Overview

Definition

Total anomalous pulmonary venous return (TAPVR) is a cyanotic congenital heart defect that results in the drainage of the 4 pulmonary veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. 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 PDA The ductus arteriosus (DA) allows blood to bypass pulmonary circulation. After birth, the DA remains open for up to 72 hours and then constricts and involutes, becoming the ligamentum arteriosum. Failure of this process to occur results in patent ductus arteriosus (PDA), a condition that causes up to 10% of congenital heart defects. Patent Ductus Arteriosus (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 Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. 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.

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)

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 Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension → RVH → right-sided heart failure

Clinical presentation

The degree of obstruction of pulmonary veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins determines the age of presentation:

• Obstructed:
  • At birth
  • Cyanosis 
  • Signs of shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types 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 Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive
• Heart sounds Heart sounds Heart sounds are brief, transient sounds produced by valve opening and closure and by movement of blood in the heart. They are divided into systolic and diastolic sounds. In most cases, only the first (S1) and second (S2) heart sounds are heard. These are high-frequency sounds and arise from aortic and pulmonary valve closure (S1), as well as mitral and tricuspid valve closure (S2). 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 Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure:
  • Tachypnea
  • Grunting 
  • Nasal flaring
• Signs of heart failure:
  • Hepatomegaly
  • Tachycardia
  • Hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension
  • Cool extremities
  • Weak pulses
• Asplenia Asplenia Asplenia is the absence of splenic tissue or function and can stem from several factors ranging from congenital to iatrogenic. There is a distinction between anatomic asplenia, which is due to the surgical removal of the spleen, and functional asplenia, which is due to a condition that leads to splenic atrophy, infarct, congestion, or infiltrative disease. 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 ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Normal Electrocardiogram (ECG):
  • Right axis deviation
  • Right ventricle hypertrophy

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 Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. 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 Tetralogy of Fallot Tetralogy of Fallot is the most common cyanotic congenital heart disease. The disease is the confluence of 4 pathologic cardiac features: overriding aorta, ventricular septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy. 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 Transposition of the Great Vessels Transposition of the great vessels (TGV) is a cyanotic congenital heart disease characterized by "switching" of the great arteries. There are 2 presentations: the dextro (D)- and levo (L)-looped forms. The L-looped form is rare and congenitally corrected, as the ventricles are also switched. 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 Truncus arteriosus Truncus arteriosus (TA) is a congenital heart defect characterized by the persistence of a common cardiac arterial trunk tract that fails to divide into the pulmonary artery and aorta during embryonic development. Truncus arteriosus is a rare congenital malformation with a high mortality rate within the 1st 5 weeks of life if not managed promptly. 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.