Neonatal Nurse Practitioner Practice Exam

What causes cardiac enlargement in neonates with congestive heart failure?

1. Hypoxia

2. Increased blood flow diverted from extremities

3. Pressure overload

4. Decreased heart rate

The correct answer is: Pressure overload

Cardiac enlargement in neonates with congestive heart failure is primarily caused by pressure overload. In conditions such as aortic stenosis or coarctation of the aorta, the heart experiences increased resistance to blood flow, which forces the cardiac muscle to work harder. This increased workload can lead to hypertrophy of the heart muscle, resulting in an enlarged heart. As the heart adapts to the stressors placed upon it—particularly in infants who may already have underlying congenital heart defects—this compensatory mechanism can lead to significant enlargement of the heart chambers. The body prioritizes maintaining adequate circulation, and while hypertrophy may initially serve to enhance cardiac output, it can eventually contribute to a decline in overall cardiac function as heart failure progresses. In contrast, hypoxia does not directly cause cardiac enlargement but rather affects oxygen delivery to tissues. Increased blood flow diverted from extremities is a consequence of heart failure, as the body prioritizes vital organs. Decreased heart rate is generally associated with reduced cardiac output rather than promoting enlargement. Thus, understanding the mechanism of pressure overload in the context of heart failure is crucial in recognizing the pathophysiology involved in cardiac enlargement in neonates.