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Case 015: Infant with Undiagnosed Coarctation

Clinical Presentation

Setting: Pediatric Emergency Department

Patient: 3-week-old male brought by parents for "not eating well" and "breathing fast"

History: - Born full-term via uncomplicated vaginal delivery - Birth weight 3.4 kg, discharged home at 48 hours - Passed CCHD screen (both pre- and post-ductal SpO2 99%) - Initially breastfeeding well - Over past 3 days: taking longer to feed, sweaty during feeds, seems tired - Today: refused breast, very sleepy, "gray color"

Review of Systems: - Decreased urine output (3 wet diapers in 24 hours) - No fever - No vomiting or diarrhea - No cough or congestion

Initial Assessment

Vital Signs: - HR 185 - RR 68 - BP (right arm): 78/50 mmHg - SpO2 88% on room air - Temp 36.8°C - Weight 3.2 kg (lost 200g from birth)

Physical Exam: - General: Lethargic, ashen/gray, mottled extremities - HEENT: Anterior fontanelle sunken - Cardiac: Tachycardic, no murmur appreciated, weak femoral pulses bilaterally, bounding right arm pulse - Lungs: Diffuse crackles, subcostal retractions, nasal flaring - Abdomen: Hepatomegaly (liver 4cm below costal margin) - Extremities: Cool, mottled, capillary refill 5 seconds

Immediate Actions

Question 1

This infant is in cardiogenic shock. What is your immediate management?

Answer **Immediate Stabilization (ABC + D for Ductus):** 1. **Airway/Breathing:** - Supplemental oxygen (but avoid hyperoxia) - Prepare for intubation if worsening - Gentle positive pressure if needed 2. **Circulation:** - IV/IO access immediately - **Fluid bolus**: 10 mL/kg NS (cautious - don't fluid overload) - Avoid aggressive fluids in cardiogenic shock 3. **START PROSTAGLANDIN E1 (PGE1):** - **0.05-0.1 mcg/kg/min IV** - start immediately - This is the life-saving intervention for ductal-dependent lesions - Can reopen closing/closed ductus - Continue until diagnosis confirmed and intervention performed 4. **Additional Measures:** - Correct acidosis (sodium bicarbonate if pH <7.1) - Dextrose bolus if hypoglycemic - Consider dopamine/dobutamine if remains hypotensive **Critical Point:** Do NOT delay PGE1 waiting for echocardiogram. In any neonate with shock + weak femoral pulses, start PGE1 presumptively.

Question 2

Why did this infant pass the CCHD screen at birth?

Answer **CCHD Screening Limitation:** **Coarctation is the lesion most commonly missed by pulse oximetry screening.** **Why the Screen Passed:** 1. **Patent ductus arteriosus at birth** - provided adequate flow past the coarctation 2. **Both pre- and post-ductal saturations were normal** because the PDA was supplying well-oxygenated blood to both upper and lower body 3. **Coarctation often doesn't cause desaturation** - it's an obstruction, not a cyanotic lesion **As the PDA closes (typically days 1-14):** - Flow past coarctation decreases - LV afterload increases dramatically - Heart failure develops - Lower body perfusion depends on collaterals (minimal in neonates) **Key Teaching Points:** - **Normal CCHD screen does NOT rule out coarctation** - Coarctation can present catastrophically after discharge - **Femoral pulse assessment** remains critical in newborn exam - Some propose adding BP gradient screening (not yet standard) **Window of Presentation:** - PDA closes: Days 3-14 typically - Symptoms develop: Often Days 7-21 - "Second week of life" is classic timing for undiagnosed coarctation

Diagnostic Workup

Labs (obtained with IV placement): - pH 7.18, pCO2 28, HCO3 12, lactate 8.2 mmol/L - Creatinine 1.4 mg/dL (elevated for age) - AST 245, ALT 198 - BNP 4,500 pg/mL - Troponin I 2.1 ng/mL

Chest X-ray: - Severe cardiomegaly - Pulmonary edema

4-Extremity Blood Pressures (after PGE1 started): | Location | Systolic/Diastolic | |----------|-------------------| | Right arm | 82/48 | | Left arm | 80/50 | | Right leg | 52/38 | | Left leg | 50/36 |

Echocardiogram: - Severe coarctation of aorta (discrete narrowing in juxtaductal region) - Small PDA with left-to-right flow (reopening with PGE1) - Severely depressed LV function (EF 25%) - Moderate-severe mitral regurgitation - Small VSD (2mm) - Bicuspid aortic valve

Clinical Reasoning Questions

Question 3

What associated cardiac lesions should you look for with coarctation?

Answer **Shone Complex/Associated Lesions:** Coarctation is often not isolated. Associated lesions (Shone complex spectrum): | Lesion | Frequency | Significance | |--------|-----------|--------------| | **Bicuspid aortic valve** | 50-85% | Most common; may cause AS/AR later | | **VSD** | 30-40% | Common; usually small | | **Mitral valve abnormality** | 25-50% | Parachute MV, supravalvar ring | | **Aortic arch hypoplasia** | Variable | Affects surgical approach | | **Subaortic stenosis** | 10-20% | May develop over time | **Complete Shone Complex:** 1. Supravalvar mitral ring 2. Parachute mitral valve 3. Subaortic stenosis 4. Coarctation **This Patient Has:** - Coarctation (primary lesion) - Bicuspid aortic valve (very common association) - VSD (small, likely will close) - MR is likely functional (from LV dysfunction, not structural valve disease) **Why This Matters:** - Long-term outcomes affected by associated lesions - May need multiple interventions over lifetime - Bicuspid valve requires lifelong surveillance - Shone complex = worse prognosis than isolated coarctation

Question 4

What explains the multiorgan dysfunction (elevated creatinine, liver enzymes)?

Answer **Cardiogenic Shock with End-Organ Hypoperfusion:** **Pathophysiology:** 1. PDA closure → Severe LV afterload mismatch 2. LV cannot pump against obstruction → LV failure 3. Decreased cardiac output → Tissue hypoperfusion 4. Lower body receives minimal perfusion (below coarctation) **Organ-Specific Effects:** | Organ | Finding | Mechanism | |-------|---------|-----------| | **Kidney** | Elevated Cr (1.4) | Renal hypoperfusion, ATN developing | | **Liver** | Elevated AST/ALT | Shock liver, venous congestion | | **GI** | (Risk of NEC) | Mesenteric hypoperfusion | | **Brain** | Lethargy | Cerebral hypoperfusion (if severe) | **Lactic Acidosis:** - Lactate 8.2 = severe tissue hypoxia - Anaerobic metabolism - Worsens myocardial function (acidosis impairs contractility) **Recovery:** - Organ function typically recovers with restoration of perfusion - Renal function usually normalizes - Liver enzymes improve - If repair not performed quickly, can progress to multi-organ failure

Question 5

After PGE1 is started, what changes do you expect?

Answer **Response to PGE1:** **Expected Improvements (within 30-60 minutes):** - Improved femoral pulses - Decreased upper/lower extremity BP gradient - Improved perfusion (warmer extremities, better cap refill) - Improved lactate/acidosis - Improved urine output - More alert **Echocardiographic Changes:** - PDA reopens or dilates - Improved lower body perfusion - May see decreased MR as LV unloads - LV function may remain depressed initially **Potential PGE1 Side Effects:** | Side Effect | Frequency | Management | |-------------|-----------|------------| | Apnea | 10-20% | May need intubation | | Fever | Common | Monitor, usually benign | | Hypotension | Occasional | Volume, vasopressors if severe | | Flushing | Common | Reassurance | | Seizure-like activity | Rare | Monitor | **Critical Point:** Even if baby looks "stable" on PGE1, surgical repair should not be delayed unnecessarily. PGE1 is a bridge to definitive therapy.

Question 6

What is the surgical approach for this patient?

Answer **Surgical Management:** **Timing:** - Urgent repair indicated - Stabilize 24-48 hours if possible (allows organ recovery) - Earlier if not responding to medical management **Surgical Options:** | Technique | Description | Pros/Cons | |-----------|-------------|-----------| | **Extended end-to-end anastomosis** | Resect coarctation, anastomose with arch augmentation | Gold standard for neonates | | **Subclavian flap** | Use subclavian to augment | Sacrifices subclavian artery | | **Patch aortoplasty** | Patch augmentation | Higher recoarctation risk | **Addressing the VSD:** - Small VSD (2mm) - likely will close spontaneously - No intervention needed at initial surgery - If large VSD, PA band or repair would be considered **This Patient:** - Extended end-to-end anastomosis preferred - Bicuspid valve monitored (not intervened on unless stenotic) - VSD observed **Post-Operative Concerns:** 1. **Rebound hypertension** - common, treat with beta-blockers/vasodilators 2. **Abdominal pain** - mesenteric arteritis from reperfusion 3. **Spinal cord ischemia** - rare but devastating (paraplegia) 4. **Recurrent/residual coarctation** - 5-10% over lifetime

Hospital Course

The infant was started on PGE1, intubated for apnea, and stabilized. Over 24 hours, lactate normalized to 1.8 mmol/L, and femoral pulses improved. He underwent extended end-to-end repair on hospital day 2. Post-operatively, he had rebound hypertension requiring esmolol infusion, which was transitioned to propranolol. LV function recovered to EF 50% by discharge on day 10.

Follow-Up Planning

Question 7

What is the long-term surveillance plan for this patient?

Answer **Lifelong Cardiology Follow-Up Required:** **Early Post-Repair (First Year):** - Clinic visit 1-2 weeks post-op - Echo before discharge, 1 month, 3-6 months, 1 year - Watch for recoarctation - Monitor BP at each visit (all 4 extremities initially) **Ongoing Surveillance:** | Concern | Monitoring | |---------|------------| | **Recoarctation** | BP gradient, echo, may need CT/MRI | | **Hypertension** | Lifelong risk even after "successful" repair (20-40%) | | **Bicuspid aortic valve** | Annual echo - AS/AR progression | | **Aortic root/ascending aorta** | Dilation risk with BAV | | **VSD** | Usually closes; monitor | | **Arch hypoplasia** | May need intervention if severe | **Key Statistics:** - Recoarctation rate: 5-15% (higher if infant repair) - Long-term hypertension: 20-40% - Bicuspid valve may need intervention: ~25% lifetime - Normal life expectancy if uncomplicated **Exercise Recommendations:** - Usually no restrictions for isolated repaired coarctation - Avoid isometric exercise if residual hypertension or gradient - Sports clearance after complete evaluation **Pregnancy Counseling:** - Coarctation is risk factor for aortic complications - Needs pre-conception cardiology evaluation - Genetic counseling (Turner syndrome association)

Key Teaching Points

  1. CCHD screening does not reliably detect coarctation - femoral pulse exam remains essential
  2. "Second week of life" is classic timing for ductal-dependent coarctation presentation
  3. Start PGE1 immediately in any neonate with shock + weak femorals - don't wait for echo
  4. Coarctation is rarely isolated - look for bicuspid valve, VSD, mitral abnormalities (Shone complex)
  5. End-organ dysfunction from cardiogenic shock typically recovers with restoration of perfusion
  6. Lifelong follow-up required for hypertension, recoarctation, and bicuspid valve surveillance
  7. Rebound hypertension post-repair is common and requires treatment
  8. Bicuspid aortic valve may become the dominant cardiac issue over lifetime

References

  • Kenny D, et al. JACC. 2020 - Coarctation outcomes
  • 2025 CCHD Screening Update