PWD should be used as it measures localised blood velocity

The sample volume is placed at the tip of the mitral leaflets during LV filling (blue arrow)

Diastolic function is assessed by:

– Left ventricular myocardial thickness
– Left atrial size
– Mitral in-flow with pulsed wave Doppler
– Tissue Doppler imaging
– Indices combining PWD and tissue Doppler
– Pulmonary venous flow
– Colour M-mode Doppler flow wave propagation

Pulmonary venous flow and colour M-mode Doppler flow wave propagation are beyond the scope of this e-course

After having completed the e-learning module, the next step is to attend one of our hands-on-training (HOT) courses

You can join any one of these which are offered in more than 20 different countries

All Advanced FATE courses are standardised with a comprehensive and very structured learning program

The courses are lead by one of our experienced chief instructors who ensures that all learning objectives are fulfilled while the supervisors at the workstations are often local experts

After the Advanced FATE course you will be able to estimate cardiac output by means of pulsed wave Doppler

You have now learned:
– The basic principles of cardiac output measurement using Doppler echocardiography
– The reason for using pulsed wave Doppler as opposed to CWD
– That the accuracy is low and the method should only be used as a trend monitor
– To recognise the most important pitfalls

Remember, it is when you press the Doppler buttons that you are most likely to make the biggest mistakes in point-of-care ultrasound

When you are confident with the content of this module, move forward to the next module to learn about the assessment of the diastolic function

Pulsed wave Doppler should always be used for the assessment of cardiac output

The velocity recording and vessel diameter should be measured in the same location

The method relies on the heart rate and sinus rhythm

Use the LVOT although theoretically all vessels can be used

The accuracy of the method is debatable, use it to monitor trends

Be careful with Doppler ultrasound – there are many pitfalls and mistakes are extremely easy to make

The angle of insonation is a potential source of error

In this case we use a GE echo machine as an example

Tracing of the velocity curve to obtain the VTI:
12. Press Measure
13. Select Aortic
14. Choose LVOT trace
15. Use the trackball and mark the beginning of the systolic curve (1)
16. Press Set (1 on the image)
17. Cross the line at “2” or mark just before the zero line is reached (2)
18. Mark the beginning of the next systolic curve (3) (heart rate indication)
19. Press Set to get the cardiac output

In this case we use a GE echo machine as an example

The velocity signal:
6. Display the apical 5 chamber view
7. Activate the cursor
8. Place the SV in the LVOT as close as possible to where you measured the diameter
9. Press the PWD button
10. Record a uniform spectral curve
11. Press Freeze when optimised

Please proceed to the next page

In this case we use a GE echo machine as an example

The cross-sectional area:
1. Display the parasternal long axis view
2. Freeze the image in mid-systole
3. Press the measurement button and select “Dimension”
4. Select “LVOT diam”
5. Mark the diameter just beneath the aortic valve and press Set

Please proceed to the next page

PWD should always be used for the assessment of CO since it records velocities locally

Procedure:
– From tracing of a single spectral curve the “velocity time integral” (VTI) is obtained

– The estimated VTI for one minute can be calculated by multiplying the VTI by the heart rate

– Finally VTI for one minute multiplied by the CSA will give the cardiac output (L/min)

A systematic approach will help to ensure correct assessment of the CSA:

On the screen:
– Display and optimise the correct parasternal long axis view

– Measure the diameter just under the aortic cusps from inner edge to inner edge in mid systole

– Calculate CSA

Most ultrasound machines have software that automatically calculate CO when the diameter has been entered and velocity curve traced