Classification of Interventricular Communication in Relation to the Tricuspid Valve

Anatomical Classification of Interventricular Communications

The American College of Cardiology notes that interventricular communications are classified into four main anatomical types based on their location in the ventricular septum, with Type 1 (Outlet/Supracristal) representing approximately 6% of defects in non-Asian populations and up to 33% in Asian patients, and spontaneous closure of this type is uncommon 1, 3
The American Heart Association indicates that Type 2 (Membranous/Perimembranous) defects are the most common, accounting for almost 80% of defects, located in the membranous septum, and adjacent to the septal leaflet of the tricuspid valve, with possible formation of a "aneurysm" of the ventricular septum when the tricuspid valve adheres to the defect 1, 3
The European Society of Cardiology states that Type 3 (Inlet) defects occur in the lower part of the right ventricle and adjacent to the tricuspid valve, typically found in patients with Down syndrome 1, 3
The American College of Cardiology reports that Type 4 (Muscular) defects can be centrally located, apically, or at the margin of the septum and the free wall of the right ventricle, may be multiple, and spontaneous closure is common 1, 3

The European Heart Journal notes that in the anatomical-physiopathological classification of congenital heart defects, interventricular communications are classified as post-tricuspid defects, in contrast to pre-tricuspid defects (such as interatrial communications), referring to their position in relation to blood flow and not their specific anatomy 2
The European Society of Cardiology indicates that post-tricuspid defects, such as interventricular communications and patent ductus arteriosus, occur after the tricuspid valve in the circulation circuit 2

The Journal of the American College of Cardiology states that in inlet interventricular communications (Type 3), the defect opens predominantly in the inlet component of the right ventricle in the absence of a common atrioventricular junction 4, 5, 6
The American College of Cardiology notes that muscular interventricular communications (Type 4) are found within the trabeculated component of the ventricular septum 4, 5, 6

The American Heart Association indicates that precise classification of interventricular communications is essential for determining the most appropriate surgical approach, with perimembranous, supracristal, and inlet defects generally requiring surgical closure, while muscular defects may be considered for percutaneous or hybrid methods 1
The American College of Cardiology reports that muscular interventricular communications have a higher probability of spontaneous closure than other types 1