Rheumatic Fever Flashcards
ARF Case Studies:
๐ฉบ Rheumatic Fever Unveiled in a 13-Year-Old Misdiagnosed With Appendicitis
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What is Rheumatic fever?
Rheumatic fever is an acute, immunologically mediated multisystem inflammatory disease which may develop a few weeks after a Group A Beta haemolytic streptococcal infection pharyngitis and often involves the heart.
Outline the epidemiology of Rheumatic fever.
๐ฉบ The highest prevalence is found in low- and middle-income countries, especially in the African, South-East Asia, and Western Pacific regions.
๐ฉบ India has the highest global prevalence, accounting for about 27% of all cases.
๐ฉบ Rheumatic fever most commonly occurs in children aged 5-15 years.
๐ฉบ Most regions report an equal male-to-female ratio.
State two risk factors of Rheumatic fever.
๐ฉบ Socioeconomic factors such as poverty, overcrowding, and limited access to healthcare.
๐ฉบ A history of untreated or inadequately treated streptococcal pharyngitis (strep throat).
Briefly discuss the pathogenesis of Rheumatic fever.
๐งฌ Rheumatic fever is an acute, immune-mediated multisystem inflammatory disease caused by Group A ฮฒ-hemolytic streptococci (GAS).
๐งฌ Onset typically occurs 2-6 weeks after the initial streptococcal infection, with an average onset of 3 weeks.
๐งฌ Heart valves and brain tissues contain proteins that mimic the cell wall M proteins of certain strains of streptococci, leading to an autoimmune response.
๐งฌ Antibodies directed against the M proteins cross-react with tissue glycoproteins in the heart, joints, and other tissues, causing inflammation.
๐งฌ [Rheumatogenic serotypes of streptococci and genetic susceptibility in the host contribute to the development of Rheumatic fever.]
Briefly explain the Jones Criteria system of diagnosis of acute Rheumatic fever.
[clinical manifestations covered in other cards]
โพ The Jones Criteria are used to diagnose acute Rheumatic fever.
โพThe criteria are divided into major and minor manifestations.
โพ Diagnosis of ARF typically requires evidence of a preceding Group A Streptococcal (GAS) infection along with either two major criteria or one major and two minor criteria.
Outline the major criteria used in the diagnosis of Rheumatic fever.
(1) Carditis: Inflammation of the heart, which can affect the endocardium, myocardium, or pericardium. It may present as a new heart murmur, cardiomegaly, heart failure, or pericarditis.
(2) Polyarthritis: Migratory arthritis that typically affects large joints such as the knees, ankles, elbows, and wrists.
(3) Chorea (Sydenhamโs Chorea): Involuntary, rapid, and irregular movements, often affecting the face, hands, and feet.
(4) Erythema Marginatum: A distinctive rash with pink rings on the trunk and inner surfaces of the limbs, which may come and go.
(5) Subcutaneous Nodules: Painless, firm collections of collagen fibers over bones or tendons, commonly found on the back of the wrist, the outside elbow, and the front of the knees.
Further notes:
J: Joints (Polyarthritis)
O: <3 (Heart) (Carditis)
N: Nodules (Subcutaneous Nodules)
E: Erythema Marginatum (Rash)
S: Sydenhamโs Chorea (Chorea)
Outline the major criteria used in the diagnosis of Rheumatic fever.
๐ Fever: Elevated body temp above 37.2
๐ Arthralgia: Joint pain without swelling
๐ Laboratory abnormalities: increased ESR [Erythrocyte Sedimentation Rate], increased C reactive protein, leucocytosis
๐ Electrocardiogram abnormalities: e.g. increased PR interval
๐ Evidence of Group A Strep infection: positive culture for Group A Strep, elevated or rising antistreptolysin O titres (ASOT)
๐ Previous rheumatic fever or inactive heart disease
Further notes:
A helpful mnemonic to remember the minor Jones criteria is โCAFE PALโ.
C: CRP Increased (C-reactive protein)
A: Arthralgia (Joint pain without swelling)
F: Fever
E: Elevated ESR (Erythrocyte Sedimentation Rate)
P: Prolonged PR Interval (on an ECG)
A: Anamnesis (History of previous rheumatic fever)
L: Leukocytosis (Increased white blood cell count)
List key antibody titres that may be used in the diagnosis of ARF.
(a) Antistreptolysin O (ASO) Titer: measures the level of antibodies against streptolysin O, a toxin produced by GAS.
(b) Anti-DNase B (ADB) Titer: detects antibodies against DNase B, another enzyme produced by GAS.
(c) Antistreptococcal Hyaluronidase (AH) Test
Discuss histological findings in ARF.
Aschoff bodies: these are microscopic features found within the heart and constitute foci of fibrinoid degeneration surrounded by lymphocytes, occasional plasma cell and plump macrophages called Anitschkow cells (pathognomonic for rheumatic fever). During ARF, diffuse inflammation and Aschoff bodies may be found in any of the three layers of the heart, hence pancarditis. In the pericardium, they are accompanied by fibrinous pericardial exudates.
Discuss treatment of Rheumatic fever.
[Hints: arthralgia, arthritis and/or carditis without cardiomegaly, carditis with cardiomegaly or heart failure, eradication of GAS]
๐ฉบ All patients with acute rheumatic fever should be placed at bed rest. [The duration and degree of bed rest should vary with the severity of the disease.]
๐ฉบ Anti-inflammatory drugs
โพ arthralgia: analgesics only e.g. acetaminophen
โพ arthritis and/or carditis without cardiomegaly: salicylates e.g. aspirin
โพ carditis with cardiomegaly or heart failure: prendisone, salicylates following prendisone regimen to manage inflammation
๐ฉบ Eradication of GAS
penicillin or amoxicillin
What is the fate of acute rheumatic carditis?
(1) healing with complete resolution
(2) progression to chronic rheumatic carditis (Rheumatic Heart Disease) and infective endocarditis
Discuss the pathogenesis of Rheumatic Heart Disease.
๐ RHD is a chronic condition that results from repeated episodes of acute rheumatic fever (ARF), which causes inflammation in the heart.
๐ Each episode of ARF leads to inflammation and subsequent healing, resulting in scarring of the heart valves.
๐ The scarring and fibrosis of the heart valves can cause them to thicken and become stiff, leading to valvular stenosis (narrowing of the valve opening).
๐ The heart has to work harder to pump blood through the narrowed valves, increasing the demand on the myocardium (heart muscle).
๐ Over time, the increased workload and pressure can lead to congestive cardiac failure, where the heart is unable to pump blood effectively.
๐ The damaged and scarred valves are more susceptible to infection, leading to infective endocarditis, which can be acute or sub-acute.
List complications that may be associated with ARF.
(a) Hypertrophy that may lead to heart failure [the heart muscle thickens as it works harder to pump blood through damaged valves, leading to heart failure over time]
(b) Atrial fibrillation [as a result of dilatation of the atria due to increased pressure and volume overload]
(c) Thromboembolism [blood clots can form on the walls of the heart chambers (mural thrombi) due to stagnant blood flow, increasing the risk of thromboembolism, where clots travel to other parts of the body and cause blockages]
(d) Infective endocarditis
