Circulatory Case Study 6

Blue Baby

 

Baby Stephen was a full-term baby and at first glance he appeared healthy. In the hours following his birth, however, the nurses caring for him noticed that he didnÕt "pink up" as babies should. Rather, his skin had a bluish cast, a condition known as cyanosis, caused by inadequate oxygenation of his blood. Normal babies do appear somewhat blue at the time of birth due to the normal conditions of fetal circulation. However, as they begin to breathe air and are exposed to its richer supply of oxygen, their skin develops the normal coloration.

 

One of the nurses from the neonatal nursery listened to his heart and lung sounds with a stethoscope. His lung sounds were normal, but his heart sounds revealed a significant murmur. The attending physician ordered echocardiography to identify the location and extent of any abnormalities of StephenÕs heart. He was diagnosed with a congenital disorder known as Tetralogy of Fallot, a well-known malformation of the heart which prevents blood from being adequately oxygenated in the lungs. It involves four disorders: the aorta displaced to the right so that it receives some blood from both the right and left ventricles, a ventricular septal defect, pulmonary stenosis, and hypertrophy of the right ventricle. Fortunately, surgery can be done to correct much of the problem associated with this disorder, and can prolong the life expectancy of children with it.

 

QUESTIONS:

  1. Trace a drop of blood from the heart to the body and back to the heart.

  2. Distinguish between arteries, veins and capillaries both functionally and structurally.  Describe the composition and functions of blood.

  3. Elaborate on the symptoms of Tetralogy of Fallot- displaced aorta, ventricular septal defect, pulmonary stenosis, hypertrophy of right ventricle.

  4. What is the problem with the aorta receiving blood from both sides?

  5. In this disorder, what factors cause blood to be shunted into the aorta and therefore by-pass pulmonary circulation?

  6. What is the normal path of blood flow through both sides of the heart? Does blood normally cross from the right side to the left side or vice versa?

  7. What is the normal path of fetal circulation? How does a fetus get its oxygen? (hint: fetal hemoglobin). What are the circulatory changes which must occur at birth?

  8. How would a pediatric cardiologist treat a patient withTetralogy of Fallot?

 

Adapted from: Human Physiology-from cells to systems by Lauralee Sherwood

Thomson/Brooks-Cole Publ. 5th edition 2004