Total Anomalous Pulmonary Venous Return (TAPVR)

Total anomalous pulmonary venous return (TAPVR) is a cyanotic congenital heart defect wherein the pulmonary veins drain into anatomical sites other than the left atrium. The most common sub-type is the supra cardiac form, where the drainage is into the superior vena cava. Patients are usually cyanotic from birth and present with respiratory and heart failure right after birth. On examination there is a fixed, wide split-second heart sound, and a chest X-ray might reveal the “snowman” sign. Diagnosis is confirmed by an echocardiogram, which can be prenatal. All patients require surgery for survival and medical management is used to bridge the gap to surgery.

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Overview

Definition

Total anomalous pulmonary venous return (TAPVR) is a cyanotic congenital heart defect that results in the drainage of the 4 pulmonary veins into the systemic venous circulation, rather than into the left atrium, resulting in mixing of oxygenated and deoxygenated blood. An interatrial defect (ASD, PFO, or PDA) must be present to allow mixed blood to shunt to the left side of the heart and the systemic arterial circulation.

Classification

  • Based on where pulmonary veins drain:
    • Supra cardiac (50% of cases): into superior vena cava (SVC)
    • Intracardiac (20%): into inferior vena cava (IVC)
    • Cardiac (20%): into right atrium (RA)
    • Mixed (10%): combination of above forms
  • Obstructed TAPVR: Pulmonary vein is narrowed, resulting in impedance to blood flowing out of pulmonary circulation.
TAVR vs normal heart

A heart with normal anatomy versus a heart with total anomalous pulmonary venous return:
The most common form of TAPVR features the 4 pulmonary veins draining into the superior vena cava (SVC) as shown here. Notice the increased size of the right ventricular wall, due to progressive ventricular overload.

Image by Lecturio.

Epidemiology

  • Rare condition: 0.7%–1.5% of all CHD
  • Prevalence: ~ 6.8 per 100,000 live births

Embryology

This condition arises due to the failure of the left atrium to merge with the pulmonary venous plexus during.

  • 1st month of gestation: Primitive cardinal and umbilicovitelline vessels drain systemic circulation into fetal heart.
  • 27–29 days from conception: 
    • Pulmonary venous plexus arises from splanchnic plexus.
    • Embryonal left atrium (LA) gives rise to common pulmonary vein (CPV).
    • CPV merges with venous plexus.
    • CPV splits into 4 and is incorporated into wall of LA.
  • Failure of common pulmonary vein to merge with venous plexus resulting in TAPVR:
    • Connection with primitive cardinal venous system (draining into RA or SVC) and umbilicovitelline system (IVC, hepatic, or portal vein)
Embryology of TAPVR

A: During the 1st month of gestation, the left and right common cardinal vein (LCCV, RCCV) and the umbilical vein (UV) drain the splanchnic plexus (the primitive pulmonary vasculature) into the fetal heart.
B: At the end of the 1st month of gestation, the embryonal left atrium (LA) gives rise to common pulmonary vein (CPV), which merges with the venous plexus.
C: The connection to the LCCV, RCCV, and UV disappear.
D: CPV splits into 4 and is incorporated into the wall of the left atrium.
RA: right atrium
LBB: left lung bud
RLB: right lung bud

Image by Lecturio.

Pathophysiology and Clinical Presentation

Pathophysiology

  • In non-obstructed TAPVR:
    • Oxygenated blood from pulmonary venous plexus flows into deoxygenated blood found in RA, IVC, or SVC → venous mixing 
    • Mixed blood is shunted right to left through intra-atrial shunt (ASD) into systemic circulation → causing cyanosis
    • RA and RV dilate to accommodate extra volume → right-sided heart failure 
  • In moderate obstruction to pulmonary return: increased pressure in pulmonary vein → increased pressure in pulmonary artery → pulmonary hypertension → RVH → right-sided heart failure
Total anomalous venous return patho

Blood mixing in total anomalous pulmonary venous return:
In TAPVR, oxygenated blood from the lungs returns to the systemic venous circulation mixing with deoxygenated blood. This mixed blood then shunts to the left side of the heart through an atrial septum defect and flows to the rest of the body resulting in cyanosis.

Image: “Illustration of totaly anomalyous pulmonary venous return” by Centers for Disease Control and Prevention. License: CC0

Clinical presentation

The degree of obstruction of pulmonary veins determines the age of presentation:

  • Obstructed:
    • At birth
    • Cyanosis 
    • Signs of shock
    • Difficult to arouse
    • Severe shortness of breath or apnea
  • Unobstructed:
    • 30 + days of age
    • Subtle cyanosis
    • Poor feeding
    • Labored breathing

Diagnosis

Physical examination

  • Cyanosis: 
    • Pulse oximetry: ↓ Sp02
  • Failure to thrive
  • Heart sounds:
    • Fixed, split, loud S2
    • Continuous murmur at site of obstruction
    • Pulmonary valve → systolic ejection murmur
    • Tricuspid valve → diastolic rumble
  • Signs of respiratory failure:
    • Tachypnea
    • Grunting 
    • Nasal flaring
  • Signs of heart failure:
    • Hepatomegaly
    • Tachycardia
    • Hypotension
    • Cool extremities
    • Weak pulses
  • Asplenia (seen in patients with heterotaxy syndromes)

Imaging

  • Echocardiogram:
    • Confirms diagnosis
    • Can be performed prenatally
    • Evaluates:
      • Type of TAPVR
      • Degree of obstruction
      • Right-to-left shunt
      • RV dilation
      • With doppler → pulmonary vascular pressure
  • Chest X-ray:
    • Classic “snowman” sign seen in supra-cardiac TAPVR
    • Pulmonary venous congestion
    • Right heart enlargement
  • ECG:
    • Right axis deviation
    • Right ventricle hypertrophy
Total anomalous pulmonary vein drainage

Total anomalous pulmonary vein drainage: marked pulmonary congestion and diffuse bilateral reticulogranular infiltrates

Image: “Total anomalous pulmonary vein drainage” by Departments of Pathology and Cell Biology, School of Medicine, University of Occupational and Environmental Health, Fukuoka Shin Mizumaki Hospital, Kitakyushu, Japan. License: CC BY 2.5

Management

  • Surgery required in all patients
  • Medical management required to stabilize patient and bridge to surgery:
    • Supplemental 02
    • Inotropes
    • Prostaglandin E1 IV to keep ductus arteriosus open (if that is the only intra-atrial connection)
    • Ventilator support
  • Surgical management:
    • Definitive therapy aiming to redirect drainage of pulmonary veins into LA 
    • Palliative surgery in severely obstructed TAPVR (sick newborns) includes:
      • Atrial septostomy
      • Placement of stent

Prognosis

  • If untreated, neonate usually dies within 1st month of life.
  • Surgical repair has very low mortality rate and excellent long-term outcome.

Differential Diagnosis

  • Tetralogy of Fallot (TOF): congenital heart disease characterized by occurrence of 4 key cardinal features: overriding aorta, ventricular septal defect, right ventricular outlet obstruction, and right ventricular hypertrophy. Patients present with cyanosis and history of “tet spells” (fainting while crying). Diagnosis is confirmed by echocardiogram and patient is surgically managed.
  • Tricuspid valve atresia (TVA): congenital heart disease characterized by lack of development of tricuspid valve. Presents with cyanosis, labored breathing, and hypoxic spells. Holosystolic murmur and single S2 are present on exam. Diagnosis made by echocardiogram. Ultimate treatment is surgical.
  • Transposition of the great vessels (TGV): congenital heart defect characterized by switching of great vessels, so aorta originates from right ventricle and pulmonary artery from left. Presents with cyanosis, tachypnea, heart failure, hypoxemia, and lack of response to supplemental oxygen. Ultimate treatment is surgical.
  • Truncus arteriosus (TA): emergence of aorta and pulmonary artery from common trunk overriding ventricular septal defect (VSD). Symptomatic from 1st days of life, including cyanosis, respiratory distress, heart failure, poor feeding, and excessive sweating. Diagnosed by echocardiogram. Ultimate treatment is surgical.
  • Ebstein anomaly (EA): congenital heart defect in which there is downward displacement of tricuspid valve leaflets causing right ventricular outflow tract tachycardia (RVOT) obstruction. Presents with cyanosis, arrhythmias, and failure to thrive. Diagnosed by echocardiogram. Ultimate treatment is surgical.

References

  1. Burroughs JT, Edwards JE. Total anomalous pulmonary venous connection. Am Heart J. 1960 Jun;59:913-31. doi: 10.1016/0002-8703(60)90414-2. PMID: 13806293.
  2. Hoffman JI, Kaplan S. The incidence of congenital heart disease. J Am Coll Cardiol. 2002 Jun 19;39(12):1890-900. doi: 10.1016/s0735-1097(02)01886-7. PMID: 12084585.
  3. Sadler, T. W., & Langman, J. (2012). Langman’s medical embryology (12th ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins.
  4. Seale AN, Uemura H, Webber SA, Partridge J, Roughton M, Ho SY, McCarthy KP, Jones S, Shaughnessy L, Sunnegardh J, Hanseus K, Berggren H, Johansson S, Rigby ML, Keeton BR, Daubeney PE; British Congenital Cardiac Association. Total anomalous pulmonary venous connection: morphology and outcome from an international population-based study. Circulation. 2010 Dec 21;122(25):2718-26. doi: 10.1161/CIRCULATIONAHA.110.940825. Epub 2010 Dec 6. PMID: 21135364.

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