Valves
Valves
Valvular assessment
FUSIC HD similar to BSE level 1 aims to assess the aortic, mitral and tricuspid valves for any significant problems that could be causing haemodynamic instability.
The main basic ways to do this are with visual assessment and colour flow doppler assessment.
Within the FUSIC HD curriculum spectral doppler is used for assessment of the aortic valve and this is also covered below.
Values will be given to help grade severity below but this is not part of the FUSIC HD scan, but hopefully will be useful to help distinguish normal and significantly abnormal valves.
General approach to valvular assessment
The key components to the assessment of valves are:
- Visual assessment
- Colour flow doppler
- Spectral doppler across aortic valve
Visual
Perform 2D visual assessment of aortic, mitral and tricuspid valves from all available views, assessing for:
- Thickness, calcification, mobility
- Forward/backward flow through the valve – looking at valve opening/restriction during systole and valve closure during end-systole/diastole.
- Any flail or prolapse?
- Any masses adherent to the valve?
- Any destruction of the valve?
Colour doppler
Assess valves with colour flow doppler, looking for regurgitation.
Ensure that the echo beam plane is fanned through the whole of the valve in each view. This will help determine where the regurgitation is maximal.
Considerations:
- Box size – should cover the whole of the valve and the chamber which the regurgitant jet flows into
- Nyquist limit – assessing regurgitation should be set to 50-70cm/s
- Vena contracta – size is proportional to size of regurgitant orifice
- Flow convergence and jet area – both represent regurgitant volume
Cautions
- Eccentric regurgitant jets into chamber walls will have reduced velocity and look less severe.
- Haemodynamic instability will affect the pressure gradient across valves – e.g. low systolic BP will lead to reduced velocity of mitral regurgitation (if present) leading to underestimation.
A3Ch view assessing mitral valve regurgitation
Note the nyquist limit in the top right of the image set at 54.2 cm/s.
Images:
Nyquist limit example
Vena contracta
Flow convergence and jet area
Normal valves visual and colour
Fanning through valves
How different views may look more or less severe because of the angle of blood flow against the probe.
Spectral doppler
Only used on the aortic valve in FUSIC HD.
- Peak velocity is measured using continuous wave (CW) doppler through the aortic valve – this can be used to grade severity
- Dimensionless index can also be calculated
Cautions
- Can underestimate peak velocity if incorrectly aligned (note cannot overestimate)
- Large angle between US beam and the direction of blood flow will also underestimate velocity (particularly >20 degrees)
Valvular assessment
- FUSIC heart clinical questions:
- FUSIC heart clinical questions:
- FUSIC heart clinical questions:
Aortic valve assessment
Views
Aortic valve assessment should take place in all views in which the aortic valve is seen. The best views are:
- PLAX
- PSAX – aortic valve level
- A5Ch
- A3Ch
Anatomy of aortic valve
INSERT VIEWS OF normal AV in all views
PLAX, PSAX AV, A5Ch A3Ch
Aortic Stenosis
Abnormalities of aortic valve
- Calcific
- Bicuspid aortic valve
- Rheumatic
Visualisation of the valves thickness, mobility and calcification is important.
Clinical features of severe aortic stenosis
- Syncope
- Angina
- Dyspnoea
Echo assessment aortic stenosis
- Visual
- Thickened/calcified aortic valve leaflets
- Reduced mobility of valve
- Reduced leaflet opening
- Colour flow doppler
- Increased flow velocity/turbulent flow
- At the valve level and downstream
- CW doppler of AV
Other echo features in severe AS
- Look for aortic regurgitation and other valvular abnormalities
- Look for evidence of left ventricular hypertrophy
- Look for aortic root dilatation
PLAX view - Aortic valve thickened, calcified with restricted opening. Visually severe aortic stenosis.
PSAX AV level - zoomed in on aortic valve - showing severely calcified trileaflet aortic valve
Spectral doppler assessment of aortic valve
CW doppler across aortic valve
The best alignment of the CW doppler is in the A5Ch and A3Ch views. The doppler is placed through the line of the LVOT and AV and a sample is taken.
The baseline needs to be moved up on the screen so that the doppler trace below the line can be seen and the scale may need to be adjusted.
Care needs to be taken when aligning the CW doppler sample line as if it is slightly off it will underestimate the actual velocities across the AV.
Peak velocity (Vmax)
Look at the shape of the doppler and measure on the ultrasound machine the peak of the doppler trace. This will give you the Vmax value in m/s.
>4m/s is indicative of severe aortic stenosis.
This is a flow dependent parameter so can be underestimated in low flow states.
Dimensionless index (DI)
On the doppler trace from the CW through the AV it is sometimes possible to see two traces. The large one from the aortic valve and a smaller on inside the doppler trace which is from the LVOT.
Trace around both the AV and the LVOT doppler signals to obtain the velocity time integral (VTI).
The continuity equation is one way to work our aortic valve cross sectional area (CSA).
LVOT VTI x LVOT CSA = AV VTI x AV CSA
Rearranged to:
AV CSA = (LVOT VTI x LVOT CSA)/AV LVOT
This gives a value in cm², however, inaccuracies in measuring the LVOT diameter can lead to significantly inaccurate results. This is because the diameter needs to be converted to the cross sectional area using πr². So any inaccurate measurements are squared.
The continuity equation shows us how the LVOT VTI and AV VTI are related to the AV and can be used to give a ratio if the LVOT CSA is removed from the equation. This ratio is known as the dimensionless index and the equation is:
AV dimensionless index = LVOT VTI/AV VTI ratio
<0.25 indicates severe aortic stenosis
Clinically, instead of using VTI ratio (LVOT VTI/AV VTI), the velocities can be used instead as their ratios are nearly identical. Therefore:
AV dimensionless index = LVOT Vmax / AV Vmax
The dimensionless index has it’s advantages because it is less flow dependent than AV Vmax and it is less affected by the angle of the spectral doppler to flow across the aortic valve.
CW doppler through the aortic valve - Vmax is about 4m/s indicating severe aortic stenosis. It is possible to visualise the smaller LVOT VTI trace within the AV VTI trace. The LVOT Vmax is visually about 1m/s. This would give a DI = 1/4 = 0.25
References for severe aortic stenosis
Visual
Heavily thickened & calcified
Severely restricted opening
Colour
Turbulent flow
At the valve level and downstream
CW Vmax
>4m/s
Dimensionless index
<0.25
Aortic Regurgitation
Echo assessment aortic regurgitation
- Visual
- Valve prolapse?
- Vegetations consistent with infective endocarditis?
- Aortic root dilatation or dissection flap?
- Colour flow doppler
- Jet extension back into LV – not a reliable marker of severity
- Width of Jet in LVOT (within 1cm of AV)
- Vena contracta width (narrowest region of colour flow at AV level)
Other echo features in aortic regurgitation
- Look for aortic stenosis and other valvular abnormalities
- Look for evidence of left ventricular dilatation
- Look for aortic root dilatation
- VC width >0.6cm is severe
- This cannot be measured if more than one regurgitant jet
- Jet width ratio with LVOT >65% is severe
- This is misleading in eccentric jets
For the FUSIC HD curriculum measurements of the vena contracta or jet width ratio with the LVOT are not expected, but these values help to give an idea of what severe aortic regurgitation may look like visually.
Aortic Root
Aortic root can be measured in the PLAX view . This is covered in the aorta section of FUSIC HD.
Measurement of proximal ascending aorta:
- Inner edge to inner edge
- End diastole
- 1cm above the sino-tubular junction
A value >40mm indicates dilated proximal ascending aorta
Mitral valve assessment
Views
Mitral valve assessment should take place in all views in which the mitral valve is seen. The best views are:
- PLAX
- PSAX – mitral valve level
- A4Ch
- A3Ch
- A2Ch
Anatomy of mitral valve
There are two papillary muscles:
- Posteromedial papillary muscle – attached to mid-inferior LV wall
- Anterolateral papillary muscle – attached to mid-anterolateral LV wall
The papillary muscles attach to the mitral valve via the chordae tendinae, and each papillary muscle supplies chordae that attach to both mitral valve leaflets.
Mitral Stenosis
Abnormalities of mitral valve
- Mitral annular calcification
- Rheumatic
Visualisation of the valves thickness, mobility and calcification is important.
Echo assessment mitral stenosis
- Visual
- Thickened/calcified aortic valve leaflets
- Reduced mobility of valve
- Reduced leaflet opening
- Colour flow doppler
- Increased flow velocity/turbulent flow
- At the valve level and downstream
Other echo features in severe mitral stenosis
- Dilated LA +/- spontaneous echo contrast
- AF
- Pulmonary hypertension
- RV dilatation or dysfunction
- Tricuspid regurgitation
Mitral Regurgitation
Echo assessment mitral regurgitation
- Visual
- Valve prolapse or flail?
- Vegetations consistent with infective endocarditis?
- Calcification/thickening?
- Annular dilatation?
- Colour flow doppler
- Jet extension back into LA
- Vena contracta width (narrowest region of colour flow at MV level)
- Size of PISA
References for severe mitral regurgitation
Severe
Visual
Flail or prolapse
Colour
Jet area >10cm²
Ratio of jet area to LA area >40%
VC width >/=0.7cm
PISA radius >1cm
Causes of mitral regurgitation
Primary
(leaflet abnormality)
Secondary
(ventricule remodelling)
Prolapse, flail, rupture
Ischaemic
Degeneration, calcification
Non-ischaemic cardiomyopathy
Infective endocarditis, vegetations
Annular dilatation
Inflammatory - rheumatic
Congenital
Causes of mitral regurgitation
Acute mitral regurgitation
Echo features
- LV & LA are normal size
- LV appears hyperdynamic
Clinical features
- Sudden onset
- Severe breathlessness
- Hypotension and cardiogenic shock
- Acute coronary syndrome
- Acute pulmonary oedema
- Enlarged LA, LV and RV
- Normal/reduced LV contractility
Clinical features
- Gradual onset
- Slowly progressive breathlessness on exertion
- Atrial fibrillation
- LA dilatation
- LV dilatation
- LV dysfunction
- Pulmonary hypertension
Tricuspid valve assessment
Views
The best views for tricuspid valve assessment are:
- RV inflow view (RVI)
- PSAX – aortic valve level
- A4Ch
Anatomy of tricuspid valve
- Rheumatic disease
- Infective endocarditis
- Carcinoid
- Valve prolapse
- Annular dilatation – secondary to RV dilatation (functional TR)
- Pacing wire passing into RV
Tricuspid Regurgitation
A small amount of tricuspid regurgitation is present in about 70% of individuals with a structurally normal heart.
Echo features of tricuspid regurgitation
- Visual inspection
- Look at annulus, leaflets, papillary muscles and chordae
- Look at thickness, mobility, calcification and for signs of prolapse
- Colour
- Jet area >10cm²
- VC width >/=0.7cm
- CW doppler – jet density/contour
- Density – dense = moderate to severe
- Contour – triangular early peaking = severe
- PW doppler in hepatic vein (VEXUS) – normally directed towards RA throughout cardiac cycle, predominant systolic component
- S wave blunted in moderate TR
- Reversed in severe TR
- RA/RV/IVC size – dilated in severe
The severity of TR does not correlate with the PA pressure
Although the CW doppler and PW doppler are not used to assess severity of TR in FUSIC HD, the CW doppler is used to work out TR Vmax when measuring pulmonary artery pressures and the PW doppler of the hepatic vein is used in the VEXUS assessment. So it may be useful to know about grading severity of TR using these different methods as they may be measured for other reasons.
Severe TR
MAPSE
This is taken in the A4Ch view. As the LV contracts in systole in shortens longitudinally, radially and circumferentially. The distance that the MV lateral annulus travels in systole towards the LV apex is measured and this is known as the MAPSE.
To get the MAPSE value the A4Ch view is obtained and the M-mode line is placed over the lateral annulus of the MV. When in the correct position record M-mode by pressing the button again and freeze the screen once a few cardiac cycles have been recorded by M-mode. Place the calipers on the M-mode image and measure the lowest and highest points of the line of the MV.
MAPSE >12mm predicts normal LV function
MAPSE < 6mm predicts severe LV systolic dysfunction
MAPSE is good for distinguishing between normal and significant impairment of the LV, but is harder to interpret when the value lies between 6-12mm.
MAPSE measurement taken in M-mode with the cursor over the lateral mitral valve annulus.
Measurements taken from lowest to highest point of the line on M-mode representing the mitral annulus.
Fractional shortening
Fractional shortening can be useful because it is not too dissimilar to measuring the LVIDd. Again it is taken in the PLAX and LVIDd is measured, but at the same time LV internal diameter in systole is measured along the same plane as the LVIDd.
Systole can be determined by a few different ways:
- The frame where the LV is at its smallest
- The frame after AV closure
- The end of the T wave
This is a PLAX view of the LVIDs (measuring at 2.60cm)
Fractional shortening is then calculated using these 2 values:
FS = [(LVIDd – LVIDs)/LVIDd] x 100
This is a normal value for fractional shortening
BSE reference for fractional shortening
LV function
Fractional shortening
Normal
25-43%
Mildly impaired
20-24%
Moderately impaired
15-19%
Severely impaired
<15%
RWMAs
In health the LV contracts and the walls thicken and they move equally towards the centre of the LV cavity. Whilst looking at the LV from the PLAX, PSAX and A4Ch it is important to assess how the LV is contracting in all the different areas of its walls.
RWMAs can be due to ischaemia such as in an acute coronary syndrome and in this case the RWMA will be in the area supplied by the affected blood vessel. The RWMA will look like reduced excursion and thickening in this case. For FUSIC heart one of the ways to assess for RWMAs is to look in the PSAX at the papillary muscle level. The LV should be circular and all areas of the LV should be contracting and thickening equally towards the centre.
PSAX view showing antero-septal RWMA - note the reduced contractility in the upper left corner of the LV on this clip
Blood supply to the heart ↔︎
PLAX view showing the areas of coronary blood supply to the LV
PSAX view showing the areas of coronary blood supply to the LV
A4Ch view showing the areas of coronary blood supply to the LV - the lateral free wall of the LV can sometimes be supplied by the LCx.
Summary
Using the knowledge of the assessments above and gaining experience in scanning the LV, over time, you will get better at using an ‘eyeball’ assessment of the LV and answer the questions:
- Is the LV dilated?
- Is the LV significantly impaired?
Right ventricular assessment
The RV can be assessed from the:
- PLAX – RVOT
- PSAX – RV size and septal shape
- A4Ch – RV size & function (TAPSE)
- Subcostal – global impression
If the patient has a dilated LV then this rule can lead to underestimating RV size, and if the image is foreshortened then this can lead to overestimating the RV size.
The main view for assessing the RV size and function is the A4Ch view but the other views can be helpful as well.
3. Is the RV dilated?
The main way to assess for RV dilatation is in the A4Ch view. This is done using an ‘eyeball’ assessment where the LV and RV are seen next to each other. The RV is determined to be normal size when the RV basal width is no more than 2/3 that of the LV.
RV is mildly dilated when it is >2/3 the basal width of the LV
RV is moderately dilated when it is equal to the size of the LV
RV is severely dilated when it is larger than the LV
The PSAX is not usually used to assess RV size but can give an indication of whether RV dilatation is present – see images below.
No RV dilatation - A4Ch view showing the RV roughly 2/3 the size of the LV and the LV is the apex forming ventricle
RV severely dilatation - A4Ch view showing RV basal diameter > LV basal diameter
PSAX view of a normal RV
PSAX view of dilated RV
4. Is the RV severely impaired?
RV systole is predominantly in the longitudinal plane with some inward motion of the RV free wall. This makes the tricuspid annular plane systolic excursion (TAPSE) reflects longitudinal function and equates well with RV ejection fraction – making it ideal for measuring systolic function of the RV. The technique is similar to the MAPSE but performed on the lateral annulus of the tricuspid valve.
To measure the TAPSE get an optimal view in the A4Ch and place the M-mode line through the lateral annulus of the tricuspid valve. Press M-mode again and freeze the image after a few cardiac cycles. Measure using callipers the distance from the highest to the lowest point of lateral annulus of the tricuspid valve.
BSE reference values for TAPSE:
- TAPSE ≥17 is normal
- TAPSE <10mm is severely impaired.
TAPSE assessment using M-mode with a measurement of 2.05cm from the lowest to the highest point of the lateral annulus of the tricuspid valve. This is a normal TAPSE.
TAPSE assessment using M-mode with a measurement of 0.95cm from the lowest to the highest point of the lateral annulus of the tricuspid valve. This indicates the RV is severely impaired.
5. Is there evidence of low preload? (vasodilation/hypovolaemia)
The methods used to assess for low preload within FUSIC heart are inferior vena cava (IVC) assessment, combined with LV/RV assessment.
In a low preload state, which can be either due to vasodilation (for example in sepsis), or hypovolaemia (for example in dehydration/blood loss), the LV and RV will appear on echo to be hyperdynamic to try and increase the cardiac output through increasing the heart rate or contractility. This can be assessed in all views but may be well visualized in the A4Ch view.
In severe hypovolaemia there may be evidence of papillary muscle apposition in systole in the PSAX view. This gives the impression that most of the LV is emptying during systole and is evidence that there is low preload and the LV is underfilled.
The IVC assessment is also used to assess preload, however, it will differ depending on whether the patient is spontaneously breathing or is mechanically ventilated – which is not ideal for the ITU population for which FUSIC heart is used.
IVC
The IVC is assessed using the subcostal view with the probe rotate through 90 degrees anticlockwise from the original view of the heart. This brings into view the IVC in its long axis passing through the diaphragm and draining into the right atrium. Using M-mode place the line through the IVC perpendicular to its walls 1-2cm before its junction with the RA. Measuring on the M-mode image the maximum and minimum distance using calipers, as the IVC diameter changes with respiration.
The IVC diameter changes with respiration due to a negative intrathoracic pressure during inspiration and a positive intrathoracic pressure during expiration. During inspiration the negative intrathoracic pressure draws blood from the IVC into RA and the diameter reduces. During expiration the opposite occurs. This is during spontaneous respiration.
Normal IVC diameter is 1.5-2.1cm – outside of these limits suggest hypovolaemia or well-filled fluid status.
Limitations of IVC measurement
The IVC size and reactivity can be affected by multiple factors, including:
- Raised intra-abdominal pressure
- Tricuspid regurgitation
- RV failure
Spontaneous breathing and IVC assessment
An IVC diameter <2.1cm with collapsibility >50% with a sniff suggests right atrial pressure (RAP) 0-5mmHg
An IVC diameter ≥ 2.1cm with collapsibility <50% with a sniff suggests RAP of 15mmHg
Assume a RAP of 8mmHg for any other value that dies not meet the criteria above
SC IVC view in a spontaneously breathing patient with a sniff
SC IVC M-mode assessment of collapsibility with a sniff. Callipers can be used to measure between the largest and smallest diameter of the IVC.
Mechanically ventilated and IVC assessment
During mechanical ventilation there is positive intrathoracic pressure during inspiration and reduced intrathoracic pressure relatively in expiration. So the phasic collapse of the IVC is reversed.
The assumption is made that a dilated IVC with low respiratory variability reflects a high RAP (high preload).
A small IVC with high respiratory variability reflects a low RAP (reduced preload).
IVC measurement in M-mode showing a dilated IVC (2.57cm) with very little respiratory variation indicating a raised RAP - this could be due to RV failure or fluid overload
Putting LV and RV assessment together
Difference between LV and RV
Difference between pressure and volume overload of the RV
In both severe pressure and volume overload RV dilatation is seen with a D-shaped septum on the PSAX view. In normal circumstances the LV is circular with the inter-ventricular septum bowed towards the RV. In conditions of pressure or volume overload the IVS can start to flatten and become D-shaped.
Depending on which phase of the cardiac cycle the IVS appears D-shaped will determine whether it is pressure or volume overload or a combination of the both.
Pressure overload – the IVS is D-shaped in systole
Volume overload – IVS is D-shaped in diastole, paradoxical septal motion may be present where hyperdynamic ventricles appear to move the septum anteriorly during systole.
Combination of both pressure and volume overload – IVS appears D-shaped throughout both systole and diastole.
In both pressure and volume overload the IVC will start to dilate >2cm and there will be minimal respiratory variability.
PSAX view with a normal circular LV ↔︎
PSAX view of a D-shaped septum in both systole and diastole - indicating both pressure and volume overload
PSAX view with a flattened inter-ventricular septum making the LV appear D-shaped ↔︎
6. Is there pericardial or pleural fluid?
Assessment for pericardial fluid should be made in all views of the heart. Fluid on echo appears anechoic (black) and for it to be pericardial fluid needs to be between the myocardium and the pericardium. It is normal to see very small amounts of pericardial fluid in some patients. In patients with high body fat content the epicardial fat pad can appear similar to pericardial fluid, however this has a much more granular appearance which can help distinguish it and it is usually small. The pericardial collection can either be concentric or localized and it is best seen in the PLAX and SC views.
To distinguish between pericardial and pleural fluid this is best done in the PLAX view. Pericardial fluid appears anterior to the descending thoracic aorta whereas pleural effusions are posterior to the descending thoracic aorta.
PLAX view showing a small amount of pericardial fluid below the infero-lateral wall of the LV. ↔︎
Note: The fluid is anterior to the descending thoracic aorta meaning it is pericardial and not pleural fluid
This is best distinguished in the deep PLAX view.
PLAX view showing a small amount of pericardial fluid below the infero-lateral wall of the LV.
The pericardial effusion size can be measured at end diastole perpendicular to the pericardium and myocardium.
Pericardial effusion size
Small < 0.5cm Moderate 0.5-2cm Large >2cm
Maximal measurements around each regional wall should be made.
The appearance of the effusion can help distinguish its cause:
Simple effusion – uniform, anechoic
Exudative/fibrinous – stranding/loculation
Old blood – echogenic & grainy
Acute blood – similar to simple serous effusion
Purulent effusion – echogenic
Deep PLAX view demonstrating fluid posterior to the descending thoracic aorta meaning that it is pleural fluid.
Are there any signs of tamponade?
Early signs of pericardial tamponade are:
- IVC dilated, not collapsing
- RA collapse in systole
Late sign:
- RV early diastolic collapse → significant haemodynamic compromise
Very late sign:
- LV/LA collapse
SC view with evidence of pericardial fluid
Peri-arrest echo – where it fits in
Focused echo can be used during cardiac arrest and fits into the ALS algorithm at the pulse check. Usually the only place to assess the patient is via the subcostal view and limited to only 10 seconds.
Echo during cardiac arrest can help distinguish between true PEA (where coordinated electrical activity is seen on the monitor but there is no cardiac movement on echo and no palpable pulse) and pseudo PEA (where there is coordinated electrical activity on the monitor but there is cardiac activity on echo but with no palpable pulse).
- Only skilled operators should use intra-arrest point-of-care ultrasound (POCUS).
- POCUS must not cause additional or prolonged interruptions in chest compressions.
- POCUS may be useful to diagnose treatable causes of cardiac arrest such as cardiac tamponade and pneumothorax.
- Right ventricular dilation in isolation during cardiac arrest should not be used to diagnose massive pulmonary embolism.
- Do not use POCUS for assessing contractility of the myocardium as a sole indicator for terminating CPR.
Content created by Ben Stoney
Design by Max Broadbent
The ultrasound images and clips used on this website have be reproduced following the local clinical governance guidance.