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Franklin OM*, Burch M**. Dilated cardiomyopathy in childhood. Images Paediatr Cardiol 2000;2:3-10 |
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Specialist Registrar in paediatric cardiology, John Radcliffe Hospital, Oxford, UK |
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Consultant Paediatric Cardiologist, John Radcliffe Hospital, Oxford, UK |
| MeSH | ||
| Cardiomyopathy, congestive | Myocarditis/diagnosis | Heart transplantation |
| Prognosis |
Article
Presentation and investigation dilated cardiomyopathy
| At the time of presentation the child with dilated cardiomyopathy (DCM) is usually in symptomatic cardiac failure, and at initial assessment, it is important to differenciate this condition from bronchiolitis. The chest x-ray features of increased cardiothoracic ratio, with evidence of lateral bronchial displacement due to left atrial enlargement and pulmonary plethora in association with hepatomegaly, raises clinical suspicion of the diagnosis (figure 1). |
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More commonly in idiopathic DCM sinus tachycardia, increased left ventricular voltages and ischaemic changes are seen on ECG at presentation. The QRS complex may be broad due to conduction disturbance and evidence of right atrial hypertrophy and left atrial hypertrophy is sometimes evident. 24 hour ECG monitoring will exclude chronic tachycardia with secondary ventricular dilatation e.g. permanent junctional reciprocal tachycardia, which is associated with a moderate increased heart rate and an abnormal P axis and will also identify children with secondary arrhythmias.
Differential diagnosis
There are a number of alternate diagnoses that need to be excluded
at the time of presentation, as management and therapeutic strategies may
need to be altered accordingly. Anomalous origin of the left coronary artery,
the ECG features of which are described above, usually presents at 2-3
months and can be confirmed at cardiac catheter. This condition is surgically
correctable. Myocarditis is more difficult to diagnose with accuracy but
an attempt should be made as spontaneous resolution is likely and short-term
mechanical support may be more appropriate than referral for transplantation.
Positive viral cultures or increased antibody titres on paired serum samples
may help. Common causes include viral infection with coxachie, echo, HIV,
measles, mumps and rubella but all families of micro-organisms have been
implicated. Myocardial biopsy is rarely indicated, because of the risk.
In most children dilated cardiomyopathy is a sporadic condition of unknown cause. However familial cases have been reported with autosomal dominant with incomplete penetrance, recessive and x-linked inheritance patterns described. Michels et al3 demonstrated a prevalence of familial disease in 20% of index cases in a prospective study where asymptomatic first-degree relatives were screened. No features specific to familial disease have been identified. It is our policy to offer such screening, and this needs to be handled sensitively.
DCM as a secondary disease
DCM is rarely due to systemic disease however as myocardial damage
may be reversible with treatment of the underlying pathology it is essential
to attempt to rule out metabolic, endocrine, storage, mitochondrial and
connective tissue disorders at first presentation. Blood may be taken for
lactate, glucose, amino acids, carnitine and acylcarnitine, cholesterol
and triglycerides, thyroid function, creatinine kinase, iron and iron binding
capacity and uric acid. A full blood count to assess absolute neutrophil
count and vacuolated lymphocytes may also be helpful. Early morning urine
analysis for amino-acids, organic acids and glycosamine glycans may further
exclude metabolic disease.
Medical management
The objective of drug therapy in DCM is to give supportive relief and
maximize cardiac function. There is not as yet a treatment that offers
a cure.
Diuretic have an established role particularly in their ability to produce rapid symptom relief, but earlier use of ACE inhibitors has probably resulted in lower doses being used in recent years. ACE inhibitors have been consistently shown to reduce morbidity and mortality in adult studies, 4,5 Enalapril maleate was used in these series, there is limited information available on its use in children where captopril is most commonly prescribed. ACE inhibitors are generally well tolerated, their principle side effects include first dose hypotension, non-productive cough, and a risk of hyperkalaemia, especially in patients already on potassium supplements or potassium sparing diuretics.
Treatment with B-blockers needs also to be considered. The increased sympathetic drive that occurs as a compensatory mechanism in chronic heart failure appears to have an inverse relationship with prognosis 6,7. B-blockers down regulate this sympathetic overdrive 8 and the evidence that they improve outcome in adult patients with chronic heart failure is increasing 9,10,11. The a-adrenergic effects of the third generation B-blockers e.g. Carvedilol and Timolol also cause vasodilatation and this may be helpful.
Digoxin has a place as an orally active inotrope, but its failure to
actively reduce mortality in adults 12 means it is increasingly
relegated to second line therapy. Intravenous inotropes may occasionally
be necessary to support the child in end stage cardiac failure. Their use
is an indication for transplant assessment in some centres 13
| Arrhythmias may also require treatment but this needs to
be carefully evaluated, as many anti-arrhythmic drugs are negatively inotropic.
All children with poor LV function are at risk of mural thrombus and should
be treated prophylactically with aspirin, the detection of clot requires
urgent anticoagulation (fig. 4).
Growth hormone may be effective as add on therapy in the child who is failing to improve on conventional medical management. Early studies in adults 14 have shown improvement in LV function and exercise tolerance and reduced myocardial oxygen consumption with GH therapy that deteriorated when therapy was discontinued. In the future subcutaneous GH could have a role as a medical ‘bridge to transplantation’ but further work need to be done. |
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Mechanical and surgical support
| Left ventricular assist devices and biventricular assist devices, although not widely available yet in the UK will have a role in the short term, providing a bridge to transplant for the child with intractable cardiac failure. In the future indwelling axial flow impeller pumps such as the JARVIK2000 Heart may have a place in the long term mechanical support of this difficult group of patients.19 (fig. 5). |
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A second surgical option is the Batista operation where a partial left ventriculectomy is combined with mitral valve repair to restore left ventricular dimensions to normal thus improving pump function. Paediatric experience of this operation is limited but a 55% 2 year survival was reported in adult patients in the US, with most survivors showing symptomatic improvement.21
Conclusion
Management of children with dilated cardiomyopathy remains difficult
but recent advances including early introduction of ACE inhibitors and
B-blockers may improve what is currently a bleak outlook. In the future
implantable left ventricular assist devices may provide interim mechanical
support, but referral for transplantation remains the cornerstone of treatment.
References
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I would like to thank the following individuals for help
in producing these first, in-house digitised animations:
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