Pulmonary Stenosis

Question 1

Sites of pulmonary stenosis?

Answer 1

• Valvular (most common)
• Sub-pulmonary (aka infundibular, below valve in RVOT)
• Supravalvular (above valve in MPA)
• Branch/peripheral PS

Question 2

What are the three morphological types of congenital valvular PS?

Answer 2

1. Dome-shaped pulmonary valve (most common)
2. Dysplastic pulmonary valve
3. Unicuspid or bicuspid pulmonary valve

Question 3

Characteristics of dome-shaped PV?

Answer 3

• Characterised by preserved valve mobility with a narrowed central opening caused by two or four rudimentary raphes
• Most common type of PS

Question 4

Characteristics of dysplastic PV?

Answer 4

• Valve is trileaflet with severely thickened and deformed leaflets
• Valve mobility is poor
• Frequently associated with Noonan syndrome

Question 5

Characteristics of unicuspid/bicuspid PV?

Answer 5

• Fusion between commissures of pulmonary leaflets
• Unicuspid valves may be acommissural or unicommissural
• Bicuspid pulmonary valves frequently found in patients with Tetralogy of Fallot

Question 6

Characteristics of acommissural unicuspid PV?

Answer 6

Central office and no apparent commissural attachment to pulmonary root

Question 7

Characteristics of unicommissural unicuspid PV?

Answer 7

Eccentric orifice with one commissural attachment to pulmonary root

Question 8

Can you have significant PS in the absence of PV leaflet thickening?

Answer 8

• Yes
• Congenital PS most commonly occurs due to dysplasia of the leaflets - means leaflets are deformed and immobile

Question 9

When can a bicuspid pulmonary valve be diagnosed?

Answer 9

• Can only be diagnosed when valve is seen in short axis (i.e. transposition of the great arteries)
• PV is in position of AV so can be seen in short axis

Question 10

What is post-stenotic dilatation in PS?

Answer 10

• Dilatation of MPA post valve often occurs with PS; indicates weakening of the arterial wall
• Can occur with mild PS so not indicative of degree of stenosis

Question 11

Clue to peripheral (branch) PS?

Answer 11

• Layered CW Doppler signal
• Stronger lower velocity = PV
• Weaker signal = branch stenosis
• May also see turbulent flow with CFI

Question 12

How to assess severity of PS?

Answer 12

Maximum and mean pressure gradients on CW Doppler

Question 13

Velocities and pressure gradients in mild PS?

Answer 13

• Peak velocity < 3m/s
• Maximum pressure gradient < 36mmHg

Question 14

Velocities and pressure gradients in moderate PS?

Answer 14

• Peak velocity 3 - 4m/s
• Maximum pressure gradient 36 - 64mmHg

Question 15

Velocities and pressure gradients in severe PS?

Answer 15

• Peak velocity > 4m/s
• Maximum pressure gradient > 64mmHg

Question 16

When may there be increased velocities across the PV in the absence of PS?

Answer 16

• ASD
• VSD
• Significant PR

Question 17

How to measure PV annulus size?

Answer 17

• Best zoomed PLAX or PSAX of RVOT
• CFI may be useful in delineating lateral border to RVOT

Question 18

Size of PV annulus in balloon pulmonary valvuloplasty?

Answer 18

• Procedure of choice for patients with symptomatic or congenital severe PS is balloon pulmonary valvuloplasty
• For balloon size, PV annulus needs to be measured prior to procedure

Question 19

RVSP/PASP in PS?

Answer 19

• When RVOT obstruction, RVSP ≠ PASP
• RVSP > PASP
• PASP is equal to RVSP minus the Doppler parameter which best correlates to the peak-to-peak gradient

Question 20

Formula to calculate PASP in most cases?

Answer 20

• PASP = RVSP - mPG
• Subtract mean pressure gradient across the PV

Question 21

Formula for PASP in ‘very-severe’ PS?

Answer 21

• PASP = RVSP - MIPG
• Subtract maximum instantaneous pressure gradient across PV

Question 22

CW Doppler signal: Mild PS?

Answer 22

• V-shaped
• Peaks in early systole
• Reflects gradual rise in PAP over systole

Question 23

CW Doppler signal: Very Severe PS?

Answer 23

• Rounded-shape
• Peaks mid systole
• Occurs due to flattening of pulmonary pressure trace