Tricuspid Atresia

Introduction to Tricuspid Atresia

Tricuspid Atresia is a congenital heart defect characterized by the absence or underdevelopment of the tricuspid valve, resulting in no direct communication between the right atrium and right ventricle.

Key points:

  • Incidence: Approximately 1-2% of all congenital heart defects
  • Occurs in about 1 in 10,000 live births
  • Slight male predominance
  • Classified as a form of single ventricle physiology
  • Often associated with other cardiac anomalies

Anatomy of Tricuspid Atresia

The anatomical features of Tricuspid Atresia include:

  1. Absence or severe underdevelopment of the tricuspid valve:
    • Imperforate valve tissue or muscular floor of the right atrium
  2. Hypoplastic or absent right ventricle:
    • Due to lack of blood flow from the right atrium
  3. Atrial septal defect (ASD) or patent foramen ovale (PFO):
    • Essential for right-to-left shunting of blood
  4. Associated defects:
    • Ventricular septal defect (VSD): Present in most cases
    • Great artery relationships: Normally related or transposed
    • Pulmonary stenosis or atresia: Common, affects pulmonary blood flow

Classification:

Tricuspid Atresia is classified based on:

  • Presence and size of the VSD
  • Relationship of the great arteries
  • Presence of pulmonary stenosis or atresia

Pathophysiology of Tricuspid Atresia

The pathophysiology of Tricuspid Atresia involves:

  1. Systemic venous return:
    • Blood from the superior and inferior vena cava enters the right atrium
    • Unable to enter the right ventricle due to absent tricuspid valve
  2. Right-to-left shunting:
    • Blood shunts from right atrium to left atrium via ASD/PFO
    • Results in mixing of oxygenated and deoxygenated blood
  3. Pulmonary blood flow:
    • Dependent on VSD size and pulmonary outflow tract obstruction
    • Can be decreased, normal, or increased
  4. Single ventricle physiology:
    • Left ventricle pumps blood to both systemic and pulmonary circulations
    • Volume overload of the left ventricle
  5. Cyanosis:
    • Due to mixing of oxygenated and deoxygenated blood
    • Severity depends on pulmonary blood flow
  6. Potential complications:
    • Polycythemia due to chronic hypoxemia
    • Clubbing of fingers and toes
    • Potential for paradoxical embolism

Clinical Presentation of Tricuspid Atresia

The clinical presentation of Tricuspid Atresia varies depending on the associated defects and pulmonary blood flow:

1. Neonatal Presentation:

  • Cyanosis: Usually apparent within the first few hours or days of life
  • Tachypnea and respiratory distress
  • Poor feeding and failure to thrive
  • Fatigue and irritability

2. Infancy and Childhood:

  • Persistent cyanosis
  • Clubbing of fingers and toes
  • Exercise intolerance
  • Growth retardation
  • Recurrent respiratory infections

Physical Examination Findings:

  • Central cyanosis
  • Tachypnea and increased work of breathing
  • Single S2 heart sound (loud)
  • Systolic murmur (if VSD present)
  • Continuous murmur (if patent ductus arteriosus present)
  • Hepatomegaly (in heart failure)

Presentation based on Pulmonary Blood Flow:

  1. Decreased pulmonary blood flow:
    • Severe cyanosis
    • Hypoxic spells
  2. Normal pulmonary blood flow:
    • Moderate cyanosis
    • Better initial tolerance
  3. Increased pulmonary blood flow:
    • Mild cyanosis
    • Signs of congestive heart failure

Diagnosis of Tricuspid Atresia

Diagnosis of Tricuspid Atresia involves several modalities:

1. Echocardiography:

  • Primary diagnostic tool
  • Demonstrates absence of the tricuspid valve
  • Assesses size and function of the left ventricle
  • Identifies associated defects (VSD, ASD, great artery relationship)
  • Evaluates pulmonary blood flow

2. Electrocardiogram (ECG):

  • Left axis deviation
  • Left atrial enlargement
  • Left ventricular hypertrophy
  • Absence of right ventricular forces

3. Chest X-ray:

  • Decreased pulmonary vascular markings (in reduced pulmonary blood flow)
  • Cardiomegaly (more prominent with increased pulmonary blood flow)
  • "Egg-on-side" cardiac silhouette

4. Cardiac Catheterization:

  • Not always necessary for diagnosis
  • Provides detailed hemodynamic information
  • Assesses pulmonary vascular resistance
  • May be used for interventional procedures

5. Cardiac MRI or CT:

  • Provides detailed anatomical information
  • Useful for surgical planning
  • Assesses ventricular function and volumes

6. Pulse Oximetry:

  • Demonstrates persistent hypoxemia
  • Used for initial screening and monitoring

Management of Tricuspid Atresia

Management of Tricuspid Atresia is staged and aims to achieve a balanced circulation:

1. Initial Medical Management:

  • Prostaglandin E1 to maintain ductal patency in neonates
  • Supplemental oxygen as needed
  • Management of congestive heart failure if present
  • Correction of metabolic acidosis

2. Surgical Management:

Staged palliative surgeries are typically performed:

  1. Stage I (Neonatal period):
    • Blalock-Taussig shunt: For inadequate pulmonary blood flow
    • Pulmonary artery banding: For excessive pulmonary blood flow
  2. Stage II (4-6 months):
    • Bidirectional Glenn procedure (superior cavopulmonary anastomosis)
  3. Stage III (2-4 years):
    • Fontan procedure or total cavopulmonary connection (TCPC)

3. Catheter-Based Interventions:

  • Balloon atrial septostomy: To improve mixing at atrial level
  • Stenting of stenotic shunts or pulmonary arteries

4. Long-term Management:

  • Regular cardiology follow-up
  • Anticoagulation post-Fontan procedure
  • Management of potential Fontan complications
  • Endocarditis prophylaxis as indicated
  • Exercise recommendations based on functional status

5. Heart Transplantation:

  • Considered in cases of failed palliation or severe ventricular dysfunction

Prognosis of Tricuspid Atresia

The prognosis for patients with Tricuspid Atresia has improved significantly with advancements in surgical techniques and medical management:

Factors Influencing Prognosis:

  • Timing and success of initial palliation
  • Associated cardiac defects
  • Development of pulmonary vascular disease
  • Ventricular function
  • Complications related to Fontan circulation

Survival Rates:

  • Overall survival to adulthood: 70-80%
  • Post-Fontan procedure: 80-90% survival at 20 years
  • Highest mortality risk in the first year of life

Long-term Considerations:

  • Fontan-associated complications:
    • Arrhythmias
    • Thromboembolic events
    • Protein-losing enteropathy
    • Liver dysfunction
    • Plastic bronchitis
  • Exercise capacity: Generally reduced compared to normal population
  • Pregnancy: High-risk, requires careful management
  • Neurodevelopmental outcomes: Risk of developmental delays and learning difficulties

Lifelong specialized cardiac care is essential for optimal outcomes in patients with Tricuspid Atresia. Regular follow-up allows for early detection and management of complications, potentially improving long-term quality of life and survival.



Tricuspid Atresia
  1. What is Tricuspid Atresia?
    A congenital heart defect where there is no tricuspid valve between the right atrium and right ventricle
  2. What percentage of congenital heart defects is Tricuspid Atresia?
    Approximately 1-2%
  3. Which gender is more commonly affected by Tricuspid Atresia?
    Males (slight predominance)
  4. What is the primary embryological defect in Tricuspid Atresia?
    Failure of development of the tricuspid valve and often hypoplasia of the right ventricle
  5. What is the characteristic clinical sign of Tricuspid Atresia in newborns?
    Cyanosis
  6. Which diagnostic test is considered the gold standard for diagnosing Tricuspid Atresia?
    Echocardiogram
  7. What is the classic chest X-ray finding in Tricuspid Atresia?
    Boot-shaped heart due to right atrial enlargement and a concave pulmonary arterial segment
  8. Which ECG finding is common in patients with Tricuspid Atresia?
    Left axis deviation and left ventricular hypertrophy
  9. What is the name of the palliative surgical procedure often used in the first few months of life for Tricuspid Atresia?
    Blalock-Taussig shunt or Pulmonary artery banding (depending on pulmonary blood flow)
  10. Which medication is used to keep the ductus arteriosus open in Tricuspid Atresia before surgical palliation?
    Prostaglandin E1
  11. What is the name of the staged surgical repair approach for Tricuspid Atresia?
    Fontan procedure
  12. At what age is the final stage of the Fontan procedure typically performed?
    Between 2-4 years of age
  13. What is the mortality rate for the Fontan procedure in experienced centers?
    Less than 5%
  14. Which genetic syndrome is associated with a higher incidence of Tricuspid Atresia?
    No strong association with a specific genetic syndrome
  15. What is the risk of recurrence of Tricuspid Atresia in offspring if a parent has the condition?
    Approximately 1-2%
  16. What is the most common long-term complication after Fontan procedure?
    Fontan circulation failure
  17. Which organ system is commonly affected in patients with Fontan circulation?
    Liver (hepatic congestion and fibrosis)
  18. What is the recommended follow-up interval for patients after Fontan procedure?
    Annual follow-up with a cardiologist specializing in congenital heart disease
  19. Which imaging modality is often used for long-term follow-up of Tricuspid Atresia patients after Fontan procedure?
    Cardiac MRI
  20. What is the name of the fenestration sometimes created during the Fontan procedure?
    A small communication between the Fontan circuit and the atrium to allow right-to-left shunting
  21. Which arrhythmia is more common in patients with Fontan circulation?
    Atrial arrhythmias (flutter or fibrillation)
  22. What is the life expectancy for patients with Tricuspid Atresia who have undergone Fontan procedure?
    Reduced compared to the general population, with many surviving into adulthood
  23. Which complication can occur due to chronic elevated systemic venous pressure in Fontan patients?
    Protein-losing enteropathy
  24. What is the most common indication for heart transplantation in Fontan patients?
    Fontan failure (ventricular dysfunction, arrhythmias, or end-organ dysfunction)
  25. Which non-invasive test is used to assess exercise capacity in Tricuspid Atresia patients after Fontan procedure?
    Cardiopulmonary exercise testing
  26. What is the name of the procedure used to assess Fontan circuit patency and pressures?
    Cardiac catheterization
  27. Which biomarker is used to assess ventricular function and congestion in Fontan patients?
    B-type natriuretic peptide (BNP)
  28. What is the recommended frequency of liver imaging in adults with Fontan circulation?
    Every 3-5 years, or more frequently if clinically indicated
  29. Which pregnancy-related complication is more common in women with Fontan circulation?
    Increased risk of arrhythmias, heart failure, and thromboembolic events
  30. What is the name of the surgical technique used to connect the inferior vena cava directly to the pulmonary arteries in the Fontan procedure?
    Extracardiac conduit Fontan


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