A 6-week-old infant presents with poor feeding, excessive sweating during feeds, and tachypnea. On examination, heart rate is 180/min, respiratory rate is 60/min, and the liver is palpable 4 cm below the costal margin. A loud pansystolic murmur is heard at the left lower sternal border. Which of the following is the most likely underlying cardiac defect?

• A Atrial septal defect (ASD)
• B Tetralogy of Fallot
• C Pulmonary stenosis
• D Ventricular septal defect (VSD) ✓

Explanation

This infant has signs of congestive heart failure (tachycardia, tachypnea, hepatomegaly) presenting at 6 weeks — when pulmonary vascular resistance naturally falls, increasing left-to-right shunt. A pansystolic murmur at the left lower sternal border is the hallmark of VSD, the most common congenital heart defect. VSD causes volume overload of the left ventricle and pulmonary vasculature, precipitating heart failure. ASD typically does not cause heart failure in infancy, and Tetralogy of Fallot causes cyanosis rather than heart failure.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.