Pulmonary stenosis

 Pulmonary stenosis

Pulmonary stenosis is also known as Pulmonary valve stenosis.

Narrowing of pulmonary valve which controls the outflow of blood from right ventricle to pulmonary artery.

Obstructive lesions that interferes with blood outflow from right ventricle.

Types of pulmonary stenosis

1. Subvalvular 

Stenosis occurs below pulmonary valve in infundibular area.

2. Valvular 

Occurs pulmonary valve level

3. Supravalvular 

Present above pulmonary valve.

Pathophysiology

Vary in degree from mild to severe.

Involve malformation of cusps of pulmonary valve that controls flow of blood from right ventricle into pulmonary artery.

Obstruction increases, right ventricular hypertrophy increases

Thickening of right ventricular wall ( hypertrophy) develops.

If right ventricular hypertrophy severe 

Critical pulmonary stenosis, right atrial pressure can increases, resulting in right to left shunting through foramen ovale. 

When obstruction is at valvular level, jetting of blood through stenotic valve, which dilates main pulmonary artery.

Infundibular or subvalvular stenosis occur alone or in conjunction with valvular stenosis.

Supravalvular pulmonary stenosis isolated constriction involving - 

Main pulmonary artery

Left and right pulmonary artery

Smaller peripheral arterial branches.

Clinical features

Depend upon degree of obstruction

Majority asymptomatic

Symptoms of severe stenosis

1. Poor excercise tolerance

2. Exertional dyspnea, due to poor or insufficient blood flow to lungs.

3. Fatigability

4. Strenuous exercise; result in syncope or sudden death

5. With critical pulmonary stenosis

Right ventricular failure occurs - early in infancy, untill ductus arteriosus is patent, allow some pulmonary blood flow.

But it closes- symptoms of pulmonary stenosis increase.

Diagnostic Evaluation

1. Cardiac Examination

Auscultation systolic ejection murmur heard.

Ejection click heared

2. Electrocardiogram

Mild to moderate pulmonary stenosis, ECG normal or show right ventricular hypertrophy.

In severe pulmonary stenosis - ECG shows right ventricular hypertrophy and right atrial enlargement.

3. Chest radiograph

Chest X rays shows right ventricular hypertrophy and post stenotic dilatation of pulmonary artery.

4. Echocardiogram

Color flow 2D echo

Demonstrate size of right ventricle and outflow tract - level of obstruction visualized

Therapeutic Management

1. Child with mild to moderate pulmonary stenosis- need no treatment

2. In severe stenosis pulmonary

1. Balloon valvuloplasty

When right ventricular pressure exceeds left ventricular pressure, pulmonary stenosis is severe or critical.

2. In newborn infants PGE1 infusion - given to maintain patency if ductus arteriosus, allowing adequate pulmonary blood flow untill relief of obstruction.

3. If valve annulus

Ring of tissue to which leaflets of pulmonary valve attached, incision into annulus. And patch is used to inlarge annulus.

4. If infundibular stenosis present 

Resection of hypertrophied muscle.

Pericardial or Dacron patch is used to widen the outflow tract.

5. If supravalvular stenosis 

Area of obstruction incised and patch graft inserted to widen the area.