Causes: almost always congenital. The normal PV is trileaflet. The congenitally stenotic
valve may be trileaflet, bicuspid, unicuspid, or dysplastic. Acquired stenosis of the PV is very
uncommon. Rheumatic PS is rare even when the valve is affected by the rheumatic process.
Carcinoid disease is the commonest cause of acquired PV disease (combined stenosis and
regurgitation with usually predominant regurgitation).
Part of more complex congenital lesions such as tetralogy of Fallot, complete AV
canal, double outlet RV, and univentricular heart. Peripheral pulmonary artery stenosis
may co-exist with valvular pulmonary stenosis such as in Noonan’s sd and Williams sd.
Stenosis below (proximal to) the PV may result from: Congenital VSD may also be
associated with RVOT obstruction secondary to development of obstructive midcavitary or
infundibular muscle bundles (double chamber RV) or in rare cases as a result of the jet
lesion produced by the VSD in this area. Severe RVH of any cause but in some cases
caused by valvular pulmonary stenosis itself may be responsible for narrowing of the
infundibular area below the pulmonary valve. Other causes include hypertrophic or infiltrative
processes such as HOCM or glycogen storage disorders and compression from a
tumour or vascular structure.
Stenosis of the pulmonary artery above the valve (distal to the valve) may occur in the
main pulmonary trunk at the bifurcation, or more distally in the branch vessels. In rare cases,
a membrane just above the valve may cause stenosis. Pulmonary artery stenosis may
occur as an isolated finding without other malformations.
(CWD - PSSA)The estimation of the systolic pressure gradient is derived from the transpulmonary
velocity flow curve using the simplified Bernoulli equation:
In most instances of valvular pulmonary stenosis, the modified
Bernoulli equation works well and there is no need to account for the
proximal velocity as this is usually, 1 m/s. There are exceptions to this,
however. In the setting of subvalvular or infundibular stenosis and
pulmonary stenosis as part of a congenital syndrome or as a result of
RV hypertrophy, the presence of two stenoses in series may make it
impossible to ascertain precisely the individual contribution of each.
In addition, such stenoses in series may cause significant PR resulting
in a higher Doppler gradient compared with the net pressure drop
across both stenoses. PWD Pulsed-wave Doppler may be useful to
detect the sites of varying levels of obstruction in the outflow tract and
in lesser degrees of obstruction may allow a full evaluation of it.
Muscular infundibular obstruction is frequently characterized by a
late peaking systolic jet that appears ‘dagger shaped’, reflecting the
dynamic nature of the obstruction; this pattern can be useful is
separating dynamic muscular obstruction from fixed valvular obstruction,
where the peak velocity is generated early in systole.
Measurement of RVSP from TR jet. PASP = RVSP - PV pressure gdt (1)
The failure of the measured pulmonary valve gradient to account for much of the RVSP may be a
clue for the presence of alternative stenoses.
The size of the pulmonary annulus should be measured in order to define the optimal balloon
size for successful dilatation of the valve
The normal thickness of the RV is 2–3 mm but given the difficulties in estimating thickness, a
thickness of 5mm is usually considered abnormal. RV enlargement is typically assessed in the apical
or subcostal four-chamber view