Embryologic Development and Defects · USMLE Step 1

A neonate exhibits a holosystolic murmur due to a ventricular septal defect. This defect is most commonly due to failure of formation of which septum?

  1. Membranous interventricular septum
  2. Muscular interventricular septum
  3. Endocardial cushion septum
  4. Septum transversum
Show answer and explanation

Correct answer: Membranous interventricular septum

Most VSDs occur in the membranous part of the IV septum, derived from endocardial cushions. These defects are the most common congenital heart defects.

Difficulty: Medium Question 14 of 20

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