Adult Echocardiography Practice Exam

Which type of ventricular septal defect is the most common?

1. Muscular

2. Outlet

3. Membranous

4. Inlet

The correct answer is: Membranous

The membranous ventricular septal defect (VSD) is recognized as the most common type of VSD. This type of defect occurs in the thin membranous part of the interventricular septum, which separates the left and right ventricles. Membranous VSDs account for a significant majority of the ventricular septal defects found among patients, often making them a focal point in both diagnosis and management of congenital heart disease. The prevalence of membranous VSDs can be attributed to the developmental processes of the heart, as this area is more prone to failure in proper closure during fetal development compared to other regions of the septum. Their frequent occurrence highlights the importance of detecting and appropriately managing these defects to help prevent complications such as heart failure or pulmonary hypertension that may arise from significant left-to-right shunting. In contrast, muscular VSDs, while common, do not outnumber the membranous type. Similarly, outlet VSDs (also known as conal or infundibular VSDs) and inlet VSDs are less prevalent in the overall population of patients with ventricular septal defects. Understanding the differences in incidence among these types of defects is crucial for clinicians in determining the appropriate diagnostic and therapeutic