In the case of children who present with acquired cardiac failure – that is, not secondary to operated or unoperated structural congenital heart disease – and in the context of an echocardiogram that demonstrates a dilated and poorly contractile left ventricle, the usual diagnosis is of dilated cardiomyopathy (DCM). These patients then embark on a well-worn management and investigation pathway.

There are several causes for dilated cardiomyopathy in the paediatric population, although a large proportion are still idiopathic (Wilkinson et al. 2010). Known causes account for approximately one-third of DCM cases, and include myocarditis, vitamin D deficiency, neuromuscular conditions, chronic arrhythmia, familial causes, inborn errors of metabolism and malformation syndromes.

When faced with a child with poor left ventricular function it is important to exclude structural causes, which in the paediatric population include:

Severe coarctation of the aorta often presents in the neonatal or early infant period, usually within 1 to 2 weeks of birth following closure of the arterial duct. These babies have a duct-dependent systemic circulation and present collapsed with severe metabolic acidosis as the arterial duct closes. If the coarctation is not duct-dependent, babies can present with breathlessness, sweatiness, restlessness, and irritability and they may feed poorly. Blood pressure in the arms may be mildly to moderately elevated. Often, blood pressure in the lower limbs is unrecordable or is significantly lower than that in the upper limbs. In older infants, it is possible for much higher blood pressures to be recorded in the upper limbs only, as neurohormonal mechanisms (renin-aldosterone-angiotensin and sympathetic nervous systems) are activated to maintain perfusion pressure to the kidneys (distal to the coarctation) at the expense of hypertension in the vasculature proximal to the coarctation. In circumstances where the obstruction develops over time, sometimes there is compensatory left ventricular hypertrophy and the development of collateral vessels bypassing the aortic obstruction. Such patients may be relatively asymptomatic, presenting later in life either incidentally or with systemic hypertension or its complications (e.g., stroke). In some infants, however, the left ventricle fails to compensate and dilates with poor systolic function. The left ventricular failure may progress, and infants will present with persistent tachypnoea, sweating, poor feeding and other signs of cardiac failure. It is important to note that aortic coarctation is the only pathology in the preceding list where the patient may have systemic hypertension on presentation, in the upper limbs only.

Our patient was hypertensive in both upper and lower limbs, and echocardiography excluded any structural heart disease. Therefore, other causes of systemic hypertension in children needed to be considered. Amongst adults systemic hypertension is a known cause of dilated cardiomyopathy, presumably via a progression from a hypertrophied ventricle secondary to pressure loading, to a dilated, ‘burnt out’ left ventricle (Drazner 2011). It seems likely that a similar mechanism operates in children who have systemic hypertension.