NHS blood and transplant donor echocardiography standard to improve organ utilisation in heart transplantation

Introduction

There is a pressing need to improve donor heart utilisation. ¹ We have previously demonstrated the value of focused echocardiography in the United Kingdom for the assessment of donor hearts. ² In the absence of focused echocardiography, there are insufficient resources to assess all those donors using an on-site cardiothoracic retrieval team.

We have also shown that many UK intensive care units (ICUs) are equipped with multiple echocardiography-capable ultrasound machines and have a significant number of staff who are trained in focused echocardiography. ³ Despite this, further expansion and development of 24/7 delivered services are still required.

To help units improve their donations rate, we have sought to establish pragmatic guidance on the assessment of donor hearts by focused echocardiographers.

Methods

The NHS Blood & Transplant National Organ Donation Committee established a working group, listed in the authorship of this article, consisting of medical, surgical and nursing specialists in heart transplantation, organ donor retrieval and focused echocardiography to develop guidance for focused echocardiographers.

A literature review was conducted using MEDLINE with the search terms ‘donor heart’, ‘heart transplantation’ and ‘echocardiography’. Studies were included if they assessed the utility of echocardiography parameters in donor heart assessment with any transplant outcome measures. A modified Delphi approach was used to develop the minimum expected dataset that focused echocardiographer should acquire during donor heart assessment. ⁴ Consensus was defined as ⩾75% agreement among panel members in the final round.

Results

There was limited registry and observational data in 23 manuscripts related to specific echocardiographic parameters with transplant outcomes (see Supplemental Appendix 1).

Following four rounds of the modified Delphi process, a donor focused echocardiography proforma was developed in December 2022 (Figure 1) to define a minimum image dataset. This includes up to 18 different images, and where possible data image transfer to a transplant centre for expert review.

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Figure 1.

Donor echocardiography proforma.

Colour Doppler imaging and key dimensional measurements were included as optional, building upon the 2D assessment as part of the focused echocardiography accreditation. This was deemed to be of significant importance from transplant teams, in particular left ventricular wall thickness, which may affect heart transplant outcomes.^{5 –7} These measurements are marked with an asterisk on the proforma to indicate that acquisition should be based on the clinician’s capabilities. A training video (https://www.nhsbt.nhs.uk/) and accompanying guidance, found on the reverse of the proforma, guide the acquisition of these additional data.

Discussion

Current focused echocardiography accreditations are in some cases limited to 2D image acquisition and assessment only. Pragmatically, this has to be sufficient where comprehensive assessment is unavailable, which is the case in nearly half of donor offers. ² There would not be adequate cardiothoracic retrieval resources to assess half of donor offers without some screening through focused echocardiography.

Working within the limits of the current NHS structure, it was agreed that, with minimal additional instruction, focused echocardiographers should be encouraged to acquire colour Doppler images and perform three specific measurements: left ventricular wall thickness, left ventricular size and right ventricular size. This is important because the low availability of dedicated inter-hospital image transfer systems leads to a significant use of mobile applications and email, where measurements cannot subsequently be made. This information must be made available for review by the transplant centre, along with the relevant images for interpretation. The focused echocardiographer should not report any imaging outside of their area of competence.

There is also a case for repeated imaging over the course of the assessment of a potential donor with changes in the neurohormonal milieu that can affect apparent cardiac function. Comprehensive echocardiography and other advanced imaging in donor hearts must remain the ambition with increasing complexity of variables suggesting survival outcome relationship post transplantation. ⁸

The proposed proforma is based primarily on expert opinion and it possible that some of the recommended views may not significantly influence outcomes. In addition, requesting focused echocardiographers to perform imaging outside of their expertise raises significant issue. Thus, it is essential that appropriate training is provided to support the acquisition of these additional images in supplement to existing focused echocardiography practices. There must also be work across the NHS to enhance compatibility between cardiology and radiology picture archiving and communication systems to ensure ability to transfer imaging across NHS when needed.

To conclude we present a pragmatic proforma to support focused echocardiographers in the assessment of donor hearts. There is a need to consider the delivery of the echocardiography services more widely in the United Kingdom, especially in the context of heart transplantation.

Supplemental Material