Congenital Absence of the Pulmonary Valve Syndrome

Congenital Heart Disease Introduction Embryology & Pathophysiology Clinical Presentation Diagnosis Management Complications & Outcomes Special Considerations

Congenital Absence of the Pulmonary Valve Syndrome (APVS)

APVS is a rare cardiac malformation characterized by rudimentary pulmonary valve cusps resulting in severe pulmonary regurgitation and varying degrees of pulmonary stenosis. It occurs in approximately 3-6% of patients with Tetralogy of Fallot.

Key Points

• Two distinct forms:
  • Tetralogy of Fallot-associated (TOF-APVS) - 75% of cases
  • Non-Tetralogy variant (Non-TOF-APVS) - 25% of cases
• Associated with significant morbidity and mortality in infancy
• Characterized by massive dilation of pulmonary arteries
• Often presents with respiratory symptoms due to bronchial compression

Embryological Development

• Occurs during weeks 5-9 of gestation
• Abnormal neural crest cell migration
• Defective development of pulmonary valve cushions
• Associated with chromosome 22q11.2 deletion in 25% of cases

Pathophysiology

• Primary Cardiac Anomalies:
  • Absent or rudimentary pulmonary valve leaflets
  • Annular stenosis with free pulmonary regurgitation
  • Massive dilation of main pulmonary artery and branches
  • Right ventricular hypertrophy
  • Variable ventricular septal defect (in TOF variant)
• Hemodynamic Effects:
  • To-and-fro flow across pulmonary valve annulus
  • Volume overload of right ventricle
  • Pressure overload from stenotic component
  • Aneurysmal dilation of pulmonary arteries
• Respiratory Effects:
  • Bronchial compression by dilated pulmonary arteries
  • Reduced lung volumes
  • Air trapping
  • Atelectasis
  • Recurrent respiratory infections

Clinical Manifestations

Neonatal/Infant Presentation

• Respiratory symptoms predominate:
  • Respiratory distress
  • Cyanosis
  • Persistent wheezing
  • Recurrent bronchiolitis
  • Failure to thrive

Physical Examination

• Cardiac Findings:
  • To-and-fro murmur at left upper sternal border
  • Systolic ejection click
  • Hyperactive precordium
  • Right ventricular heave
• Respiratory Findings:
  • Tachypnea
  • Intercostal retractions
  • Diffuse wheezing
  • Decreased breath sounds
  • Rales/crackles
• Other Features:
  • Growth retardation
  • Dysmorphic features (if 22q11.2 deletion)
  • Digital clubbing in chronic cases

Diagnostic Evaluation

Prenatal Diagnosis

• Fetal echocardiography findings:
  • Cardiomegaly
  • Massive pulmonary artery dilation
  • Absent pulmonary valve with to-and-fro flow
  • VSD in TOF variant

Postnatal Imaging

• Echocardiography:
  • Primary diagnostic tool
  • Evaluates cardiac anatomy and function
  • Measures pulmonary artery dimensions
  • Assesses severity of stenosis and regurgitation
• Chest CT/MRI:
  • Detailed pulmonary artery anatomy
  • Degree of bronchial compression
  • Surgical planning
  • 3D reconstruction capability
• Cardiac Catheterization:
  • Hemodynamic assessment
  • Pulmonary vascular resistance
  • Coronary anatomy

Additional Studies

• Chest X-ray:
  • Cardiomegaly
  • Prominent pulmonary arteries
  • Air trapping
  • Atelectasis
• Genetic testing for 22q11.2 deletion
• Bronchoscopy in selected cases

Treatment Strategies

Medical Management

• Initial Stabilization:
  • Respiratory support
  • Management of heart failure
  • Nutritional support
  • Prevention/treatment of infections
• Medical Therapy:
  • Diuretics
  • Bronchodilators
  • Anticoagulation if indicated
  • Prophylactic antibiotics

Surgical Management

• Timing:
  • Early intervention in symptomatic infants
  • Elective repair in stable patients
• Surgical Options:
  • Complete repair:
    • VSD closure (in TOF variant)
    • Right ventricular outflow tract reconstruction
    • Pulmonary valve replacement
    • Pulmonary artery plication
  • Staged repair in high-risk cases
  • Novel techniques:
    • Lecompte maneuver
    • Pulmonary artery reduction plasty
    • Various valve options (homograft, bioprosthetic, mechanical)

Complications

• Early Complications:
  • Respiratory failure
  • Post-operative right ventricular dysfunction
  • Arrhythmias
  • Pleural effusions
  • Prolonged ventilation
• Late Complications:
  • Pulmonary valve dysfunction
  • Right ventricular failure
  • Residual pulmonary artery dilation
  • Chronic respiratory issues
  • Exercise intolerance

Outcomes

• Mortality:
  • Higher in symptomatic neonates
  • Better survival in older infants/children
  • Improved with modern surgical techniques
• Prognostic Factors:
  • Age at presentation
  • Severity of respiratory symptoms
  • Degree of pulmonary artery dilation
  • Associated genetic syndromes

Special Considerations

Long-term Follow-up

• Regular cardiology follow-up
• Serial imaging studies
• Pulmonary function monitoring
• Exercise testing when appropriate
• Genetic counseling

Quality of Life

• Impact on daily activities
• School/sports participation
• Psychological support
• Family counseling

Pregnancy Considerations

• Pre-conception counseling
• Risk assessment
• Multidisciplinary management
• Close monitoring during pregnancy

Disclaimer

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