Introduction

Cardiac abnormalities in children are predominantly congenital. There are a wide range of diseases that can be classified as congenital heart diseases, some of which are life-threatening, whilst other are so minor they may never be diagnosed.

It is important to consider heart defects in children with failure to thrive (particularly those who feed in short, sharp bursts), and in older children with poor exercise tolerance.

  • Cardiac abnormalities are the largest group of congenital defects
Typically, congenital heart defects cause obstruction of blood flow through the heart (including through the large blood vessels shortly afterwards) , or they cause altered route of blood flow through the heart. 
Treatment of congenital heart disease has improved dramatically in recent decades, any many patients even with severe disease survive well into adulthood.
Typically, defects are classified into cyanotic and non-cyanotic (cyanotic) disorders.

Epidemiology

  • 8 per 1000 children have a significant congenital cardiac abnormality
  • Account for about 1/3 of congenital abnormalities
  • 1 in 10 still births have a cardiac abnormality
  • 10-15% of cases have more than one abnormality
  • 10-15% have another non-cardiac abnormality
  • 80% of congenital cardiac abnormalities are one of the 9 main types (below)

Aetiology

  • Mainly unknown
  • 8% caused by chromosomal abnormality: E.g. Down’s syndrome, Edward’s syndrome, Patau’s syndrome, Turner’s syndrome, Williams syndrome
  • Small proportion due to teratogenesis
  • Increased risk (roughly 3x) if first degree relative has a congenital heart defect
  • As they are sometimes associated with other genetic abnormalities (10-15%), it is worth considering echocardiography in a neonates with other abnormalities.
  • Maternal illness
    • Rubellacan cause PDA (persistent ductus arteriosus), pulmonary stenosis
    • SLE – can cause complete heart block
    • Diabetes mellitus – Generalised increased incidence (10x greater risk!) of congenital heart defects
  • Maternal drugs
    • Warfarin therapy – PDA, pulmonary stenosis
    • Fetal alcohol syndrome – ASD, VSD, tetralogy of fallot

Summary of the 9 main congenital heart defects

Acyanotic

Resulting in Left to Right shunt

Resulting in outflow obstruction

Cyanotic

  • Tetralogy of Fallot – 5%
  • Transposition of the great arteries – 5%
  • Complete atrioventricular septal defect
Some doctors have taught that it is easier to work out what is happening in a cardiac presentation from first principles, rather than trying to remember the 9 main abnormalities, and match the signs to the disease. This can make diagnosis easier to an extent, and below are a few principles that might help:
Cyanotic baby – a baby can be cyanotic even if it suffers from one of the acyanotic conditions, if the condition is severe enough, however, in the majority of cases, a cyanotic baby will be the result of one of the cyanotic heart conditions
  • Cyanosis is more likely to occur when blood cannot get to the lungs, rather than when blood cannot be circulated around the body, thus it is more likely in right sided heart problems.
  • Cyanosis is typically present where there is a right to left shunt
  • Acyanotic disease is typically present when there is a left to right shunt – however – in pulmonary hypertension, the shunt can be reversed, and cyanosis can result.

Left heart pressure is higher than right heart pressure after birth

Compensated or not?

If a defect is compensated, the outcome is likely to be better. For example, you could have a perfectly well baby that is blue!
Signs of decompensation:
  • Poor feeding
  • Dyspnoea
  • Hepatomegaly
  • Engorged neck veins
  • ↑pulse
    • ↓pulse is a very poor prognostic sign!
  • Weak pulse
  • Cold peripheries
  • Acidosis

Presentation

Congenital heart disease can present:
  • Antenatally on USS
    • Most severe cases are now identified on antenatal USS
  • Antenatally / neonatally with murmur
  • In neonate with murmur
    • Murmurs present within the first 2 days of life should be referred to paediatrician urgently
  • In neonate with heart failure
  • In neonate with shock
  • On neonatal O2 saturation monitoring

Signs

Vary widely but may include:

  • Increased respiratory rate
  • Increased work of breathing
  • Cyanosis
  • Reduced O2 saturation
  • Dysmorphic features – associated with underlying congenital disorder
  • Murmur (see below)
  • Hepatomegaly
  • Weak femoral pulses (coarctation)
  • Peripheral oedema
    • A rare sign in children
    • If it is present – tends to be in the scrotal / labial region

Signs that are uncommon in children

Despite being common signs of heart failure in adults, the following are rarely seen in chdilren

  • Peripheral oedema
  • Bibasal crackles
  • Raised JVP

Assessing Cyanosis

Peripheral cyanosis – can be seen in an ill child of any cause
Central cyanosis – is more closely associated to a cardiorespiratory abnormality
  • Only visible when [Hb] >5 g/dl – thus may not be apparent in the anaemic child
  • If in any doubt, use pulse oximetry to confirm PO2

Causes in the neonate

  • Congenital heart disease
  • Respiratory disorders – e.g. surfactant deficiency (pre-term), meconium aspiration
  • Persistent pulmonary hypertension of the newborn – PPHN – results from a failure of pulmonary vascular resistance to fall after birth
  • Infection
  • Metabolic disease
  • Polycythaemia

Assessing Heart Murmurs

The vast majority of children with a murmur have a harmless ‘innocent’ murmur!
Innocent murmurs can be heard in 30% of children at some point.
Characteristics
  • Usually soft (less than grade 3/6)
  • Often position dependent – e.g. may be apparent when supine, but disappear when upright.
  • Typically systolic but can be constant – throughout systole and diastole
  • No palpable thrill
  • No radiation
  • Best heard at the left sternal edge
  • More likely to be heard in febrile child – due to increased cardiac output
  • Child otherwise well
  • ECG and CXR normal

Some differentiate innocent murmurs into:

  • Ejection murmur – caused by turbulent blood flow in the ventricles, outflow tracts, or great vessels on either side of the heart. No structural abnormality.
  • Venous hum – turbulent blood flow in the veins of the head and neck. A continuous low pitched ‘hum’ best heard in the infraclavicular region, bilaterally. Amy be louder after exercise, and on inspiration.
  • Disappears when lying flat, or when jugular vein is occluded – thus can be differentiated from PDA.
  • Can be difficult to differentiate from pathological murmur – if in any doubt, then send for further analysis (ECG, echocardiogram, X-ray)
  • Remember the signs as the 5 S’s: Soft, systolic, left Sternal edge, asymptomatic

Features suggestive of a pathological murmur

  • Changes with position or Valsalva manoeuvre
  • Harsh sounding

Features suggestive of an innocent murmur

  • Ejection systolic
  • Soft

Investigations

Antenatal diagnosis

  • All neonates scanned at 18-20 weeks for identification of abnormalities
  • Detects 70% of cases that will subsequently require surgery in the first 6 months of life
  • If an abnormality is detect, then fetal echocardiography can be performed for a detailed analysis
  • If a defect is detected, parents can be offered counselling, and termination. The vast majority of mothers will chose to continue with delivery

After birth

  • Echocardiography is the investigation of choice for any child with suspected heart disease
  • Cardiac catheterisation may be used in severe cases to assist with assesemtn of severity

Management

Management depends on the underlying cause

  • No specific treatment is required in many cases
    • However, these children may still be at increased risk of infective endocarditis, and in some circumstances, prophylaxis may be required
  • Acutely unwell neonates
    • May require immediate resuscitation
    • Consider prostaglandin infusion for ductus dependent lesions
    • May require acute surgical correction
    • Exact treatment depends on the underlying lesion
  • Children >1 month of age
    • More likely to present to primary care, with a murmur, failure to thrive, or in older children – reduced exercise tolerance
    • Referral to paediatrics for an echocardiogram is the most likely first step in management
    • Many may require surgery
      • Whilst awaiting surgery, ACE inhibitors may reduce the risk o development of pulmonary hypertension
      • High calorie diet can reduce the risk of failure to thrive

Complications

  • Risk of infective endocarditis (except in atrial septal defect)
  • Failure to thrive
  • Reduced exercise tolerance
    • Can lead to psychosocial problems as it prevents socialising with other children
  • Paradoxical embolism (if left-right-shunt)
  • Polycythaemia – including a haemoglobin as high as 20 g/dL

Prognosis

  • Is highly dependent on the underlying disorder
  • Some, such as VSD may have the same long-term outcomes as the general population after repair
  • Many have reduce survival compared to the general population, but survival has dramatically improved in recent decades

Prevention

Controlling maternal risk factors can reduce the risk of congenital heart disease. This includes:

  • Avoidance of alcohol and drugs in pregnancy
  • Ensuring vaccination against rubella prior to pregnancy
  • Prevention and management of diabetes in pregnancy

References

  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

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