Sandbox:Pulmonary valve stenosis

Epidemiology and Demographics

Incidence of isolated PS is 1.5-6.5 per 10,000live births and accounts for 2 to 13% of all congenital heart lesions.

Causes

Pulmonary valve stenosis is due to a structural changes resulting from thickening and fusion of the pulmonary valve. The valve pathology can be congenital or acquired. The following is the list of causes:

• Congenital causes: Account for 95% of the cases and they include:
  • Associated with congenital heart disease:
    • Tetralogy of Fallot
    • Double outlet right ventricle
    • Univentricular atrio-ventricular connection
    • Atrioventricular canal defect
    • Bicuspid pulmonary valve: Frequently associated with Tetralogy of Fallot.
    • Quadricuspid pulmonary valve: They are benign and an incidental finding.
  • Isolated pulmonic stenosis: Incidence is 1.5-6.5 per 10,000live births
    • Acommissural pulmonary valves: Valves have a prominent systolic doming of the valve cusps and an eccentric orifice.
    • Dysplastic pulmonary valves: Thickened and deformed cusps with no commissural fusion.
    • Other variations include of commissural malformation include: unicommissural pulmonary valve, bicuspid valve with fused commissures.
• Acquired Causes: These are less frequent and account for less than 5% of the cases.
  • Carcinoid Syndrome: It is the most common acquired cause of PS.
  • Post infectious causes
  • Rheumatic heart disease

Pathophysiology

Anatomy

• Pulmonary valve is located at the distal part of the right ventricular outflow tract at the junction of the pulmonary artery.
• It is located anterior and superior to the aortic valve at the level of the third intercostal space and separated from the tricuspid valve by the infundibulum of the right ventricle.
• It is comprised of three equal sized, semilunar cusps or leaflets (right, left, anterior), nomenclature based on the corresponding aortic valve.
• The three cusps are joined by commissures and the cusps are thinner when compared to the aortic valve, due to a low pressure in the right ventricle.
• The area of the valve is related to body surface area and men usually have greater valve area when compared with women.
• The normal orifice area is approximately around 3cm².
• The pulmonary valve opens in the right ventricular systole allowing the deoxygenated blood to be delivered to the lungs.
• During the right ventricular diastole the pulmonary valves close completely to prevent regurgitation of blood into the right ventricle.

Pathogenesis

• Pulmonic valve stenosis can result from structural alterations resulting from congenital and acquired causes.

Prevention

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