Focused echocardiography in the potential cardiac donor

Hello, and welcome to this ORACLE education video on the NHSBT organ donation echocardiography proforma.

This video is designed for those that have done some echocardiography. This can include people who are currently collecting the logbook of scans for a basic focused accreditation such as Fusic Heart, or for those who are already accredited and wanting to know the additional views and measurements that can be done.

Whilst a comprehensive level 2 study is ideal, data shows that in most cases, echocardiography is done by those with or attaining focused accreditations.
This video will cover these additional views and measurements that can be obtained to transfer to the transplant centre.

It is important to remember that you do not necessarily need to be able to interpret these additional views and measurements. Simply obtaining them and transferring them to the relevant centre can be incredibly useful.

If you are focused echo accredited, you can report as you would normally. In all the views obtained, remember to assess for all the basics that you would with a focused echo, including visual function of the RV and LV, and visual assessment of chamber sizes.

If you are fully accredited, please complete a full level 2 study and report as per BSE standards.

The first view obtained is the parasternal long axis view. The views and measurements in the parasternal long axis window including those beyond a basic focus scan are shown here from the donor heart proforma and will be demonstrated now.

Once the image is optimised, a visual assessment of chamber sizes and valvular function is done.

The relevant sonoanatomy can be seen highlighted here.

Following this, colour should now ideally be applied over the mitral and aortic valve separately. Care should be taken to ensure that the Nyquist limit on the ultrasound machine is set between 50 to 60 cm per second. This is the maximum Doppler shift frequency that can be accurately measured.

On a cardiac preset, all machines will default to this. However, if it’s not between 50 to 60, adjusting this is straightforward. Here we can see the Nyquist limit being changed on this machine.

If the limit is not between 50 to 60, there is a risk of under or overestimation of flow and regurgitation.

Here, colour Doppler can be seen applied over the aortic and mitral valve. Ideally, the colour box should be adjusted such that it’s covering the valve and part of its proximal chamber. The smaller the colour box, the better the image quality will be.

Next, the LV dimensions are measured. The image is frozen and scrolled to end diastole which is the frame where the LV looks biggest. The anteroseptal wall, the left ventricle and the posterior wall dimensions can now be measured. Care should be taken to avoid any valvular apparatus, and only measurement of the compacted myocardium done.

Following diastolic measurements, a single measurement of the left ventricle end systolic diameter is done.
It is also important to ensure that the left ventricle is not foreshortened, which will significantly affect dimensions. Here, the parasternal long axis window is purposefully being foreshortened for demonstration.

Next, we move on to the parasternal short axis view. The views and measurements in the parasternal short axis window including those beyond a basic focus scan is shown here from the donor heart proforma and will be demonstrated now.

The relevant sonoanatomy can be seen highlighted here.

Colour is now applied over the tricuspid and pulmonary valves, ensuring that the box size and Nyquist limit is appropriate as mentioned earlier.

The probe tail can be tilted such that the entire LV cavity can be visualised. Small tilt up of the tail can visualise the LV at the mitral valve level, which can be seen here. Further tilting the tail up, we’ll then move on to the mid papillary level, which is demonstrated here.

Finally, further tilting will then visualise the left ventricle at apex.

The next view is the apical 4 chamber.

The views and measurements in the apical 4 chamber window including those beyond a basic focus scan is shown here from the donor heart proforma and will be demonstrated now.

As with all of the views, chamber sizes, function and valvular function is assessed.

The relevant sonoanatomy can be seen highlighted here.
Colour Doppler is now applied over the mitral valve and tricuspid valve separately, which can be seen demonstrated here.

Next, a 2D measurement of RV basal diameter is done in end diastole, ensuring the compacted myocardium is measured and any trabeculations are ignored.

Here we can see the operator scrolling back and forth to identify end diastole. This can be done by looking at chamber sizes where the chambers are at its largest, or can be done using the valve position (in this instance the tricuspid and mitral valve will be closed), or if ECG is attached, can be done by looking at the beginning of the QRS complex.

The next view is the apical 5 chamber. The views and measurements in the apical 5 chamber window including those beyond a basic focus scan is shown here from the donor heart proforma and will be demonstrated now.

Following acquisition of standard view, colour Doppler is now placed over the aortic valve to assess for any turbulent flow or significant regurgitation.

The final view is the subcostal view. The views and measurements in the subcostal window including those beyond a basic focus scan is shown here from the donor heart proforma and will be demonstrated now.

The relevant sonoanatomy can be seen highlighted here.

After obtaining the standard subcostal window, colour Doppler is placed over the inter-atrial septum, to see if any shunts.

For the purposes of donor heart assessment by non-level 2 accredited practitioners, the Nyquist level does not need to be adjusted.

Once these views have been obtained and saved, they can be transferred over to the transplant centre according to your local hospital governance structure.
When reporting this study, it’s important to try and comment on levels of cardiovascular support and PEEP on ventilator, as this can significantly affect the heart.

An example of a reporting template from the proforma is shown here, which includes a summary of all the parameters that we have explained in this video.

If you are not qualified to take measurements or comment on valvular function, simply transferring the relevant images discussed in this video to the transplant centre can be helpful to be interpreted in the context of transplant eligibility.

Pathologies such as regional wall motion abnormalities or takotsubo cardiomyopathy can be very common in this cohort of patients.

Additionally, there can be rapid fluctuations in left ventricular and right ventricular function in patients with severe brain injury.

It is important to note that none of these would necessarily preclude transplantation, and often a repeat scanning a few hours later will show resolution of these pathologies.

Here is a link once again to the donor heart transthoracic echo assessment proforma.

Here is a QR code for access to ORACLE Education. This is a completely free resource for online radiology education. As well as modules on acute radiology, within the point of care ultrasound section there are extensive resources covering echocardiography, all the way from the basics to advanced critical care echocardiography.

That concludes this ORACLE education video, covering the NHSBT donor heart transthoracic echocardiography assessment.