Patient with VSD develops pulmonary hypertension. Which of the following will be present?
**Core Concept**
Pulmonary hypertension in a patient with ventricular septal defect (VSD) leads to a significant increase in pulmonary vascular resistance. This causes a decrease in the left-to-right shunt, resulting in an increase in pulmonary artery pressure. The key concept here is the reversal of shunt direction due to increased pulmonary resistance.
**Why the Correct Answer is Right**
In patients with VSD, the increased pulmonary resistance causes a decrease in the left-to-right shunt, leading to a reversal of shunt direction to right-to-left. This is known as Eisenmenger syndrome. The increased pulmonary resistance is due to the remodeling of pulmonary arteries, which involves the proliferation of smooth muscle cells and the deposition of extracellular matrix. This remodeling process is mediated by various growth factors, including endothelin-1 and transforming growth factor-beta.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not relate to the pathophysiology of pulmonary hypertension in VSD.
* **Option B:** This option is incorrect because it is a consequence of severe pulmonary hypertension, but not a direct result of the reversal of shunt direction.
* **Option D:** This option is incorrect because it is a feature of severe pulmonary hypertension, but not a direct result of the reversal of shunt direction.
**Clinical Pearl / High-Yield Fact**
Eisenmenger syndrome is a classic example of a "paradoxical" effect, where an initial left-to-right shunt leads to a reversal of shunt direction due to increased pulmonary resistance.
**Correct Answer: C. Reversal of shunt direction to right-to-left.**