One-liner…
Neonate with persistent cyanosis? Think TAPVD.
A 6-hour-old baby is brought to A+E with respiratory distress. On arrival, his oxygen saturations are 78% in the air. The baby was born at home at term. Mum had normal antenatal scans. Following birth the baby cried immediately, however has had increasing work of breathing and poor colour.
The A+E team has started the baby on 15 L face mask oxygen, and his saturations are now 85%. His heart rate is 190, his respiratory rate is 80, and his temperature is 36.8. The nurse is struggling to obtain a blood pressure reading.
On examination the baby has a prolonged capillary refill time of 4 seconds centrally. Heart sounds are normal, and femoral pulses are palpable bilaterally. He has moderate respiratory distress, and there are bilateral crackles on auscultation.
Chest X-ray shows pulmonary plethora.
ECG shows sinus tachycardia with right axis deviation and signs of right ventricular hypertrophy.
The echo shows intracardiac total anomalous pulmonary venous drainage with obstructed pulmonary venous drainage and an atrial septal defect with the right-to-left flow.
Background
Total anomalous pulmonary venous drainage (TAPVD) is a rare cyanotic congenital heart disease, accounting for approximately 2% of all congenital heart disease. It is difficult to detect on antenatal scanning, with only around 2% of TAPVD being diagnosed prenatally1.
What is the pulmonary venous anatomy?
- Four pulmonary veins (two for each lung) open individually into the left atrium.
- The right superior pulmonary vein drains blood from the right superior and right middle lobes. The right inferior pulmonary vein drains blood from the right inferior lobe.
- The left superior pulmonary vein drains blood from the lingula and left superior lobe of the left lung, whilst the left inferior lobe drains into the left inferior pulmonary vein.
- This usual anatomical arrangement is found in 60–70% of people.2
Anatomy in TAPVD
In TAPVD, all four pulmonary veins (PV) have abnormal connections, either to the systemic veins, the right atrium (RA), or both.
There are four main anatomical variants of TAPVD.
- Supracardiac TAPVD (50%): The pulmonary veins connect to the superior vena cava via an ascending vertical vein.
- Cardiac TAPVD (25%): Drainage is directly to the right atrium, typically via the coronary sinus.
- Infracardiac TAPVD (20%): Drainage is below the diaphragm.
The confluence is frequently vertical, tortuous, long, and thin, which is particularly difficult to identify antenatally.
The common pulmonary vein drains to the portal vein, ductus venosus, hepatic vein or inferior vena cava.
4. Mixed TAPVD (5%): Drainage of each vein may be to different locations or groups of veins may drain to different locations
Note that an atrial septal defect (ASD) is present in all types, which allows flow to the left side of the heart. Without an ASD, TAPVD is incompatible with life.
How do kids with TAPVD present?
Presentation of TAPVD largely depends on the degree of obstruction to the drainage of the pulmonary veins.
Obstructed TAPVD
These patients become unwell shortly after birth with cyanosis, respiratory distress and haemodynamic compromise.
Often, these babies are managed as more common neonatal illnesses initially, such as persistent pulmonary hypertension of the newborn, sepsis, or respiratory distress syndrome. However, without correct identification, they will continue to deteriorate despite treatment.
The obstruction to pulmonary venous return causes pulmonary venous hypertension and pulmonary oedema. There is a right-to-left shunt at both the atrial and ductal levels. Reduced left atrial filling combined with a large right ventricle results in impaired left ventricular filling and reduced cardiac output.
Unobstructed TAPVD
Patients may present with a degree of cyanosis, with oxygen saturations of 85–95% in air.
The signs of congestive heart failure, such as tachypnoea, tachycardia and hepatomegaly, alongside faltering growth and repeated chest infections, develop by four to six months of age if not diagnosed sooner.
They may also have increased flow through the pulmonary vascular beds, resulting in pulmonary hypertension.
The ECG will show right axis deviation (RAD) and right ventricular hypertrophy (RVH)—rsR pattern in V1.
If it is supracardiac TAPVD, this may show a ‘snowman’ on chest x-ray with a dominant right-sided cardiac shadow and enlarged mediastinum due to the ascending supracardiac draining vein and enlarged superior vena cava.
Associated conditions
TAPVD can be an isolated lesion or occur together with other cardiac defects, such as heterotaxies, hypoplastic left heart syndrome (HLHS), truncus arteriosus and transposition of the great arteries. Associated chromosomal anomalies are rare, but some cases have been described in the literature and include Noonan, Holt-Oram syndrome, Ivemark syndrome and unbalanced translocations.3
How do we diagnose TAPVD?
Echocardiography is diagnostic in most patients with TAPVD.
Echo features include
- All right-to-left flow across an ASD
- Right ventricular diastolic volume overload
- No pulmonary veins draining to the left atrium
- Alternative pulmonary venous drainage site seenÂ
Patients may undergo cardiac CT or MRI prior to surgery to further assess anatomy and degree of obstruction.
Factors that influence prognosis are:
- Size and presence of an atrial septal defectÂ
- Degree of obstruction affecting abnormal pulmonary venous drainage
- Degree of pulmonary vascular resistance
- Presence of additional cardiac anomalies
Management
Initial management depends on whether the TAPVD is obstructed or non-obstructed. For non-obstructed TAPVD, anticongestive treatment (diuretics) can usually delay definitive surgical correction. Definitive management involves surgical intervention to connect the pulmonary veins to the left atrium.Â
Neonates with significant obstructed TAPVD will require intubation, ventilation and inotropic support pre-operatively. Prostaglandins are used cautiously in selected patients to support systemic cardiac output. ECMO may be considered as a bridge to surgery.Â
Patients with restrictive atrial communication may undergo balloon atrial septostomy to enlarge the interatrial communication before surgery.Â
Outcome
Surgical outcomes in non-obstructive TAPVD are generally good, with a reported mortality of 5% to 10%3,4. In obstructed TAPVD or when there is an associated heterotaxia syndrome, the outcome dramatically changes, with short-term mortality rates between 50% and 89%.3,5
Ji et al in 2021 suggested risk factors for post-operative mortality include pre-operative acidosis, prolonged cardiopulmonary bypass time, increased postoperative central venous pressure and severity of pulmonary hypertension post-operatively.6
In the immediate post-operative state, significant risks include:Â
- Pulmonary hypertensive crises
- Low cardiac output state
- Potential for atrial arrhythmias due to surgical atriotomy
- Increased risk of organ dysfunction, especially in the obstructed group.Â
Pulmonary hypertensive crisis can occur post-operatively in approximately 50% of patients. For this reason, the atrial communication is not always completely closed.
Signs of pulmonary hypertension include reduced end-tidal carbon dioxide, hypotension, increased CVP, and acute desaturation. Treatment includes hyperoxia, minimal handling, sedation, and paralysis. Inhaled nitric oxide (iNO) and short-term sildenafil on iNO weaning may aid in overcoming transient pulmonary hypertension. Â
Take-homes
Pulmonary hypertension is a significant post-operative risk in all patients undergoing TAPVD repair.
TAPVD is difficult to diagnose antenatallyÂ
The presentation can be non-specific. Always suspect TAPVD if cyanosed neonates are not responding to therapy as expected.
An echo is generally diagnostic.
If there is obstructed TAPVD, patients present shortly after birth, often with significant cardiovascular compromise. This group of patients have a higher peri-operative mortality than those without obstruction.Â
About PICSTAR
PICSTAR is a trainee-led research network open to all doctors, nurses and allied health trainees within Paediatric Intensive Care. We are the trainee arm of the Paediatric Critical Care Society – Study Group (PCCS-SG) and work with them on research, audit and service evaluation.
If you would like to join PICSTAR and get involved in projects, have ideas you would like to propose or get advice/mentorship via PCCS-SG, don’t hesitate to contact us at picstar.network@gmail.com. See their website for more: https://pccsociety.uk/research/picstar/
References
- Seale AN, Uemura H, Webber SA, et al. Total anomalous pulmonary venous connection: morphology and outcome from an international population-based study. Circ. 2010;122(25):2718–2726.Â
- Tarniceriu, C.C., et al., The Pulmonary Venous Return from Normal to Pathological-Clinical Correlations and Review of Literature. Medicina (Kaunas), 2021. 57(3).
- Crispi, F. and J.M. Martinez, 91 – Anomalies of Pulmonary Venous Return, in Obstetric Imaging: Fetal Diagnosis and Care (Second Edition), J.A. Copel, et al., Editors. 2018, Elsevier. p. 409-411.e1.
- Park, M.K., Preface, in Park’s Pediatric Cardiology for Practitioners (Sixth Edition), M.K. Park, Editor. 2014, Mosby: Philadelphia. p. vii-viii.
- St Louis, J.D., et al., Repair of “simple” total anomalous pulmonary venous connection: a review from the Pediatric Cardiac Care Consortium. Ann Thorac Surg, 2012. 94(1): p. 133-7; discussion 137-8.
- Ji, E., et al., The Outcomes of Total Anomalous Pulmonary Venous Connection in Neonates-10-Year Experience at a Single Center. Front Cardiovasc Med, 2021. 8: p. 775578.
- Feins, E.N., R. Callahan, and C.W. Baird Pulmonary Vein Stenosis—Evolving Surgical Management of a Challenging Disease. Children, 2021. 8, DOI: 10.3390/children8080631.
- Cooley, D.A. and A. Ochsner, Jr., Correction of total anomalous pulmonary venous drainage: technical considerations. Surgery, 1957. 42(6): p. 1014-21.
- Lacour-Gayet, F., C. Rey, and C. Planché, [Pulmonary vein stenosis. Description of a sutureless surgical procedure using the pericardium in situ]. Arch Mal Coeur Vaiss, 1996. 89(5): p. 633-6.
- Kalfa, D., et al., Outcomes and prognostic factors for postsurgical pulmonary vein stenosis in the current era. The Journal of Thoracic and Cardiovascular Surgery, 2018. 156(1): p. 278-286.
- Krivenko, G., et al., Combination Chemotherapy in Severe Pulmonary Vein Stenosis-A Case Series. Children (Basel), 2023. 10(2).
- Ungerleider, R. et al. (eds.) (2019)Â Critical heart disease in infants and children. Third edition. Philadelphia, PA: Elsevier. Available at: https://www.sciencedirect.com/science/book/9781455707607 (Accessed: July 13, 2024)