In the last decade, the use of focused cardiac ultrasound (FCU) has been growing in small animal emergency and critical care settings, due to its ability to provide several important pieces of information for the criticalist and the general practitioner evaluating traumatic and non-traumatic critically ill patients.

It consists in the acquisition of four basic echocardiographic views including (left or right) long-axis view also called 4-chamber view, right parasternal transventricular view, right parasternal transaortic view allowing the measurement of left atrium to aorta and subxiphoid view. FCU allows subjective assessment of heart chamber dimensions and function, such as left ventricular contractility, left ventricular chamber size, left atrial size, and right heart changes. It is also useful to detect the presence of pericardial effusion with or without cardiac tamponade and the presence of cardiac tamponade due to extracardiac causes (thoracic tumors, pleural effusion).

This diagnostic tool allows the identification of various clinical conditions such as left and right-sided congestive heart failure, severe systolic dysfunction, hypovolemia, cardiac tamponade, and moderate to severe pre-capillary pulmonary hypertension. Early detection of these clinical scenarios is pivotal for the criticalist and the general practitioner allowing better management of critically ill patients. FCU has also been shown to detect chronic cardiac disease such as hypertrophic cardiomyopathy in cats and degenerative mitral valve disease in combination with careful cardiac auscultation.

Those are facts. Why can those important diagnoses become fiction? Essentially, like other imaging techniques, FCU is an operator dependent exam, and it depends on experience, knowledge, and practice achieved by the clinician performing it. If good quality image acquisition is the first difficulty when performing FCU, several studies have shown that this technique is reproducible with a relatively short learning curve.

On the other hand, image interpretation is more challenging and knowledge of normal cardiac morphology on echography is pivotal to correctly interpret this exam. In adult human cardiology, 3 months of hands-on work including 75 performed scans and 150 interpreted scans are the training requirements to detect large pericardial effusion, marked right ventricular dilatation and recognize severe left ventricular systolic dysfunction. Non-expert operators can improperly interpret a pericardial effusion as pleural effusion and vice versa, can interpret dilated right chambers as pleural effusion, can misinterpret right heart remodeling as left ventricular concentric hypertrophy, etc.

The examiner should be trained with a proper hands-on training program, covering all cardiac scans, most common alterations evaluated with FCU, and common pitfalls. Why is clinical training so important? The answer is quite easy. We evaluate our patients, sometimes unstable, with a point-of-care approach. It means that patients can be evaluated in the emergency room, in the treatment area, in a surgery suite, and in ICU. Scans can be performed in patients in lateral or sternal recumbency, so operators should be familiar with all scans and common diagnostic scenarios.

While FCU can be beneficial for patient care, there is potential for harm with inappropriate use. The implications of relying on a false negative exam could include delayed or missed diagnoses. Similarly, false positive findings or misinterpretations could lead to unwarranted testing or procedures and increased owners spending. Despite the potential for those things, formal training programs have not been widely embraced, and quality control metrics are often lacking.

Creating training standards and possibly certificate programs for FCU will be the future in which we trust, as happened in human medicine.

References

References are available upon request.