A neonate presents with features of hea failure. On examination anterior fontanelle was found to be bulging. On auscultation, a cranial bruit was heard. A CT angiography done showed the following: Which vessel is mainly involved in this abnormality?

**Core Concept**
The condition described is a congenital anomaly affecting the cerebral vasculature, leading to heart failure in a neonate. This is an example of a left-sided cardiac obstructive lesion, which results in increased pulmonary vascular resistance and subsequent heart failure.

**Why the Correct Answer is Right**
The bulging anterior fontanelle and cranial bruit suggest increased cerebral blood flow due to a left-to-right shunt. The CT angiography findings point towards a vascular anomaly. In this case, the main vessel involved is the **ductus arteriosus**, which fails to close after birth. The ductus arteriosus is a normal fetal structure connecting the pulmonary artery to the aortic arch, allowing blood to bypass the lungs. Failure of closure leads to a patent ductus arteriosus (PDA), causing excessive blood flow to the lungs and subsequent heart failure.

**Why Each Wrong Option is Incorrect**
* **Option A:** The aorta is not directly involved in this condition, although the aortic arch is connected to the ductus arteriosus.
* **Option B:** The pulmonary artery is affected indirectly due to the increased blood flow caused by the PDA.
* **Option C:** The superior vena cava is not directly involved in this condition.

**Clinical Pearl / High-Yield Fact**
A cranial bruit in a neonate with heart failure should raise suspicion for a left-sided cardiac obstructive lesion, such as a PDA. This is a classic clinical correlation to remember for exams.

**Correct Answer: C. Ductus arteriosus**

✓ Correct Answer: A. Median prosencephalic vein