Acute Rheumatic Fever (ARF) PDF

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