Key Facts

Pulmonary stenosis (PS) is obstruction to right ventricular outflow, most commonly at the valvular level. It is predominantly congenital and accounts for approximately 10% of all congenital heart defects.

Epidemiology

• ~10% of all congenital heart disease
• Valvular PS is most common form (~90%)
• Equally affects males and females
• Usually diagnosed in childhood or incidentally in adulthood

Aetiology

• Congenital valvular PS (most common): dome-shaped valve with fused commissures
• Dysplastic valve: thickened, immobile leaflets (associated with Noonan syndrome — less responsive to balloon valvuloplasty)
• Infundibular (subvalvular): muscular obstruction in RVOT
• Supravalvular: pulmonary artery stenosis (associated with Williams syndrome, Alagille syndrome, rubella)
• Acquired: carcinoid syndrome, external compression (tumour)

Pathophysiology

• Obstruction increases RV afterload → RV concentric hypertrophy → maintained cardiac output initially
• With progressive stenosis: RV compliance falls → elevated RA pressure → right heart failure
• Severe PS may cause right-to-left shunting via patent foramen ovale → cyanosis
• Post-stenotic dilatation of the main pulmonary artery is common even in mild PS

Typical Presentation

• Mild-moderate: usually asymptomatic; murmur found incidentally
• Severe: exertional dyspnoea, fatigue, chest pain, syncope (fixed cardiac output)
• Right heart failure in advanced cases: peripheral oedema, hepatomegaly, ascites

Examination Findings

• Ejection systolic murmur at left upper sternal edge, radiating to the back
• Widely split S2 with soft or absent P2 (reduced valve mobility)
• Ejection click (may decrease with inspiration — opposite to most right-sided phenomena)
• RV heave if significant hypertrophy
• Prominent 'a' wave in JVP (forceful RA contraction against stiff RV)

Red Flags

• Exertional syncope (severe obstruction)
• Cyanosis (right-to-left shunt via PFO)
• Signs of right heart failure
• Progression of gradient on serial echocardiography

Bedside

• ECG: RAD, RVH (tall R in V1, deep S in V5-V6), P pulmonale, RBBB in severe cases
• CXR: post-stenotic dilatation of pulmonary artery, oligaemic lung fields in severe PS

Bloods

• BNP/NT-proBNP: if right heart failure suspected
• Routine bloods: FBC, U&Es

Imaging

• Echocardiography: valve morphology, peak gradient across PV, RV hypertrophy, RV function, associated defects
• Cardiac MRI: RV volumes, function, RVOT anatomy (especially if subvalvular or supravalvular)

Severity Grading

Special Tests

• Cardiac catheterisation: direct gradient measurement; pre-interventional
• Genetic testing: if Noonan syndrome suspected (PTPN11, RAS pathway genes)

Non-pharmacological

• Mild PS: no treatment needed; reassurance and periodic monitoring (echo every 3-5 years)
• Moderate PS: echo monitoring annually; intervention if symptoms or gradient increases
• No exercise restriction for mild-moderate PS

Pharmacological

• No medical therapy alters natural history of PS
• Diuretics for right heart failure symptoms
• Endocarditis prophylaxis: not routinely recommended (only if prior endocarditis)

Surgical/Interventional

• Percutaneous balloon pulmonary valvuloplasty: treatment of choice for typical valvular PS
  • Indicated when peak gradient >60 mmHg (even if asymptomatic) or >40 mmHg with symptoms
  • Success rate >90%; low complication rate
  • Less effective for dysplastic valves (Noonan syndrome)
• Surgical valvotomy/valvectomy: if balloon valvuloplasty fails or dysplastic valve
• RVOT reconstruction: for infundibular stenosis
• Pulmonary valve replacement: for severe PR following previous intervention

Referral Criteria

• Severe PS (gradient >60 mmHg): cardiology referral for intervention
• Symptomatic moderate PS: specialist assessment
• Noonan syndrome features: genetics referral

• Mild PS: excellent prognosis; normal life expectancy; rarely progresses
• Moderate PS: generally good; may require intervention if gradient increases
• Severe PS: without treatment, symptoms progress; excellent outcomes post-valvuloplasty
• Post-balloon valvuloplasty: gradient reduced by >50% in >90%; long-term results excellent
• Late complication: pulmonary regurgitation post-intervention (may eventually require PVR)
• Noonan syndrome with dysplastic PS: higher rate of re-intervention

Associated Syndromes

Comparison of Right-Sided Systolic Murmurs