Acute Rheumatic Fever (ARF) PDF

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acute rheumatic fever autoimmune disease clinical manifestations medical

Summary

This document presents an overview of acute rheumatic fever (ARF), including its definition, incidence, and underlying mechanisms. It discusses the key clinical manifestations and major criteria for diagnosis.

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Part 3 3: Acu ute Rheu umatic F Fever (A ARF) Definittion: It is ann inflamma atory disea...

Part 3 3: Acu ute Rheu umatic F Fever (A ARF) Definittion: It is ann inflamma atory disea ase that m may develo op as a co omplicationn of untre eated or poorly treated Grroup A β-hemolytic c streptococcal (GA ABHS) infeection of th he URT. It is cau used by an ntibody cro oss-reactivvity (i.e. autoimmune disease). nce Inciden  Agee: 5-15 yea ars (rare 2--5 years - n never below 2 years).  Envvironmentaal factors: poor p living conditions s, overcrow wding.  Gennetic factors may plaay a role.  No sex differe ence in thee incidence e or pathog genesis. Etiolog gy and patthogenesiis The au utoimmun ne theory (molecula ar mimicrry): the disease usuually follow ws URT infectio on with GABHS. G This rheu c strain contain ssurface antigens umatogenic a (hyaluro onic acid, cell wall polysaccha p arides, M protein, p c.) that aree immunologically etc similar to some host's h tissu ue. Antiboddies forme ed against these ant igens will later on cross-react with h connecttive tissuee antigens in the heart, syno ovial membranes, caudate nucleus, skin and subcutan neous tissu ue. Repea ated strepttococcal in nfection is required for se n of the im ensitization mmune system. Clinica al manifes stations: “J Jones critteria first published p 1944”: Major criteria: Polyrthritis (7 70%): the joints are e swollen and a tendeer. It is fleeeting (mig gratory), affe ects large joints, j and subsides without deeformity. Carrditis (50% %): murmurrs, arrhythm mia, cardio omegaly, pericardial p rub. Rhe eumatic ch horea (10% %): jerky li mb movemments and d emotionaal instability occur moore in girls. It is revers sible. Sub bcutaneou us nodule es (5%): painless noddules besid de muscle tendons. Eryythema ma arginatum (1%): red d patches oveer the limbss and trunk. Minor criteria:  Fevver.  Arth hralgia: pa ain in the jooint.  ↑ PR interval in the ECG G.  ↑ an ntistreptolyysin O titre e (ASO). Ac cute carditis oof a child 8 years y  ↑CC-reactive protein p andd ESR. 130 Diagno osis: Revis sed Jones s criteria ( 1992 update e): At leasst 2 major criteria must m be pre esent OR 1 major + 2 mino or criteria PLUS evvidence of o previouus streptoc coccal infeection: – Hisstory of ph haryngitis confirmed c by positiv ve thro oat culture e for GABH HS. – Elevvated AS SO titer > 400 U or othe er stre eptococcal antibodie es. gement Manag ▌TREAT TMENT OF F THE ACUTE EPISOD DE Bed d rest: – 2 weeks in n absence of carditiss. – 4 weeks in n presence e of carditis. – 8 weeks in n presence e of heart ffailure or cardiomeggaly. Diet: Salt andd fluid resttriction in presence of card ditis or hea art failure to t avoid vo olume overrload. Anttibiotics: to o eradicate e streptoco occal infec ction – First choic ce: benzylp penicillin (1 1 million IUU/6h i.v. or i.m.). – Second ch hoice (in penicillin alllergy): Co--trimoxazolle or erythrromycin. Antti-inflamm gs: to sup press acutte inflammation matory drug A. RF withou ut carditis: salicylattes (aspirin n) Dose: 1000 mg/kg/d for 2 wee ks (till clinical manife estations ssubside) th hen give 75 mg/kg/d for 2 weeks w theen 50 mg//kg/d for another 2 weeks (M Max 16 ttabs/d). – Rapid breaathing (tacchypnea) i s the earliiest sign of o aspirin tooxicity. – Naproxen is an alternative for p patients who w are alle ergic to asp pirin. B. RF with se evere card ditis: cortiicosteroid ds (prednissolone) Dose: 2 mg/kg/d m forr 2 weeks (till clinica al manifesta ations sub bside) then reduce tthe dose to o 1mg/kg//d for one mmonth. 131 Why corticosteroids, but not aspirin, in presence of carditis?  Aspirin produces excellent symptomatic relief of arthritis and fever but exerts non-specific effect on carditis.  Aspirin cannot prevent pericardial rub or valve deformity, but steroids can prevent them.  High doses of aspirin increase myocardial O2 consumption and heart work and so precipitate valvular lesions and CHF. ▌TREATMENT AFTER THE ACUTE EPISODE (PREVENTION OF RECURRENCE) Long-acting penicillin: benzathine penicillin. Dose: 1,200,000 IU / 3-4 weeks by deep i.m. injection Duration of prophylaxis? – For mild or no carditis → for 3 years from last episode. – For moderate carditis → prophylaxis till 21 years. – In severe carditis or recurrent episodes of RF → lifelong prophylaxis. Precaution during treatment of ARF with other disease ARF with – Avoid using corticosteroids because they are immunosuppressant TB and cause flaring of TB infection. – If it is necessary to use corticosteroids, it must be used under umbrella of antituberculos drugs. ARF with – Fluid and salt restriction CHF – If digoxin is needed, use with caution to avoid arrhythmia (the heart is very sensitive to digoxin during Rh activity). ARF with – If corticosteroids are mandatory, consider adjusting the insulin diabetes dose to avoid hyperglycemia. – Consider possible interaction of salicylates with other antidiabetic drugs. ARF with – Give salicylates through multiple routes or as enteric coated peptic preparations to avoid gastric irritation. ulcer – Give salicylates after meals with plenty of fluids. – Use H2 blockers or proton pump inhibitors. 132

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