Rheumatic Fever Lecture Notes PDF

- The development of rheumatic fever is preceded by infection with group A B-hemolytic streptococci. - The site of infection is upper respiratory tract especially in the form of pharyngitis. - Rheumatic fever is more likely to develop following severe & recurrent infections. - The mechanism b...

- The development of rheumatic fever is preceded by infection with group A B-hemolytic streptococci. - The site of infection is upper respiratory tract especially in the form of pharyngitis. - Rheumatic fever is more likely to develop following severe & recurrent infections. - The mechanism by which this infection elicits rheumatic fever remain unknown. The most accepted theory suggests that it is autoimmune process. Pathogenesis: The current concept of the pathogenesis of acute rheumatic fever is that it is due to group A (rheumatogenic) beta hemolytic streptococcal pharyngitis occurring in a susceptible host, which leads to an autoimmune response triggered by molecular mimicary between M protein of infecting streptococcus and host own tissues like heart, joints, brain, connective tissue. How? - Body produces antibodies against streptococci. - These antibodies cross react with human tissues because the antigenic similarity between streptococcal component and human connective tissues ( molecular mimicry). There is certain amino acid sequence that is similar between M protein of infecting streptococcus and human tissue. Pathogenesis(Cont.) - So, the damage which occurs to the distant tissues is not due to direct bacterial invasion but to an acute autoimmune reaction explained by the production of anti-streptococcal antibodies which cross react with the host tissues. - The cause of this cross reactivity is unknown but is probably caused by antigenic similarity. Pathogenesis: (Cont.) - The latent period between streptococcal infection and onset of rheumatic fever is 1-5 weeks except in chorea which may occur after several months. why the majority of patients do not develop acute rheumatic fever after an initial streptococcal infection and only a minority do: Host immune responses may play a role in determining who gets ARF following infection. Virulent strain: rheumatogenic serotype. Definition Rheumatic fever is an immunologically mediated inflammatory disorder, which occurs as a sequel to group A-beta hemolytic streptococcal pharyngeal infection (rheumatogenic strain). It is a multi-system disease affecting connective tissue particularly of the heart, joint, brain and skin (cutaneous and subcutaneous tissue). It is not a communicable disease, but results from a communicable disease (streptococcal pharyngitis). Pathology: There is an inflammatory process involving the following tissues: 1. Joints : synovial membrane. 2. Heart: endocardium, myocardium, pericardium 3. CNS: especially basal ganglia. 4. Skin & subcutaneous nodules. There are inflammatory reactions of two types: 1. exudative lesion: - Affecting mainly serous membranes. - Healing occurs without residual effect. 2. Proliferative lesion: “Aschoff nodule” - Affecting mainly the heart. - Consisting of central area of fibrinoid degeneration surrounded by lymphocytes, macrophages, aschoff giant cells & outer layer of fibroblasts. - Healing occurs later by fibrosis. Epidemiology The incidence and mortality of acute rheumatic fever has declined over the past 30 years due to: improved socioeconomic conditions. rapid diagnosis and treatment of strep. pharyngitis (due to the wide spread of new generation of effective antibiotics. Epidemiology (cont.) The commonest age of onset is 5-15 years but it may occur up to 25- 30 years. Males and females are equally affected. Overcrowding, poverty, lack of access to medical care contribute to transmission of upper respiratory tract (URT) infection. Clinical Presentation Clinical picture: I - major criteria: 1. Arthritis 2. Carditis 3. Rheumatic chorea (sydenham’s) 4. Subcutaneous nodules 5. Erythema marginatum II - Minor Criteria: 1. Fever 2. Arthralgia 3. History of rheumatic fever or evidence of rheumatic heart disease 4. Acute phase reactants: high ESR, C-reactive protein, polymorphnuclear leucocytosis. 5. Prolonged P-R interval more than 0.22 sec. Rheumatic arthritis Arthritis is the most common presentation of acute rheumatic fever. Rheumatic arthritis is characterized by: (a) Polyarthritis. (b) Migratory or fleeting character. (c) Predilection for large joints. (d) Dramatic response to salicylates within 24-48 hours. (e) Complete recovery with no residual deformities.  Artralgia Vs Arthralgia *Arthritis = inflammation of the joint, all symptoms & signs of inflammation are present ( the joint is red, hot , swollen, painful, tender, with limitation of joint movement). Arthritis is one of the major criteria of acute rheumatic fever. *Arthralgia = pain in the joint but the joint did not show the manifestations of inflammation. Arthralgia is one of the minor criteria of acute rheumatic fever. Rheumatic Carditis Carditis is the most serious manifestation of acute rheumatic fever. Why? It may lead to chronic rheumatic heart disease and sometimes severe heart failure. Rheumatic Carditis (cont.) Unlike the arthritis, the carditis does not resolve without residual ill-effects. How? It excites a process of gradual and slow fibrosis which continues in an asymptomatic manner for many years after clinical recovery from the acute phase. The outcome of this gradual fibrosis is destruction of the valvular mechanisms with the production of irreversible stenosis.  It is surprising how rheumatic fever can be so gentle with the joints and so harsh with the heart. It has been once said that rheumatic fever licks the joints and bites the heart. Rheumatic Carditis All the layers of the heart may be involved and so the condition is called pancarditis. The symptoms and signs of carditis depend on whether there is involvement of the pericardium, myocardium or endocardium. Manifestations of Rheumatic Carditis An attack of acute carditis may be diagnosed in the early stages by: Disproportionate tachycardia: Tachycardia out of proportion to the fever especially if associated with weak or muffled first sound due to prolonged P-R interval. Rapid development of functional murmurs which were not present before and which may change from day-to-day. An abnormal third heart sound due to myocarditis A pericardial rub due to pericarditis or pericardial effusion. In severe cases, heart failure may occur due to damage of the myocardial contractility Subcutaneous nodules Usually small (0.5-2cm), mobile, painless nodules. Firm, non-tender, isolated or in clusters. Most common along extensor surface of joints, on bony prominences, tendons and dorsal surface of feet. Last a few days, with complete resolution. Erythema marginatum Present in 7% of patients Highly specific to acute rheumatic fever. it is cutaneous lesion characterized by erythematous macules with migratory borders and blanching centres (reddish pink border, pale center) round or irregular shape. Often on the trunk, abdomen, inner arms or thighs. Highly suggestive of carditis. Reumatic (sydenham”s) chorea Extrapyramidal disorder (affecting basal ganglia). The damage is typically not permanent. Fast, jerky, involuntary, purposeless movements especially face, tongue and limbs (hands & feet). The involuntary movement increases with stress. It may be associated with some emotional instability but the mentality remains normal (changes in emotions). May be the only manifestation of ARF. Usually a late manifestation months after infection. Occurs in 30% of patients with ARF Affects female more than males It has a long duration of several months but resolves completely with no cerebral damage. Investigations Complete blood count (CBC): leukocytosis & anaemia Acute phase reactant : elevated erythrocyte sedimentation rate (ESR) & C-reactive protein (CRP). Anti-streptococcal O titer (ASOT) Throat culture Electrocardiogram (ECG) Plain chest x-ray echocardiogram Complications: 1. Early complications - Heart failure - Arrhythmias - Heart block 2. Late complications - Rheumatic valvular lesions e.g mitral stenosis - Rheumatic activity - Rarely; adhesive pericarditis & Jaccoud’s arthropathy Investigations Laboratory investigations Cardiac investigations Laboratory Investigations 1- Blood picture: Polymorphnuclear leucocytosis Normocytic anemia. 2- Erythrocyte sedimentation rate (ESR): It is markedly elevated. It is not specific for rheumatic fever but it is one of the minor criteria & used for follow up. 3- C-reactive protein (CRP): It is markedly elevated. It is not specific for rheumatic fever but it is one of the minor criteria & used for follow up. 4- antistreptolysin 0 titer (ASO): Elevated in 80% of cases. Titer greater than 250 Todd units/ml in adults & 500 Todd units/ml in children are indicative of recent streptococcal infection. 5- Streptozyme test: positive in more than 95% of cases. 6- Throat culture: positive in only few cases. Cardiac investigations: ECG Chest x-ray Echcardiography:  Diagnosis The is no specific diagnostic test for acute rheumatic fever. Diagnosis of Acute Rheumatic Fever Jones Criteria - Criteria developed to prevent over diagnosis. - Diagnosis depends upon the presence of two major criteria or one major and two minor criteria in the presence of data of recent streptococcal infection. Evidence of streptococcal infection The patient gives history of sore throat 2-3 weeks before. Sometimes a residual infection in the throat may still be complained of at the time of examination. Throat swab culture is often positive for streptococcus. Elevated antistreptolysin O titre( ASOT) more than 250 Todd units/ml or other antistreptococcal antibodies. History of recent scarlet fever.  Aim of Treatment Eradication of group A beta-hemolytic streptococcul infection Avoid chronic exposure of immune system to strep. bacteria. Treatment according to the presentation.  Treatment Supportive therapy Preventive therapy Antibiotics: This is essential to prevent recurrence. To eradicate streptococcal infection. Benzathin penicillin G (long acting Penicillin (benzathin penicillin G) 1.2 million penicillin) as a single dose of 1.2 million units IM once, or procaine penicillin, units monthly till the age of 25-30 600,000 units IM daily for 10 days. years or for 5 years after last attack of acute rheumatic fever. Salicylates ( for arthritis) Aspirin 6-8 gm/day. Usually excellent response. Corticosteroids (for carditis) Prednisone 1-2mg/kg/day maximum dose 60-120mg x 10-15 days Once ESR becomes normal taper 20-25% each week.  Dentist and patient with rheumatic fever Any patient will under go any minor tooth extraction must be covered with umbrella of antibiotic before, during and after the procedure. Why?