Show AllTotal anomalous pulmonary venous return results in diminished oxygen content of the arterial blood (cyanosis) and an increased volume load on the right ventricle.
Because of the abnormal pulmonary vein connection there is complete mixing together of the oxygenated blood returning from the lungs (in pulmonary veins) and the deoxygenated blood returning from the body (in the vena cavae).
The left atrium and left ventricle are filled only by mixed blood shunting across an atrial septal defect (from right atrium to left atrium). Because this blood is a mixture of 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 arterial oxygen saturations (e.g., are cyanotic).
If the atrial septal defect is small or restrictive to blood flow from the right atrium, then the volume of blood filling the left atrium and left ventricle may be diminished. This can lead to low cardiac output 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 blood pressure).
Patients with obstructed total anomalous pulmonary venous return are usually critically ill with severe cyanosis and often have marked hemodynamic instability. 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.
Patients with obstructed total anomalous pulmonary venous return are extremely ill soon after birth. These children are severely cyanotic. They also have respiratory distress, 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 be asymptomatic. There may be mild to moderate rapid or labored 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 right ventricular overload.
Measurement of oxygen saturation may detect a low value (typically in the mid- to high 80s) in children without pulmonary venous obstruction. An electrocardiogram will reveal evidence of right atrial and right ventricular enlargement.
A chest X-ray, similarly, will show right heart enlargement and will also demonstrate increased pulmonary artery blood flow. In newborns with total anomalous pulmonary venous return and obstructed pulmonary venous return, chest X-ray may show evidence of pulmonary edema.
The definitive diagnosis of total anomalous pulmonary venous return is usually made by echocardiogram. This study will demonstrate the abnormal connection of the pulmonary veins, whether in a supracardiac, cardiac or infracardiac pattern.
Echocardiography will also demonstrate enlargement of the right atrium and right ventricle and can assess the size of and flow across the atrial septal defect.
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 marked hemodynamic instability.
Children with total anomalous pulmonary venous return without obstruction typically undergo surgical repair electively days to weeks after the diagnosis is made.
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 sufficient 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.
In virtually all types of total anomalous pulmonary venous return, the pulmonary veins return to a common confluence behind the left atrium. The surgical repair takes advantage of this fact. The common pulmonary vein confluence is connected by the surgeon 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 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.
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.
