What is the workup for a 6-year-old male patient with rheumatic heart disease, pulmonary congestion, and impaired renal function, currently on Furosemide (Lasix) and Captopril (Angiotensin-Converting Enzyme inhibitor)?

Workup for Rheumatic Heart Disease in a 6-Year-Old with Pulmonary Congestion

In a 6-year-old with suspected rheumatic heart disease and pulmonary congestion, immediately obtain an echocardiography with Doppler to confirm cardiac dysfunction and assess valvular involvement, along with ECG, chest X-ray, complete blood count, electrolytes, renal function tests, and inflammatory markers (ESR/CRP) to establish the diagnosis and guide management. 1, 2

Essential Diagnostic Tests

Cardiac Imaging - First Priority

• Echocardiography with Doppler is the cornerstone diagnostic test that must be performed to objectively confirm cardiac dysfunction, assess left ventricular ejection fraction, evaluate valvular function (particularly mitral and aortic regurgitation/stenosis typical of rheumatic heart disease), and assess diastolic filling patterns 1, 2

• Echocardiography will distinguish between systolic dysfunction (LVEF <45-50%) and preserved systolic function, which is critical for management decisions 1, 2

• The study should specifically evaluate for valvular thickening, restricted leaflet motion, and regurgitation patterns characteristic of rheumatic heart disease 1

Electrocardiogram

• A 12-lead ECG must be obtained in all cases, as a completely normal ECG has a negative predictive value exceeding 90% for excluding left ventricular systolic dysfunction 1, 2, 3

• Look specifically for evidence of atrial enlargement, ventricular hypertrophy, conduction abnormalities, or arrhythmias that may accompany rheumatic heart disease 1

• QRS width >120 ms suggests cardiac dyssynchrony that may require specific treatment considerations 1

Chest X-Ray

• Obtain chest X-ray in two planes to assess for cardiomegaly, pulmonary congestion, and pleural effusions 1, 2, 3

• This is particularly important given the current pulmonary congestion to evaluate severity and response to diuretic therapy 1

• Note that cardiomegaly can be absent on chest X-ray even in chronic heart failure, so a normal X-ray does not exclude significant cardiac dysfunction 3

Laboratory Evaluation

Routine Blood Work - Essential

• Complete blood count (hemoglobin, leukocytes, platelets) to assess for anemia and infection 1, 2

• Serum electrolytes (sodium, potassium, chloride) - critical given current furosemide therapy 1, 2

• Serum creatinine and blood urea nitrogen to assess renal function, especially important as the patient is on both furosemide and captopril which can affect renal function 1, 2

• Urinalysis as part of routine evaluation 1, 2

• Liver function tests to assess hepatic congestion and baseline function 1, 2

• Fasting blood glucose for metabolic assessment 1, 2

Rheumatic Fever-Specific Tests

• Anti-streptolysin O (ASO) titer and anti-DNase B to document recent streptococcal infection (though these may be normal if the acute rheumatic fever episode occurred months prior) 2

• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to assess for ongoing inflammation 2

• Throat culture if acute presentation to identify active streptococcal infection 2

Monitoring Current Medications

Critical Monitoring Given Furosemide and Captopril Use

• Monitor electrolytes (especially potassium) 1-2 weeks after medication initiation and 1-2 weeks after any dose adjustment, then every 4 months thereafter 1

• Monitor renal function closely - an increase in creatinine up to 50% above baseline or to 3 mg/dL (266 μmol/L), whichever is greater, is acceptable with ACE inhibitor therapy 1

• At furosemide doses ≤2 mg/kg/day, excess potassium loss generally does not occur and potassium supplementation may not be needed 4

• Monitor for hyperkalemia (K+ >5.0 mmol/L) which requires dose adjustment or specialist consultation 1

• Monitor fluid status and urine output, targeting >1 mL/kg/hour with furosemide therapy 4

• Monitor blood pressure for symptomatic hypotension, particularly with the combination of furosemide and captopril 1, 4

• Monitor weight to assess fluid status and response to diuretic therapy 4

Additional Tests in Selected Cases

If Initial Workup is Inconclusive

• Cardiac magnetic resonance (CMR) should be considered when echocardiography is inconclusive or technically limited, particularly for detecting myocardial fibrosis 3

• Exercise testing has limited diagnostic value but may be useful for prognostic stratification once the patient is stabilized 1, 2

• Natriuretic peptides (BNP or NT-proBNP) can help exclude heart failure if clinical diagnosis is uncertain, with BNP <35 pg/mL or NT-proBNP <125 pg/mL making chronic heart failure unlikely 1, 2, 3

Common Pitfalls to Avoid

• Do not rely solely on chest X-ray, as cardiomegaly may be absent on imaging despite significant cardiac dysfunction 3

• Do not dismiss the diagnosis with symptoms alone - objective evidence of cardiac dysfunction through echocardiography is mandatory for diagnosis 1, 2

• Do not stop ACE inhibitor therapy for mild increases in creatinine or potassium - it is very rarely necessary to stop an ACE inhibitor, and clinical deterioration is likely if treatment is withdrawn; seek specialist advice before discontinuation 1

• Monitor for worsening renal function carefully - if creatinine increases by 100% or to above 4 mg/dL (354 μmol/L), or if potassium rises to 6.0 mmol/L, seek specialist advice immediately 1

• Never exceed furosemide 6 mg/kg/day for longer than 1 week due to significant ototoxicity risk, with an absolute maximum of 10 mg/kg/day for severe edema 4