Pulmonary Stenosis Flashcards
What views can be used to visualise the pulmonary valve?
- PLAX of RVOT
- PSAX of RVOT
- Apical with marked anterior tilting (past A5C - only achieved in patients with good windows)
- Subcostal 4 chamber with marked anterior tilting
- Subcostal SAX
What are the three PV leaflets?
- Right pvl
- Anterior pvl
- Left pvl
Which PV leaflets are seen from PLAX of RVOT?
Right and anterior
Which PV leaflets are seen from PSAX of RVOT?
Right and anterior (same as PLAX)
Which PV leaflets are seen from the apical window?
Right and left are likely to be seen
Which PV leaflets are seen from subcostal 4 chamber?
Right and left (same as apical)
Which PV leaflets are seen from subcostal SAX?
Right and anterior (same as PSAX)
Common causes of pulmonary stenosis?
- Congenital (site important)
- Rheumatic (rare)
- Carcinoid valve disease
- Extrinsic (tumours, sinus of Valsalva aneurysm)
- Scarring (post removal of PA banding)
Sites of Congenital PS?
- Valvular
- Subvalvular (RVOT) - aka subpulmonary/infundibular
- Supravalvular (MPA)
- Peripheral (branch) => pulmonary arteries
What are the anatomical features of congenital PS?
- Valve dysplasia: leaflets are deformed and immobile
- Domed - fixed central orifice (unicuspid): often won’t see leaflet thickening but will see leaflet doming
- Bicuspid pulmonary valve
- Hypoplastic annulus
- Fusion along free edge of leaflet
Carcinoid valve disease in PS/PV obstruction?
- Thickened leaflets with poor systolic mobility
- Fixed open position throughout cardiac cycle
Right sinus of Valsalva aneurysm in PS/PV obstruction?
Right side of aorta aneurysm protruding into RVOT => obstruction to flow
Scarring post removal of PA banding in PS/PV obstruction?
- Residual scarring can result in PS
- PA banding is used to prevent excessive pulmonary flow and hypertrophy thereforePA banding causes functional PS => PA debanding = flow no longer obstructed
Parameters used to assess PS severity?
- Maximum pressure gradient
- Mean pressure gradient
- Size of pulmonary annulus
Peak velocity and maximum pressure gradient in severe PS?
- Peak velocity > 4m/s
- Max. PG > 64mmHg
Peak velocity and maximum pressure gradient in moderate PS?
- Peak velocity 3-4m/s
- Max. PG 36-64mmHg
Peak velocity and maximum pressure gradient in mild PS?
- Peak velocity < 3m/s
- Max. PG < 36mmHg
Reasons for increased pressure gradients without PS?
- Atrial septal defects
- Ventricular septal defects
- Significant PR
In these situations, there is increased flow across the right heart which will increase velocities and pressure gradient across the PV in the absence of PS
How does RVH occur as a response to PS?
Response to chronic RV pressure overload which occurs with significant PS => leads to development of concentric RVH
Assessing RV wall thickness with echo
- Normal wall thickness 2-3mm
- RVH when thickness > 5mm
- Can be assessed in m-mode or 2D, subcostal view most accurate
- Measure at peak R wave at tip of atvl
Limitations of RVH measurement?
- RV wall thickness in apical and parasternal views is not recommended
- Limitations of parasternal views:
1. Reverberation artefacts common
2. Echogenicity of chest wall and anterior RV similar - Limitations of apical views: Measured in lateral plane (poorer resolution than axial resolution)
What is post-stenotic dilatation?
- Dilatation due to weakening in arterial wall
- Can only occur in mild PS
RVSP in patients with PS?
- RVSP cannot be normal in patients with PS; if PS, RVSP should be elevated as higher pressure required in RV to overcome stenosis
- If RVSP is very elevated, cannot state from this information alone if patient has PS
- Elevated RVSP as well as turbulent flow across PV and MPA means the elevated RVSP is likely due to PS or RVOTOB
Cases where RVSP may be increased?
- Pulmonary stenosis/RVOTOB
2. Pulmonary hypertension
When does RVSP ≠ PASP?
- When RVOTOB or PS
- In RVOTOB/PS, RVSP must be > PASP as blood flows from a higher to lower pressure area
Formula to calculate PASP in most patients (patients with mild to moderate RVOTOB)?
PASP = RVSP - mean pressure gradient across PV
Formula to calculate PASP in patients with very severe RVOTOB/PS?
PASP = RVSP - maximum pressure gradient across PV
What is ‘very severe’ PS?
- Mild PS: V-shaped, velocity peaks early systole
- Very severe PS: rounded shape, velocity peaks mid systole
- Round PS signal & max pressure gradient > 64mmHg = very severe PS
How to measure PV annulus?
- Balloon pulmonary valvuloplasty for PV repair in PS
- Need to determine optimal balloon size and measure annulus
- Measurement best achieved from zoomed view of RVOT from PSAX
- PV annulus measured during systole at maximal opening
- CFI may be useful to determine boarders
