Which type of ventricular septal defect (VSD) is the most common?

The most common type of ventricular septal defect (VSD) is the perimembranous VSD. This defect occurs in the membranous portion of the interventricular septum, which is the wall separating the left and right ventricles of the heart. Perimembranous VSDs account for a significant proportion of all VSD cases, estimated to be around 70% of all defects.

One of the reasons for the prevalence of perimembranous VSDs is their anatomical location. These defects can easily occur due to developmental issues during embryogenesis, which can lead to incomplete closure of the septum in this area. The perimembranous region is particularly susceptible to defects because of its position near the aortic and tricuspid valves, where the structural integrity is crucial during heart development.

In contrast, muscular VSDs, while also common, tend to occur in the muscle portion of the septum rather than the membranous area, and they have a tendency to close spontaneously over time. Inlet VSDs and outlet VSDs are less common than perimembranous VSDs and typically account for a smaller fraction of overall VSD cases. The understanding of these