Basic and Clinical Sciences (BCSE) Practice Exam

Pulmonary embolism is associated with increased pulmonary vascular resistance (PVR) because it involves the obstruction of pulmonary arteries due to blood clots. When a clot lodges in these vessels, it creates a blockage, impeding blood flow within the pulmonary circulation. This obstruction results in increased pressure within the pulmonary vasculature, which directly elevates pulmonary vascular resistance. Consequently, the right ventricle must work harder to pump blood through the narrowed or blocked vessels, leading to elevated PVR.

In contrast, conditions like chronic lung disease may also affect PVR but primarily through chronic hypoxia and inflammation, rather than through direct obstruction. Aortic stenosis mainly affects the left side of the heart, and while it can lead to pulmonary hypertension indirectly, it does not directly cause increased PVR. Similarly, coronary artery disease is more related to the heart's ischemic events and does not directly impact pulmonary vascular resistance as a primary mechanism. Thus, among the options provided, pulmonary embolism is the condition most directly linked to an acute rise in PVR due to its mechanical obstruction of pulmonary blood flow.