Andersons pediatric cardiology 1488

■Homograftafterrecentimplantation
■Chronicperiaortitis(GPA,EGPA)

Pyrexia
■Chronicinfections
■Lineinfections
■Pyrexiaofunknownorigin
■Bacteremiafromdifferentfocus
APS,Antiphospholipidsyndrome;EGPA,eosinophilicgranulomatous
polyangiitis;GPA,granulomatouspolyangiitis;SLE,systemiclupus
erythematosus.


Pathogenesis
Intactvascularendotheliumisresistanttomicrobialadhesioninmost
circumstances.InorderforIEtodevelopthereareanumberofdistinct
pathophysiologiceventsthatneedtooccur.
1.Vascularendothelialdamagewithsubsequentexposureofthe
subendothelialmatrixcanleadtofibrinandplateletdepositionandthe
formationofNBTE.Thislesioncanactasanidusformicrobial(fungal)
adhesionandestablishmentofaninfectedendovascularlesion.Vascular
damagecanoccurviaanumberofdifferentways:
■Highvelocity,turbulentjetsoccurwithregurgitantand
stenoticvalves.
■Mechanicalfriction,orinterruptiontonormalflowresulting
inturbulence,canresultinendothelialdamagewhenthere
areeitherabnormalstructures,orduetothepresenceof
foreignindwellingdevices.
■ProstheticmaterialusedtorepairCHDcanactasasubstrate
forbacterialadhesionandbiofilmformation,andthiscanlast
upto6monthspostprocedure,afterwhichtheyarerelatively

protectedthroughendothelialization.
■Childrenwithartificialvalvesandthosewithpalliativeshunts
aremoreatriskbecausethereareresidualdefectscausing
flowproblemsandoftenincompleteendothelialization.
2.Bacteria(orfungi)musteithergainaccesstothecirculationordirectly
infectmaterialforanNBTEoraprostheticdevicetobecomeinfected.
Theroutesbywhichthiscanhappen,andthevariouswaystopreventor
mitigateagainstthisoccurring,aresummarizedinTable56.3.
Table56.3
RoutesofEntryofMicrobialPathogens
Route/SourceofEntry
Activitiesofdailyliving(e.g.,
toothbrushing,flossing,
chewing)

Prevention/ProcedurestoMitigate
1.Low-levelcumulativebacteremiaislikelytoposearisk
thatwillbepotentiallyworsewhendentalhealthispoor.
2.Recommendedregulardentalreview(twiceyearlyinhighriskpatients)withemphasisondentalhygiene


Dentalprocedures:
1.High-riskmanipulationof
gingivalorperiapicalregion
orperforationoforalmucosa
2.Low-risktreatmentof
superficialcaries,local
anestheticinjection,removal
ofsutures,orthodontic
procedures

Bacterialcarriage(e.g.,
Staphylococcusaureus,groupA
streptococcus)
High-riskprocedures:
1.Insertionofpacemakeror
implantabledefibrillator
(recommended)
2.Implantationofprosthetic
valve,graft(consider)
Low-orminimal-risk
procedures:
1.Respiratory(bronchoscopy,
laryngoscopy)
2.Gastrointestinal/genitourinary
(endoscopy,colonoscopy)
Bacterialinfections/abscesses,
empyema,other

Indwellingvenouscatheters

Bodypiercingandtattooing

Prophylaxisgivenonlyinhigh-riskproceduresinhigh-risk
patient(seeBox56.6)

PreoperativescreeningforS.aureus,witheradicationoffered
presurgery
Appropriateperioperativeantimicrobialprophylaxis
recommended(1)orconsidered(2).
Optimalsurgicaltechnique,includingsterilityofdevices,

instruments,theaterairquality

1.Noprophylaxisroutinelyrequired.
2.Antimicrobialonlyrequiredwhenprocedureisdoneinthe
contextofinfection.

1.Promptdrainageofanyabscess/andoptimalantimicrobial
therapyforsystemicinfections.
2.Potentialsourcesofsepsiseliminated≥2weekspriorto
electivesurgery.
1.Avoidlong-termplacementofcentralvenouslineinhighriskpatientsunlessmedicallyrequired.
2.Strictindwellingvenouscathetercareandadherenceto
protocolstopreventexitandtunnelinfectionsandluminal
contaminationshouldbeobserved.
Probableincreasedriskwithpiercingoftheoralmucosa;
minimaldataexistforskintattoosdonewithaseptic
technique.Risksofpotentialinfectionshouldbeexplained,
aswellasthefactthattheefficacyofantibioticprophylaxis
hasnotbeenstudied.Aseptictechniqueforskinpiercingand
bodyartshouldbeused.

3.Neutrophilextracellulartrapsarearecentlyprovenmechanisminwhich
theIEpathogenpromotesvegetationformation.79Neutrophil
extracellulartrapswerediscoveredin2004asaprotectiveneutrophil
mechanismindependentofphagocytosisbyforminganetworkoffibers
outsidethecellandmaypromoteandexpandvegetationformation
throughenhancingandentrappingbacteria-plateletaggregatesonthe
injuredheartvalves.ThesuggestedpossibilityofDNAseuseto
counteractthismechanismhasnothadanyclinicaltest.