Pulmonary valve stenosis

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

Epidemiology

Pulmonary stenosis is nearly always (95%) congenital, and therefore primarily affects the pediatric 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 murmur is introduced by a systolic click ^1,2. Interestingly, while the murmur is louder on inspiration, the click is more pronounced on expiration due to the atrial kick prematurely opening the pulmonary valve thereby reducing the intensity of the click ^1,2. 

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

Pathology

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

Etiology

Isolated pulmonary stenosis is almost always congenital. Causes of congenital pulmonary stenosis 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 etiologies and associations are discussed in more depth in the article on congenital pulmonary stenosis.

In addition to congenital pulmonary stenosis, 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 tumors (generally not considered 'true' pulmonary stenosis)

Radiographic features

Plain radiograph

Signs of pulmonary stenosis on chest radiograph include ^2,3:

• right ventricular enlargement
• right atrial enlargement
• prominent pulmonary trunk
• enlargement of the left pulmonary artery: in valvular stenosis, the systolic jet of blood passing through the stenosed valve preferentially enters the left pulmonary artery, causing post stenotic dilatation (see case 8)
• 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 (see case 8)
• 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 pulmonary stenosis, depending on the underlying etiology (e.g. in the tetralogy of Fallot) ⁴.

Various parameters are used in order to determine the severity of pulmonary stenosis, 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 demonstrates 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 pulmonary stenosis is based on its severity. Management involves pharmacotherapy measures (especially diuretics) and consideration of surgery ¹. Details of this management are beyond the scope of this article.

Complications

• congestive heart failure

See also

• valvular heart disease
• general pulmonary valve pathologies:
  • pulmonary valve stenosis
  • pulmonary valve regurgitation
• specific pulmonary valve pathologies:
  • congenital pulmonary valve stenosis
  • pulmonary valve atresia
  • tetralogy of Fallot