Pulmonary valve stenosis

Pulmonary valve stenosis (PS), or pulmonic valve stenosis, is a valvulopathy that describes narrowing of the opening of the pulmonary valve between the pulmonary trunk and the right ventricle.

Epidemiology

PS is nearly always (95%) congenital, and therefore primarily affects the paediatric demographic ¹.

Clinical presentation

Clinical examination classically reveals an elevated jugular venous pressure with a dominant a-wave, and a mid-systolic (ejection systolic) murmur that is heard on praecordial auscultation ^1,2. Often, the mumur is introduced by a systolic click^1,2. Interestingly, while the murmur is louder on inspiration, the click is more pronounced on inspirationexpiration due to the atrial kick prematurely opening the pulmonary valve thereby reducing the intensity of the click ^1,2. 

In severe cases, patients with PS may also have right-predominant clinical features of heart failure such as hepatomegaly, ascites, and anasarca ^1,2.

Pathology

The characteristic haemodynamic feature of PS is an increased systolic pressure gradient between the pulmonary artery and the right ventricle ^1,2. This leads to development of right ventricular hypertrophy and right ventricular dilation, and eventually there is a decrease in cardiac output ^1,2. 

Aetiology

Causes of congenital PS are protean (e.g. Noonan syndrome, Williams syndrome, tetralogy of Fallot, etc.), and can be classified as being either supravalvular (most common), valvular, or subvalvular ^1,2. These congenital aetiologies and associations are discussed in more depth in the article on congenital PS.

In addition to congenital PS, there are other rare (5%) acquired valvular causes which can present in adulthood ^1,2:

• carcinoid heart disease (most common acquired cause, always present with pulmonary regurgitation)
• rheumatic heart disease
• nonbacterial thrombotic endocarditis
• infective endocarditis
• cardiac tumours (generally not considered 'true' PS)

Radiographic features

Plain radiograph

Signs of PS on chest radiograph include ^2,3:

• right ventricular enlargement
• right atrial enlargement
• prominent main pulmonary atrey
• Chen sign: vascular fullness at the left lung base more-so than the right lung base due to preferential flow of turbulent jet into the left pulmonary artery
• rarely, calcifications of the pulmonary valve may be seen
• features of congestive heart failure may also be present

Ultrasound: echocardiography

Echocardiography is useful for assessing the pulmonary valve, jet velocity, pressure gradients, and the right-sided chambers of the heart ⁴. It can be used in a more holistic sense to detect additional associated lesions which may accompany congenital PS, depending on the underlying aetiology (e.g. in the tetralogy of Fallot) ⁴.

Various parameters are used in order to determine severity of PS, such as ⁴:

• mild
  • peak velocity <3 m/s
  • peak gradient <36 mmHg
  • right ventricular systolic pressure 25-49 mmHg
  • transvalvular pressure gradient 50-74 mmHg
• moderate
  • peak velocity 3-4 m/s
  • peak gradient 36-64 mmHg
  • right ventricular systolic pressure 50-79 mmHg
  • transvalvular pressure gradient 75-100 mmHg
• severe
  • peak velocity >4 m/s
  • peak gradient >64 mmHg
  • right ventricular systolic pressure >80 mmHg
  • transvalvular pressure gradient >100 mmHg

Additionally, echocardiography can determine whether the pathology is supravalvular (most common), valvular, or subvalvular ⁴. In valvular causes, the pulmonary valve is characteristically dome-shaped with a narrow opening ⁴. There may be fusion of leaflets in adult patients ⁴.

CT/MRI

Cross-sectional imaging demonstrate the same radiographic features appreciated on plain film and echocardiography, but in greater detail ^5,6. In particular, cardiac MRI may be particularly useful for accurate measurements to assess the severity of the valvulopathy ^5,6.

Treatment and prognosis

The decision to treat PS is based on its severity. Management involves pharmacotherapy measures (especially diuretics) and consideration of surgery ¹. Details of this management is beyond the scope of this article.

See also

• congenital pulmonary stenosis
• pulmonary atresia