Total Anomalous Pulmonary Venous Connection 

Updated: May 02, 2015
Author: Allen D Wilson, MD; Chief Editor: Howard S Weber, MD, FSCAI 

Overview

Background

Total anomalous pulmonary venous connection (TAPVC) consists of an abnormality of blood flow in which all 4 pulmonary veins drain into systemic veins or the right atrium with or without pulmonary venous obstruction. Systemic and pulmonary venous blood mix in the right atrium. An atrial defect or foramen ovale (part of the complex) is important in left ventricular output both in fetal and in newborn circulation. See the image below.

Types of total anomalous pulmonary venous connecti Types of total anomalous pulmonary venous connection.

Embryology

Early in the formation of the lungs, the blood coming from the lung buds drains to the splanchnic plexus, which connects to the paired common cardinal and umbilicovitelline veins. The right common cardinal system later evolves into the right sinus venosus, which, in turn, becomes the right superior vena cava and azygos vein. The left common cardinal vein evolves into the left sinus venosus, which, in turn, becomes the left superior vena cava and coronary sinus. The umbilicovitelline system becomes the inferior vena cava, ductus venosus, and portal vein.

At 25-27 days' gestation, the developing pulmonary venous plexus retains connections to the right superior vena cava, left superior vena cava, and portal system. No direct communication to the left atrium exists.

At 27-29 days' gestation, the primitive pulmonary vein appears as an endothelial out-pouching from either the posterior superior left atrial wall or from the central part of the sinus venosus proximal to the primordial lung venous plexus. Connection between the primitive pulmonary vein and pulmonary venous plexus occurs by 30 days' gestation. The common pulmonary vein enlarges and incorporates into the left atrium, and, normally, the pulmonary venous part of the splanchnic plexus gradually loses its connection with the cardinal and umbilicovitelline veins.

Knowledge of the normal development of pulmonary venous pathways facilitates an understanding of how the various types of anomalous pulmonary venous return might occur. Failure of the common pulmonary vein to connect with the pulmonary venous plexus leads to persistence of one or more earlier venous connections to the right superior vena cava, to the left vertical vein/innominate vein, or to the umbilicovitelline vein/portal vein. Failure of the septum primum to normally form or abnormal septation of the sinus venosus can lead to direct connection of the pulmonary veins to the right atrium. Late obstruction of the common pulmonary vein after earlier venous channels have disappeared can lead to isolated pulmonary vein atresia, a rare and usually fatal condition. Failure of incorporation of the common pulmonary vein may lead to a left atrial shelf or membrane of cor triatriatum (ie, stenosis of the common pulmonary vein).[1]

Because all pulmonary venous return connects to the systemic venous system, right atrial and right ventricular enlargement occurs, and, if significant pulmonary venous obstruction develops, right ventricular hypertrophy occurs. Total anomalous pulmonary venous connection occurs alone in two thirds of patients and occurs as part of a group of heart defects (eg, heterotaxy syndromes) in approximately one third of patients.

An atrial septal defect or patent foramen ovale, considered part of the complex, serves a vital function in this condition for maintaining left ventricular output. Because diagnosis of most patients occurs in early infancy, a ductus arteriosus is frequently found as well

Darling proposed the most commonly used classification system for total anomalous pulmonary venous connection based on the site of pulmonary venous drainage. In type I (ie, supracardiac connection), the 4 pulmonary veins drain via a common vein into the right superior vena cava, left superior vena cava, or their tributaries. In type II (ie, cardiac connection), the pulmonary veins connect directly to the right heart (eg, coronary sinus or directly to the right atrium). In type III (ie, infradiaphragmatic connection), the common pulmonary vein travels down anterior to the esophagus through the diaphragm to connect to the portal venous system. In type IV (ie, mixed connections), the right and left pulmonary veins drain to different sites (eg, left pulmonary veins into the left vertical vein to the left innominate, right pulmonary veins directly into the right atrium or coronary sinus).

Pulmonary venous obstruction may occur in all types of anomalous connections, and, in all cases, clinicians must identify any sites of obstruction and treat the obstruction whenever possible at the time of surgical repair. In supracardiac connections, obstruction may occur at the origin of the ascending (vertical) vein or its attachment to the innominate vein, or the vertical vein may be obstructed as it crosses between the left pulmonary artery and the left bronchus. In cardiac connections, obstruction to pulmonary veins seldom develops but may occur at the junction of the common vein to the coronary sinus.

In infradiaphragmatic connections, severe obstruction almost always inhibits pulmonary venous flow with obstruction of the common pulmonary vein. This obstruction occurs either as it travels through the diaphragm, at its junction with the portal vein system, or as an obstruction of pulmonary venous flow as the ductus venosus closes and pulmonary vein flow is forced to cross the liver portal sinusoid system. Finally, in all types, obstruction may occur because of restrictive atrial septal defect size and because of small left atrial size.

Recurrent pulmonary vein stenosis remains a problem in some patients with total anomalous pulmonary venous connection. Recent studies suggest missing myocardial muscle “sleeve” layer in the abnormal-draining pulmonary vein walls and in left atrial walls of patients with total anomalous pulmonary venous connection; this might help explain the increased risk of developing stenosis.[2]

Pathophysiology

As a result of the mixture of pulmonary and systemic venous flow, right atrial and right ventricular volume loading develops in all patients with total anomalous pulmonary venous connection. Whether right heart pressure loading is also present depends primarily on whether restriction to flow occurs at the atrial septum or an obstruction to pulmonary venous flow develops. If the foramen ovale is restrictive, right atrial pressure elevates, and systemic and pulmonary venous congestion both occur. Pulmonary blood flow increases, and pulmonary artery hypertension may occur. The left atrium and left ventricle receive less than the normal flow and pump less than the normal volume, with some decrease in the cardiac index.

Most patients with isolated total anomalous pulmonary venous connection have a patent foramen ovale with some degree of restriction to transatrial flow. If no pulmonary venous obstruction is present, pulmonary blood flow increases (eg, 3-5 times the systemic volume) in early infancy, and arterial oxygen saturation is maintained, usually at 90% or higher. Signs of right heart volume load or right heart failure are evident.

If obstruction of pulmonary venous flow is present, then pulmonary venous congestion occurs with increased pulmonary lymphatic flow and increased flow through available alternate pulmonary venous pathways. Reflex pulmonary arterial vasoconstriction may also occur. Increase in pulmonary vascular resistance leads to decrease in pulmonary blood flow and a lower volume of saturated blood in the venous mixture. Decrease in systemic oxygen saturation along with a decrease in the cardiac index may lead to a severe decrease in oxygen delivery.

Epidemiology

Frequency

United States

Total anomalous pulmonary venous connection occurred in 41 of 2659 cases with cardiovascular abnormalities in the Baltimore-Washington Infant Study (1981-1987) or in 1.5% of all patients with cardiovascular malformations. Regional prevalence was 6.8 per 100,000 live births.[3] A total of 68% of these patients were diagnosed as neonates.

Sex

In the Baltimore-Washington Infant Study, the male-to-female ratio was 18:23.[3] In other reports, a strong male preponderance of 3:1 was observed in patients with infradiaphragmatic drainage.

 

Presentation

History

Patients with pulmonary vein obstruction

Pulmonary venous obstruction occurs in virtually all patients with subdiaphragmatic drainage and in approximately 50% of patients with supracardiac drainage. Patients with obstruction develop symptoms early, usually at age 24-36 hours, including tachypnea, tachycardia, and cyanosis. Signs of pulmonary hypertension progress with decreasing pulmonary blood flow and worsening cyanosis. Natural history is that of progressive clinical deterioration and early death in the first week or month of life, depending on the degree of pulmonary venous obstruction.

Physical examination findings include severe cyanosis with significant respiratory distress. Cardiac impulse is prominent anteriorly, but, usually, the heart is not clinically enlarged. The pulmonary component of the second heart sound is increased, and a gallop may be present. A murmur usually is not present, yet a systolic murmur over the pulmonary area or a tricuspid insufficiency murmur at the mid and lower left sternal border may be observed. Peripheral pulses are usually normal after birth but may decrease as heart failure progresses. Liver enlargement commonly occurs, especially in total anomalous pulmonary venous connection (TAPVC) type III, subdiaphragmatic drainage.

Patients without pulmonary venous obstruction

Patients with unobstructed pulmonary venous flow present with symptoms more similar to a very large atrial septal defect. Mild failure to thrive with greater respiratory effort than normal with activity or recurrent respiratory infections may be present. Often, chest radiography in patients with respiratory infections reveals significant cardiac enlargement.

Physical examination findings suggest right ventricular volume loading with increase in right ventricular impulse, a wide split-second sound (usually with normal-intensity pulmonary closure), and pulmonary outflow murmur with or without a tricuspid diastolic murmur. Cyanosis infrequently occurs in the first year of life.

Reverse difference cyanosis has been reported in the newborn period in total anomalous pulmonary venous connection to the superior vena cava (SVC). In this setting highly saturated blood in the SVC streams preferentially from right ventricle across ductus arteriosus to descending aorta; lower saturated blood in inferior vena cava streams across the foramen ovale to the left heart and aorta, resulting in higher saturation in the foot than in the right hand.[8]

If a restriction develops in the foramen ovale, some degree of pulmonary hypertension is more likely, with earlier onset of tachypnea, louder pulmonary closure sound, more prominent right ventricular impulse, and a greater likelihood of systemic and pulmonary venous congestion.

Causes

Sociodemographic findings in patients with total anomalous pulmonary venous connection were similar to those in control subjects.[3] Family history showed no other family members with total anomalous pulmonary venous connection. Noncardiac malformations were present in 9 patients (22%); however, other cardiac and noncardiac malformations were present in 6 first-degree relatives and 7 second-degree relatives of patients with isolated cases (41%). Altogether, a genetic etiology was suspected to contribute to a "failure of targeted pulmonary vein growth" because of the number of multiplex families. In addition, total anomalous pulmonary venous connection has been reported in siblings in other series.

Exposure histories showed possible association of total anomalous pulmonary venous connection with lead or pesticide exposure and raised questions of familial susceptibility to certain environmental teratogens.

Total anomalous pulmonary venous connection frequently occurs in association with asplenia and pulmonary atresia. Overall, one third of patients with total anomalous pulmonary venous connection have a major associated cardiovascular malformation and two thirds of patients have isolated total anomalous pulmonary venous connection.

 

DDx

Diagnostic Considerations

Important considerations

Total anomalous pulmonary venous connection (TAPVC) may be difficult to diagnose, especially in ill newborns on ventilation, if views of the atrial septum are difficult to obtain or if the common pulmonary vein is small or at an obtuse angle to the left atrial back wall. The addition of color Doppler imaging greatly aids in diagnosis in individual pulmonary veins and in analysis of the abnormal flow pattern across the atrial septal defect. Usually, the need for surgery in these patients is not debatable, although timing can be an issue.

The risk of recurrent pulmonary vein stenosis or anastomosis at the anastomosis site between the common pulmonary vein and the left atrium must be explained to families.

Other problems to be considered

Newborns

In newborns, also consider the following conditions:

  • Tachypnea

  • Cyanosis

  • Signs of pulmonary venous congestion

  • Cor triatriatum

  • Mitral stenosis

  • Hypoplastic left heart syndrome

  • Coarctation or interrupted aortic arch

  • Transposition of the great vessels

  • Persistent fetal circulation

Infants (age usually >6 wk)

Right ventricular volume load and pulmonary hypertension may indicate any of several heart defects, including the following:

  • Large ventricular septal defect

  • Common arteriovenous canal

  • Truncus arteriosus

  • Single ventricle

Children older than 1 year

Also consider large atrial septal defect as well as common atrium partial anomalous pulmonary venous connection.

Differential Diagnoses

 

Workup

Laboratory Studies

Assess and improve (as possible) the oxygenation, acid-base status, and hemogram status in newborns or young infants with total anomalous pulmonary venous connection (TAPVC) in preparation for surgery.

Electrocardiography

ECG reveals significant right ventricular hypertrophy in most of these patients, usually with a qR pattern in the right chest leads by age 5-7 days. Right atrial enlargement rarely occurs in these younger patients.

Chest Radiography

In patients with total anomalous pulmonary venous connection with pulmonary venous obstruction, chest radiographs reveal a normal heart size with a diffuse reticular pattern fanning out from the hilum.

When the pulmonary veins are unobstructed, the heart is enlarged (right atrial and right ventricular enlargement), and pulmonary markings reveal active increase in size of the pulmonary hilar and midzone vessels.

Echocardiography

Echocardiographic findings, which are usually definitive, have been vital in pinpointing the exact cardiac defect. Hyaline membrane disease may demonstrate similar findings initially. In this setting, ECG helps identify right ventricular hypertrophy in patients with total anomalous pulmonary venous connection, especially in premature babies, particularly because premature babies usually have a greater level of left ventricular force.

Echocardiography of the precordium in patients with total anomalous pulmonary venous connection reveals right ventricular and pulmonary artery volume loading with flattened or paradoxic septal motion on M-mode imaging. Apical and subcostal 4-chamber views usually best identify individual pulmonary veins and their confluence in patients with total anomalous pulmonary venous connection. Then, using multiple views, the common pulmonary vein can usually be tracked to its point of entry to the systemic venous system or to the coronary sinus.

Subcostal long- and short-axis views can also help evaluate size and flow patterns across the foramen ovale.

Total anomalous pulmonary venous connection may be difficult to diagnose, especially in an ill newborn on a ventilator, if views of the atrial septum are difficult to obtain or if the common pulmonary vein is small or at an obtuse angle to the left atrial back wall. The addition of color Doppler ultrasonography greatly aids in the diagnosis of individual pulmonary veins and in analysis of the abnormal flow pattern across the atrial septal defect

Color-flow mapping may be helpful in finding individual pulmonary veins and confirming whether they enter the left atrium. Color-flow ultrasonography may also be used to assess directional flow at the foramen ovale. In patients with total anomalous pulmonary venous connection, flow across the atrial septum predominantly occurs from the right to left.

Altogether, echocardiography with additional color Doppler can help make the diagnosis in the vast majority of patients with total anomalous pulmonary venous connection. In patients with pulmonary inflow obstruction, further diagnostic studies may be needed.

With fetal echocardiography, an attempt should be made to see the individual pulmonary veins, but most consistent diagnostic findings in total anomalous pulmonary venous connection have involved a confluence (chamber) behind the left atrium or a vertical vein.

Magnetic Resonance Imaging

MRI serves to confirm the diagnosis in patients with total anomalous pulmonary venous connection (especially in those with associated lung disease).

Selective Pulmonary Vein or Pulmonary Artery Angiography

This study may precisely reveal a vessel's anatomy.

Procedures

In some patients with multiple sites of pulmonary venous connection, cardiac catheterization serves to better define sites of pulmonary venous obstruction, when other associated cardiac defects are present (ie, pulmonary atresia), and to directly measure foramen ovale size when surgery is delayed.

 

Treatment

Medical Care

No catheter-corrective treatment is possible for total anomalous pulmonary venous connection (TAPVC), although atrial septostomy is used in some patients when the foramen ovale is restricted and corrective surgery is delayed for some reason. Catheter placement of a stent has been reported for pretreatment of obstructed vertical vein prior to surgery.[9] If a vertical vein is left patent postoperatively and significant shunt persists it may be possible to close this vessel with an Amplatzer PDA device.[10, 11]

Surgical repair is used as treatment for total anomalous pulmonary venous connection whenever it best serves the individual patient. Stabilizing the patient prior to surgery as much as possible from a cardiovascular and metabolic standpoint is important. In a newborn with obstructive total anomalous pulmonary venous connection, stabilization often involves mechanical ventilation, correction of acidosis, inotropic support, and administration of prostaglandin E1 for patency of patent ductus arteriosus and, in patients with total anomalous pulmonary venous connection type III, for patency of the ductus venous.

Nitric oxide may be useful as a pulmonary dilator postoperatively in patients experiencing episodic pulmonary hypertension that is affecting cardiac output. Reports indicate that magnesium sulfate is a useful pulmonary vasodilator in these patients. Extracorporeal membrane oxygenation (ECMO) may be life saving in some patients. If transesophageal echocardiography is used intraoperatively in infants with pulmonary vein obstruction, waiting for probe insertion until after chest is opened may be safer.[12]

Surgical Care

The goal of surgery is to redirect pulmonary vein flow entirely to the left atrium. In patients with a supracardiac or infracardiac connection, the common pulmonary vein is opened wide and connected side to side to the left atrium. The foramen ovale is closed, and the ascending or descending vein is usually ligated. In a cardiac connection (to right atrium or coronary sinus), the atrial septum is resected partially and a new septum is surgically created, directing pulmonary veins to the left atrium. A coronary sinus may be separately tunneled to the right atrium or left to drain with the pulmonary veins to the left atrium.

 

Medication

Medication Summary

Newborns or patients in early infancy with obstructed total anomalous pulmonary venous connection (TAPVC) frequently have pulmonary edema with varying degrees of increase in pulmonary arterial and venous resistance. Pulmonary edema is probably treated best with surgical relief of the pulmonary venous obstruction, but diuretics and assisted ventilation with high fraction of inspired oxygen (FIO2) and end-expiratory pressure are often helpful preoperatively and postoperatively.

Pulmonary Vasodilators

Class Summary

When sustained severe cyanosis or severe hypercyanotic episodes occur in patients with obstructed total anomalous pulmonary venous connection postoperatively, treatment with one or more pulmonary vasodilators may be helpful. The pulmonary vascular bed may be somewhat reactive in the postoperative period, resulting in episodic pulmonary hypertension and low cardiac output. Although this should improve over time, interim therapy with pulmonary vasodilator agents may be useful in this setting. Vasodilators that are specific for the pulmonary vasculature are rare; however, inhaled nitric oxide may be a good agent in this setting. Therefore, the following 3 vasodilators can be used to treat elevated pulmonary vascular resistance in the postoperative period. Note that this therapy is controversial in the preoperative patient with known pulmonary venous obstruction.

Nitric oxide, inhaled (INOmax)

Stimulates guanylate cyclase to form cyclic GMP, which causes relaxation of vascular smooth muscle.

Because it can be delivered by inhalation directly to alveolar units and is rapidly inactivated by hemoglobin, it is the most selective of currently available pulmonary vascular dilators (except for oxygen). Requires an inhalation delivery system (not available everywhere); approved for use in children in December 1999.

Magnesium sulfate

Reportedly useful in patients with obstructed TAPVC who have hypercyanotic episodes to decrease pulmonary vascular resistance and decrease pulmonary vascular reactivity. Mechanism of action is believed to be direct action on vascular muscle cells but may also increase formation or release of NO. MgSO4 has systemic and pulmonary vascular dilating effects, and use of a slow infusion of lower-dose MgSO4 is wise to avoid systemic hypotension.

Alprostadil IV (Prostin VR)

Prostaglandin E1 (PGE1) that causes dilation of vascular smooth muscle in the ductus arteriosus, systemic arteries, and pulmonary vascular muscles. In obstructed TAPVC, PGE1 is usually used as a pulmonary vascular dilator, but its effects on the ductus arteriosus and ductus venosus can be very important (eg, in subdiaphragmatic connection, PGE1 can help dilate the ductus venosus and improve pulmonary venous flow. In other types of connection with obstruction, PGE1 can dilate pulmonary arteries and increase pulmonary flow or dilate the ductus arteriosus and systemic arteries and increase right-to-left shunting and worsen cyanosis). PGE1 is readily available and easily administered, preferably via a large vessel. Care must be taken to observe its effects in the complex circulation of TAPVC.

Each 1-mL ampule contains 500 mcg/mL.