Introduction

Cardiac abnormalities in children are predominantly congenital.

  • Cardiac abnormalities are the largest group of congenital defects

Epidemiology

  • 8 per 1000 children have a significant congenital cardiac abnormality
  • 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 2x) if the parent 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 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?

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

Presentations of Congenital Heart Defects

Congenital heart disease can present:
  • Antenatally on USS
  • Antenatally / neonatally with murmur
  • In neonate with murmur
  • In neonate with heart failure
  • In neonate with shock

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

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

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

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