Total Anomalous Pulmonary Venous Return

All four pulmonary veins drain into the right atrium or a systemic vein rather than the left atrium. Survival depends on a right to left atrial communication or ductus. About 1 to 1.5% of congenital heart disease, about 6 to 9 per 100,000 live births.

• Types by drainage site: supracardiac (about 45 to 50%; vertical vein to the innominate vein or superior vena cava), cardiac (about 20 to 25%; coronary sinus or right atrium), infracardiac (about 20 to 25%; descending vein through the diaphragm to the portal vein, ductus venosus or inferior vena cava, almost always obstructed), mixed (about 5 to 10%).
• Mechanism: the whole pulmonary venous return mixes with systemic venous blood in the right atrium and crosses the atrial septal defect or foramen ovale to the left side. Obstruction of the venous pathway causes pulmonary venous hypertension and pulmonary oedema.
• Untreated, about 80% die in the first year. Obstructed forms are lethal within days.

• Obstructed (most infracardiac): cyanosis, severe tachypnoea, respiratory distress and shock in the first hours to days; no murmur; quiet precordium.
• Unobstructed: mild cyanosis, heart failure and poor feeding in weeks; fixed wide splitting of the second heart sound, systolic flow murmur at the left upper sternal edge, tricuspid diastolic flow murmur, right ventricular heave.
• Recurrent chest infections and failure to thrive.
• Differential diagnosis: persistent pulmonary hypertension of the newborn, respiratory distress syndrome, neonatal sepsis or pneumonia, hypoplastic left heart syndrome, cor triatriatum, pulmonary vein stenosis, transposition, truncus arteriosus.
• Complications: pulmonary oedema and severe hypoxaemia with obstructed drainage, pulmonary hypertensive crisis, heart failure, pulmonary vein stenosis after repair, arrhythmia, and sudden death.

• Arterial blood gas: hypoxaemia and acidosis; hyperoxia test fails to improve PaO2 to more than 150 mmHg.
• Chest X-ray: obstructed form shows a normal sized heart with diffuse "ground glass" pulmonary oedema; supracardiac form may show a "snowman" or figure-of-eight silhouette in older infants.
• ECG: right ventricular hypertrophy, right axis deviation.
• Echocardiography: small left atrium, dilated right heart, a venous confluence behind the left atrium with a vertical vein, absence of normal pulmonary vein connections, a right to left atrial shunt, estimated pulmonary pressures, flow velocity in the draining vein (greater than 1.8 m/s indicates obstruction).
• CT or MR angiography to define the veins and drainage site before surgery in stable patients.

• Obstructed form: emergency surgery is the definitive treatment, as soon as the diagnosis is made. Do not delay for further imaging.
  • Support: intubation and ventilation with moderate positive end expiratory pressure (5 to 8 cmH2O), sedation, inotropes (dopamine 5 to 10 micrograms/kg/min or adrenaline 0.05 to 0.2 micrograms/kg/min), correction of acidosis and anaemia.
  • Avoid alprostadil, which can increase pulmonary overcirculation and oedema. Avoid inhaled nitric oxide before surgery because pulmonary vasodilatation worsens oedema. Use diuretics cautiously (furosemide 1 mg/kg IV).
  • Extracorporeal membrane oxygenation as a bridge when refractory.
• Unobstructed form: furosemide 1 to 2 mg/kg per dose orally 2 to 3 times daily, nutritional support, surgery within the first weeks to 3 months.
• Operation: anastomosis of the common pulmonary venous confluence to the posterior left atrium, ligation of the vertical vein (in selected cases after a period of test occlusion, not routinely), and closure of the atrial septal defect. Sutureless in situ pericardial repair for recurrent or primary pulmonary vein stenosis.
• Mortality: about 5 to 10% in modern centres, higher in obstructed or mixed disease and with single ventricle.
• Postoperative care: pulmonary hypertensive crises are common in the first 48 to 72 hours. Use sedation and muscle relaxation, 100% oxygen, hyperventilation to a PaCO2 of 30 to 35 mmHg, inhaled nitric oxide 20 ppm, and sildenafil 0.5 to 1 mg/kg per dose orally 6 to 8-hourly after extubation (evidence in neonates is limited).
• Postoperative pulmonary vein stenosis occurs in about 10 to 15%, usually within 6 to 12 months. Treatment: repeat surgery with sutureless repair, catheter balloon dilatation or stenting (restenosis is common), and consideration of sirolimus (evidence limited). Outcomes are poor when stenosis involves all four veins.
• Arrhythmia: atrial tachyarrhythmia and sinus node dysfunction in about 5 to 10%; treat with bisoprolol 1.25 to 5 mg daily or amiodarone, with pacemaker if needed.
• Endocarditis prophylaxis: amoxicillin 50 mg/kg (maximum 2 g) orally 30 to 60 minutes before dental procedures for 6 months after repair.
• Special groups: pregnancy (repaired patients with good function usually tolerate pregnancy; check for pulmonary vein stenosis and pulmonary pressures before conception); children (growth monitoring, nutrition); heterotaxy and mixed forms have higher mortality.
• Red flags: tachypnoea, feeding failure, new hypoxaemia, pulmonary oedema (restenosis), haemoptysis, palpitations.
• Follow up: echocardiography with pulmonary vein Doppler at 1, 3, 6 and 12 months, then yearly for at least 5 years; CT angiography if velocity is greater than 1.8 m/s or symptoms recur.