Ventricular Septal Defect

The ventricular septal defect is the most common of all congenital heart anomalies. It may be caused by any of the four malformations:

• (1) Deficient development of the proximal conus swellings.
• (2) Failure of the muscular portion of the interventricular septum to fuse with the free edge of the conus septum. (Membranous VSD)
• (3) Failure of the endocardial cushions to fuse.
• (4) Excessive diverticulation of the muscular septum- perforations in the muscular interventricular septum. (Muscular VSD)

In the case of a VSD there is a massive left to right shunting of blood and pulmonary hypertension. The absence of the interventricular septum results in a Common Ventricle.

Figure

• Mem = Membranous septum
• Musc = Muscular septum