Cyanotic heart disease in the newborn

Q24.9

DESCRIPTION

Blue or grey discoloration of skin and tongue in room air, with an oxygen saturation of less than 85% in the presence of a cardiac lesion.

Note:

Strongly suspect cyanotic cardiac disease if centrally cyanosed, not in respiratory distress and normotensive.

DIAGNOSTIC CRITERIA

  • Rule out non-cardiac causes of central cyanosis:
    • Respiratory conditions, e.g. hyaline membrane disease, pneumonia and pneumothorax. Signs of respiratory distress usually improve with oxygen administration. Chest X-ray may be helpful.
    • Central nervous system involvement, e.g. sedation and asphyxia, which usually improves with oxygen administration.
    • PaCO₂ may be increased in cyanosis due to respiratory and central nervous system causes.
    • Methaemoglobinaemia.
  • To confirm cardiac cause:
    • Do hyperoxia test.
    • Tachypnoea, but usually no retraction.
    • Heart murmur (may be absent).
  • Hyperoxia Test (Nitrogen wash out test):
  • Administer 100% oxygen via a nasal cannula for 10 minutes.
    Unnecessary if saturation is under 85% in a head box or nasal cannulae delivering 100% oxygen.
  • Obtain arterial blood from the right radial artery (preductal flow).
PaO2 mmHg Interpretation
<100 Most likely to be a cyanotic heart lesion, persistent foetal circulation or severe lung disease. PaCO2 will be increased with severe lung disease.
≥100–200 Unlikely to be cyanotic heart lesion.
≥200 Excludes cyanotic heart lesion.
  • Chest X-ray may show cardiomegaly or abnormal cardiac silhouette and/or reduced pulmonary blood flow.
    • Confirm diagnosis with echocardiography.

GENERAL AND SUPPORTIVE MEASURES

  • Nurse in neutral thermal environment.
  • Monitor and maintain within physiological range for age:
    • heart rate,
    • calcium, magnesium,
    • respiration,
    • blood glucose,
    • blood pressure,
    • blood gases,
    • body temperature,
    • acid-base status, and
    • electrolytes.
  • Provide adequate hydration and nutrition.

MEDICINE TREATMENT

Referral is needed in all patients.

Prior to referral:

To keep ductus arteriosus open if a duct dependent cyanotic heart lesion is suspected:

  • Prostaglandin therapy, i.e.:
  • Alprostadil, IV, 0.05–0.1 mcg/kg/minute, initial dose, (under specialist consultation).
    • Maintenance dose : 0.01–0.1 mcg/kg/minute.

OR

  • Dinoprostone, via naso/orogastric tube, (under specialist consultation).
    • For babies < 2.5 kg: 0.125 mg 1–2 hourly (¼ tablet suspended in 2 mL sterile water), or 50 mcg/kg/dose 1–2 hourly.
    • For babies > 2.5 kg: 0.25 mg hourly (½ tablet suspended in 2 mL water).

Continue with prostaglandin therapy until corrective or palliative surgery can be done or until patency of the duct is not deemed essential for survival of the infant.

If ductal dependant lesion suspected maintain oxygen saturation just above 75%.

Serious side effects of prostaglandins to be aware of may include:
Apnoea, fever, diarrhoea, hypotension and seizures

If pH ≤7.2, correct metabolic acidosis:

  • Sodium bicarbonate 4.2 %, IV.
    HCO₃ needed (mmol) = base excess x 0.3 x body mass (kg).
    2 mL sodium bicarbonate 4.2% = 1 mmol HCO₃

SURGICAL TREATMENT

  • Corrective or palliative surgery.

REFERRAL

  • All cyanotic infants with an underlying cardiac cause for central cyanosis.