Pediatric Hypoplastic Left Heart Syndrome Clinical Presentation

Updated: Dec 15, 2020
  • Author: Syamasundar Rao Patnana, MD; Chief Editor: Stuart Berger, MD  more...
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The clinical features of hypoplastic left heart syndrome (HLHS) largely depend on the patency of the ductus arteriosus, the level of pulmonary vascular resistance, and the size of the interatrial communication.

Although hypoplastic left heart syndrome can easily be detected on fetal echocardiography, [30] many infants are not identified prenatally because routine obstetric ultrasonography examination may not concentrate on cardiac anatomy. An increase in use of routine prenatal ultrasonography and examination by obstetricians of the 4-chamber anatomy of the heart to ensure its normalcy is likely to identify hypoplastic left heart syndrome more frequently than in the past.

Pregnancies are typically uncomplicated. The fetus grows and develops normally because the fetal circulation is not significantly altered. [6, 13] Most neonates are born at term and initially appear normal.

Occasionally, respiratory symptoms and profound cyanosis are apparent at birth (2-5% of cases). In these infants, significant obstruction to pulmonary venous return (a congenitally small or absent patent foramen ovale) is usually present.

As the ductus arteriosus begins to close normally over the first 24-48 hours of life, symptoms of cyanosis, tachypnea, respiratory distress, pallor, lethargy, metabolic acidosis, and oliguria develop. Without intervention to reopen the ductus arteriosus, death rapidly ensues. Similar symptomatology may be expected if a precipitous drop in pulmonary vascular resistance occurs.


Physical Examination

Before the initiation of prostaglandin E1 infusion to reestablish patency of the ductus arteriosus, infants may exhibit signs of cardiogenic shock, including the following:

  • Hypothermia

  • Tachycardia

  • Respiratory distress

  • Central cyanosis and pallor

  • Poor peripheral perfusion with weak pulses in all extremities and in the neck

  • Hepatosplenomegaly

After reestablishment of systemic blood flow via the ductus arteriosus, signs of shock resolve, leaving the stable infant with tachycardia, tachypnea, and mild central cyanosis. If a coarctation of the aorta is present, arterial pulses in the legs may be more prominent than those in the arms, particularly the right arm.

Cardiac examination findings may include the following:

  • A prominent right ventricular impulse may be noted.

  • A normal first heart sound may be observed.

  • A loud single second heart sound may be present.

Usually no murmur is noted; however, the following murmurs may be heard:

  • Nonspecific, soft, systolic ejection murmur at the left sternal border (not always present)

  • High-pitched holosystolic murmur at the lower left sternal border, indicating tricuspid regurgitation (not always present) [3]

  • Diastolic flow rumble over the precordium, indicating increased right ventricular diastolic filling (not always present)