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Case 001: Infant with Heart Murmur

Presentation

Chief Complaint: 6-week-old infant referred for heart murmur

History: - Full-term infant, uncomplicated pregnancy and delivery - Parents noticed infant "breathing fast" during feeds - Takes 45 minutes to finish 3 oz bottle (previously 20 minutes) - Some sweating noted during feeding - No cyanosis, no fever - Weight gain: +200g in past 2 weeks (suboptimal)

Physical Examination: - Weight: 3.8 kg (10th percentile, down from 25th at birth) - HR: 160, RR: 58, SpO2: 98% on RA - Mild subcostal retractions - Hyperactive precordium with palpable thrill - Grade 4/6 harsh holosystolic murmur at LLSB, radiating to axilla - Mild hepatomegaly (liver 3 cm below RCM) - Pulses: 2+ throughout, no radiofemoral delay

Question 1

What is the most likely diagnosis based on the clinical presentation?

Answer **Ventricular Septal Defect (VSD)** with heart failure **Key features supporting this diagnosis:** - Holosystolic murmur at LLSB (classic VSD location) - Grade 4/6 with thrill suggests moderate-large defect - Heart failure symptoms: Tachypnea, poor feeding, diaphoresis with feeds, hepatomegaly - Timing: VSD murmurs often become apparent at 4-8 weeks as PVR drops The hyperactive precordium reflects volume overload of the LV.

Workup

ECG: - Sinus rhythm, 155 bpm - Normal axis - LVH voltage criteria met - LAE suggested by notched P waves

Chest X-ray: - Cardiomegaly (CTR 0.62) - Increased pulmonary vascular markings - No pleural effusions

Echocardiogram: - Large perimembranous VSD, 7 mm - Left-to-right shunt, Qp:Qs estimated 2.5:1 - LV dilation (LVEDD Z-score +3.2) - Normal LV function (EF 65%) - Mild LA dilation - PA pressure estimated elevated (TR velocity 3.2 m/s)

Question 2

What is the initial management for this infant?

Answer **Medical Management of Heart Failure:** 1. **Diuretics:** Furosemide 1-2 mg/kg/dose BID 2. **Afterload reduction:** Consider captopril if persistent symptoms 3. **Nutritional support:** - High-calorie formula (24-30 kcal/oz) - Consider NG feeds if unable to take adequate PO - Target intake: 120-150 kcal/kg/day 4. **Close follow-up:** Weight checks, repeat echo in 4-6 weeks **Goals:** - Improve symptoms (reduce work of breathing) - Support adequate weight gain - Monitor for spontaneous VSD closure vs progression

Clinical Course

The infant is started on furosemide and concentrated formula. Over the next 6 weeks: - Weight gain improves - Respiratory rate normalizes - Feeding time decreases

Repeat echo at 3 months: - VSD now 5 mm (smaller) - Qp:Qs improved to 1.8:1 - LV size normalizing

Question 3

What are the options for this infant going forward?

Answer **Conservative Management (if improving):** - Continue diuretics with periodic weaning attempts - Serial echocardiograms every 3-6 months - Many muscular and some perimembranous VSDs close spontaneously - Monitor for adequate growth **Surgical Closure Indications:** - Failure to thrive despite medical management - Persistent large shunt (Qp:Qs >2:1) - Symptoms refractory to medical therapy - Development of pulmonary hypertension - Infective endocarditis (relative) **Timing:** - If surgery needed, typically performed at 4-6 months - Earlier if refractory failure - Goal is closure before irreversible pulmonary vascular changes

Question 4

What long-term complications should be monitored for in patients with repaired VSD?

Answer **Post-Repair Complications:** 1. **Residual VSD** - Small leaks common, usually insignificant 2. **Heart block** - Risk of complete heart block if near conduction system 3. **Aortic regurgitation** - Especially if subarterial VSD 4. **LVOT obstruction** - Rare 5. **Arrhythmias** - Usually late complication 6. **Endocarditis** - Risk continues if residual defect **IE Prophylaxis:** - Required for 6 months after surgical repair - If residual defect adjacent to prosthetic material, prophylaxis continues indefinitely - Complete closure with no residual: no prophylaxis after 6 months **Follow-up:** - Annual cardiology visits for first few years - Most patients do well long-term with normal activity

Board Pearls

Pearl

VSD murmurs typically become louder at 4-8 weeks of life as PVR drops and L→R shunting increases

Pearl

Failure to thrive is a key indication for VSD closure

Pearl

IE prophylaxis for VSD: 6 months post-repair if complete closure; indefinitely if residual defect with prosthetic material

Learning Points

  1. Clinical recognition: Holosystolic murmur + heart failure symptoms in infant = VSD until proven otherwise
  2. Natural history: Many VSDs (especially muscular) close spontaneously
  3. Medical management: Diuretics + high-calorie feeds are first-line
  4. Surgical indications: Failure to thrive, refractory symptoms, large shunt
  5. Long-term: Excellent prognosis after repair; monitor for late complications

References

  • ACC/AHA CHD Guidelines
  • Pediatric Cardiology (Park)