What is Tricuspid atresia?
Tricuspid atresia is a rare congenital heart defect in which the tricuspid valve, the valve between the right atrium (upper chamber) and the right ventricle (lower chamber), does not develop. This prevents sufficient blood from reaching the lungs resulting in cyanosis, or blueness related to low oxygen levels in the blood. Also, as a consequence of tricuspid atresia, the right sided pumping chamber is often underdeveloped, leaving the left sided pumping chamber (ventricle) working as the main pump (single ventricle physiology). Tricuspid atresia can exist as an isolated defect, but more commonly is associated with holes in the heart that are essential to survival in order to divert blood flow around the undeveloped tricuspid valve (holes are called atrial septal defect and ventricular septal defect).
How does it develop?
In a developing fetus, the heart develops early , usually between the 1st and 2nd month of pregnancy. There are numerous factors that can impact a developing fetus in those early months (often before a women even knows she is pregnant), which is why heart defects are the most common form of birth defect.
When is Tricuspid Atresia diagnosed?
Tricuspid atresia is almost always diagnosed shortly after birth; the baby manifests signs of cyanosis (blue lips, nose, tongue) or heart failure with difficulty breathing and feeding. A hole in the upper chambers of the heart called an atrial septal defect is necessary for survival of the newborn with tricuspid atresia, as it provides an alternate route for some blood to reach the lungs . Some babies do ok for several days due to a patent ductus arteriosus, a naturally occurring connection during fetal life between the aorta and pulmonary artery, but this ductus usually closes in the first day or two after birth since it's purpose is only to provide blood flow to the lungs in the developing fetus. Without this ductus, the newborn requires an open hole across the atrial septum to survive, and sometimes it is necessary to do emergency surgery to create a hole.
What is the treatment for Tricuspid Atresia?
Initially, for newborns in distress, a medication is given via an IV to prevent the ductus arteriosus from closing, or a hole may need to be created in the atrial septum, using catheters or a surgical approach. Ultimately, a shunt operation may be needed in early life to provide adequate blood flow to the lungs. This involves using either a tube graft or one of the baby's own arteries to make a connection to the pulmonary artery (the vessel that leads to the lungs). This Blalock Taussig shunt is usually the first in a series of three operations aimed at correction of the abnormal circulation.
Alternatively, and less commonly, tricuspid atresia can result in too much blood flowing to the lungs via large holes in the heart, and an initial operation called a pulmonary artery band may be required. The goal of this operation is to reduce the amount of blood flow to the lungs, in order to protect the lungs from being permanently damaged.
Not every patient with tricuspid atresia is a candidate for further surgical intervention, and some children with this heart defect may grow up with continued cyanosis, requiring specialized long-term cardiology care for their cyanotic congenital heart disease. For those that qualify for further surgery, the next operation that is routinely done in the current era of pediatric congenital heart surgery, is a bidirectional Glenn shunt, and is often performed at approximately 6-12 months of age. This consists of directly connecting the vessel draining oxygen depleted blood from the upper body to the right pulmonary artery. After this operation, the blue blood from the upper body goes to the lungs without passing through the heart, which provides the child with a more direct route of picking up oxygen from the lungs.
The final operation is known as the Fontan procedure, usually performed at 3-4 years of age. In this operation, oxygen depleted venous blood from the lower part of the body is connected to the pulmonary artery either via a graft through the right atrium (lateral tunnel Fontan) or via a tube graft outside the right atrium (extracardiac Fontan). The end result is that all blue blood now returns directly to the lungs, and the single left ventricle pumps only oxygenated blood to the body.
What is the long term follow up for Tricuspid Atresia?
Patients with tricuspid atresia require lifelong follow up of their heart condition at a facility specializing in adult congenital heart disease (ACHD). In general, ongoing care consists of annual to semiannual examinations, testing such as EKG and echocardiograms and management of medications. Occasionally, surgical or catheter based procedures are required, and establishing regular care with a qualified ACHD center will enable accurate assessment and timing of these procedures, if applicable.
