Nurs 324 Chapter 40 Notes

Chapter 40 Myocarditis, Rheumatic Fever, and Rheumatic Heart Disease




What is the etiology and pathophysiology of myocarditis?
Myocarditisisafocalordiffuseinflammationofthemyocardium.Itmaybeidiopathic,butother
causesinclude:

 Viruses:
o CoxsackieAandBvirusesarethemostcommon.
 Bacteria
 Fungi
 Radiationtherapy
 Pharmacologicandchemicalfactors
 Autoimmunedisorders(e.g.,polymyositis)

Whenthemyocardiumbecomesinfected,thecausativeagentinvadesthemyocytesandcauses
cellulardamageandnecrosis:

 Immuneresponseisactivated.
 CytokinesandO2freeradicalsarereleased.
 Autoimmuneresponseisactivatedastheinfectionprogresses.
 Resultsinfurtherdestructionofmyocytesandheartdysfunction.

What are the early manifestations and late signs of
myocarditis?
Thefeaturesofmyocarditisvaryfromabenigncoursewithoutovertsymptomstoprogressive
heartfailure(HF),dysrhythmias,orsuddencardiacdeath(SCD).

Earlymanifestationsoftheviralillnessare:

 Fever
 Fatigue
 Malaise
 Myalgias
 Pharyngitis
 Dyspnea
 Lymphadenopathy
 Nauseaandvomiting

Earlycardiacsignsappear7to10daysafterviralinfection.Pericarditisoftenaccompanies
myocarditis.Signsincludepleuriticchestpainwithapericardialfrictionrubandeffusion.

LatesignsrelatetothedevelopmentofHFandinclude:

, Chapter 40 Myocarditis, Rheumatic Fever, and Rheumatic Heart Disease



 S3heartsound
 Crackles
 Jugularvenousdistention(JVD)
 Syncope
 Peripheraledema
 Angina

What studies are performed to diagnose myocarditis, and
what is the treatment to manage symptoms?
Studiesthataredonetodiagnosemyocarditisinclude:

 ECG:
o Changesareoftennonspecificbutreflectpericardialinvolvement(e.g.,diffuseST
segmentchanges).
o Dysrhythmiasandconductionproblemsmaybepresent.
 Laboratorytesting:
o Findingsareofteninconclusive.
o Mayinclude:
 Mildtomoderateleukocytosisandatypicallymphocytes
 Highviraltiters
 Increasederythrocytesedimentationrate(ESR)andC-reactiveprotein
(CRP)levels
 Increasedlevelsofcardiacbiomarkers,suchastroponin
 Fluidsampling(tissueandpericardialfluid):
o Virusisgenerallypresentonlyduringthefirst8to10daysofillness.
 Endomyocardialbiopsy:
o Provideshistologicconfirmationofmyocarditis
o Mostdiagnosticduringthefirst6weeksofacuteillness,whenlymphocytic
infiltrationandmyocytedamagearepresent
 Nuclearscans,echocardiography,andMRI:
o Usedtoassessheartfunction

Treatmentconsistsofmanagingsymptomsusingmedication.

Angiotensin-convertingenzyme(ACE)  UsediftheheartisenlargedortotreatHF
inhibitorsandβ-adrenergicreceptor
blockers(β-blockers)
Diuretics  Reducefluidvolumeandpreload

Nitroprussideandmilrinone  Notusedifpatientishypotensive
 Reduceafterloadandimprovecardiacoutput
(CO)bydecreasingsystemicvascular