Chapter 21 · Asymptomatic Murmur, Heart Failure, Infective Endocarditis

Innocent vs pathological murmurs · Evaluation of asymptomatic murmur · Heart failure in children (causes, diagnosis, management) · Infective endocarditis (Duke criteria, prevention, antibiotic treatment)
📌 Core principles: Most murmurs in children are innocent (Still's, venous hum, pulmonary flow murmur). Pathological features: diastolic, loud, thrill, abnormal S2, associated symptoms. Heart failure in children: tachypnoea, poor feeding, hepatomegaly, oedema; treat diuretics, ACEi, afterload reduction. Infective endocarditis: fever + murmur; Duke criteria (major = positive blood culture, echo vegetations). Prophylaxis only for high-risk procedures (dental extraction in prosthetic valve or previous endocarditis).

📖 Asymptomatic Murmur, Heart Failure, Infective Endocarditis – Key Concepts

🩺 Asymptomatic murmur
Innocent: Still's vibratory murmur (LLSE, musical, changes with posture), venous hum (supraclavicular, continuous, disappears when supine), pulmonary flow murmur (left upper sternal edge, soft systolic). Pathological: diastolic, pansystolic, loud (>grade 3), thrill, abnormal S2, associated cyanosis or heart failure. Investigation: ECG, CXR, echocardiography if atypical.
💔 Heart failure in children
Causes: large VSD, PDA, coarctation, cardiomyopathy, arrhythmias, anomalous coronary. Signs: tachypnoea, tachycardia, poor feeding, sweating, hepatomegaly, oedema, gallop rhythm. Diagnosis: CXR (cardiomegaly, venous congestion), echo (function, structure), NT-proBNP. Management: diuretics (furosemide, spironolactone), afterload reduction (ACE inhibitor: enalapril), beta-blockers (carvedilol), digoxin (select). Treat underlying cause (surgery for CHD).
🦠 Infective endocarditis (IE)
Predisposing conditions: VSD, bicuspid aortic valve, prosthetic valve, previous IE, complex CHD (cyanotic). Duke criteria: major (2 positive blood cultures, echocardiographic vegetation) + minor (fever, vascular/immunologic phenomena). Common organisms: viridans streptococci, S. aureus, coagulase-negative staphylococci (prosthetic). Treatment: IV antibiotics (penicillin + gentamicin for viridans; vancomycin + gentamicin for staph). Prophylaxis: only for highest risk (dental extraction, invasive respiratory procedures) – amoxicillin 1h pre-procedure.

🔎 Symptom-based approach: murmur, poor feeding, fever

1️⃣
Asymptomatic child, murmur heard at routine exam. How to differentiate innocent vs pathological?
Innocent: soft, short, systolic, vibratory, no thrill, normal heart sounds, changes with posture. Pathological: diastolic, pansystolic, loud, thrill, abnormal S2, symptoms.
2️⃣
Infant with tachypnoea, poor feeding, hepatomegaly, gallop rhythm.
Heart failure. CXR (cardiomegaly, pulmonary oedema), echo, NT-proBNP. Treat with furosemide, enalapril, consider inotropes.
3️⃣
Child with fever, known VSD, new murmur, peripheral emboli.
Infective endocarditis. Duke criteria, blood cultures, echo (vegetations). IV antibiotics, surgery for complications.
4️⃣
Infant with murmur and heart failure at 4 weeks. Likely lesion?
Large VSD (presentation at 4-8 weeks as PVR falls).
5️⃣
Child with complex cyanotic CHD, fever, and splinter haemorrhages.
Infective endocarditis (high risk); echocardiography needed regardless of murmur.
🚨 Indications for echocardiography in asymptomatic murmur: Diastolic murmur, pansystolic murmur, loud murmur (≥ grade 3), thrill, abnormal S2, associated chest pain, syncope, family history of cardiomyopathy/ sudden death.

📋 Management algorithms: Heart failure, Endocarditis

💔
Pediatric heart failure – stepwise treatment
▪️ Mild-mod: diuretics (furosemide 1-2 mg/kg/dose + spironolactone 1-3 mg/kg/day), ACE inhibitor (enalapril 0.1-0.5 mg/kg/day).
▪️ Persistent symptoms: add digoxin (controversial, for systolic dysfunction), carveDilol (beta-blocker, initiate in stable patient).
▪️ Severe acute: IV furosemide, milrinone/dobutamine, treat cause (PGE1 if duct-dependent).
▪️ Surgical: VSD/PDA closure, coarctation repair, mitral valve surgery.
🦠
Infective endocarditis – diagnosis and therapy
▪️ Blood cultures (3 sets before antibiotics).
▪️ Empiric IV antibiotics pending cultures: vancomycin + gentamicin if prosthetic valve/healthcare-associated; penicillin + gentamicin for community-acquired suspected viridans.
▪️ Duration: 2-6 weeks based on organism and complications.
▪️ Surgery: heart failure, uncontrolled infection, large vegetation >10mm, embolic events.
▪️ Prophylaxis: amoxicillin 50 mg/kg (max 2g) 1 hour before high-risk procedures (dental extraction, respiratory tract incision) only in highest risk patients (prosthetic valve, prior IE, cyanotic CHD, transplant recipients).

💡 Reflex prompts – Asymptomatic murmur, Heart failure, Endocarditis

🩺 A 5-year-old with a soft, vibratory, short systolic murmur at left lower sternal edge that disappears when supine. Diagnosis?
Still's murmur (innocent). No further workup.
📊 An infant with tachypnoea, hepatomegaly, gallop, and cardiomegaly on CXR. Diagnosis?
Heart failure. Most common cause – large VSD.
🦠 A child with fever, new pansystolic murmur, Janeway lesions. Most appropriate initial test?
Blood cultures (2-3 sets) and echocardiogram for vegetations.
💊 First-line diuretic for acute heart failure in a hospitalized infant.
Furosemide IV (1 mg/kg).
🩺 A 3-year-old with a continuous murmur at left infraclavicular area. Diagnosis?
Venous hum (innocent). Disappears when supine or occluding jugular vein.
⚠️ Which murmurs warrant cardiology referral?
Diastolic, pansystolic, grade ≥3, thrill, abnormal S2, or associated symptoms.
💊 A child with dilated cardiomyopathy and LVEF 25%. Guideline therapy?
Enalapril + carvedilol + spironolactone.
🦠 Indication for endocarditis prophylaxis in a child with VSD?
Only if prior endocarditis, prosthetic valve, or VSD repair with prosthetic material (within 6 months).
📉 A 6-week-old with poor feeding, tachypnoea, and a harsh pansystolic murmur. Most likely CHD?
Large VSD (fall in PVR at 4-8 weeks → left-to-right shunt).
🩺 A 12-year-old with fever, splinter haemorrhages, Roth spots, and blood culture positive for viridans streptococcus. Treatment duration?
4 weeks of IV penicillin + gentamicin (uncomplicated native valve).