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Case 019: Interrupted Aortic Arch with VSD

Clinical Presentation

Setting: Fetal cardiology consultation

Patient: 32-week fetus referred for cardiac evaluation after abnormal anatomy scan

Referral Findings: - Suspected coarctation vs. interrupted aortic arch - Possible VSD - Abnormal thymus appearance noted

Maternal History: - 28-year-old G2P1 - No diabetes, no teratogens - No family history of CHD

Fetal Echocardiogram Findings

Cardiac Structure: - Interrupted aortic arch Type B (between left carotid and left subclavian) - Large malalignment VSD (inlet extension) - Posterior deviation of infundibular septum - Left aortic arch - Normal biventricular size and function - Small ascending aorta (Z-score -2.5) - Dilated pulmonary artery (supplies descending aorta via ductus)

Extracardiac: - Thymic hypoplasia suspected

Assessment: Interrupted aortic arch Type B with malalignment VSD - high association with 22q11.2 deletion (DiGeorge syndrome)

Clinical Reasoning Questions

Question 1

What are the types of interrupted aortic arch and which is most common?

Answer **Interrupted Aortic Arch (IAA) Classification:** | Type | Location of Interruption | Frequency | |------|-------------------------|-----------| | **Type A** | Distal to left subclavian (isthmus) | 30-40% | | **Type B** | Between left carotid and left subclavian | **50-60%** (most common) | | **Type C** | Between innominate and left carotid | Rare (<5%) | **Type B is Most Common:** - Strong association with 22q11.2 deletion (DiGeorge) - 50-80% of Type B IAA have 22q11.2 deletion - Often has posterior malalignment VSD **This Fetus:** - Type B (between L carotid and L subclavian) ✓ - Malalignment VSD ✓ - Thymic hypoplasia (suggestive of DiGeorge) ✓ - **Very high probability of 22q11.2 deletion** **Associated Anomalies with IAA:** - VSD (nearly universal) - Bicuspid aortic valve (common) - Truncus arteriosus (differential diagnosis) - Subaortic stenosis (may develop) - 22q11.2 deletion (especially Type B) **Physiology:** - Lower body entirely ductal-dependent - Will present in cardiogenic shock when PDA closes - Without intervention, uniformly fatal

Question 2

What genetic testing is indicated and why?

Answer **22q11.2 Deletion Testing:** **Why Test Prenatally:** 1. Type B IAA = 50-80% association with 22q11.2 deletion 2. Affects counseling and prognosis 3. Multisystem implications beyond heart 4. Impacts delivery planning **Testing Options:** | Test | Method | Timing | |------|--------|--------| | **FISH** | Fluorescent probe | Rapid (24-48h) | | **Microarray** | Chromosomal analysis | 7-14 days | | **NIPT for 22q** | Cell-free DNA | If available | | **Amniocentesis** | Karyotype + microarray | Standard | **22q11.2 Deletion Syndrome (DiGeorge) Features:** | System | Manifestation | |--------|---------------| | **Cardiac** | Conotruncal defects (IAA, truncus, TOF, VSD) | | **Thymic** | Hypoplasia/aplasia → T-cell immunodeficiency | | **Parathyroid** | Hypocalcemia | | **Facial** | Cleft palate, characteristic facies | | **Developmental** | Learning difficulties, speech delay | | **Psychiatric** | Increased schizophrenia risk (adolescence/adulthood) | **Implications for This Baby:** - **Immune function**: May need irradiated, CMV-negative blood products - **Calcium**: Monitor for hypocalcemia - **Feeding**: Velopharyngeal dysfunction common - **Development**: Early intervention services - **Genetic counseling**: 50% recurrence risk if parent affected

Question 3

How would you counsel this family about the diagnosis and expected postnatal course?

Answer **Prenatal Counseling Framework:** **1. Explain the Anatomy:** - "The aorta, the main blood vessel to the body, is interrupted - there's a gap in it" - "Currently, blood reaches the lower body through a temporary vessel (ductus) that normally closes after birth" - "There's also a hole between the two pumping chambers (VSD)" **2. Discuss the Immediate Postnatal Plan:** - Delivery at tertiary center with cardiac surgery - Will need IV medication (prostaglandin) immediately to keep ductus open - May need breathing tube and intensive care support - Will need surgery in first week of life **3. Surgical Plan:** - **Single-stage repair:** - Reconstruct aortic arch (connect the segments) - Close VSD - **Timing:** Days 3-7 typically, after stabilization - **Surgical mortality:** 5-10% at experienced centers **4. Prognosis:** - Good surgical outcomes at experienced centers - 85-90%+ survive to hospital discharge - Long-term survival depends on associated anomalies - May need additional interventions over time: - Subaortic stenosis (may develop) - Arch obstruction (recoarctation) **5. Genetic Testing:** - High likelihood of 22q11.2 deletion - Recommend amniocentesis for testing - Will affect care beyond the heart - Can connect with genetic counselor **6. Support:** - Connect with other families - Social work involvement - Mental health resources

Question 4

The baby is born at 38 weeks. Describe the immediate postnatal management.

Answer **Immediate Delivery Room Management:** **Before Delivery:** - Neonatology, cardiology, cardiac surgery aware - PGE1 prepared and ready - Delivery room with resuscitation capability **At Delivery:** 1. Standard resuscitation as needed 2. **Start PGE1** immediately (0.05-0.1 mcg/kg/min) - Do NOT wait for symptoms - Start before ductus has chance to close 3. Establish IV access 4. Avoid supplemental oxygen unless needed (delays ductal closure less) **NICU Admission:** | Parameter | Goal/Action | |-----------|-------------| | **PGE1** | Maintain infusion, watch for apnea | | **SpO2** | 75-85% acceptable (mixing) | | **Ventilation** | Intubate if apnea or respiratory distress | | **BP** | Maintain adequate perfusion | | **Calcium** | Monitor q6h (22q11.2 → hypocalcemia) | | **Blood products** | Irradiated, CMV-negative until immune status known | | **Feeds** | NPO, IV fluids | **Confirmatory Echo:** - Confirm diagnosis - Define arch anatomy precisely - Assess VSD size and location - Evaluate for additional lesions **Preoperative Workup:** - CBC, chemistry, coagulation - Blood type and screen - Calcium, ionized calcium - Head ultrasound - Genetic testing (FISH for 22q11.2) - Renal ultrasound (associated anomalies) **Timing to Surgery:** - Optimize over 24-72 hours - Correct acidosis, optimize perfusion - Typically surgery DOL 3-7 - Earlier if unstable

Question 5

Describe the surgical repair and expected postoperative course.

Answer **Surgical Repair:** **Procedure: Single-Stage Complete Repair** 1. **Median sternotomy** 2. **Cardiopulmonary bypass** with deep hypothermic circulatory arrest or regional perfusion 3. **Arch reconstruction:** - Ligate and divide PDA - Connect proximal and distal arch segments - Usually direct anastomosis with augmentation - May need patch augmentation 4. **VSD closure:** - Patch closure via right atriotomy or ventriculotomy - Avoid conduction system (bundle of His) 5. **Address subaortic area if narrowed** **Postoperative Course:** **Early (Days 1-7):** | Issue | Management | |-------|------------| | **Hemodynamics** | Inotropic support, maintain BP | | **Bleeding** | Common with arch surgery, may need reoperation | | **Arrhythmias** | Monitor for heart block (VSD closure near conduction) | | **Laryngeal nerve** | Risk of injury (hoarseness, feeding difficulty) | | **Hypocalcemia** | Frequent if 22q11.2 | | **Infection** | Higher risk if T-cell deficiency | **Intermediate (Weeks 1-4):** - Wean respiratory support - Establish feeds (may be difficult if 22q11.2) - Monitor for residual lesions on echo - May need calcium supplementation **Potential Complications:** - Recurrent arch obstruction (5-15%) - Residual VSD (small usually tolerated) - Subaortic stenosis (may develop over time) - Heart block (rare) - Vocal cord paralysis - Need for reoperation (20-30% over 10 years)

Question 6

What is the long-term follow-up plan for this patient?

Answer **Lifelong Cardiac Follow-Up:** **First Year:** - Clinic q1-2 months - Echo at discharge, 1 month, 3 months, 6 months, 12 months - Watch for: - Arch re-obstruction (BP gradient, echo) - Subaortic stenosis development - Residual VSD - Ventricular function **Ongoing Surveillance:** | Issue | Monitoring | |-------|------------| | **Arch obstruction** | Echo, BP in all 4 extremities, may need CT/MRI | | **Subaortic stenosis** | Echo - can develop/progress over years | | **Ventricular function** | Echo | | **Aortic valve** | If bicuspid - watch for AS/AR | | **Hypertension** | BP monitoring at all visits | **Reintervention Rates:** - Arch reintervention: 15-25% by 10 years - Subaortic stenosis surgery: 10-20% - Overall freedom from reintervention ~60-70% at 10 years **If 22q11.2 Deletion Confirmed:** | System | Follow-up | |--------|-----------| | **Immunology** | T-cell studies, vaccination planning | | **Endocrine** | Calcium, thyroid monitoring | | **ENT** | Velopharyngeal function, hearing | | **Speech** | Early intervention | | **Development** | Early intervention, school support | | **Psychiatry** | Screening in adolescence | | **Genetics** | Family planning counseling | **Quality of Life:** - Most children do well developmentally - Activity usually not restricted after repair - Normal life expectancy if uncomplicated - Lifelong cardiology follow-up required

Hospital Course

Amniocentesis confirmed 22q11.2 deletion. The baby was delivered at 38 weeks at the cardiac surgery center. PGE1 was started immediately. Initial calcium was 6.8 mg/dL (low), requiring supplementation. Irradiated, CMV-negative blood products were used. On DOL 5, he underwent single-stage repair with arch reconstruction and VSD closure.

Postoperatively, he had a complex course with: - Temporary pacing for junctional rhythm (resolved by day 7) - Mild vocal cord paresis (improved with therapy) - Hypocalcemia requiring IV then oral supplementation - Feeding difficulties requiring NG feeds initially

Discharged home on DOL 21 on calcium supplementation, prophylactic antibiotics, and early intervention services. Follow-up echo showed no residual VSD, no arch obstruction, and normal biventricular function.

Key Teaching Points

  1. Type B IAA has 50-80% association with 22q11.2 deletion
  2. Thymic hypoplasia on fetal echo strongly suggests DiGeorge
  3. PGE1 must start immediately at birth - don't wait for symptoms
  4. Irradiated, CMV-negative blood products until immune status known
  5. Monitor calcium - hypocalcemia common with 22q11.2
  6. Single-stage repair is standard (arch reconstruction + VSD closure)
  7. Subaortic stenosis may develop over time - requires surveillance
  8. Multidisciplinary care essential for 22q11.2 (cardiac + immune + developmental + ENT)

References

  • Brown JW, et al. IAA Outcomes. Ann Thorac Surg. 2020
  • McDonald-McGinn DM, et al. 22q11.2 Deletion Syndrome. Nat Rev Dis Primers. 2015