Adult Echocardiography Practice Exam

Ventricular septal defects may be difficult to detect if they are smaller than which size?

1. 3 mm

2. 1 cm

3. 5 mm

4. 10 mm

The correct answer is: 3 mm

Ventricular septal defects (VSDs) that are smaller than 3 mm can often be challenging to detect through standard echocardiographic imaging techniques. Smaller defects may lead to less significant left-to-right shunting of blood, which could result in subtle changes in cardiac function or hemodynamics that are difficult to identify. An echocardiogram’s sensitivity for detecting smaller VSDs is limited because the volume of shunted blood may be insufficient to create noticeable turbulence or flow patterns that are easily visualized. Furthermore, smaller VSDs may not generate distinctive Doppler signals compared to larger defects, making their detection more difficult. In practice, defects that are only a few millimeters across require a high-quality imaging technique and an experienced sonographer to assess their presence clearly. The sensitivity of detection decreases significantly as the size of the defect diminishes, reinforcing why smaller VSDs, particularly those less than 3 mm, can elude detection in routine examinations.