**Question:** Difference in Murmurs of PDA and ASD is/are

**Core Concept:**

The core concept being tested here pertains to the auscultatory findings in patent ductus arteriosus (PDA) and atrial septal defect (ASD). Murmurs are the heart sounds produced due to turbulent blood flow in congenital heart defects. ASD and PDA are two such defects.

**Why the Correct Answer is Right:**

Correct Answer: **D**.

A PDA is a congenital heart defect where a persistent fetal blood vessel, the ductus arteriosus, remains open after birth, allowing oxygenated blood from the pulmonary artery to mix with deoxygenated blood in the aorta, leading to a decrease in oxygen saturation. This results in a continuous, low-pitched, and diastolic murmur, commonly heard second intercostal space on the left side, radiating to the left sternal border.

An ASD is an abnormal connection between the right and left atria, allowing oxygenated blood from the pulmonary veins to mix with deoxygenated blood in the left atrium. This leads to a decrease in oxygen saturation, but the murmur is different from a PDA.

**Why Each Wrong Option is Incorrect:**

A. Option A: Murmurs in ASD are systolic. This is incorrect because the murmur in ASD is diastolic, as the oxygenated blood flows from the right to the left atrium during diastole.

B. Option B: Murmurs in PDA are continuous. While murmurs in PDA are generally continuous, the specific characteristics of the murmur may change with varying heart rates, making this option less precise compared to option D.

C. Option C: Murmurs in ASD are loudest at the right sternal border. While the murmur in ASD is heard best at the right sternal border, the correct answer (option D) highlights that the murmur is heard best second intercostal space on the left side, radiating to the left sternal border.

**Clinical Pearl:**

Auscultation of heart murmurs is a crucial skill in clinical medicine, particularly for diagnosing heart diseases in pediatric patients. The distinct differences between PDA and ASD murmurs help in differentiating these conditions and form part of the clinical examination in diagnosing congenital heart diseases.