ebook img

19 Fetal Arrhythmia PDF

16 Pages·2006·0.43 MB·English
by  
Save to my drive
Quick download
Download
Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.

Preview 19 Fetal Arrhythmia

19 Fetal Arrhythmia Elizabeth V. Saarel and Carlen Gomez Clinical auscultation of fetal heart began in Beat-to-beatorshort-termvariabilityre- the late 1800s, and the first reports of fetal fer to changes in FHR (cycle length) be- arrhythmia detection were published in the tween successive cardiac impulses. Periodic 1930s. The detection, diagnosis, and treat- changesinFHRorlong-termvariabilityrefer ment of fetal arrhythmias have evolved con- to changes in FHR between successive time siderablybeyondtheseearlyobservations. intervals(secondstominutes).Adecreasein heart rate variability may be a sign of fetal distress. Heart rate variability is also mod- FETALELECTROPHYSIOLOGY ulated by the parasympathetic nervous sys- tem,andcanbeinhibitedbyatropine.Short- NormalSinusFetalHeartRate and long-term heart rate variability tends to bereducedorexaggeratedinaparallelfash- Thesinusnode(SN),formedbythesev- ion,andthereisnoclearevidencethatdistin- enthweekofgestation,generatesthenormal guishingbetweenthetwoentitiesisclinically fetal rhythm. Important normal characteris- helpful. tics of fetal heart rate (FHR) include base- AbaselineFHRlessthan120bpmaris- linerate,beat-to-beatvariability,andperiodic ingfromtheSNwithnormalconductionhas changes (transient decelerations or acceler- been defined as sinus bradycardia. A base- ations). Baseline rate is significantly higher lineFHRgreaterthan160bpmgeneratedand early in gestation than at term. At a nor- propagatedinanormalmannerhasbeende- mal gestation of 20 weeks, the FHR is close fined as sinus tachycardia. As in infants and to 160 bpm; by the mid-second trimester, children,sinusarrhythmia,evidencedbyheart baseline FHR ranges from 120 to 160 bpm; ratevariability,isnormalinthefetus. and at normal term, it is near 120 bpm. The gradual decline in baseline FHR is modu- latedbyanincreaseinparasympathetictone OVERVIEW:FETAL withresultantprogressivevagalinfluenceon ARRHYTHMIA the SN. If atropine is administered (to the mother),FHRrevertstothehigherbaselineof Considerationoffetalarrhythmiaisusu- 160bpm. ally triggered by auscultation of an irregular 241 242 FETALARRHYTHMIA heartrate,bradycardia,ortachycardiaduring familyandthehealthcareteam,andimproves a prenatal visit. Abnormal FHR occurs in medicaloutcomes. 0.2%–2%ofpregnancies,with10%ofthese havingsignificantarrhythmia.Oncethepos- sibility of arrhythmia is raised, careful as- TECHNIQUESFORDIAGNOSIS sessmentofoverallmaternalandfetalhealth OFFETALARRHYTHMIA shouldbeperformed.Ifthearrhythmiaissus- tained at a markedly fast or slow rate, or Electrocardiography if it is associated with structural congenital heart disease, fetal well-being may be com- Several non-invasive techniques are promised. Indeed, a less common presenta- availableforfetalarrhythmiaanalysis.Incon- tion of fetal arrhythmia is hydrops fetalis— trasttopostnatalevaluation,electrocardiogra- generalized edema that represents an end- phyisnotpracticablefordiagnosis.Although stage fetal response to significant stress and fetalelectrocardiogramscanberecordedfrom insults.Moreover,severalmaternalconditions electrodes placed on the maternal abdomen, areassociatedwithfetalarrhythmia,making signal detection is not reliable due to a low maternal assessment essential in all cases of signal-to-noise ratio. Fetal cardiac electrical abnormalFHR. activity is low in amplitude, on the order of Whenafetalarrhythmiaissuspected,a about10µV,1/10ththeamplitudeofmaternal detailed prenatal echocardiogram should be cardiacelectricalactivity.Inaddition,mater- obtained in an experienced pediatric prena- nalabdominalwallmusculatureaddslowam- talechocardiographicunit.Althoughreferral plitude noise to the electrocardiogram, often patterns vary by institution, abnormal FHR obscuringfetalmyocardialelectricalactivity. prompts roughly 25% of prenatal cardiol- ogy referrals. In addition to the evaluation Magnetocardiography ofthefetalcardiacanatomyandfunctionby echocardiogram during these visits, it is im- Amagnetocardiogramrecordsthemag- portanttoobtainathoroughmaternalandfam- neticfieldgeneratedbycardiacelectricalac- ilyhistory.Asmanyas50%offetuseswithar- tivity.Thistechniquehasbeenappliedtothe rhythmia(particularlythosewithheartblock) fetus for the last decade. There have been haveassociatedstructuralcardiacmalforma- multiplereportsfromseveralinstitutionsde- tions. scribingmagnetocardiogramsthatdetailfetal Optimal patient evaluation and treat- cardiac electrical activity, including P-wave mentrequiresateammedicalapproach.The and QRS inscription, similar to a postna- team should consist of obstetricians, peri- talelectrocardiogram.Magnetocardiographic natologists, pediatric cardiologists with fetal equipment is complex and large, requires echocardiographic expertise, social workers, shieldinganddedicatedspace,isveryexpen- and nurses that work closely with pediatric sive, and is not yet commercially available; electrophysiologists to care for affected fe- widespreaduseisnotavailable.Fetalmagne- tuses. Other relevant ad hoc members may tocardiography would undoubtedly become includeneonatologists,anesthesiologists,ge- morewidespreadiftechnicalrefinementsde- neticists, and endocrinologists. If significant creasedcostandincreasedaccessibility. structuralheartdiseaseisidentified,pediatric cardiothoracic surgeons should be alerted Echocardiography near term. A team approach streamlines pa- tient care, allows more accurate prognos- Because of limited access to the elec- tication, improves communication between trocardiographic forces of the fetal heart, FETALARRHYTHMIA 243 FIGURE1.M-modeechocardiogramfromafetusinsinusrhythm.Upperimagedemonstratesbeampositionthrough theatriumandventricle.Smallarrowsmarkatrialcontractions,andarrowheadsmarkventricularseptalmotion.Note 1:1ratioofatrialtoventricularcontractions. echocardiography is the current method for diastoleasrepresentationofatrialandventric- the diagnosis of fetal arrhythmias. Evalua- ular motion. An apical four-chamber image tion for arrhythmia begins by examining the of the fetal heart is obtained, and the pulsed timing and association of atrial and ventric- Doppler cursor is positioned with the gate ular wall motion. This is best accomplished spanningthemitralinflowaswellastheaortic through the use of M-mode and Doppler outflow(Figure2). echocardiography. Doppler tissue color M-mode imaging M-modeechocardiographydisplaysmo- mayaidinthediagnosisoffetalarrhythmias tionofthecardiactissuewithrespecttotime. whenstandardM-modeandDopplerechocar- An M-mode tracing of the fetal heart cham- diography are indeterminate. Gated pulsed bers is obtained by placing the cursor line DopplermaybeusedtomeasurefetalPRin- acrossboththeatrialandventricularwallssi- tervals. In addition, new techniques includ- multaneously (Figure 1). The display shows ing tissue velocity imaging, with creation of movement of both chamber walls with time, a “fetal kinetocardiogram,” as well as strain reflectingatrialandventricularsystole. rate imaging, have recently been described. Many factors influence the quality of Tissue velocity and strain rate imaging may the M-mode tracing. First, alignment with significantly enhance current fetal echocar- bothheartchamberscanbechallenging,and diographicdiagnosticcapabilities. several different probe positions and angles In addition to determination of the should be attempted to optimize the tracing. arrhythmia mechanism, echocardiographic Second, a clearer tracing will be obtained evaluationofthefetusshouldincorporateas- where chamber walls have the greatest ex- sessmentforanyhemodynamicandanatomic cursion with contraction, such as the atrial abnormality. Both tachyarrhythmias and appendage,orlateralventricularwall. bradyarrhythmiascancauseheartfailure,and Dopplerechocardiographyutilizesspec- ultimately hydrops fetalis. Complete evalua- tral blood flow patterns during systole and tionforfetalheartfailureincludesassessment 244 FETALARRHYTHMIA FIGURE2.Dopplerechocardiogramfromfetusinsinusrhythm.Upperimagedemonstratesbeampositioninthe ventricle.Note1:1relationshipofnormalmitralinflow(E-andA-wavesabovebaseline)andnormalaorticoutflow (belowbaseline). of heart size, ventricular systolic function, SPECIFICFETALARRHYTHMIAS atrioventricular valve incompetence, venous Doppler patterns (increased reversal with Extrasystole atrialcontraction)includingumbilicalvenous Doppler (Figure 3), and documentation of Extrasystoles account for 60% to 90% the presence and size of pleural, pericardial, of fetal arrhythmia. Ectopic beats may arise andabdominaleffusions.Alloftheseindices in the atria, junctional tissue, or ventri- needtobereassessedforprogressionbyserial cle. Supraventricular ectopy (SVE) is most echocardiographicstudiesalongwithongoing common. Ventricular ectopy (VE) com- obstetricalevaluationoffetalwellbeing. prises fewer than 10% of fetal extrasystole. FIGURE3.PulsedspectralDopplertracingfromtheumbilicalveininafetuswithhydropsfetalis.Upperpanel demonstratesgatepositionintheumbilicalvein.Arrows(lowerpanel)indicatepulsationswithatrialsystole,consistent withhighatrialpressure. FETALARRHYTHMIA 245 Frequencyofectopicbeatsinthenormalfe- or quadrigeminy. Diagnosis can be made tus has not been well established; however, withacombinationofDopplerandM-mode therateofextrasystolesinhealthypremature echocardiography.WithM-mode,simultane- infants is 20% to 30%, with a slightly lower ous atrial and ventricular recording is per- frequencyinterminfants. formed,demonstratinganormalsequenceof Ectopic beats present as an irregular A-V contractions and an early atrial beat. FHR.Asinolderpatients,veryearlySVEre- The atrial beat after the premature contrac- sults in blocked atrioventricular conduction, tion demonstrates an incomplete compen- eithercompleteorpartial(intheformofbun- satorypause. dle branch block with aberrant depolariza- Dopplersamplingatthejunctionofthe tion).Hence,SVEcanpresentasbradycardia. mitralinflowandleftventricularoutflowtract Themajorityoffetuseswithprematurebeats displays E- and A-waves (early, rapid ven- arehealthy,andtheectopyresolvesovertime. tricular filling followed by atrial contraction Although the vast majority of fetuses with active ventricular filling) and ventric- withextrasystoleshaveastructurallynormal ular systole (with semilunar valve outflow). heart, SVE and VE can be associated with SVE will cause early active ventricular fill- anatomiccongenitalheartdisease,cardiactu- ing (A-wave), obscuring part of the early mors, and fetal genetic abnormalities such ventricularfilling(E-wave)tracingwithsub- as Trisomy 18. In addition, SVE precedes sequent early ventricular systole (Figure 4). supraventricular tachycardia (SVT) in 15%. In cases of fully blocked SVE, no ventric- Thus,allfetuseswithprematurebeatsshould ular systole will follow the premature atrial bemonitoreduntildelivery,oruntilresolution contraction. The post-extrasystolic contrac- oftheectopyhasbeensustained. tion will demonstrate a prolonged filling (diastolic) time interval. An additional Doppler finding is flow reversal in the IVC SupraventricularEctopy duringearlyatrialcontraction. Prematureatrialandjunctionaldepolar- The fetal PR interval can be measured izations occur most often as single beats, usingagatedpulsedDopplertechnique.Pre- but can present with bigeminy, trigeminy, matureatrialcontractionsshoulddemonstrate FIGURE4.DopplerechocardiogramfromafetuswithSVE.Thelargearrowmarkstheprematureatrialcontraction. Thefirstsmallarrow(lowerpanel)marksthediminishedaorticoutflowvolumewiththeSVE,andthesecondsmall arrowshowstheincreasedaorticoutflowvolumeduringthepost-extrasystoliccontraction.Notetheprolongeddiastolic timeintervalfollowingtheSVE. 246 FETALARRHYTHMIA FIGURE5.PulsedspectralDopplerthroughthemitralinflowandaorticoutflowinanormalfetus,demonstrating mechanicalPRintervalmeasurement.E-andA-wavecomponentsofmitralinflowareabovethebaseline,whereas theaorticoutflowsignalisbelowthebaseline.CalipersmeasurefromthebeginningoftheA-wave(lineA)tothe beginningoftheaorticoutflowsignal(lineB). anormal(Figure5)orprolongedPRinterval ultrasound demonstrates a characteristic AV (ifslowconductionoccurs). valveinflowpatternwithdecreaseddiastolic The prognosis is favorable for the ma- antegradeflow.Markedretrogradeflowinthe jority of fetuses with SVE. In addition to IVCisseenduringatrialcontraction. the conditions mentioned earlier, fetal SVE Inadditiontotheconditionsmentioned can be associated with maternal drug use or previously,VEhasbeenassociatedwithfetal hyperthyroidism.Forfetuseswithassociated myocarditis, cardiomyopathy, long QT syn- maternal disease, structural congenital heart drome,andcompleteAVblockwithaslowes- disease, tumors, or sustained tachyarrhyth- caperate.Prematureventricularcontractions mias,theprognosiscorrelateswiththeasso- also occur in healthy fetuses, for whom the ciatedcondition.Notreatmentisindicatedfor prognosisisexcellent.Prognosisisdependent isolatedfetalSVE. ontheassociatedcondition.Notreatmentof isolatedprematureventricularcontractionsis indicated. VentricularEctopy M-modeechocardiographymaydemon- Tachyarrhythmias strate subtle distortion of normal ventricular contraction due to aberrant muscle depolar- Most cases of elevated FHR are due to ization (Figure 6). Also, a complete atrial sinus tachycardia. SVT, atrial flutter, atrial compensatory pause is seen after most pre- fibrillation,andventriculartachycardia(VT) mature ventricular depolarizations. Doppler are less common. In one large single-center FETALARRHYTHMIA 247 FIGURE6.M-moderecordingfroma36-weekfetuswithitsbacktowardthetransducerpresentinganinvertedviewof theheart.Prematureaorticvalveopening(largearrow)canbeclearlyseentobefollowedbyatrialwallcontractionbut withnovariationinP-Pinterval(A-waveinterval),givingacompensatorypause(smallarrow,allowingdiagnosisof ventricularprematurebeat).LA=leftatrium;Ao=aorta;RVOT=rightventricularoutflowtract(5MHztransducer). ReprintedfromClinicalCardiology1985;8:1–10withpermissionfromClinicalCardiologyPublishingCompany,Inc, Mahwah,NJ07430USA. retrospectivereport,SVTandatrialflutterto- gated-Dopplerultrasound,shouldbeconstant getheraccountedfor12%offetalarrhythmia andofnormalduration. diagnoses. Fetal sinus tachycardia is due to an un- derlyingfetalormaternalabnormalitysuchas SinusTachycardia drugexposure,hyperthyroidism,myocarditis, infection, hypoxia, or other causes of fetal Fetalsinusratesrarelyexceed210bpm, distress.Treatmentisdirectedattheprimary whereasfetalSVTrarelyfallsbelow200bpm. causeofsinustachycardia. In sinus tachycardia, fetal M-mode echocar- diography shows synchronous atrioventric- SupraventricularTachycardia ular contractions. Sinus arrhythmia with varyingcyclelengthsmaybepresent.Certain Fetal supraventricular tachycardia tachyarrhythmiasthattendtowardlongerand (SVT) can be sustained or intermittent. more variable cycle lengths, such as persis- Typicalratesare240–250bpm,witharange tentjunctionalreciprocatingtachycardiaand from 200 to 320 bpm. Detection is most ectopicatrialtachycardia,aredifficulttodif- common after 15 weeks gestation, although ferentiate from sinus tachycardia using cur- earlier presentation has been reported. Fetal rentultrasounddiagnostictechniques. toleranceofSVTdependsonthedurationand Insinustachycardia,Dopplertracingof rate of arrhythmia; intermittent and slower atrioventricular valve inflow often demon- (≤260 bpm) rhythms are less malignant. stratesamalgamationoftheE-andA-waves. Mechanisms of SVT in the fetus are similar ThemechanicalPRinterval,asmeasuredby tothoseinneonates(Figure7). 248 FETALARRHYTHMIA FIGURE7.M-modeechocardiogramfromafetuswithsupraventriculartachycardia.Arrowheadsindicateatrial contractions,andlargearrowsindicateventricularcontractions.Notethe1:1relationshipofatrialandventricular contractions.Thecalipersmeasure243msbetweensuccessiveventricularcontractions,indicatingaheartrateof approximately250bpm. Atrioventricularreentrytachycardia,uti- by gated-Doppler, the PR interval will be lizing an accessory connection between the constantinreentrytachyarrhythmias. atria and ventricles, is most common when Treatmentispredicatedontheeffectof examined post partum. AV node reentry the tachyarrhythmia on fetal well being. If tachycardia, ectopic atrial foci, persistent SVT is intermittent, slow, and late in preg- junctional reciprocating tachycardias, and nancy,fetalhealthisusuallynotjeopardized. junctional tachycardias are less common. Insuchpatients,prognosisisgenerallyexcel- Althoughanabruptonsetandterminationof lent, and no treatment is indicated. If tachy- the tachycardia, if observed during the fe- cardia is sustained at fast rates (>260 bpm), tal echocardiogram, would support the di- prenatal demise may be as high as 25%. It agnosis of a reentry tachycardia, it is not isthereforeimportanttofrequently(every3– possible to distinguish with certainty be- 5 days) assess all fetal patients with SVT. tweentheseentitiesusingcurrentultrasound Moreover,mothersshouldbeeducatedtolook techniques. forsymptomsoffetaldistress.Bothobstetri- Diagnosis of SVT is consistent with an ciansandcardiologistsshouldfollowpatients. M-mode tracing through the atria and ven- Of note, patients with structural congenital tricle showing sequential 1:1 contractions at heartdiseaseareatgreaterriskfortachycar- retrogradetimeintervalsof80–120ms.Simi- diaassociatedcomplications.Twooftheearli- larly,Dopplerultrasoundofventricularinflow estsignsoffetalcompromiseareexaggerated and outflow demonstrates sequential atrial umbilicalvenousorinferiorvenacavaflowre- and ventricular contractions. If measurable versal (greater than 30%) and cardiomegaly. FETALARRHYTHMIA 249 Othersignsoffetaldistressincludedecreased setting of fetal distress. Maternal flecainide ventricular systolic function, atrioventricu- by mouth in cases where premature delivery lar valve regurgitation, and hydrops fetalis of the fetus is too high a risk may be help- (pericardialeffusion,pleuraleffusion,ascites, ful.Cardioversionwithflecainideisgenerally and/orskinedema).Ominoussignsofdistress achieved within 3 to 4 days. Sotalol appears includedecreasedfetalmovementandabnor- to be effective for atrial flutter, but probably malumbilicalarterypulsations. shouldbeavoidedforSVT.Successwiththe Fetal treatment options include early combination of digoxin with amiodarone or delivery, transplacental (maternal) pharma- the combination of digoxin with verapamil cotherapy,ordirectfetalpharmacotherapy.In hasbeendescribed. addition,thereisonereportoffetalSVTcon- Atrial flutter (intra-atrial reentry tachy- versionusingtransabdominalumbilicalcord cardia)isresponsibleforapproximatelyone- compression. Although not described in hu- third of non-sinus fetal tachyarrhythmias. mans, there has been a single report of SVT Atrial rates vary from 400 to 550 bpm. As conversion using transesophageal pacing in in postnatal patients, ventricular response is fetal sheep. Labor induction is the treatment variable, but rates are greater than 200 bpm ofchoicefortermandnear-termpregnancies inamajorityofuntreatedfetuses.Variations with sustained fetal tachycardia or evidence inatrioventricularconductionfrequentlylead offetalcompromise. toanirregularFHR.Whenconductioniscon- Althoughcontroversyexists,itisgener- sistent,thereisgreaterelevationoftheFHR; ally agreed upon that transplacental digoxin 2:1 atrioventricular block is most common. shouldbethefirst-linetreatmentofchoicein Although atrial flutter is usually sustained, pre-termpregnancieswithsustainedtachycar- paroxysmalcasesdooccur. dia or fetal compromise (Table 1). Digoxin The diagnosis of prenatal atrial flutter treatmentissafeandofteneffective.Thedrug is confirmed by characteristic echocardio- can be administered to the mother in oral or graphic findings. M-mode tracings through IVformatrelativelyhighmaternaldoses(up the atria and ventricle demonstrate regular, to1mgqdbymouth)inordertoachievean fastatrialcontractionswithvariableatrioven- adequateleveloffetaldrug.SVTcessationis tricularblock,andthuslessfrequentventric- achieved in approximately three-quarters of ulardepolarizations (Figure8).Atrialrateis cases with maternal oral therapy. If conver- calculated after measurement of the time in- sion has not been achieved after two weeks terval between successive atrial contractions of therapy, a second antiarrhythmic agent (themechanicalP-Pinterval).Similarly,ven- may be added; flecainide, along with other tricular rate is calculated after measurement drug choices are reasonable (Table1). Other of the time interval between successive ven- medications with reported efficacy include tricularcontractions(themechanicalR-Rin- procainamide, verapamil, quinidine, amio- terval). Using this information, the degree darone,orsotalol.Therehasbeennodefinitive of atrioventricular block can be determined. large,randomizedpublishedstudycomparing Doppler echocardiography of ventricular in- fetalantiarrhythmicagents. floworoutflowcanalsobeusedtocalculate In the case of significant fetal distress theventricularresponserate. orrapid,sustainedSVT,whereprompttreat- Cardiac lesions reported in association mentisessential,digoxincanbegivendirectly with fetal atrial flutter include atrial septal tothefetusthroughumbilicalvein,intramus- defect, Ebstein’s malformation of the tricus- cular,orintraperitonealadministration;how- pid valve, atrioventricular septal defect with ever, the later two routes are unreliable due atrioventricularvalvarregurgitationandatri- to unpredictable drug absorption. Umbilical oventricular block, right ventricular outflow cordocentesiscarriesasignificantriskinthe tractobstructionwithtricuspidregurgitation, 250 FETALARRHYTHMIA Maternal/FetalAdverseEffects TachycardiacommonlyrecursrequiringadditionalagentMaternalorfetalhypothyroidism(common);bradycardia(common);IUGR;prematuredelivery;hepatotoxicityMaternaloverdose;heartblock;arrhythmiainduction Dizziness;headache;paraesthesias;tremors;visualdisturbances;nausea;vomiting;flushing;possibleneonatalconjugatedhyperbilirubinemiaorneonatalprolongedQTHypotension;asystole;seizures;respiratoryarrest Atrialandventriculararrhythmias;bradycardia;hypotension;confusion;dizziness;nervousness;tremor;ataxia;numbnessoffingersortoes;weakness;blurredvision;tinnitus;nausea;hepatotoxicityHypotension;nausea;vomiting;blooddyscrasias;lupus-likesyndrome;rash;confusion;prolongedQT Idiosyncraticreaction(prolonged>.QRS002sec);prolongedQT;torsadesdepointes;nausea;vomiting;diarrhea;hypotension;tinnitus;confusion;blooddyscrasias;rash;heartblockMyocardialdepression;arrhythmiainduction;torsadesdepointesMyocardialdepression;bradycardia;heartblock;hepatotoxicity VT No Yes No Yes Yes Yes Yes Yes 1Yes Yes AFL No No 1Yes No No No Yes No 2Yes Yes SVT Yes Yes 1Yes 2Yes No No Yes Yes No Yes MaximumDosage 0.2mg/kg 800mgQDmaint. PO:0.25mgBIDmaint.IV:1.0mgQDmaint. Totaldailydosenottoexceed600mg;maternalbloodlevelnottoexceed1mg/L 3–5mg/kgwithinfirsthour Max1200mg/d;maternalbloodlevelnottoexceed2mg/L IV:6mg/minPO:500mgq3hrs;plasmalevels4–10mg/L PO:600mgq4–6hrsIV:0.5mg/kg/min<(infuse10mg/min) 320mgBID Maygivesecond10mgdoseafter30min. a ofFetalTachyarrhythmi StartingDosage 0.1mg/kg ×800–1200mgQD8–14dload;then200–400mgQDmaint. PO:0.25–1.5mgload,then0.125BIDmaint.IV:1–2mgload(mayrepeat),then0.5mgQDmaint.Startat100mgBID,advanceto200mgBID-TID 1mg/kgloadover2min,may×repeatin10–15min2(alternate20–50mg/kg/min)200mgPOq8hrs;therapeuticlevel0.5–2mg/L IV:100mgloadover2min.,then1–6mg/minPO:1gloadthen200–500mgq3–6hrsPO:Testdose200mg;800–1000mgload,then200mgq4–6hrsmaint.IV:0.3mg/kg/min<(infuse10mg/min) 80mgBID 5–10mgover3–5min.(alternate0.005mg/kg/min) present DrugsforTreatment RouteofAdministration FetalIV MaternalPO(FetalIV;FetalIM;FetalIP) MaternalPO;MaternalIV(FetalIV;FetalIM;FetalIP) MaternalPO MaternalIV MaternalPO MaternalIV;MaternalPO MaternalPO(sulfateform);MaternalIV(gluconateform) MaternalPO MaternalIV first-lineagentsecond-lineagentmecautionifhydropsfetalisis TABLE1. Drug Adenosine Amiodarone Digoxin Flecainide Lidocaine Mexiletine Procainamide Quinidine ∗Sotalol Verapamil 1Recommended2Recommended∗Usewithextre

Description:
are associated with fetal arrhythmia, making maternal . Pulsed spectral Doppler tracing from the umbilical vein in a fetus with hydrops fetalis.
See more

The list of books you might like

Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.