Wednesday, March 25, 2009

Excerpts from the scientific seminar of cure 2008 ( part 1)

Rheumatic Fever

Definition

Diffuse non suppurative  inflammatory disease of connective tissue as a sequalae to Group A beta hemolytic streptococcal infection of the throat by rheumatogenic strains, primarily involving heart, blood vessels, joints, subcut. tissue and CNS

Magnitude of Pattern

Common cause of CV morbidity and mortality in underdeveloped and developing countries

Less in developed world

Prevalence of RHD in school children

USA                          :           0.6 / 1000

JAPAN                      :           0.7 / 1000

ALGERIA                :           15 / 1000 ( WHO 1970)

INDIA                      :           6 – 11 / 1000 (WHO 1970)

                                                6 / 1000 (5 CITIES – 1 Cm2)

 

Aetiopathogenesis

Incompletely understood

Non suppurative sequelea to  ‘GAS’

Repeated infection important

Genetic predisposition ?

Autoimmunity – Antigenic mimicry between st.cell wall component and human myocardium, valvular glycoprotein etc.

Delayed immune response to infection with group.A beta hemolytic streptococci.

After a latent period of 1-3 weeks, antibody induced immunological damage  occur to heart valves, joints, subcutaneous tissue & basal ganglia of brain 

Determinants

Severity of throat infection

Severe exudative infection - upto 3%

Mild sporadic – 0.5 to 1%

Immune response (ASO) – 1 to 5%

GAS persisting in throat

Previous RF : many times

Established RHD – very high

Recurrence rate –  50% - 1st year

                                    10% after 5 years 

Pathologic Lesions

Fibrinoid degeneration of connective tissue,inflammatory edema, inflammatory cell infiltration &  proliferation of specific cells resulting in formation of  Aschoff nodules, resulting in

                        -Pancarditis in the heart

                        -Arthritis in the joints

                        -Aschoff nodules in the subcutaneous tissue

                        -Basal gangliar lesions resulting in chorea 

Rheumatic fever licks the joint & bites the heart 

Incubation period

1 to 5 weeks

Shortest for Arthritis

Longest for Chorea 

Clinical features

Commonest age – 5- 15 years

Arthritis

Migratory polyarthritis

Mainly - major joints, no residual deformity

Usually mild in young children esp. <>

Prominent in older children and adolescents

Occur upto 30%, more in girls

May appear even 6 m after the attack of RF

Clumsiness, deterioration of handwriting, emotional lability or grimacing of face

Clinical signs- pronator sign, jack in the box sign, milking sign of hands

Occur in 2 %

Painless, pea-sized, palpable nodules:- 0.5 - 2 cm, mainly over extensor surfaces of  

  joints, spine, scapulae & scalp

Typically appear > 3 wk after the onset

Always associated with severe carditis

Rarely seen in our population -.5 to 2%

Transient, serpiginous, non-itchy, pale center with red irregular margin, mainly trunks/ limbs

Often associated with carditis

Carditis - Pancarditis

Endocarditis – Valvulitis, Mitral & /or aortic

Significant murmur – MR, AR, Carey Coombs

Myocarditis

 Cardiomegaly–Clinical, X-Ray CCF, Prolonged PR, relative Tachycardia, Soft S1, S3

Pericarditis

Pericardial rub  ± effusion 

Diagnosis of RF

No single symptom

No single sign

No single lab test 

Revised Jones Criteria for Guidance in Diagnosis

1994 – by Dr. T. Duckett Jones

Modified by AHA in 1956, 1965, 1982, 1992

1987 – WHO study group accepted 1982 AHA criteria

Revised Jones Criteria, AHA 1992

Major:

            Carditis

            Arthritis

            Chorea

            Erythema marginatum

            Subcutaneous nodules

Minor:

            Clinical:    Arthralgia

                                  Fever 

            Lab:   ­ level of acute phase reactants –ESR & C-reactive protein

                          Prolonged PR interval 

Essential criteria:

            Evidence of antecedent group A Streptococcal infection

 

Diagnosis of rheumatic fever highly probable

If

Two major criteria      

or

One major & two minor criteria

With

Essential criteria satisfied

Relaxation of Criteria

Chorea as sole manifestation (other causes excluded)

Insidious onset / Late onset carditis

Established RHD

One major criteria

Fever with arthralgia + increased acute phase reactants

If evidence of recent GAS infection present

Acute Carditis in Chronic RHD often difficult

New murmur

Sudden increase in heart size

Recent onset CHF

Pericardial rub

Erythema marginatum / Subcutaneous nodules

            Previous carditis – recurrence of RF ® Carditis almost always present

Supportive evidence of Streptococcal infection

ASO + others

Throat culture – positive

Recent scarlet fever

History of sore throat – commonest viral

 

Laboratory Findings

High ESR, Elevated C-reactive protein

Anemia, leucocytosis

ECG - prolonged PR interval, non specific ST-T changes  rarely heart blocks

2D Echo cardiography - valve edema, mitral regurgitation, LA & LV dilatation, decreased contractility, pericardial effusion,

Streptococcal antibody tests

ASO - most commonly used

> 200 IU  suggestive, rising titre in 2 to 4 wks

Peaks in 4to 6  wks , remain high for 4 to 6 wks and comes down

Sensitivity- 80%

Specificity low – skin infection, other strep. Inf.

Others

Antistreptokinase, Antihyaluronidase

Anti DNAse, Antistreptozyme(most sensitive)

Throat Culture

Positive in minority (latency, antibiotic Use)

About 20 % school children – carrier state

 

Differential Diagnosis

Rheumatoid Arthritis

SLE

Infective Endocarditis

Serum sickness

Gonococcal Arthritis

Tuberculosis

Viral myopericarditis

Leukaemias

Overdiagnosis - Problems

Trauma + anxiety – parent + children

Unnecessary prophylaxis – risk

Missing another disease

 

Under Diagnosis

No prophylaxis

Risk of reactivation

Natural History of RF

Period of activity 

                        75%          - 6 weeks

                        90%          - 12 weeks

                        < style="mso-spacerun:yes">     - upto 6 months (Chronic RF) 

Arthritis

                        > 12 years – 80%

                        3 to 6 years – 50% 

Carditis

                        <>

                        14 to 17 years – 30%

Natural History – RF with Carditis

Initial attack, no carditis – excellent prognosis

Initial attack, mild carditis – 70% normal heart after 10 years

Initial attack, severe carditis – 40% normal heart at 10 years

 

 

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