USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

Which condition may lead to increased perfusion of bronchial arteries in chronic inflammatory lung disease?

1. Obstructive Lung Capacity

2. Left-to-Right Shunt

3. Anatomic Shunt

4. Physiological Shunt

The correct answer is: Anatomic Shunt

In chronic inflammatory lung disease, increased perfusion of bronchial arteries can occur as a compensatory mechanism in response to chronic hypoxia and inflammation in the lungs. This adaptive response is particularly relevant in conditions like chronic obstructive pulmonary disease (COPD) or bronchiectasis, where inflammation leads to increased metabolic activity and needs for oxygen delivered by the bronchial circulation. An anatomical shunt refers specifically to a situation where blood bypasses the lungs entirely, resulting in a portion of deoxygenated blood entering the systemic circulation without being oxygenated. In the context of chronic inflammatory lung disease, the body may react to the reduced oxygen levels by increasing blood flow through the bronchial arteries to nourish the affected lung tissue. This results in heightened perfusion within bronchial circulatory pathways to meet the inflammatory demands. The other conditions mentioned do not typically result in increased perfusion of bronchial arteries in the same manner. An obstructive lung capacity does not directly correlate with an increase in bronchial artery perfusion due to an increase in airflow resistance. Left-to-right shunts usually refer to blood flow within the heart that bypasses pulmonary circulation but doesn’t stimulate bronchial artery perfusion. Physiological shunts involve mixed venous blood returning to systemic circulation and do