Tricuspid Atresia: Symptoms, Causes, Diagnosis and Treatment

Tricuspid atresia is a life-threatening congenital heart disease characterized by the complete absence of development of the valve between the right atrium and the right ventricle during fetal life. Because of this structural anomaly, oxygen-depleted blood returning from the body cannot pass directly into the right ventricle and, consequently, cannot reach the lungs. From the perspective of pediatric cardiology, this disorder represents one of the clearest examples of univentricular, or single-ventricle, heart physiology, in which the nonfunctional right ventricle remains underdeveloped. To sustain both the systemic and pulmonary circulations, the left side of the heart must bear the entire workload alone, completely altering all blood flow dynamics from birth onward.

What Is Tricuspid Atresia?

A healthy heart consists of four chambers, with two chambers on the right and two on the left. Blood that has circulated throughout the body and become depleted of oxygen first enters the upper right chamber of the heart. From there, it passes through a gateway-like structure called the tricuspid valve into the lower right chamber and is then pumped to the lungs to be oxygenated. In tricuspid atresia, however, this vital gateway fails to develop during fetal life. Instead of a functioning valve, there is a thick layer of tissue that does not allow blood to pass. This blocks blood flow on the right side of the heart and prevents blood from following its normal route. Under normal circumstances, the right and left sides of the heart function in perfect coordination, but when faced with this obstruction, they are forced to change the way they operate.

Why Does the Right Ventricle Fail to Develop in Tricuspid Atresia, and How Is the Circulatory Obstruction Overcome?

Heart muscle is a tissue that develops and grows in response to the pressure and workload created by the blood filling it. When blood returning from the body cannot reach the lower right chamber because the valve is absent, that ventricle becomes nonfunctional and cannot grow adequately. This severely underdeveloped right ventricle is unable to pump blood to the lungs. At this point, the heart finds a natural alternative pathway to sustain life. Blood trapped in the upper right chamber passes to the left side of the heart through a congenital opening in the wall separating the atria. In the left atrium, this blood mixes with oxygen-rich blood returning from the lungs. The mixed blood then enters the left ventricle, which alone bears the enormous burden of pumping blood to both the body and the lungs. The left ventricle performs far more work than it normally should, effectively becoming the heart’s only functional pump.

What Is the Edwards Classification Used for Tricuspid Atresia, and What Are the Different Types of the Disease?

The severity of the disease and the balance of blood flow throughout the body are not the same in every infant. To better understand these differences and accurately plan treatment, a system known as the Edwards Classification is used in medical literature. This system categorizes the disease according to the position of the great arteries leaving the heart and the amount of blood reaching the lungs.

The main groups defined according to the Edwards classification are:

• Type 1 (with subtypes a, b, and c)
• Type 2 (with subtypes a, b, and c)
• Type 3

These major types are further divided into subgroups based on the degree of narrowing in the pulmonary arteries and the presence of a ventricular septal defect (VSD, a defect between the ventricles), serving as an important guide in determining the most appropriate timing of treatment for each infant.

How Does the Amount of Blood Reaching the Lungs Affect the Clinical Condition of Infants with Tricuspid Atresia?

In this condition, where only one ventricle is functional, the proportion of mixed blood that reaches the lungs is of vital importance. If there is severe narrowing along the pathway to the lungs, the infant’s blood cannot be adequately oxygenated. This reduces the amount of oxygen delivered to the tissues, resulting in a serious clinical condition early in life. In the opposite scenario, if there is no narrowing in the pulmonary arteries, a large proportion of the blood flows into the lungs because of their lower resistance. This excessive blood flow may lead to signs of heart failure and fluid accumulation in the lungs.

Common symptoms seen in infants when blood flow to the lungs is either insufficient or excessive include:

• Cyanosis
• Rapid breathing
• Feeding difficulties
• Becoming tired easily
• Excessive sweating

How Do Pediatric Cardiology Specialists Diagnose Tricuspid Atresia?

The diagnostic process ranges from noninvasive screening tests to more advanced imaging techniques. Even a simple blood oxygen measurement performed before a newborn is discharged from the hospital may represent the first step in this process. When tricuspid atresia is suspected, physicians use methods that map the heart’s electrical activity and provide clues about the size of the cardiac chambers.

The methods commonly used during diagnosis include:

• Oxygen saturation measurement
• Electrocardiography (ECG)
• Echocardiography (ECHO)
• Chest X-ray
• Cardiac catheterization

Why Is Echocardiography Considered the Gold Standard in Diagnosing Tricuspid Atresia?

Echocardiography, which displays the internal structures of the heart in real time using sound waves, is the cornerstone of the diagnostic process. This method allows detailed evaluation of the heart chambers, the condition of the valves, ventricular size, and the direction of blood flow without exposing the patient to radiation. The absence or complete closure of the tricuspid valve is visualized most clearly on the echocardiography screen. With these images, specialists can measure the size of cardiac defects, calculate how much blood reaches the lungs, and establish the timing of future surgical or interventional procedures based largely on these findings.

What Do Magnetic Resonance Imaging and Computed Tomography Contribute to Advanced Imaging in Tricuspid Atresia?

As the infant grows and especially when major surgical procedures are being planned, ultrasound images alone may not provide sufficient anatomical detail. In such cases, magnetic resonance imaging or computed tomography is used. These advanced technologies provide high-resolution, three-dimensional visualization of the volume of the left ventricle, which supplies the entire body, the flexibility of the heart muscle, and the pulmonary vascular anatomy. These images provide valuable information in determining whether the heart and blood vessels are suitable for future surgical procedures.

Can Tricuspid Atresia Be Detected During Pregnancy with Fetal Echocardiography?

Thanks to advances in medicine, diagnosis of this disease no longer has to wait until after birth. During specific weeks of pregnancy, fetal echocardiography, a specialized ultrasound examination, can evaluate the fetal heart. This detailed prenatal assessment can reveal the absence of development of the right-sided valve and abnormalities in the outflow tracts of the great vessels. Early detection enables delivery to be planned at specialized centers with comprehensive pediatric cardiology and cardiac surgery services rather than at a standard hospital, providing the infant with a significant advantage.

Why Are Cardiac Catheterization and Angiography So Important in the Management of Tricuspid Atresia?

Although noninvasive imaging provides extensive information about how the heart functions, it is sometimes necessary to directly measure intracardiac pressures and vascular resistance. During cardiac catheterization, thin, flexible tubes are advanced through blood vessels into the heart. This allows accurate measurement of pressure within the heart chambers. These measurements are particularly essential before the final stages of surgical treatment to determine whether the pulmonary vessels are suitable for the planned circulation.

The main assessments performed during this procedure include:

• Pressure measurement
• Resistance calculation
• Shunt analysis
• Vascular mapping

What Are the Initial Life-Saving Medical Interventions for Newborns with Tricuspid Atresia?

Infants with severely restricted pulmonary blood flow depend on certain fetal blood vessels that normally begin closing after birth remaining open. Closure of this temporary vessel after delivery may cause a rapid decline in the infant’s blood oxygen level. During this critical period, the primary goal is to maintain safe oxygen levels until the infant is ready for definitive surgical intervention. In the intensive care unit, various medications and stabilization measures are initiated to support breathing and tissue oxygenation.

How Does Prostaglandin Therapy Buy Time for Infants During the Medical Treatment of Tricuspid Atresia?

In infants whose main pathways to the lungs are obstructed, keeping the fetal vessel known as the ductus open is essential for survival. Specialists continuously administer prostaglandin intravenously to prevent closure of this vessel and keep it dilated. Although this medication does not cure the disease, it greatly reduces the risk of oxygen deprivation, buying valuable time for the surgical team and specialists. Throughout this period, the infant’s heart rhythm, blood pressure, and acid-base balance are closely monitored.

How Is Balloon Atrial Septostomy Performed in Tricuspid Atresia?

To allow all oxygen-poor blood returning from the body to pass from the upper right chamber into the upper left chamber, the opening in the wall between these two chambers must be sufficiently large. If this opening is too narrow, blood accumulates on the right side, leading to problems such as swelling throughout the body and enlargement of the liver. A specialized balloon technique is used to relieve this pressure. A deflated balloon is advanced into the heart through a blood vessel and passed across the narrow opening, where it is inflated on the left side. It is then gently but firmly pulled back to enlarge the opening. This procedure significantly improves the infant’s circulation by allowing trapped blood to pass more freely to the left side of the heart.

When Is Catheter-Based Patent Ductus Arteriosus Stenting Preferred in Cases of Tricuspid Atresia?

In some cases, newborn infants may have a very low birth weight or additional medical conditions that make open-heart surgery too risky. In these situations, the goal is to maintain blood flow to the lungs using catheter-based techniques rather than surgery. Thin tubes called catheters are advanced into the heart, and a small metal mesh tube is placed inside the vessel at risk of closing. This stent prevents the vessel from narrowing and closing, maintains continuous blood flow, and helps the infant grow without requiring immediate open-heart surgery.

Why Is Staged Single-Ventricle Repair Performed in Three Stages During the Surgical Treatment of Tricuspid Atresia?

If we think of a normal heart as having two separate pumps, in this disease the right-sided pump does not function at all. Since medicine cannot create a new ventricle from scratch, an alternative circulation has been developed in which blood returning from the body is directed to the lungs without passing through the heart. However, the pulmonary vessels of a newborn are not ready to receive blood directly. Pulmonary vascular resistance must decrease over time. To facilitate this adaptation, surgical reconstruction is usually divided into three stages according to the infant’s age and development and performed over several years.

Which Surgical Methods Are Used During the First Stage of Tricuspid Atresia Surgery?

The primary goal of the first operation during the newborn period is to establish a balance that ensures survival. If too little blood reaches the lungs, a new pathway is created by connecting a systemic artery to the pulmonary artery with an artificial graft. If too much blood floods the lungs, a constricting band is placed around the pulmonary artery to reduce excessive pressure.

The main approaches used during this stage include:

• Shunt surgery
• PDA stent implantation
• Pulmonary artery banding surgery
• Norwood procedure

How Does the Glenn Procedure, the Second Stage of Tricuspid Atresia Treatment, Benefit the Infant?

When the infant reaches several months of age (4–6 months), pulmonary vascular resistance begins to decrease, allowing the lungs to accept more blood at lower pressure. During this operation, the main vein carrying oxygen-poor blood from the upper body is disconnected from the heart and attached directly to the pulmonary artery. As a result, blood returning from the head and arms flows passively into the lungs without entering the heart. This reduces the volume load on the single functioning left ventricle, delays fatigue of the heart muscle, and improves oxygen levels.

What Is the Final Circulation Achieved with the Fontan Procedure, the Last Stage of Tricuspid Atresia Treatment?

When the child reaches approximately 2–4 years of age, the final stage of circulatory separation is performed. During this procedure, the inferior vena cava, which carries oxygen-poor blood from the lower body, is connected directly to the pulmonary artery through an artificial conduit or surgically created tunnel. As a result, all oxygen-poor blood returning from the body bypasses the heart completely and flows directly to the lungs under the influence of gravity and venous pressure alone. Oxygen-rich blood returning from the lungs then enters the left ventricle and is pumped throughout the body. This circulation largely eliminates cyanosis and raises the child’s blood oxygen level to nearly normal values.

What Criteria Must Be Met for Fontan Circulation in the Treatment of Tricuspid Atresia?

For blood to pass through the lungs without being actively pumped by a ventricle, the pulmonary vessels must be healthy and unobstructed. Not every patient’s vascular anatomy is suitable for this passive circulation. Therefore, before the final surgical stage, specialists must confirm that certain values are appropriate through cardiac catheterization.

The required characteristics include:

• Low pulmonary artery pressure
• Low pulmonary vascular resistance
• A well-functioning heart muscle
• Adequate pulmonary vascular bed/diameter

What Kind of Long-Term Life Awaits Children After Tricuspid Atresia Surgery?

Patients who successfully complete this staged series of operations can attend school, participate in daily social activities, and continue their lives with a highly satisfactory quality of life. This surgically created circulatory system largely meets the body’s oxygen requirements. However, because it differs from the body’s natural design, it may require support over time. Since blood reaches the lungs only through venous pressure, long-term pressure changes may develop throughout the body. Therefore, lifelong care becomes a process of regular medical follow-up.

Why Can Heart Rhythm Disorders Develop During Long-Term Follow-Up of Tricuspid Atresia, and How Are They Managed?

Multiple cardiac surgeries may leave scar tissue within the heart muscle and cause some chambers to enlarge over time. These changes may interfere with the transmission of electrical impulses, leading to episodes of excessively rapid or irregular heart rhythms. When rhythm abnormalities occur, the heart rate is managed with appropriate interventions based on the nature of the problem.

Methods used to manage rhythm disorders include:

• Medications
• Catheter ablation
• Pacemaker implantation

What Is Protein-Losing Enteropathy in Tricuspid Atresia, and How Does It Affect the Intestines?

Chronically elevated venous pressure associated with passive circulation may gradually impair the function of the intestinal lymphatic vessels. As lymphatic fluid leaks into the intestines, essential substances that should remain in the body, particularly proteins, may be lost through the bowel. This condition may cause fluid accumulation in the body, swelling of the eyelids, and chronic diarrhea. Nutrition specialists and physicians carefully manage this condition with specialized diets and intravenous supplementation.

Approaches used in nutritional and medical management include:

• Specialized diet
• Medication therapy
• Pressure-reducing interventions
• Lymphatic interventions

What Are the Effects of Fontan Circulation on the Liver After Tricuspid Atresia?

When blood flow depends only on gravity and venous pressure, circulation through the liver may also become slower. Over many years, this sluggish flow and increased blood pooling within the liver may silently initiate gradual structural changes. Although these changes usually do not cause noticeable symptoms early on, they may eventually lead to liver fibrosis after many years. Regular specialized evaluations are performed to detect these subtle changes as early as possible.

Methods used for liver monitoring include:

• Blood tests
• Ultrasonography
• Liver elastography (US, MRI)
• Biopsy

Is Organ Transplantation Considered in Advanced Stages of Tricuspid Atresia When Heart Failure Develops?

Despite all modern medical approaches and supportive therapies, the strength of the remaining single ventricle may gradually decline over the years. In very advanced cases where the heart muscle becomes exhausted, rhythm disorders become more frequent, and other organs begin to be affected, the existing circulation may no longer be sufficient. When quality of life deteriorates and other treatments are no longer effective, heart transplantation may be considered a medical necessity to provide patients with a new beginning and, in some cases, offer significant hope.

Why Is Lifelong Specialist Follow-Up Essential for Individuals Living with Tricuspid Atresia?

This unique heart anatomy demonstrates how resilient and adaptable the human body can be from the newborn period through adulthood. The life-saving interventions that begin in infancy, the carefully staged surgical planning extending over many years, and the specially reconstructed circulatory system represent an extraordinary achievement of modern medicine. However, completing the surgeries does not mean the journey is over. Ensuring that this delicate new balance continues to function properly, identifying potential problems before they progress, and protecting the function of all organ systems are only possible through continuous guidance by an experienced specialist team. Timely interventions help patients look toward life with greater confidence, comfort, and hope.