Ventricular Septal Defects Overview

Ventricular Septal Defects

• A ventricular septal defect (VSD) is a hole in the wall between the left and right ventricles of the heart.
• VSDs occur when the interventricular septum (IVS) does not close completely during fetal development.
• VSDs are generally classified into six categories: Endocardial Cushion Defect / Atrioventricular Defect, Inlet VSD, Muscular / Trabecular VSD, Outlet / Supracosm VSD, Membranous / Perimembranous VSD, and Malalignment VSD.

Endocardial Cushion Defect / Atrioventricular Defect

• This type of VSD occurs when the endocardial cushions, which are structures that help to form the heart septa, do not develop properly.
• Endocardial cushion defects are commonly associated with Down syndrome (Trisomy 21).
• The defect results in a single common AV valve with a "butterfly" appearance.

Inlet VSD

• Characterized by a hole located near the AV valve, where "inlet" comes from (aka inflow).
• This type of VSD is bordered by the mitral valve (MV), tricuspid valve (TV), and muscle.
• Inlet VSDs are commonly associated with Atrioventricular VSD (common AV valve).
• Lytic activity occurs where the RV valves are located.

Muscular / Trabecular VSD

• Found in the thicker portion of the septum.
• Usually located near the apex of the heart.
• This type of VSD can have multiple holes that look like "swiss cheese."

Outlet / Supracosm VSD

• Occurs between the left ventricle (LV) and right ventricle (RV) outflow tracts.
• Bordered by the pulmonary artery (PA) and pulmonary valve (PV).
• Commonly associated with pulmonic stenosis and Tetralogy of Fallot (TOF).
• Higher prevalence in Asian populations.

Membranous / Perimembranous VSD

• Most common type of VSD.
• Bordered by the tricuspid valve, AV valve, and muscle.
• Located high up on the wall near the valves and great vessels.
• Extends and pushes with the right ventricle.
• Often small and flexible, denoted by the letter "L."

Malalignment VSD

• Occurs when two portions of the IVS fail to align properly during development.
• Frequently associated with other heart defects, such as TOF (Tetralogy of Fallot) and Truncus Arteriosus (T.A.).

This quiz covers the fundamentals of Ventricular Septal Defects (VSDs), including their classification and specific types such as Endocardial Cushion Defects and Inlet VSD. Explore how these conditions impact heart development and their associations with other syndromes. Test your knowledge on the anatomy and implications of VSDs.