✅ Model Answer:
• Snowman sign (figure‑8) – supracardiac shadow formed by dilated left vertical vein and SVC.
• Mild to moderate cardiomegaly (right heart enlargement).
• Increased pulmonary vascularity (unobstructed type).
• Clear lung fields (no pulmonary edema).
• Diagnosis: Total Anomalous Pulmonary Venous Return (TAPVR) – Supracardiac type.

✅ Model Answer:
• TAPVR: All four pulmonary veins drain anomalously into the systemic venous circulation (instead of the LA).
• Confluence of pulmonary veins forms a common chamber (pulmonary venous confluence).
• Drainage sites: Supracardiac (50%), Cardiac (25%), Infracardiac (20%), Mixed.
• ASD required for survival: Blood returning to the right heart must cross an ASD or PFO to reach the left heart and systemic circulation (mixing lesion).
• Without an ASD, the infant would die from pulmonary venous obstruction and low cardiac output.

✅ Model Answer:
• Type 1 – Supracardiac (50%): Pulmonary veins → confluence → left vertical vein → innominate vein → SVC → RA.
• Type 2 – Cardiac (25%): Pulmonary veins → confluence → coronary sinus → RA (or directly to RA).
• Type 3 – Infracardiac (20%): Pulmonary veins → confluence → descending vein → through diaphragm → IVC → RA. This type is almost always obstructed.
• Type 4 – Mixed (5%): Combination of the above patterns.

✅ Model Answer:
• Unobstructed TAPVR (supracardiac, cardiac): Mild cyanosis, tachypnoea, poor feeding, failure to thrive, heart failure (2-4 months).
• Obstructed TAPVR (infracardiac, some supracardiac): Severe cyanosis, respiratory distress, shock, and acidosis in the first few days of life. Pulmonary venous obstruction → pulmonary edema, severe hypoxemia.
• Examination: Single S2, systolic ejection murmur (LUSB), fixed split S2 (if ASD), signs of heart failure.

✅ Model Answer:
• Right axis deviation.
• Right ventricular hypertrophy (RVH) – tall R waves in V1-V2.
• Right atrial enlargement – tall peaked P waves (P pulmonale) in leads II, III, aVF.
• May show right bundle branch block (RBBB) pattern.
• In obstructed TAPVR: Right axis deviation with severe RVH and ST-T changes.

✅ Model Answer:
• Subcostal and suprasternal views: Identify the pulmonary venous confluence and its drainage site.
• Absence of pulmonary veins entering the LA.
• Dilated right heart (RA, RV).
• ASD (required for survival).
• In supracardiac: Dilated vertical vein, innominate vein, and SVC.
• In infracardiac: Descending vertical vein, hepatic veins, IVC (often with obstruction).
• Color Doppler: Turbulent flow at the site of obstruction (infracardiac).

✅ Model Answer:
• Timing: Urgent surgical repair is required for obstructed TAPVR (infracardiac) – within hours to days. Unobstructed TAPVR is repaired at 2-4 months (electively).
• Procedure: Median sternotomy, cardiopulmonary bypass.
- Anastomose the pulmonary venous confluence directly to the LA.
- Close the ASD/PFO.
- Ligate the anomalous vein(s).
• Post-operative: Excellent outcomes for unobstructed TAPVR (>95% survival). Obstructed TAPVR has higher mortality (especially if pulmonary venous obstruction is severe).

✅ Model Answer:
• Early: Pulmonary hypertensive crisis, low cardiac output, arrhythmias, residual pulmonary venous obstruction.
• Late (long-term):
- Pulmonary venous stenosis – at the anastomosis site (most common complication).
- Arrhythmias – atrial flutter/fibrillation.
- Right heart dysfunction.
- Pulmonary hypertension – if repair is delayed.
- Recurrent obstruction of pulmonary veins (can be progressive).

✅ Model Answer:
• Diagnosis: Echocardiogram with color Doppler (turbulent flow at the anastomosis), cardiac catheterization for accurate pressure gradients and angiography.
• Management:
- Mild to moderate: Medical management (diuretics, oxygen).
- Severe: Surgical revision of the anastomosis or catheter-based interventions (balloon angioplasty, stenting) – but restenosis is common.
- Prognosis: Pulmonary venous stenosis is a challenging complication; may require multiple interventions.

✅ Model Answer:
• Excellent prognosis for unobstructed TAPVR (>95% survival).
• Obstructed TAPVR: Survival ~80-90% with early repair.
• Long-term issues: Pulmonary venous stenosis (most common), arrhythmias, pulmonary hypertension.
• Lifelong cardiology follow-up required with periodic echocardiograms.
• Activity restrictions: Usually none if normal RV function and no pulmonary hypertension.

✅ Model Answer:
• TAPVR: All four pulmonary veins drain anomalously to systemic veins. ASD is required for survival. Cyanosis is present. Repair is mandatory.
• PAPVR: One or more (but not all) pulmonary veins drain anomalously. ASD is NOT required. Usually asymptomatic. May be discovered incidentally. Often requires no treatment (unless significant shunt or RV volume overload).
• PAPVR is commonly associated with sinus venosus ASD.

✅ Model Answer:
• Infracardiac TAPVR – almost always obstructed.
• Features: Severe cyanosis, respiratory distress, acidosis, and pulmonary edema on CXR (due to venous obstruction).
• The heart is usually not massively enlarged (unlike supracardiac type).
• Urgent surgical repair is required within hours.