**Core Concept**
Large Patent Ductus Arteriosus (PDA) is a congenital heart defect characterized by the failure of the ductus arteriosus to close after birth, resulting in a persistent communication between the aorta and the pulmonary artery. This abnormal connection allows for excessive blood flow to the lungs, leading to pulmonary overcirculation and potential complications.

**Why the Correct Answer is Right**
The persistent flow of oxygenated blood from the aorta to the pulmonary artery in a large PDA causes an increase in pulmonary blood flow, leading to pulmonary overcirculation and potential pulmonary hypertension. This can result in left ventricular volume overload, dilatation of the left ventricle, and eventually, left ventricular failure. The increased pressure in the pulmonary artery also leads to its dilatation and potential complications such as pulmonary edema and congestive heart failure.

**Why Each Wrong Option is Incorrect**
* **Option A:** Pulmonary stenosis is a condition characterized by narrowing of the pulmonary valve or artery, which is not directly related to a large PDA.
* **Option B:** Cardiomyopathy refers to diseases of the heart muscle, which can be caused by various factors, but is not a direct consequence of a large PDA.
* **Option D:** Hypertension is a condition characterized by high blood pressure, which can be caused by various factors, but is not a direct consequence of a large PDA.

**Clinical Pearl / High-Yield Fact**
A large PDA can lead to pulmonary hypertension, which is a significant risk factor for the development of Eisenmenger syndrome, a condition characterized by reversal of the left-to-right shunt, resulting in cyanosis and right ventricular failure.

**Correct Answer:** C. Pulmonary overcirculation and potential pulmonary hypertension.