Hypoplastic Left Heart Syndrome
Marked hypoplasia (underdevelopment) or even absence of the left ventricle and severe hypoplasia of the aorta. Often a coarctation of the aorta is also present. The main pulmonary artery is enlarged, and gives rise to a large ductus arteriosus. This allows blood to flow from the right ventricle into the aorta and out to the body. Other characteristics of HLHS often include a combination of aortic and mitral stenosis or aortic and mitral atresia.
1 - patent foramen ovale
2 - pinched aorta
3 - patent ductus arteriosus
4 - narrowed aorta
5 - hypoplastic left ventricle
6 - aortic atresia
The lack of a developed left ventricle, plus the aortic coarctation leads to reversed blood flow through the aorta. Partially oxygenated blood reaches the aorta after travelling through the patent foramen ovale, up the pulmonary trunk and through the patent ductus arteriosus. The major blood flow to the systemic circulation is through the PDA.
Obstructive defect... Generally, severe stenoses in the neonatal period are associated with CHF symptoms and/or cyanosis depending on the location of the lesion.
Often a coarctation of the aorta is also present.
The main pulmonary artery is enlarged, and gives rise to a large ductus arteriosus. This allows blood to flow from the right ventricle into the aorta and out to the body.
Other characteristics of HLHS often include a combination of aortic and mitral stenosis or aortic and mitral atresia.
Right sided structures, PA, coronary arteries, and lungs normal.
PDA and ASD are essential for survival and considered a part of the complex.
Systemic venous blood returns normally to RA and flows normally out RV through pulmonary artery. Flows across PDA to aorta and supplies systemic flow but with mixed blood. Pulmonary venous blood empties into LA and flows across ASD, this oxygenated blood mixes with normal venous return
Death occurs within 1 week if not treated.
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.
Symptoms of CHF become evident and if unrecognized will progress to vascular collapse.
The PaO2 is optimally between 30-45 mmHg, and the PaCO2 is ideally between 45-50 mm Hg.
Assessment of PaO2 and PaCO2 is important for respiratory management and manipulation of pulmonary vascular resistance by mechanical ventilation and the addition of supplemental inhaled nitrogen.
IV, O2, Monitor.
3cc/kg/hr D10W for infants under 1 year of age, D5W if over 1 year.
Blood flow to the systemic circulation (coronary arteries, brain, liver, kidneys) is dependent on flow through the ductus arteriosus. If a diagnosis is suspected, start prostaglandin (PGE) infusion immediately to establish ductal patency and ensure adequate systemic perfusion
Avoid supplemental oxygen unless severe hypoxia is present (SaO2 < 60%)
Most infants should remain in room air with acceptable oxygen saturation (pulse oximeter) in the 60's.
Maintain balance between systemic and pulmonary blood flow by manipulating SVR and PVR.
If cyanotic with low pulmonary blood flow... hyperventilate, hyperoxygenate, relieve pulmonary congestion, maintain Hct over 45%.
Pulmonary overcirculation may result in hypotension and acidosis as systemic circulation is compromised.
Foley catheter insertion to follow renal perfusion and urine output.
ABG to follow acidosis.
Factors that can affect PVR:
Effect on PVR
Effect on systemic O2 delivery
Inotropes (dopa or Epi)
Increases (by raising CO)