Rheumatic fever/rheumatic heart disease/IE Flashcards
What is PC of rheumatic fever?
following a sore throat
fever
joint pain
How does rheumatic fever lead to rheumatic heart disease?
Group A streptococcus (GAS) infection, G+, streptococcus pyogenes
onset 2-4 weeks following infection –> pharyngitis, skin infections
autoimmune infection to the heart as a result of molecular mimicry after 10-20 years after original disease
Repeated rheumatic fever is the biggest risk factor for developing rheumatic heart disease
mitral valve > aortic valve
How does molecular mimicry work?
- S pyogenes strains ARF contain cell-surface antigens which are similar self-antigens
- Immune response to pathogens produces antibodies which are cross-reactive with hosts tissues
- Does not affect ALL individuals
Genetic differences – HLA associations and other genetic polymorphisms associated with susceptibility
Other predisposing/protective factors
GAS infection –> epithelial adhesion & invasion –> activation of T & B cells by GAS antigen –> cross-reactive antibody formation –> tissue specific damage such as heart, brain (chorea), joints (arthritis), skin (erythema and subcutaneous nodules)
What is Jones criteria?
How does it diagnose rheumatic fever?
recent streptococcal infection and either presence of 2 major, 1 major + 2 minor
Major (J♡NES) Joints/arthritis Heart/carditis, valves Nodules Erythema Sydenham's chorea
Minor (PEACE) Previous rheumatic fever ECG with prolong PR Arthralgia/joint pain CRP and ESR elevation Elevated temperature
J♡NES
Joints/arthritis
75%
- Within 21 days after GAS infection
- Migratory pattern: affect several large joints such as knees, ankle, elbows, wrists asymmetrical
- Immune complex deposition on synovial membranes, collages –> recruitment of inflammatory cells
J♡NES
Carditis
- Within 3 weeks after GAS infection
- Cross-reactivity b/w M proteins and cardiac myosin –> Pancarditis is typical
- Predominant: SOB, PND/orthopnoea, infective endocarditis, affecting valves (mitral & aortic)
Diagnosed by new murmur (MR) pansystolic heard loudest at apex, radiating to axilla
(AR): decrescendo, diastolic loudest at base of heart, accentuated by sitting forward
J♡NES
Subcutaneous nodules
rare
- Within the first weeks of illness, along with severe carditis
- Firm, painless nodules, extensor surface, over olecranon (elbow)
J♡NES
Erythema marginatum
- Early in disease course, may recur or persist after resolution of other symptoms
- Pink, circular rash, non-pruritic, can appear and disappear within hours
- Distributed over trunk, limbs
- Cross reactivity with keratin
J♡NES
Sydenham’s chorea
rare in adults, 25% in children
- Present 8 months after GAS infection –> takes a long time for antibody to cross BBB barrier
- Asymmetrical abrupt, non-rhythmical movements such as child become fidgety
- Offset within 6 weeks – 6 months but can result in long term
- Milkmaid’s sign: inability to maintain grip and rhythmical squeezing
How does rheumatic heart disease lead to infective endocarditis?
chronic rheumatic heart disease → valves (mitral typically) develop scar tissue from repeated inflammation → leaflets of valves become thicker from fibrosis and fuse together (comissural fusion) → chordae tendinea become thickened → regurgitation (don’t close properly) → stenosis of opening roughened areas are also higher risk for microbial attachment and invasion → infective endocarditis
Investigations for rheumatic fever?
Microbial culture & sensitivity
- throat swab, blood
ESR/CRP + WBC
- elevated
ECG
- prolonged PR interval
Echo
- morphological changed to mitral/aortic valves
Rapid antigen test for GAS
- positive
Measurement of specific antibodies: anti-streptococcal serology/ELIZA
- ASOT (anti-streptolysin O antibodies), anti-DNAse B
- Levels often rise rapidly 3-4 weeks after infection then decline might remain elevated for several months
Management for rheumatic fever?
- Symptomatic relief
Arthritis: aspirin, NSAID (6 weeks)
HF: diuretic, ACE
Chorea: antiepileptics - Eradication of GAS antibiotic therapy: phenoxymethylpenicillin (10-day course, given to high-risk individuals, history of GAS infection)
- Management of cardiac disease
HF: diuretic, ACE, regular echo
Monitor arrythmia
Valve leaflets/chordae tendinea rupture: valve surgery - Prevention
o Secondary prophylaxis to prevent recurrent episodes + RHD
Monthly injection of penicillin every 3-4 for 10-15 years
o Progressive cardiac disease - Long term monitoring
Education to patient and family
Dental treatment and education to prevent IE, Follow-up
What are some risk factors of IE?
- Underlying heart disease: chronic rheumatic heart disease (aboriginal), congenital heart disease, VHD
- Prosthetic heart valves, previous IE
- IV drug use (staph aureus), indwelling venous catheter
- Nosocomial (hospital) bacteriaemia due to IV lines (staph aureus)
- Poor dental hygiene (Strep viridans)
- DM, HIV
- Long term haemodialysis
Rheumatoid heart disease vs IE
RHD
- immunological molecular mimicry after GAS infection
- complication after 10-15 years
IE
- active bacteria growing
What is endocardium?
inner most layer
heart valve, septum, chordae tendinae
How does vegetation on valves form due to endocarditis?
- Fibrin + platelets + organisms (circulating pathogens) + inflammatory cells (monocytes)
- Circulating pathogens are wrapped inside fibrin and platelet clot. When treating with antibiotics, the clot acts as a biofilm to protect the pathogens. Also, valves are relatively avascular structures so that system circulation containing antibiotics cannot reach the pathogens –> bio filming
Acute endocarditis vs subacute endocarditis
Acute
- Normal valves/native valve
Virulent bacteraemia able to colonise a healthy and undamaged valve –> rapid, massive vegetation
- Risk factor: IV drug use, IV line, catheters, immunocompromised
- Virulent organisms: S. aureus (IV, hospital), S Pneumoniae
Subacute
- Abnormal valves
Predisposing valve damage allows indolent organisms to colonise
- Risk factor: congenital/past valvular heat disease, prosthetic valve
- Indolent organisms (weaker): Streptococci viridans (oral flora G+), enterococci, HACEK culture negative
- vague constitutional symptoms
Diagnostic features of IE
New/changing murmur + fever
Symptoms
- fever (common but not mandatory)
Diagnostic features of IE
New/changing murmur + fever
Symptoms
- fever (common but not mandatory)
- constitutional symptoms
Signs (FROM JANE) fever Roth's spots (retinal) Osler's nodes: painful raised, red Murmur Janeway's lesion Anaemia Splinter haemorrhage Emboli --> renal emboli, flank pain
Mech for fever
Exogenous pyrogen induction of fever by bacteria and its toxins –> self-produced pyrogenic cytokines IL-1/6/TNF –> cytokine formation triggers hypothalamus up-regulate the set point
What is duke’s criteria?
Diagnose IE definitive diagnosis - 2 major - 1 major + 3 minor - 5 minors BE FIVER
Major
- positive blood culture from 2 separate blood cultures for typical IE organisms such as s.aureus, strep viridans, HAECK
- evidence of endocardial involvement via echo
Minor
- predisposing conditions (abnormal heart valves, IV)
- fever
- vascular: janeway
- immunological: osler’s, roth’s
investigations of IE?
CBE
- Raised ESR, CRP
- Normocytic anaemia of chronic disease subacute endocarditis
Urinalysis: proteinuria, haematuria
Echocardiograms - Transthoracic echo 98% specific for vegetations 60-70% sensitivity: obesity, COPD as the chest is inflated with air, chest wall defects Negative TTE does not exclude IE
ECG
- Prolonged PR interval, non-specific ST abnormality, AV block
Blood culture –> most important
3 sets of blood culture collected from different site > 1 hr apart
Persistent bacteraemia is the hallmark of IE
Repeat at least twice after 48-72 hr of antibiotics to confirm clearance
Management of IE
ABCDE, pain relief
obtain blood culture + echo
Start empiric as soon as you have 3x blood culture then direct therapy once organism is identified + susceptibility profile
IV + prolonged course 6 weeks
antibiotics given to IE patients
G+
- benzylpenicillin
- flucloxacillin
- gentamicin
if not safe to administer penicillin (generally true for most kinds of organisms)
- gentamicin
- vancomycin
What is the specific anti-staphy penicillin?
Flucloxacillin
