A 3-year-old girl presents with a loud holosystolic murmur and a palpable thrill. What is the most likely defect?

• A. Aortic regurgitation
• B. Atrial septal defect
• C. Ventricular septal defect
• D. Coarctation of the aorta

Answer: (C)

In a 3-year-old girl presenting with a loud holosystolic murmur and a palpable thrill, the most likely defect is a ventricular septal defect (VSD).

A VSD is characterized by a defect in the ventricular septum, which allows blood to flow from the left ventricle into the right ventricle during systole. This shunting of blood leads to an increase in pulmonary blood flow, resulting in the characteristic holosystolic murmur. The continuous nature of the murmur (holosystolic) is due to the pressure gradient between the higher-pressure left ventricle and the lower-pressure right ventricle throughout the entire ventricular contraction. Additionally, the presence of a palpable thrill—an unusual vibration felt on the chest wall—indicates a significant amount of turbulence in the blood flow, which is commonly associated with larger defects such as VSD.

The other conditions mentioned either produce different clinical findings or do not typically present with a palpable thrill or loud holosystolic murmur in a child of this age. For example, aortic regurgitation would likely cause a diastolic murmur rather than a systolic one, while an atrial septal defect typically presents with a different type