Types of TAPVR
Total anomalous pulmonary venous return is classified into different types, based on how and where the pulmonary veins drain to the heart:
Supracardiac Total Anomalous Pulmonary Venous Return
The pulmonary veins drain to the right atrium via the superior vena cava. In this type of TAPVR, the pulmonary veins first come together behind the heart and then drain upwards to an abnormal “vertical vein.” This vertical vein joins the innominate vein which connects to the right superior vena cava and drains to the right atrium.
Cardiac Total Anomalous Pulmonary Venous Return
The pulmonary veins come together behind the heart and then drain to the right atrium through the coronary sinus. The coronary sinus is the vein that normally returns blood from the heart muscle itself back to the right atrium after its oxygen has been depleted. The coronary sinus drains directly into the right atrium.
Infracardiac Total Anomalous Pulmonary Venous Return
The pulmonary veins drain to the right atrium via the hepatic (liver) veins and inferior vena cava. In this type, the pulmonary veins join together behind the heart and then typically drain downwards, connecting to the liver's portal vein system. They then drain through the vascular bed of the liver and enter the right atrium from the hepatic veins.
All types of total anomalous pulmonary venous return have to have an atrial septal defect (ASD). An ASD is a hole in the wall between the right and left upper chambers of the heart. This hole will allow some of the oxygenated blood that has entered the right atrium from the pulmonary vein to go across to the left atrium and out to the body.
Because of the abnormal pulmonary vein connection red (oxygenated) blood returning from the lungs mixes with the blue (lower oxygenated) blood returning from the body.
The left side of the heart (left atrium and left ventricle) are filled only by mixed blood shunting across a hole in the atrial wall (atrial septal defect – ASD). Because this blood is a mixture of red and blue (oxygenated and deoxygenated) blood, the overall oxygen content is decreased in the blood leaving the heart and going to the body. This explains why patients with total anomalous pulmonary venous return have low oxygen saturations (e.g., are cyanotic).
If the atrial septal defect (ASD) is small or restrictive to blood flow from the right atrium to the left atrium, then the volume of blood filling the left atrium and left ventricle may be diminished. This can lead to low blood supply to the body and shock.
In some cases of total anomalous pulmonary venous return, the route of blood from the pulmonary veins back to the heart may have areas of narrowing or obstruction. This obstruction may prevent adequate blood return from the pulmonary veins and may increase the pressure in the veins. Obstruction in the pulmonary veins leads to congestion in the lungs (pulmonary edema, or excessive fluid) and pulmonary hypertension (high pressure in the lung vessels).
Patients with obstructed total anomalous pulmonary venous return are usually critically ill with severe cyanosis and often have very unstable blood pressure. Emergent surgical intervention may be necessary in these cases.
Obstructed pulmonary veins most commonly occur in the infracardiac type of total anomalous pulmonary venous return, although it can occur with the other anatomic types as well.
Signs and Symptoms
Patients with obstructed TAPVR (total anomalous pulmonary venous return) are extremely ill soon after birth. These children are severely cyanotic. They also have respiratory problems, with rapid breathing, grunting and retractions of the rib cage muscles. Often such infants may be initially thought to have pneumonia or other respiratory diseases of the newborn, until an accurate cardiac diagnosis is made.
If obstruction to pulmonary venous return is not present, children with total anomalous pulmonary venous return may not have many symptoms. There may be some rapid or difficult breathing. There is often cyanosis, but it may be mild and difficult to detect.
Some children with this more common type of total anomalous pulmonary venous return are first detected when a physician hears a heart murmur during a physical examination. It is not uncommon for these children to go undiagnosed for several weeks to months.
The diagnosis of total anomalous pulmonary venous return may be initially suspected when a physician hears a typical heart murmur and detects evidence of overload on the right side of the heart.
Measurement of oxygen saturation may detect a low value (typically in the mid- to high 80s) in children without pulmonary venous obstruction. An electrocardiogram (ECG) may be helpful to show if there are problems with enlargement of the heart.
A chest X-ray, similarly, will show enlargement of the right side of the heart and will also demonstrate increased blood flow into the pulmonary vessels. In newborns with total anomalous pulmonary venous return and obstructed pulmonary venous return, chest X-ray may show evidence of pulmonary edema (fluid in the lungs).
The definitive diagnosis of total anomalous pulmonary venous return is usually made by echocardiogram (echo). This study will show the abnormal connection of the pulmonary veins, whether in a supracardiac, cardiac or infracardiac pattern.
Echocardiography (echo) will also show whether there is enlargement of the right atrium and right ventricle and can assess the size of and flow across the atrial septal defect (ASD).
On occasion, cardiac catheterization is required to make a definite diagnosis of total anomalous pulmonary venous return.
Cardiac catheterization will define the abnormal connection of all pulmonary veins, and is particularly helpful in unusual patterns of mixed total anomalous pulmonary venous return (for example, when some veins drain in a supracardiac and others in an infracardiac pattern in the same patient).
Cardiac catheterization can also determine accurately whether pulmonary veins are obstructed and if the atrial septal defect is “restrictive” (too small). If the ASD is restrictive, a balloon dilation procedure can be performed to enlarge the defect, in turn allowing better shunting of blood from right atrium to left atrium.
Total anomalous pulmonary venous return is a defect which requires surgical correction. The timing of the surgical repair varies depending on the type of total anomalous pulmonary venous return present as well as the condition of the child.
Surgical repair is performed emergently for newborns with obstructed total anomalous pulmonary venous return. Some of these children will actually require extracorporeal life support (ECMO) prior to surgery because of their blood flow instability.
Children with total anomalous pulmonary venous return without obstruction typically undergo surgical repair electively days to weeks after the diagnosis.
In these children, although the surgery is not emergent, there is generally little benefit to be gained by waiting more than one or two months.
Rarely, total anomalous pulmonary venous return is complicated by a restrictive atrial septal defect (i.e., a hole in the atrial septum that is not big enough to let enough blood through to the left side). In these children, a balloon dilation procedure may be performed at cardiac catheterization to improve the child's condition prior to surgical repair.
The surgical repair connects all of the veins to the back of the left atrium, resulting in a normal connection of pulmonary veins to left atrium.
All other routes for pulmonary venous drainage (such as the abnormal vessels which had carried pulmonary vein blood to the supracardiac or infracardiac areas) are tied off.
Finally, the atrial septal defect (ASD) is also closed. This surgical repair therefore results in a normal circulation: the pulmonary veins returning normally to the left atrium, without abnormal connections or septal defects.
Outcomes and Long-Term Outlook
The outcome of surgical repair for total anomalous pulmonary venous return is generally excellent. The surgical mortality is less than 5 percent when repair is performed electively, in relatively healthy children without obstructed pulmonary veins.
As one might guess, the surgical mortality (death rate) is higher when surgery is performed emergently on critically ill newborns with obstructed pulmonary venous return. This is because they are very sick before going to surgery. Furthermore, critically ill newborns who do survive the surgery may require a prolonged period of post-operative intensive care. They often are on a ventilator (breathing machine) for an extended time as their lungs recover.
The long-term outcome after surgical repair of total anomalous pulmonary venous return is also excellent. Because the surgical repair results in a normal circulation, these children are typically expected to grow and develop normally. They usually have few symptoms, if any.
Rare complications of total anomalous pulmonary venous return can occur late following surgery. Regular follow-up by a qualified cardiologist is essential to detect these problems early, if they occur.
Rarely, obstruction to one or more pulmonary veins can develop. This can occur at the site of surgical repair, or due to abnormalities of the pulmonary veins themselves. Such pulmonary vein obstruction can lead to a shortness of breath or wheezing, particularly on exertion. The diagnosis can be somewhat difficult to make, and may require cardiac catheterization.
Abnormal cardiac rhythm is another late complication of total anomalous pulmonary venous return, but is also rare. Because of the extensive atrial surgery involved in the repair, some patients can experience abnormal electrical impulses arising in the atrium.
When these impulses occur in single beats, they are typically benign and do not require any treatment. On rare occasion, patients can have either sustained episodes of rapid heartbeat, or very slow heart rates. Either sustained fast heart rates or slow heart rates might require treatment. Fortunately, the results of such treatment (either medical or with a pacemaker) are excellent.
Adult and Adolescent Management
Patients with total anomalous pulmonary venous return started life out as blue babies, and the surgical repair made them pink. Fortunately, many or most of these patients do so well after repair that they do not need expert follow-up as adults. Some do, however.
Learn more about the Adolescent and Adult Congenital Heart Disease Program.