Infective endocarditis and rheumatic heart disease

Question 1

What is infective endocarditis (IE) and what are its forms?

Answer 1

IE: Infection of the endocardial surface, usually heart valves.

Forms:

Acute: Rapid, fulminant illness (e.g., Staphylococcus aureus).

Subacute/chronic: Slower onset (e.g., Streptococcus viridans).

Question 2

What are the main predisposing factors for infective endocarditis?

Answer 2

Pre-existing valve disease (e.g., rheumatic heart disease, bicuspid aortic valve)

Prosthetic heart valves

Intravenous drug use

Intravascular devices (e.g., pacemakers)

Recent dental/surgical procedures

Question 3

Which microorganisms most commonly cause infective endocarditis?

Answer 3

Native valves:
Streptococcus viridans (oral flora)
Staphylococcus aureus
Enterococci

Prosthetic valves:
Early (<60 days): Staphylococcus epidermidis
Late: Streptococcus species

IV drug users:
Staphylococcus aureus (right-sided heart valves)

Question 4

What are common symptoms and signs of infective endocarditis?

Answer 4

Symptoms: Fever, chills, night sweats, weight loss, fatigue.

Signs:
New/changing murmurs
Splenomegaly
Petechiae
Osler nodes (painful, fingers/toes)
Janeway lesions (painless, palms/soles)
Roth spots (retinal hemorrhages)
Haematuria

Question 5

What are the key investigations for infective endocarditis?

Answer 5

Blood cultures (at least 3 sets before antibiotics)
Echocardiography (TTE, or better: TEE/TOE)
Full blood count (anemia, leukocytosis)
ESR/CRP (inflammatory markers)
Urinalysis (microscopic haematuria)
ECG (may show heart block in abscess)

Question 6

What is the Modified Duke’s Criteria for diagnosing infective endocarditis?

Answer 6

Major criteria:
Positive blood cultures
Evidence of endocardial involvement on echo

Minor criteria:
Predisposing condition
Fever >38°C
Vascular phenomena
Immuologic phenomena
Positive blood cultures not meeting major criteria
→ Definite IE if 2 major or 1 major + 3 minor or 5 minor.

Question 7

How is infective endocarditis managed?

Answer 7

Empirical IV antibiotics immediately after cultures.

Tailor antibiotics after sensitivities known (4–6 weeks therapy).

Surgical intervention if:
Heart failure
Uncontrolled infection
Large vegetations (>10mm)
Embolic events
Valve dysfunction

Question 8

What is rheumatic heart disease (RHD)?

Answer 8

Chronic valve damage after acute rheumatic fever (ARF), caused by immune cross-reaction following Group A Streptococcal pharyngitis.

Most commonly affects the mitral valve (stenosis, regurgitation).

Question 9

What are the long-term effects of rheumatic heart disease?

Answer 9

Chronic valve dysfunction: mainly mitral stenosis, mitral regurgitation.

Atrial fibrillation
Heart failure
Infective endocarditis susceptibility
Pulmonary hypertension

Question 10

What are key investigations for rheumatic heart disease?

Answer 10

Echocardiography (main diagnostic tool: valve thickening, regurgitation, stenosis)
ECG (e.g., atrial fibrillation)
Chest X-ray (cardiomegaly)
Throat culture (if acute)
ASO titre (if evidence of recent streptococcal infection)

Question 11

Outline management strategies for rheumatic heart disease.

Answer 11

Primary prevention: Early treatment of streptococcal pharyngitis (penicillin).
Secondary prevention: Long-term penicillin prophylaxis.
Valve repair/replacement surgery if severe.
Management of arrhythmias and heart failure as needed.