Rhuematic Fever and Infective Endocarditis Flashcards
Acute Rheumatic Fever:
Definition:
Acute Rheumatic Fever(ARF) is an autoimmune non-suppurative inflammatory disease caused by Streptococcus pyogenes
A complication of Strep pyogenes pharyngitis
Tissues commonly affected include: Connective tissues of heart, joints, brain, and skin
Endocardial, myocardial, epicardial damage = cardiac
enlargement, valvar murmurs, effusions
Joints = arthralgia to arthritis (migratory or flitting)
Acute Rheumatic Fever:
Pathogenesis
The disease process starts when the S. pyogenes bacterium affects an individual which causes an acute episode of pharyngitis
Following the infection, there is an activation of the innate immune system
S. pyogenes antigens are introduced to T and B cells
This leads to activation of CD4+ T cells which further
activates B cells to produce IgG and IgM antibody
The CD4+T cells identify Streptococcal M5 protein peptides and generate various inflammatory cytokines which can further cause fibrotic valvular lesions
There is cross-activation of antibodies and at the same time the human proteins are attacked by the Tcells
The infected person’s peripheral blood lymphocyte gives rise to monoclonal antibodies which cross-reacts with myosin resulting in valvular heart disease
Acute Rheumatic Fever:
Clinical Presentation
Acute fever, tiredness and breathlessness from cardiac
failure, with or without other manifestations (most
commonly joint pain and/or swelling) and pansystolic
murmur of mitral regurgitation
Large joint arthritis and/or arthralgia, usually with fever, and sometimes with pansystolic murmur of mitral regurgitation
Choreiform movements, commonly with behavioural
disturbance but often without other manifestations
Gradual onset of tiredness and breathlessness, which is indicative of cardiac failure, without fever or other
manifestations, and pansystolic murmur of mitral
regurgitation, which indicates the insidious onset of carditis
N/B: Skin manifestations (erythema marginatum and
subcutaneous nodules) are less commonly observed in acute
rheumatic fever (ARF)
Rheumatic Heart Disease:
Definition
A chronic disease caused by accumulated heart valve
damage from a single severe or, more commonly, multiple recurrent ARF episodes
Rheumatic Heart Disease:
Pathogenesis
Repeated upper respiratory attacks by Streptococcus
pyogenes/Group A streptococcus (triggered by the new M
types)
Antibodies formed against Streptococcal M proteins cross react with sarcolemma of the heart
Inflammation of the endocardium and heart valves
Rheumatic Heart Disease:
Diagnosis
1.Based on clinical findings (Jones’s criteria)
- Recent evidence of Streptococcus pyogenes infection
- laboratory
Recent evidence of Streptococcus pyogenes infection:
Culture Based Tests
Non Culture Based Tests
• Cult Non culture based tests
•
• Increase in anti-ASO or anti-DNAse B – Antibody test • Anti-streptolysin O titers get raised within 1 week
• Antideoxyribonucleas (Anti DNAse) B titers get raised within 1-2 week
• PCR based diagnosis
• For identifying the Streptococcus pyrogenic exotoxin B gene
•
Rheumatic Heart Disease:
Culture Based Tests
Positive throat culture for Streptococcus pyogenes
Rheumatic Heart Disease:
Non-Culture Based Tests
Positive Streptococcus pyogenes antigen test on throat swab
Increase in anti-ASO or anti-DNAse B – Antibody test:
- Anti-streptolysin O titers get raised within 1 week
- Antideoxyribonucleas (Anti DNAse) B titers get raised within 1-2 week
PCR based diagnosis:
-For identifying the Streptococcus pyrogenic exotoxin B gene
Rheumatic Heart Disease:
Prevention
Involves prophylactic strategies to avoid GAS infection
ARF is triggered by GAS pharyngitis and the GAS transmission is facilitated by close contact between people
Thus, living conditions, knowledge regarding the importance of a sore throat caused by GAS and an understanding of the mechanisms of transmission are important
*GAS-Group A Streptococcus
Rheumatic Heart Disease:
Prophylactic Treatment
- Primary Prophylaxis
2. Secondary Prophylaxis
Primary Prophylaxis
Treatment of throat infections
- Benzathine Penicillin G 1,2 MU IMI
- Penicillin VK 500 mg po 4 times a day for 10 days
Individuals allergic to penicillin: Erythromycin for 10 days
Secondary Prophylaxis
Prevention of recurrence
Continuous prophylaxis for:
- Documented rheumatic fever
- Definite rheumatic heart disease
Duration of therapy is dependent on whether the patient has developed carditis or chronic valvular heart disease.
- Rheumatic fever with carditis and persistent valvular disease-10 years or until age 40 years (whichever is longer); lifetime prophylaxis may be needed
- Rheumatic fever with carditis but no residual heart disease-10 years or until age 21 years (whichever is longer)
- Rheumatic fever without carditis- 5 years or until age 21 years (whichever is longer)
Rheumatic Fever/Heart Disease:
Treatment
Benzathine Pen G 1.2 MU IMI every 3 to 4 weeks
OR
Penicillin V 250mg twice daily orally
OR
Erythromycin 250mg twice daily po
Infective Endocarditis:
Definition
Infective Endocarditis (IE) • Refers to infection of the endocardial surface of the heart and the physical presence of microorganisms in the lesion
Typically involves cardiac valves (native / prosthetic) or an indwelling cardiac device
Disease may also occur within septal defects or mural
endocardium
Infective Endocarditis:
Heart valves involved
Mitral valve alone 28 – 45%
Aortic valve alone 5 – 36%
Aortic and mitral valves combined 0 - 35%
Tricuspid valve rarely involved 0 – 6%
Both right and left-sided disease present in 0 – 4% of cases
NB:
Rheumatic heart disease underlying lesion in 37 – 76% of infections
Important causes of cardiac valve damage:
•
Infective Endocarditis:
Predisposing Factors
Rheumatic fever
Congenital cyanotic heart abnormalities
Atherosclerotic aortic valve
Prosthetic valve replacements
Intravenous drug abuse
