Pulmonic Stenosis is a congenital disorder characterized by a narrowing of the right ventricular outflow tract or defect of the pulmonary valve that leads to decreased blood flow from the right ventricle into the pulmonary artery.
Pulmonic stenosis can occur at three locations: valvular, subvalvular, supravalvular.
In valvular pulmonic stenosis, the trileaflet valve is present with varying degrees of fibrous thickening and fusion of commissures. There is primary and secondary valvular pulmonic stenosis. Unlike the aortic valve, calcification of the pulmonary valve is rare.
Primary valvular pulmonic stenosis can be associated with congenital heart defects such as tetralogy of Fallot, congenital rubella syndrome and Noonan syndrome.
Secondary valvular pulmonic stenosis is much less common than primary (congenital) pulmonic stenosis, and can be due to carcinoid syndrome, in which case it is frequently accompanied by tricuspid regurgitation (TIPS for tricuspid insufficiency and pulmonic stenosis).
Subvalvular pulmonic stenosis results in limited blood flow through the right ventricular outflow tract due to fibromuscular hypertrophy below the pulmonary valve.
Supravalvular pulmonic stenosis results in decreased blood flow to the lungs due to areas of narrowing within the pulmonary artery or its branches.
Patients with pulmonic stenosis typically present with dyspnea on exertion, fatigue, and cyanosis in severe cases.
Physical examination of a patient with pulmonic stenosis may reveal the following:
In newborns, increased right ventricular pressures can cause right-to-left shunting through a patent foramen ovale or ventricular septal defect causing cyanosis.
Asymptomatic patients in childhood can present later in life with signs and symptoms of right heart failure due to untreated pulmonic stenosis.
A transesophageal echocardiogram and doppler study confirms the diagnosis of pulmonic stenosis.
A transesophageal echocardiogram will reveal the outflow obstruction, right ventricular hypertrophy, and systolic doming of the valve due to decreased movement during systole.
A doppler will allow for assessment of decreased blood flow across the obstruction.
Prolonged untreated pulmonic stenosis may result in right sided heart failure.
Right sided heart failure is due to the progressive weakening of the right ventricle caused byincreased ventricular pressures. The weakening of the right ventricle leads to fluid backup throughout the venous and portal system.
Treatment of pulmonic stenosis consists of balloon valvotomy to widen the outflow tract from the right ventricle into the pulmonary artery.
Surgery is indicated over balloon valvotomy when pulmonic stenosis is caused by a dysplastic pulmonary valve.
Neonates with severe stenosis may require a patent ductus arteriosus to maintain oxygenation. This is achieved with synthetic prostaglandin E1, such as alprostadil.