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Over recent years echocardiography has changed from a purely research tool to an essential part of adequate management of the critically ill newborn. In the hypotensive or shocked infant, there is no better way to find a treatable underlying cause of their circulatory failure such as myocardial dysfunction, a large ductal shunt, pericardial effusion, or hypertrophic cardiomyopathy in infants of mothers with diabetes. A large ductal shunt sufficient to cause severe reduction in effective cardiac output and even cardiorespiratory collapse after extubation can be clinically silent and may only be revealed by echocardiography.1 Similarly, septic vegetations or thrombi on valves or central lines can only be seen this way, and it is feasible to assess pulmonary arterial pressure non-invasively in most ill newborns.
Therefore, someone needs to be available 24 hours a day in all neonatal units to do echocardiography. There are about 60 paediatric cardiologists in the UK, about one per million of the population; this is simply not enough to provide a 24 hour service for all neonatal units, many of which are long distances from big cities. Some units outside the UK have echocardiography technicians based and trained within the paediatric cardiac unit who provide a useful service—for example, screening on the third day of life for ductal shunting, but even they are not usually available outside normal working hours.
Should neonatologists be doing the scans?
To date, I have run five echocardiography courses specifically designed for neonatologists. All have been oversubscribed and other recent courses elsewhere in the UK have been equally popular. Neonatologists feel the need to learn echocardiography and most trainees leave the courses with more rather than less respect for the technique. Recognising this, I approached the committee of the British Society of Echocardiography, of which I am a member, to ask if they could help to organise national guidelines and set standards for such courses; they have taken on the role of accreditation of both echocardiography courses and trainees. The idea was firmly rejected—the committee did not feel that such courses were desirable. Many paediatric cardiologists are uncomfortable with neonatologists doing echocardiography because they feel they may miss or wrongly diagnose congenital heart disease (CHD). How justified are they in believing this?
During a research project using echocardiography in a neonatal unit,2 3 33 babies being treated for persistent hypoxaemia were assessed echocardiographically: one was found to have transposed great arteries and another had severe hypertrophic cardiomyopathy. Some cyanotic CHD can be difficult to diagnose echocardiographically (such as anomalous pulmonary venous drainage) and these infants must be seen by a paediatric cardiologist.4However, among 60 infants examined using echocardiography to assess ductal shunting, none had CHD. One infant from another institution was referred with coarctation having been given indomethacin without previously being evaluated echocardiographically. Echocardiographic evaluation of ductal shunting is necessary before treatment, relatively easy to learn, and aortic coarctation can be excluded in this group before giving indomethacin by confirming that pure left to right ductal shunting is present using Doppler in association with good foot pulses.
As the British Society of Echocardiography will not help us, I would like to begin a discussion on this subject by proposing who should be trained, how they should be trained, and what should and should not be expected of a trainee. This is based on my experience as a paediatric cardiologist with experience in neonatology, a background of research into neonatal haemodynamics, and experience in teaching echocardiography to neonatologists.
Who should learn echocardiography on the neonatal unit?
Each unit should have one consultant with special skills in echocardiography. Some trainees in neonatology may usefully elect to spend a year or more within a paediatric cardiac centre to train in echocardiography and CHD—a handful of neonatologists in post in the UK have already done this.
How should they be trained?
Each trainee should attend a course in basic echocardiography and paediatric echocardiography, currently available from the British Society of Echocardiography, and/or a specialist course in echocardiography for the neonatologist. The neonatologist echocardiographer should have ongoing, regular, and documented contact with a local paediatric cardiac unit allowing continued exposure to echocardiography in CHD and allowing for specialist audit. Some form of certification of competence needs to be organised through a body as yet unspecified.
Which infants should be referred to the paediatric cardiologist?
Those with clinically suspected congenital heart disease
Those ventilated for severe persistent hypoxaemia, particularly if extracorporeal membrane oxygenation is being considered
Those in whom an adequate echocardiogram is not obtained by the neonatologist or where echocardiography reveals previously unsuspected CHD.
Which infants can reasonably be assessed by a trained neonatologist echocardiographer?
The hypotensive or shocked newborn in the first few hours of life without clinical evidence of congenital heart disease
Those requiring assessment of ductal and/or interatrial shunting
Those with a central line to assess its position or to exclude vegetation or thrombus
Those in whom pulmonary arterial pressure or cardiac output needs to be assessed (once CHD has been excluded by a paediatric cardiologist in infants with persistent hypoxaemia).
Echocardiography is an essential part of modern neonatal intensive care. Its use should not be limited to cardiologists in the diagnosis and assessment of CHD but should be extended to the routine care of critically ill neonates. As with any investigative tool, echocardiography should be used in combination with clinical acumen and not as a replacement. Paediatric cardiologists should not be worried about neonatologists learning echocardiography, rather they should encourage, support and supervise them—live video links may even help to avoid unnecessary transfer to cardiac centres of cyanotic infants without CHD. Being involved in establishing guidelines for the safe practice of neonatal echocardiography is surely better than ignoring it.