Hsc106 M1D1

1. A baby is born with a hole between the right and left atrium. Thinking of the anatomy of the heart, what symptoms would you expect to see? How would the symptoms be different if the hole was located between the right and left ventricles? Explain your answer.

At approximately seven weeks gestation, the heart forms a partition between the left and right atrium. In this partition is located the foramen ovale, a hole located between the right and left atrium. (Tortora and Grabowski, Principals of Anatomy and Physiology. Pg 615.) At birth, this hole closes due to increased pulmonary circulation brought on by breathing. This increase of circulation back to the left atrium causes the hole to close. (Scanlon and Sanders, Essentials of Anatomy and Physiology. Pg 532). If this hole does not close, the newborn is considered to have an interatrial septal defect. Since pressure in the left atrium is higher than that in the right atrium, blood would flow back into the right atrium without entering the baby’s central circulation. Thus, the oxygenated blood would return again to the lungs instead of the oxygen starved cells of the body. If this was the case, the baby would have a decreased oxygen saturation (hypoxia). Signs would include lethargy and cyanosis.

If they hole was located between the right and left ventricles (interventricular septal defect), the oxygen rich blood found in the higher pressure left ventricle would flow into the lower pressure, deoxygenated right ventricle. Again, the oxygen rich blood is needed for normal cellular metabolism and will show as lethargy and hypoxia in the newborn.

Both of these conditions (interventricular septal defect and interatrial septal defect) are similar to the Tetralogy of Fallot and share some similar characteristics. In both cases, deoxygenated blood mixes with oxygenated blood and both cases will present with a hypoxic newborn. This hypoxic state is commonly referred to as a “blue baby”. Tetraolgy of Fallot is...