What are the types of tricuspid valve atresia and their management?

Tricuspid Valve Atresia: Classification and Management

Anatomic Classification

Tricuspid atresia is classified into three main types based on great artery relationships and associated cardiac anatomy, with Type I being the most common (approximately 70% of cases). 1

Type I: Normally Related Great Arteries

• The aorta arises from the left ventricle and pulmonary artery from the rudimentary right ventricle 2, 3
• Subdivided by pulmonary blood flow patterns:
  • Type Ia (Group A): Decreased pulmonary vascularity due to pulmonary stenosis or atresia—most common subtype at 54% of all cases 4
  • Type Ib (Group B): Increased pulmonary blood flow without obstruction 4
  • Type Ic (Group C): Spontaneously changing hemodynamics with variable pulmonary flow 4

Type II: Transposed Great Arteries (D-Transposition)

• The aorta arises anteriorly from the rudimentary right ventricle 3
• The pulmonary artery arises posteriorly from the left ventricle 2
• Less common than Type I, representing approximately 12-30% of cases 3

Type III: Corrected Transposition (L-Transposition)

• Rare variant with both atrioventricular and ventriculoarterial discordance 3
• The morphologic left ventricle connects to the pulmonary artery 2

Fundamental Anatomic Features

The essential pathology is absence of the right atrioventricular connection, not simply an imperforate valve membrane as commonly misunderstood. 2

• Atrioventricular sulcus tissue extends to the septal junction, completely separating the right atrium from ventricular myocardium 2
• The right ventricle is rudimentary and lacks an inlet portion 2
• True imperforate tricuspid valve membranes are rare and represent a distinct minority of cases 2
• An obligatory atrial septal defect or patent foramen ovale allows right-to-left shunting 1
• A ventricular septal defect provides the pathway for blood to reach the pulmonary circulation 4

Management Strategy by Type

Type I, Group A (Decreased Pulmonary Flow)

Early surgical palliation is mandatory, as these patients have only 10% survival beyond the first year without intervention. 4

• Waterston shunt is the procedure of choice for symptomatic small infants with diminished pulmonary flow 4
• Surgical intervention improves 15-year survival to approximately 50% 4
• These patients typically require shunting procedures in early infancy 4

Type I, Group B (Increased Pulmonary Flow)

Pulmonary artery banding is indicated to protect the pulmonary vasculature and prevent pulmonary vascular disease 4

• This prevents the development of Eisenmenger physiology 1
• Banding is performed early in infancy when symptoms of congestive heart failure develop 4

Type I, Group C (Balanced Circulation)

These patients may survive without surgery into adulthood (documented survival to ages 21-41 years) if pulmonary blood flow remains naturally balanced 3

• Surgical intervention is delayed compared to Group A patients 4
• When shunting becomes necessary, operative results are more favorable than in Group A 4

Type II (Transposed Great Arteries)

Management depends on the presence or absence of pulmonary stenosis, similar to Type I classification 3

• Pulmonary artery banding is rarely needed due to inherent pulmonary stenosis in most cases 4
• Accurate anatomic diagnosis via biplane left ventriculography with long axial view (60-degree LAO with cranial angulation) is essential for surgical planning 3

Definitive Surgical Options

Fontan-Type Procedures

Right atrium-to-pulmonary artery anastomosis (Fontan procedure) should be considered for definitive palliation in appropriate candidates 4, 3

• Bidirectional cavopulmonary anastomosis is considered in selected patients with severe right ventricular dysfunction and preserved left ventricular function with low left atrial pressure 1
• Prerequisites include: low pulmonary vascular resistance, good left ventricular function, and adequate pulmonary artery anatomy 1

Single-Ventricle Pathway

The single-ventricular Fontan pathway may be considered for profound right ventricular dysfunction, most often when operation is required during infancy 1

Diagnostic Evaluation

Cardiac Catheterization

Catheterization is indicated to assess potential for definitive palliation in unoperated or shunt-palliated adults 1

Essential data to obtain includes: 1

• Intracardiac, pulmonary artery, and aortic pressures
• Oxygen saturations throughout all chambers
• Estimations of pulmonary and systemic blood flow and resistances
• Angiograms of systemic venous anatomy and great vessel anatomy
• Pulmonary artery anatomy and size
• Ventricular volume, hypertrophy, and ejection fraction
• Coronary angiography in older patients

Imaging Modality Priority

Biplane left cineventriculography with long axial view is the most important diagnostic mode for revealing ventricular and great vessel relations 3

Surgical Outcomes and Prognosis

Overall surgical mortality is approximately 23%, with 15-year survival reaching 50% with appropriate intervention. 4

• Early mortality in experienced centers is 5-10% 1
• Late survival after Fontan-type procedures is 92% at 10 years postoperatively 1
• All surgical interventions should only be performed in specialized congenital heart disease centers by surgeons with specific training and expertise 1

Critical Management Principles

Lifelong specialized surveillance is required in tertiary CHD centers with experienced medical and surgical personnel 1

• Regular follow-up (at least yearly) is mandatory in all patients 1
• Prudent surgical decisions based on accurate anatomic diagnosis and optimal effective pulmonary blood flow are essential for favorable outcomes 3
• Natural history without surgery shows approximately 50% survival to 15 years of age overall, but only 10% in Type Ia patients 4