Total anomalous pulmonary venous connection

INTRODUCTION — 

Total anomalous pulmonary venous connection (TAPVC), also referred to as total anomalous pulmonary venous return (TAPVR), is a cyanotic congenital defect in which all four pulmonary veins fail to make their normal connection to the left atrium. This results in drainage of all pulmonary venous return into the systemic venous circulation.

The anatomic variants, clinical manifestations, diagnosis, and management of TAPVC will be reviewed here. Partial anomalous pulmonary venous connection (PAPVC) is discussed separately. (See "Partial anomalous pulmonary venous return".)

PREVALENCE — 

The reported prevalence of TAPVC ranges from 0.6 to 1.2 per 10,000 live births [1,2]. TAPVC accounts for approximately ranges between 0.7 and 1.5 percent of all congenital heart defects in newborns.

EMBRYOLOGY — 

In normal development, the lung buds are formed from the primitive foregut and share a common vascular plexus (splanchnic plexus), which initially drains into the common cardinal and umbilicovitelline venous systems. With the formation of the lungs (27 to 29 days of gestation), a portion of the splanchnic plexus differentiates into the primitive pulmonary vascular bed [3,4]. During this same time period, the primitive left atrium forms a primordial evagination (common pulmonary vein) that grows into and joins the pulmonary portion of the splanchnic plexus. Once the connection is made, the primitive pulmonary venous system separates from the cardinal and umbilicovitelline veins. Portions of the common pulmonary vein are subsequently incorporated into the wall of the left atrium and become the two right and two left pulmonary veins, each of which enters the left atrium through a separate orifice.

TAPVC arises from the failure of the left atrium to link with the pulmonary venous plexus, which results in the retention of connections through the primitive cardinal and umbilicovitelline drainage pathways. The anatomic variants of TAPVC are dependent upon which specific connections are retained. The cardinal venous system provides connections to the innominate vein, right atrium, superior vena cava, or azygous vein and the umbilicovitelline system to the portal or hepatic vein, or inferior vena cava.

ANATOMY — 

TAPVC can be divided into four anatomic types based on the location of the connections relative to the heart (figure 1) [5]:

●Supracardiac – Supracardiac TAPVC results from retained pulmonary vein connections to the cardinal venous systems. In affected patients, the pulmonary veins from both lungs course to a confluent chamber that is located just posterior to the left atrium. From this chamber, blood ascends through a vertically oriented vein that most often connects to the left innominate vein. Other locations for supracardiac TAPVC connections include the right-sided superior vena cava, azygous vein, or a persistent left superior vena cava, which would drain to the right atrium via the coronary sinus.

●Cardiac – Cardiac TAPVC results from retained pulmonary vein connections to the cardinal venous systems. In affected patients, the pulmonary veins course directly toward the heart, but instead of the normal linkage within the left atrium, the pulmonary veins connect to the posterior aspect of the coronary sinus or to the right atrium itself (movie 1).

●Infracardiac – Infracardiac TAPVC results from retained pulmonary vein connections to the umbilicovitelline venous system. In affected patients, the pulmonary veins drain into a common vertical vein that courses inferiorly from the mediastinum, through the diaphragm via the esophageal hiatus, and inserts most often into the portal vein [3,6]. Other insertions include the hepatic vein, ductus venosus, or inferior vena cava either above or below the level of the diaphragm [7].

●Mixed – Mixed TAPVC refers to any combination of connections that enter at two or more different levels (movie 2). The most common arrangement of mixed TAPVC is that of three pulmonary veins joining to form a single confluence and a fourth vein draining via a separate venous connection [8].

In the available case series, the relative frequencies of these four variants were as follows [9,10]:

●Supracardiac – 45 to 50 percent

●Cardiac – 15 to 20 percent

●Infracardiac – 20 to 25 percent

●Mixed – Approximately 10 percent

PHYSIOLOGY — 

Key physiologic factors that impact the timing of presentation and degree of symptoms in infants with TAPVC include the following:

●Venous mixing – In patients with TAPVC, the entire oxygenated pulmonary venous return mixes with deoxygenated blood from the systemic venous system. In supracardiac and infracardiac TAPVC, mixing of the blood occurs where the pulmonary veins join the systemic veins before the return to the heart. In cardiac TAPVC, the mixing occurs either within or just adjacent to the right atrium.

The mixed, partially oxygenated blood is then shunted right-to-left at the atrial level (or infrequently through a patent ductus arteriosus) into the systemic circulation, resulting in cyanosis.

Because the right atrium is receiving blood from both the pulmonary and systemic venous systems, both the right atrium and ventricle become dilated.

●Pulmonary venous obstruction – In obstructed forms of TAPVC, there is significant obstruction of pulmonary venous return to the heart. When this occurs, pulmonary venous pressure rises and the high pressure is transmitted back to the lung vasculature, resulting in progressive interstitial and alveolar edema. These changes, in turn, lead to increased pulmonary vascular resistance and elevated pulmonary artery pressure (ie, pulmonary hypertension). In some cases, pulmonary artery pressure can exceed systemic pressure, resulting in right ventricular dilation, hypertrophy, and right heart failure.

Pulmonary venous obstruction can occur at different levels:

•Supracardiac – Obstruction may occur where the vertical vein courses between the left pulmonary artery and left mainstem bronchus.

•Infracardiac – Obstruction usually occurs in cases of infracardiac TAPVC. Constriction of the vertical vein commonly occurs at the level of the diaphragm, within the liver in cases where the connection involves the ductus venous, or by the liver parenchyma when the connection is with the portal vein.

•Cardiac – In some cases of cardiac TAPVC, obstructed flow may be due to stenosis at the mouth of the coronary sinus where the pulmonary veins connect.

•Other – Other sources of obstruction include stenotic, tortuous, or atretic pulmonary and common vertical veins, or a restrictive atrial septum.

●Left-to-right shunting – In unobstructed forms of TAPVC, there is no significant stenosis or compression of the pulmonary veins or the venous confluence. Unobstructed forms typically have a net left-to-right shunt due to the relatively low resistance in the lungs. The pulmonary bed thus receives a disproportionate amount of stroke volume from the heart, leading to pulmonary overcirculation. Due to the high amount of pulmonary blood flow, pulmonary artery pressures in the unobstructed forms are usually elevated, though not as severely as the obstructed forms. If uncorrected, this will lead to right ventricular hypertrophy and pulmonary vascular changes that may result in right ventricular failure. (See "Pathophysiology of left-to-right shunts".)

NATURAL HISTORY — 

The natural history of TAPVC depends upon the severity of obstruction and the size of the interatrial communication. In general, the outcome without treatment is poor, with a mortality rate of 80 percent by one year of age [11,12].

●Severe obstruction – Patients who present in the first few days of life with severe pulmonary obstruction usually die within the first month without surgical intervention.

●Restrictive interatrial communication – Without surgery or palliative intervention with cardiac catheterization, patients with limited interatrial communication (restrictive atrial septum) have a mortality rate of approximately 80 percent in the first year of life. These patients develop severe heart failure, failure to thrive, and recurrent pulmonary infections.

●Unobstructed disease and large interatrial communication – The natural course of uncorrected patients with unobstructed TAPVC and sufficient interatrial communication varies. Some patients may have only mild symptoms with exertion, but most develop progressive right heart failure and pulmonary vascular disease due to pulmonary overcirculation. (See "Pulmonary hypertension in children: Classification, evaluation, and diagnosis".)

CLINICAL MANIFESTATIONS

Presentation — The clinical manifestations vary and are dependent upon the presence and degree of pulmonary venous obstruction (PVO). In general, the more severe the obstruction, the earlier and more severe the presentation.

●Obstructed TAPVC – Patients with severe obstruction generally present as critically ill newborns with profound cyanosis, respiratory failure, and shock. These patients are more likely to have infracardiac TAPVC anatomy [13]. Obstructed TAPVC results in elevated pulmonary artery pressure, pulmonary edema, respiratory distress, diminished systemic output, and hypotension. In the preterm newborn, obstructed TAPVC may be difficult to distinguish from respiratory distress syndrome (RDS). (See 'Differential diagnosis' below.)

●Unobstructed TAPVC – Patients with unobstructed lesions may only have subtle cyanosis immediately after birth, which may be detected with pulse oximetry screening. Although hypoxia is invariably present in unobstructed TAPVC, the degree can vary, and some patients may not appear to be cyanotic. In one series of 75 patients with TAPVC, two appeared to be acyanotic yet oxygen saturations (SaO₂) measured by cardiac catheterization were 88 and 92 percent, respectively [14]. (See "Newborn screening for critical congenital heart disease using pulse oximetry".)

After the immediate newborn period, symptoms are related to pulmonary overcirculation, including tachypnea, poor feeding, and failure to thrive. Over time, these patients develop right ventricular hypertrophy and pulmonary vascular changes that may result in right ventricular failure.

Physical examination — The physical examination varies with the degree of obstruction and the degree of shunting.

In patients with unobstructed TAPVC, physical findings are associated with the amount of left-to-right shunting and are similar to those seen in patients with an atrial septal defect. These include the following:

●Fixed split second heart sound (S₂) due to right ventricular overload (movie 3)

●Systolic ejection murmur due to increased stroke volume across the pulmonary valve (movie 3)

●Diastolic rumble due to increased flow across the tricuspid valve (movie 4)

●Hepatomegaly due to right-sided failure

●Tachypnea

●Variable degrees of cyanosis

Patients with obstructed TAPVC have physical findings that include the following:

●S₂ is prominent

●Ejection murmurs are less frequent than in unobstructed TAPVC

●A soft, continuous murmur may be detected across the anomalous vertical vein with close auscultation over the area of obstruction

●Cyanosis

●Cool extremities

●Hypotension and diminished pulses may be noted if there is severe obstruction

●Hepatomegaly due to direct venous congestion in cases of obstructed infracardiac lesions

●Tachypnea

Other congenital anomalies — Although TAPVC can occur as an isolated cardiac lesion, it also is associated with other complex congenital heart lesions (eg, functional single ventricles) or visceroatrial situs abnormalities. There is an increased incidence in heterotaxy patients diagnosed with asplenia or right atrial isomerism.

TAPVC is a common finding in patients who have heterotaxy with asplenia or polysplenia [15]. In these patients, it is presumed that disruption of both cardiac and abdominal viscera early in embryology result in the characteristic congenital anomalies of this syndrome. (See "Heterotaxy (isomerism of the atrial appendages): Anatomy, clinical features, and diagnosis".)

Electrocardiography and chest radiography findings — Findings on electrocardiography (ECG) and chest radiography are variable, nonspecific, and can depend upon the presence and severity of obstruction.

●ECG – Findings on ECG are both insensitive and nonspecific and cannot be used to make a diagnosis of TAPVC. They include evidence of right ventricular hypertrophy [14]. However, in neonates, it is sometimes difficult to differentiate pathologic right ventricular hypertrophy from the physiologic increase in right-sided voltage normally seen during the newborn period. Tall P waves indicating right atrial enlargement may be commonly seen in patients greater than one month of age. Conduction abnormalities usually are not present.

●Chest radiography – In patients with unobstructed TAPVC, lung parenchyma may be normal except for mild prominence of the pulmonary arteries. The heart size is mildly enlarged. The classic snowman sign is present in young children with supracardiac TAPVC (image 1) but is usually masked by the thymic shadow in neonates. In patients with obstructed TAPVC, the cardiac silhouette is not enlarged. Pulmonary vein congestion and interstitial edema may be present, and in many cases, pulmonary artery dilation is also present. In severe obstruction, the combination of vascular congestion and pulmonary edema leads to a ground glass appearance (image 2).

DIAGNOSIS — 

The diagnosis of TAPVC is generally made by echocardiography. TAPVC is one of three diagnoses that should be suspected in infants presenting with cyanotic congenital heart disease and clinical evidence of pulmonary overcirculation. The other two are transposition of the great arteries and truncus arteriosus, which are discussed separately. (See "D-transposition of the great arteries (D-TGA): Anatomy, clinical features, and diagnosis" and "Truncus arteriosus".)

Echocardiography — The diagnosis of TAPVC is made based upon a composite of findings, including:

●Right-to-left interatrial shunting

●Demonstration of a common ascending collecting vein along with a dilated superior vena cava and innominate vein (because of increased blood flow) in patients with supracardiac lesions

●Demonstration of a common descending collecting vein with a connection to either the hepatic or portal vein, and a dilated inferior vena cava (because of increased blood flow) in patients with infracardiac lesions

●Demonstration of a direct connection between the pulmonary venous system and the right atrium or coronary sinus in patients with cardiac TAPVC (movie 1)

●In all forms of TAPVC, the right atrium and ventricle will be dilated

●Inability to demonstrate the normal pulmonary venous connections to the left atrium

●Doppler imaging can also estimate pulmonary artery pressures and measure the blood flow rates through the ascending or descending vertical veins

The diagnostic accuracy of echocardiography was illustrated in a case series that reported that 22 of 23 patients with TAPVC were accurately diagnosed [16]. The sites of connection of the individual pulmonary veins were identified in all but one patient.

Prenatal diagnosis of TAPVC is challenging [17,18]. In a single-center retrospective study of 137 cases, 12 percent of the 137 cases were diagnosed prenatally [18].

Other imaging studies — Though echocardiography can establish the diagnosis of TAPVC in most cases, imaging with computed tomographic angiography [CTA], magnetic resonance angiography [MRA], or cardiac catheterization is sometimes needed to provide additional detail.

●CTA and MRA – CTA and MRA are typically reserved for cases when the initial echocardiogram could not completely resolve the anatomy or was unable to identify the individual pulmonary veins and vertical veins, which are important for surgical planning. Both CTA and MRA can evaluate pulmonary pathways and connections in great detail [19-21]. CTA better visualizes lung parenchyma and airways; however, it requires exposure to ionizing radiation, while MRA does not. MRA has the disadvantages of requiring more time to image with spatial resolution that is inferior to CTA. Infants and young children often need sedation for this modality. Both CTA and MRA require intravenous contrast for optimal visualization of the vasculature. In patients with kidney failure or insufficiency, certain vessels can be visualized without intravenous contrast, but image quality may vary.

●Cardiac catheterization – Although cardiac catheterization was previously the gold standard for diagnosis of TAPVC, it is generally not needed to make the diagnosis. Other less invasive and less costly diagnostic modalities (ie, echocardiography, CTA, and MRA) have generally replaced cardiac catheterization. However, cardiac catheterization may be indicated if more hemodynamic information is required or in rare patients who may require palliative interventional procedures, such as atrial septostomy to improve interatrial blood flow in those with a restrictive atrial septum. (See 'Management' below.)

DIFFERENTIAL DIAGNOSIS — 

The differential diagnosis of TAPVC includes other conditions that present with cyanosis and respiratory distress in the neonatal period:

●Obstructed TAPVC – Patients with severe obstruction generally present as critically ill newborns with cyanosis and with symptoms of respiratory failure and shock. TAPVC may be difficult to distinguish clinically from respiratory distress syndrome (RDS), persistent pulmonary hypertension of the newborn (PPHN), or septic shock. The timing of the onset of symptoms can help differentiate TAPVC from RDS. Signs of RDS begin immediately after birth, whereas the presentation of obstructed TAPVC is slightly delayed, with onset of symptoms typically appearing after the first 12 hours of life [22]. Ultimately, echocardiography is required to make the correct diagnosis. (See 'Diagnosis' above and "Overview of neonatal respiratory distress and disorders of transition" and "Respiratory distress syndrome (RDS) in preterm neonates: Clinical features and diagnosis" and "Persistent pulmonary hypertension of the newborn (PPHN): Clinical features and diagnosis".)

●Unobstructed TAPVC – Newborns with unobstructed TAPVC may only have subtle cyanosis immediately after birth, which may be detected by a pulse oximetry screening. The approach to evaluating cyanosis in newborns is discussed separately. (See "Approach to cyanosis in the newborn" and "Cyanotic congenital heart disease (CHD) in the newborn: Causes, evaluation, and initial management".)

After the immediate newborn period, symptoms of unobstructed TAPVC include tachypnea, poor feeding, and failure to thrive. The clinical findings are similar to other disorders with large left-to-right shunts, such as a large ventricular or atrial septal defect. TAPVC is distinguished from these with echocardiography. (See "Isolated atrial septal defects (ASDs) in children: Classification, clinical features, and diagnosis", section on 'Clinical features' and "Isolated ventricular septal defects (VSDs) in infants and children: Anatomy, clinical features, and diagnosis", section on 'Clinical features'.)

MANAGEMENT

Initial medical management — Initial medical management of TAPVC depends upon the degree of obstruction:

●Obstructed TAPVC – Patients with severe obstructed TAPVC present as critically ill neonates. Initial medical management is focused on stabilizing these patients prior to surgery. This may include:

•Supplemental oxygen. (See "Respiratory support, oxygen delivery, and oxygen monitoring in the newborn".)

•Mechanical ventilation. (See "Overview of mechanical ventilation in neonates".)

•Inotropic support.

•Prostaglandin E1 (alprostadil) therapy may be needed to prevent closure of the ductus arteriosus, which helps maintain systemic cardiac output. However, a patent ductus arteriosus may also increase the degree of cyanosis. (See "Cyanotic congenital heart disease (CHD) in the newborn: Causes, evaluation, and initial management", section on 'Prostaglandin E1'.)

In some cases, the above medical management fails to stabilize the patient. In these patients, additional interventions include:

•Extracorporeal membrane oxygenation (ECMO) – ECMO has been used when medical management is unable to correct severe hypoxemia, acidosis, and hemodynamic instability [23-25]. This has allowed surgical correction to be performed even in the most severely ill patients. Postoperatively, continued ECMO may be needed in cases with severe persistent pulmonary hypertension.

•Palliative cardiac catheterization procedures – Temporizing cardiac catheterization procedures include atrial septostomy in patients with restrictive interatrial blood flow [25] and stent placements into severely obstructed pulmonary and common vertical veins [26]. These measures are used to stabilize patients prior to surgical correction.

●Unobstructed TAPVC – Patients with unobstructed TAPVC typically present after the immediate newborn period with signs of heart failure. Initial medical management for these infants consists of diuretic therapy (eg, with furosemide) and other supportive measures as needed. (See "Heart failure in children: Management", section on 'Diuretics' and "Heart failure in children: Management", section on 'General measures'.)

Surgery — Surgical correction is indicated in all patients with TAPVC, regardless of the degree of obstruction, because the prognosis without surgery is generally poor. (See 'Natural history' above.)

Surgery should be performed once the diagnosis is made and the patient is stabilized. As previously discussed, in some instances of severely obstructed TAPVC, it is difficult to stabilize the patient and interventions such as emergency surgical correction or ECMO are needed. (See 'Initial medical management' above.)

The goal of surgery is to reestablish a direct pathway between the pulmonary veins and the left atrium, while at the same time avoiding obstruction of pulmonary venous drainage. The surgical approach is via a median sternotomy and is performed under cardiopulmonary bypass with circulatory arrest. The specific surgical procedure varies depending upon the anatomy of the TAPVC lesion.

●In supra- and infracardiac TAPVC with a common vertical vein, a normal pulmonary venous pathway is created by opening and forming an anastomosis between the pulmonary venous confluence and the left atrium. The vertical vein is then ligated and divided.

●In cases where the pulmonary veins drain directly into the superior vena cava, an intracardiac baffle is usually formed to channel the blood from the right atrium across the atrial septum into the left atrium.

●In cardiac TAPVC to the coronary sinus, the partition between the coronary sinus and left atrium is incised or excised and a patch is used to close any atrial septal defect between the left atrium and right atrium. With this procedure, both pulmonary vein and coronary vein flow returns to the left atrium.

●In infracardiac TAPVC that drains close to the right atrium, an anastomosis is created between the pulmonary venous confluence with reconstruction of the interatrial septum to direct blood flow from the pulmonary veins directly to the left atrium.

OUTCOME

Mortality — With improvements in medical and surgical management, and greater availability of extracorporeal membrane oxygenation (ECMO) to support the most severely affected neonates, the survival rate has improved such that most patients with isolated TAPVC survive into adulthood. Overall, early mortality (death within 30 days of surgical correction) is approximately 5 to 10 percent, and late mortality occurs in approximately an additional 5 to 7 percent [13,27-31]. Long-term survival to adolescence is approximately 85 percent [28,30].

Reported risk factors associated with mortality include [10,27,29,32-34]:

●Complex TAPVC (ie, TAPVC with other complex cardiac anomalies, particularly those with single-ventricle physiology)

●Small pulmonary vein and confluence size

●Younger age at operation

●Need for emergency repair (hospital admission on day 0 or 1)

●Longer total bypass and circulatory arrest time

●Postoperative pulmonary hypertension

●Postoperative pulmonary venous obstruction (PVO)

Single ventricle physiology and postoperative PVO are particularly important risk factors [10,28,30]:

●Impact of single ventricle physiology – For patients with single ventricle physiology, the estimated 20-year transplant-free survival rate is approximately 55 percent compared with 85 percent for patients with two ventricles [28].

●Impact of postoperative PVO – Reported survival rates at 15 to 20 years are approximately 35 to 50 percent among patients with significant postoperative PVO compared with 90 to 95 percent for patients without postoperative PVO [28,30].

Morbidity — Long-term complications following repair of TAPVC in infancy may include recurrent PVO, cardiac arrhythmias, neurodevelopmental delays, and growth delay.

Risk factors for long-term morbidity

●Complex cardiac anomalies – Patients with associated complex cardiac anomalies have increased morbidity compared with those with isolated TAPVC. In a study that prospectively followed 67 patients with TAPVC for 4.5 years after initial surgery, most patients with associated complex cardiac anomalies required at least one hospitalization each year during follow-up, and 78 percent were on chronic cardiac medications [29]. By contrast, few patients isolated TAPVC required subsequent hospitalizations and only 2 percent were taking chronic cardiac medications. In addition, children with complex cardiac anomalies were more likely to have growth delays, whereas children with isolated TAPVC had normal growth.

●Pre- or postoperative PVO – PVO can be extrinsic (eg, vertical vein obstruction in unrepaired supracardiac TAPVC) or intrinsic (spontaneous stenosis of one or more pulmonary veins). Patients with preoperative PVO are at risk for recurrent PVO after surgery, which conveys an increased risk of early and late morbidity [10,27,33]. However, postoperative PVO can occur even in patients without preoperative PVO. Preoperative PVO is a risk factor for postoperative PVO in most studies [35]; however, in at least one study, preoperative PVO was not a strong predictor of this complication [28].

●Other risk factors – Other reported risk factors for postoperative PVO and other long-term complications include younger age at operation, need for emergency repair, longer bypass and aortic cross-clamp time, and mixed type TAPVC [28,35]. Sutureless repair is a protective factor [35].

Long-term complications

●Reintervention for PVO – Transcatheter or surgical intervention may be required to address stenosis of individual pulmonary vein(s) and/or stenosis at the surgical anastomosis site [10,27,29,36-40]. Reported rates of reintervention for postoperative PVO after repair of TAPVC range from 13 to 20 percent [3,10,30,33,41]. As discussed above, for patients who require reintervention for PVO, the risk of mortality is substantially higher than in patients without postoperative PVO. (See 'Mortality' above.)

In most cases, clinically significant postoperative PVO is evident within the first year after surgical repair of TAPVC. Patients who are free from restenosis at one year are unlikely to subsequently experience this complication [38,42].

●Arrhythmias – Several case series have noted an increased risk of arrhythmias, especially sinus node dysfunction [43,44]. This may be due to disruption of the conduction system by the atrial incision used to repair TAPVC. (See "Bradycardia in children", section on 'Sinus node dysfunction'.)

In one report of 256 patients with TAPVC and biventricular anatomy who underwent repair at a single institution with median follow-up of 10 years, arrythmias occurred in 5 percent of patients, including sick sinus syndrome in 4 percent and atrial flutter in 1 percent [30]. Two patients (1 percent) required permanent pacemaker placement.

●Developmental outcomes – Neurocognitive outcomes were evaluated in a prospective follow-up study of 67 infants with TAPVC who underwent repair in the neonatal period [29]. Developmental scores at 4.5 years of age were in the low-normal range for patients with isolated TAPVC (mean full-scale intelligence quotient [IQ] 92±18) but were lower in patients with associated complex cardiac anomalies (mean full-scale IQ 81±10).

In another single-center retrospective study of 30 children who had undergone TAPVC repair in infancy and were later assessed at school age (mean age 11 years), scores on standardized neurodevelopmental tests were lower than population norms [45]. Fine motor function, visual-motor integration, and attention are the most commonly affected domains.

FOLLOW-UP CARE — 

After surgical repair of TAPVC, follow-up care should be individually planned through the primary caregiver in collaboration with a pediatric cardiologist, who should be involved in periodic follow-up evaluations.

●Physical activity – In the absence of residual pulmonary vein stenosis or pulmonary hypertension, exercise tolerance is generally normal in children with repaired TAPVC, regardless of the anatomic subtype. Physical activities and sports participation should not be restricted. (See "Physical activity and exercise in patients with congenital heart disease".)

●Antimicrobial prophylaxis – Infective endocarditis prophylaxis precautions prior to relevant dental and oral procedures are appropriate within the first six months after surgical repair, after which it is no longer required. This is discussed in greater detail separately. (See "Prevention of endocarditis: Antibiotic prophylaxis and other measures".)

●Developmental screening – Children with TAPVC should undergo appropriate surveillance, screening, and/or referral for neurodevelopmental impairment [46]. (See "Developmental-behavioral surveillance and screening in primary care".)

●Arrhythmia screening – Periodic screening for arrhythmias is not routinely recommended in asymptomatic children with repaired TAPVC. Because of the known association between intracardiac surgical repairs and atrial arrhythmias, however, periodic Holter monitoring may be considered in asymptomatic adolescents.

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Congenital heart disease in infants and children".)

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword[s] of interest.)

●Basics topics (see "Patient education: Total anomalous pulmonary venous connection in children (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Anatomy – Total anomalous pulmonary venous connection (TAPVC) is a form of cyanotic congenital heart disease in which the four pulmonary veins fail to make their normal connection to the left atrium and all drain into the systemic venous circulation through various anatomic pathways. (See 'Introduction' above and 'Embryology' above.)

The four anatomic variants of TAPVC are defined by the location of their connection relative to the heart: supracardiac, cardiac, infracardiac, and mixed TAPVC (figure 1). (See 'Anatomy' above.)

●Physiology – In TAPVC, the entire oxygenated pulmonary venous return mixes with the systemic venous system. A portion of this mixed, partially oxygenated blood is then shunted right-to-left at the atrial level (or infrequently through a patent ductus arteriosus) into the systemic arterial circulation, causing cyanosis. (See 'Physiology' above.)

●Presentation – The clinical presentation varies and is dependent upon the presence and degree of pulmonary venous obstruction (PVO). (See 'Presentation' above.)

•Obstructed TAPVC – Patients with severe obstruction generally present as critically ill newborn infants with cyanosis, respiratory distress, and signs of shock.

•Unobstructed TAPVC – Those with unobstructed lesions may only have subtle cyanosis immediately after birth, which may be detected by a pulse oximetry screening. After the immediate newborn period, symptoms are related to pulmonary overcirculation, including tachypnea, poor feeding, and failure to thrive. Over time, these patients develop right ventricular hypertrophy and pulmonary vascular changes that may result in right ventricular failure.

●Diagnosis – The diagnosis of TAPVC is usually made by cardiac echocardiography. (See 'Diagnosis' above.)

●Initial medical management – Initial medical management focuses on stabilizing patients prior to surgical correction (see 'Initial medical management' above):

•Patients with obstructed TAPVC typically present as critically ill with severe respiratory failure and/or shock. Management includes supplemental oxygen, mechanical ventilation, administration of inotropic drugs, and in some cases, prostaglandin E1 (alprostadil) therapy. If initial medical management does not adequately stabilize the patient, extracorporeal membrane oxygenation (ECMO) and palliative cardiac catheterization procedures have been used to stabilize severely affected patients prior to surgical correction.

•Patients with unobstructed TAPVC generally have milder symptoms and require less intensive supportive care. However, patients with signs of pulmonary overcirculation (eg, tachypnea, respiratory distress, poor feeding) may require diuretic therapy (eg, furosemide).

●Surgical correction – The definitive treatment for TAPVC is surgical correction. The goal of surgery is to reestablish a direct pathway between the pulmonary veins and the left atrium, while avoiding obstruction of pulmonary venous drainage. The specific surgical procedure varies depending upon the anatomy of the TAPVC lesion. (See 'Surgery' above.)

●Outcome – With improvements in medical management and surgical techniques, TAPVC has changed from a condition that was often fatal during infancy to having long-term survival rates of approximately 85 percent. Approximately 10 to 20 percent of patients require reintervention. Postoperative PVO is associated with increased risk of morbidity and mortality. (See 'Natural history' above and 'Outcome' above.)

●Follow-up care – After surgical repair, follow-up care should be individualized. In uncomplicated cases, physical activity is not restricted and endocarditis prophylaxis is not indicated beyond six months after the surgery. Other important aspects of follow-up care include developmental screening and monitoring for arrhythmias. (See 'Follow-up care' above and "Developmental-behavioral surveillance and screening in primary care" and "Prevention of endocarditis: Antibiotic prophylaxis and other measures".)