Pulmonary stenosis
Stenosis (narrowing of a valve) means that that the valve is unable to open fully.

Pulmonary stenosis is narrowing of the pulmonary semi-lunar valve. This is due to the fusion of the valve cusps; the valve forms a dome with a central opening (valvular). It can also be supravalvular or subvalvular ( a membrane or ridge forms, occluding the valve).

Infundibular pulmonary stenosis occurs when the conus arteriosus (the part of the right ventricle leading to the valve) is underdeveloped.

Pulmonary stenosis is usually a congential defect, but it can also result from rheumatic fever (which causes the cusps of the valve to fuse together) or from carcinoid syndrome (which is an array of symptoms occurring secondary to the carcinoid/neruoendorcrine tumour (tumour of the enterochromaffin cells in your small intestine)– causes flushing, diarrhoea, bronchoconstriction. I couldn’t really find anything that said what exactly it did to the valve, but basically, it makes them stick together).

Symptoms and signs
· Restricted right ventricular outflow, can lead to hypertrophy of the right ventricle à this, in turn, leads to right atrial hypertrophy
· Pulmonary obstruction
o Syncope
o Fatigue
o Symptoms of right heart failure
§ fatigue
§ breathlessness
§ anorexia
§ nausea
· Mid-systolic ejection murmur
o Best heard on inspiration
o Left of sternum, 2nd intercostals space
o Is often associated with a thrill
· Pulmonary closure sound – delayed and soft
· Pulmonary ejection sound – if obstruction is valvular
· Right ventricular heave (sustained impulse) can be felt
· Mild pulmonary stenosis – asymptomatic
· Moderately severe stenosis
o Right ventricular fourth sound
o Prominent jugular venous a-wave
Investigations
· Chest x-ray
o Prominent pulmonary artery – post-stenotic dilation
· ECG
o Shows right ventricular and atrial hypertrophy
o Can be normal
· Echocardiogram
o Doppler investigation – utilises echoes from tissue surfaces, and on amplification, can detect the echoes from RBCs
§ If blood is moving in the same direction as the ultrasound beam, the frequency of the returning echoes is changed according to the Doppler effect (Doppler Effect is the shift in frequency and wavelength of waves which results from a source moving with respect to the medium, a receiver moving with respect to the medium, or even a moving medium. If you want to see pretty moving diagrams, go to: http://www.kettering.edu/~drussell/Demos/doppler/doppler.html)
§ Shift in Doppler frequency is directly proportional to blood velocity
· Cardiac catherisation
o Catheter into right heart – level and degree of stenosis can be established by measuring systolic pressure gradient

Treatment
- Pulmonary valvotomy
o Balloon valvotomy
o Direct surgery