FAST cardiac scans for veterinarians
In the United Kingdom, there is a growing enthusiasm among recently qualified veterinarians to incorporate ‘FAST’ cardiac scans into their consultations to rule out acute pathology and obvious cardiac disease. This mirrors a similar movement in human medicine, where registrars are being encouraged to learn a limited protocol to use in the emergency setting using a portable or handheld ultrasound machine.
FAST scans offer a fantastic service to pet owners, making a cardiac screen affordable and accessible to patients whose owners might otherwise decline one. It is best used to answer a specific question to rule out a differential diagnosis: for example, to look for impaired systolic function or the presence of a significant pericardial effusion, or as a cardiac screening test prior to non-cardiac surgery. It should not be used in place of a full echocardiogram, or where a cardiac cause of symptoms is already strongly suspected and the operator won’t have the capabilities to confirm or rule out the suspected pathology with the available equipment (see one example here of the danger of a false negative study in a young dog with subaortic stenosis).
Handheld machines invariably have no spectral Doppler capabilities, and many shared service ultrasound machines in veterinary practices may not have been equipped with a phased array probe and continuous wave Doppler. This can make stenotic lesions, in particular, very difficult to detect, particularly in younger animals where there may be no accompanying 2D signs such as left ventricular hypertrophy in aortic stenosis, and right ventricular dilatation and hypertrophy in pulmonary stenosis. In animals, these lesions are also far less likely to be valvular in origin, so relying on visual inspection of the valves without the use of Doppler may again lead to a false negative study.
In summary, a focused cardiac study by a trained operator offers enormous benefits to the patient, but it should never be used as a substitute for a full echocardiogram, reported and billed as a full echocardiogram, or performed without advising the client of the limitations of the examination.
If you would like to incorporate cardiac screening in your practice and need advice on training or equipment, please get in touch.
Stowell, C. (2015). Pocket echocardiography for the preoperative screening of non-cardiac patients. Imperial College, London.
September 17, 2021
June 19, 2021