysical ExamEKG第18页/共37页EKGDespite careful analysis of EKG 20%of SVTs are incorrectly diagnosedCertain features can lead to the diagnosis of particular SVTs第19页/共37页Atrial TachycardiasUnifocalAtrial Rate usually 250 helping to distinguish from A.FlutterRegular Rhythm Positive P waves

12、in inferior leads before each QRS if high atrial originP wave will have different morphology from Sinus P wavesRhythm terminates with QRS complex第20页/共37页Sinus RhythmSinus RhythmAtrial TachycardiaAtrial Tachycardia第21页/共37页Atrial TachycardiasMultifocalIrregular rhythmGenerally slower rates than othe

13、r SVTsGenerally more incessant in natureRequires 3 distinct P wave morphologies with isoelectric periods between them.第22页/共37页第23页/共37页AVNRTRapid rate 150-180RegularP waves generally hidden within the QRS complexMay see a pseudo r in V1 or pseudo S in inferior leadspseudo r:sens.58%,spec.91%pseudo

14、S:sens.14%,spec.100%J.Am.Coll.Card 1993;21(1):85-9第24页/共37页第25页/共37页AVRTFastRegularMay see widened QRS if antegrade conduction down accessory pathway or signs of preexcitation in sinus(delta wave)retrograde P waves follow QRSQRS alternans第26页/共37页Orthodromic第27页/共37页Antidromic第28页/共37页Goals of Treat

15、mentAcuteBreak reentry circuitControl rateChronicPrevent recurrences第29页/共37页AcuteIf unstable DC CardiovertVagal ManeuversDiagnostic and Therapeutic63%responded in a series by Mehta with younger patients more likely to respontLancet 1988,May:1181-530%response in series by MullerAm J of Card 1994;74:

16、500-503第30页/共37页AdenosineBegan to be investigated in the 1980sBecame the first line treatment in the early 1990sMulticenter placebo-controlled trial by DiMarco showed that Adenosine was equally effective to Verapamil with better side effect profileAnnals of Internal Med 1990;113:104-110第31页/共37页Aden

17、osine(cont.)Blocks Adenosine receptors causing hyperpolarization of the cellExtremely short half life limits side effectsMaybe ineffective in patients taking methylxanthinesHas replaced Ca channel blockers that had previously been the first line treatmentWill break most reentrant SVTs dependent on t

18、he AV node第32页/共37页Chronic TreatmentDependent on the severity and frequency of symptomsDrug TherapyCa Channel blockers,Beta blockers,Dig,Flecainide,PropafenoneNot entirely effective and side effectsCatheter Ablation第33页/共37页Catheter AblationHas become the treatment of choice for persistently symptom

19、atic patientsThose with WPW may be referred for ablation even without persistent symptomsSuccess rates of about 96%have been reportedAbout 1%risk of 2nd or 3rd degree AV Block第34页/共37页SummaryMechanism and Location of SVT has implications for treatmentEKG holds clues for the type of SVT,although 20%will not be discernable by the EKGAdenosine is the mainstay of Acute tx.Catheter Ablation is preferred for chronic management第35页/共37页第36页/共37页感谢您的观看！第37页/共37页