Cardiology > Pulmonary Stenosis

  Background

Pulmonary stenosis (PS) is a narrowing of the right ventricular outflow tract (RVOT) at the level of the pulmonary valve or just above or below it, impeding blood flow from the right ventricle (RV) to the pulmonary artery. This obstruction increases RV pressure, causes hypertrophy, and may lead to right-sided heart failure if severe and untreated.

II) Classification or Types

By Anatomic Level:

• • Valvular (most common): Fusion or thickening of pulmonary valve leaflets.
  • Subvalvular (infundibular): Hypertrophy or fibromuscular narrowing below the valve.
  • Supravalvular: Narrowing of the main pulmonary artery above the valve.
  • Branch pulmonary artery stenosis: Involves right or left pulmonary artery branches.

By Onset and Progression:

• • Congenital PS: Most common, often isolated or part of complex congenital syndromes (e.g., Tetralogy of Fallot, Noonan syndrome).
  • Acquired PS: Rare, may result from carcinoid syndrome, rheumatic fever, or prior surgical repair.

By Severity (via echocardiographic Doppler gradient):

• • Mild: Peak gradient <36 mmHg
  • Moderate: 36–64 mmHg
  • Severe: >64 mmHg

III) Epidemiology

• • Age: Primarily a pediatric condition; diagnosed in infancy or childhood.
  • Sex: Slight female predominance in isolated congenital PS.
  • Geography: Global incidence; increased in regions with high rates of congenital heart disease.
  • Comorbidities: Associated with congenital syndromes (e.g., Noonan syndrome, Williams syndrome), other congenital heart defects, and maternal rubella infection during pregnancy.

  Etiology

I) Causes of Pulmonary Stenosis:

• • Congenital Valve Malformation (most common): Dysplastic, bicuspid, or domed pulmonary valve.

  • Noonan Syndrome: Genetic disorder often associated with dysplastic pulmonary valves.

  • Carcinoid Heart Disease: Serotonin-induced fibrosis affecting right-sided valves.

  • Rheumatic Heart Disease: Rare cause of acquired PS.

  • Post-Surgical or Post-Interventional Scar Tissue

II) Risk Factors

• • Family history of congenital heart disease

  • Genetic syndromes (e.g., Noonan, Alagille, Williams)

  • Maternal rubella or other teratogens during pregnancy

  • Carcinoid syndrome or metastatic tumors

  • Previous cardiac surgery or catheter-based interventions

   Clinical Presentation

I) History (Symptoms)

Mild PS: Often asymptomatic, discovered incidentally on auscultation or echocardiography.
 Moderate to Severe PS:

• • Exertional dyspnea or fatigue
  • Chest pain (rare)
  • Syncope or presyncope on exertion
  • Signs of right heart failure (edema, abdominal bloating)
    Infants/Neonates with Critical PS:
  • Cyanosis due to right-to-left shunting via patent foramen ovale or atrial septal defect
  • Poor feeding, lethargy

II) Physical Exam (Signs)

Vital Signs:

• • Often normal in mild cases
  • Hypoxemia or cyanosis in critical PS

Cardiac Exam:

• • Harsh systolic ejection murmur at left upper sternal border
  • Murmur intensity correlates with severity (louder in moderate cases, softer if severe with poor flow)
  • Systolic ejection click (valvular PS), decreases with inspiration
  • Right ventricular heave
  • Widely split second heart sound (delayed pulmonary closure)

Peripheral Signs:

• • Jugular venous distension

• • Peripheral edema (if RV failure develops)

Abdomen

• • Hepatomegaly

  Differential Diagnosis (DDx)

• • Atrial septal defect (ASD)

  • Tetralogy of Fallot

  • Pulmonary atresia

  • Tricuspid stenosis

  • Right ventricular outflow tract obstruction from other causes

  • Heart failure with preserved EF

  • Congenital syndromes with complex cardiac anomalies

   Diagnostic Tests

Initial Tests

Transthoracic Echocardiogram (TTE):

• • Diagnostic test of choice
  • Measures pressure gradient, valve morphology, RV size/thickness
  • Doppler flow across pulmonary valve

Electrocardiogram (ECG):

• • Right ventricular hypertrophy
  • Right axis deviation
  • Possible right atrial enlargement

Chest X-ray:

• • Prominent main pulmonary artery segment (post-stenotic dilation)
  • Normal or enlarged heart silhouette
  • Clear lung fields unless heart failure present

Cardiac MRI/CT:

• • Useful for detailed anatomy in complex cases
  • Evaluates branch pulmonary arteries and RV function

Cardiac Catheterization:

• • Confirms pressure gradient
  • Useful before surgical or interventional therapy

   Treatment

I) Medical Management

Asymptomatic Mild to Moderate PS:

• • Observation with periodic echocardiographic monitoring
  • No pharmacologic treatment needed if hemodynamically stable

Right Heart Failure (in advanced cases):

• • Diuretics for volume overload
  • Oxygen if hypoxemic

Critical PS in Neonates:

• • Prostaglandin E1 to maintain ductus arteriosus patency
  • Urgent balloon valvotomy

II) Interventional/Surgical

Balloon Pulmonary Valvuloplasty:

• • First-line treatment for isolated valvular PS (especially in children)
  • High success rate; avoids open surgery

Surgical Repair:

• • Indicated in dysplastic valves not amenable to balloon dilation
  • Also for supravalvular, subvalvular, or branch PS
  • May require valve replacement if severe or calcified

   Patient Education, Screening, Vaccines

• • Importance of regular follow-up with echocardiograms
  • Awareness of exercise limitations in moderate to severe PS
  • Educate on signs of right heart failure (edema, fatigue, dyspnea)
  • Endocarditis prophylaxis not routinely indicated unless prior endocarditis or prosthetic material
  • Encourage good dental hygiene

Vaccinations:

• • Influenza (annually)
  • Pneumococcal vaccine
  • COVID-19 vaccine
  • RSV prophylaxis in infants with significant congenital heart disease

   Consults/Referrals

• • Pediatric Cardiology: All children with congenital PS
  • Adult Congenital Heart Disease (ACHD) Specialist: For adolescents/adults with repaired or unrepaired PS
  • Cardiothoracic Surgery: For surgical intervention or complex congenital anatomy
  • Genetics: If syndromic features present (e.g., Noonan syndrome)
  • Pulmonology: If secondary pulmonary disease suspected

   Follow-Up

• • Mild PS: Echocardiogram every 3–5 years
  • Moderate PS: Annual to biennial echocardiograms
  • Severe or Repaired PS: Every 6–12 months, depending on symptoms and RV function
  • Monitor for:
    
    • RV hypertrophy or dysfunction
    • Progression of stenosis
    • Development of arrhythmias
  • Lifelong surveillance for those with congenital PS,  even after intervention