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Posted On : 26 Mar 2013

in hypoplastic left heart i noticed that manifestation starts after murmur being audible and baby is stable with no symptoms till murmur appears . if this is ductus so the reverse must occur.

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N

naif flahy

0

left to right

12 years ago

Answer 1

The newborn infant with hypoplastic left heart syndrome has a complex cardiovascular physiology. Fully saturated pulmonary venous blood returning to the left atrium cannot flow into the left ventricle because of atresia, hypoplasia, or stenosis of the mitral valve. Therefore, pulmonary venous blood must cross the atrial septum. In most babies, a patent foramen ovale is present and is small and partially obstructive. This blood mixes with desaturated systemic venous blood in the right atrium. The right ventricle then must pump this mixed blood to both the pulmonary and the systemic circulations that are connected in parallel, rather than in series, by the ductus arteriosus. Blood exiting the right ventricle may flow to the lungs via the branch pulmonary arteries or to the body via the ductus arteriosus. The amount of blood that flows into each circulation is based on the resistance in each circuit. 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. Most neonates are born at term and initially appear normal. Occasionally, respiratory symptoms and profound cyanosis are apparent at birth {2-5 percent 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.

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