Which description best matches the murmur of a ventricular septal defect?

• A. Pansystolic murmur best heard at the apex
• B. High-pitched harsh systolic murmur best heard at the left lower sternal border with a palpable thrill
• C. Continuous machinery murmur best heard at the left infraclavicular area
• D. Late systolic murmur at the apex without thrill

Answer: (B)

Ventricular septal defect murmurs come from turbulent blood flow across a hole between the ventricles during heart contraction. Because the left ventricle pumps with higher pressure, blood shunts from left to right in systole, creating a holosystolic, harsh-sounding murmur. It’s typically heard best along the left lower sternal border, where the septal defect is closest to the chest wall, and a palpable thrill may be present when the jet is high-velocity, usually in smaller defects. This pattern helps distinguish it from other murmurs: a pansystolic murmur at the apex suggests mitral regurgitation, a continuous machinery murmur at the left infraclavicular area points to patent ductus arteriosus, and a late systolic murmur at the apex without a thrill is classic for mitral valve prolapse.