Of clefts, commissures, and things.

Area of Science:

• Cardiovascular Anatomy
• Congenital Heart Disease Morphology

Background:

• Atrioventricular septal defects (ASDs), also known as endocardial cushion defects or atrioventricular canal malformations, present complex morphological challenges.
• Understanding the precise nature of leaflet tissue breaches at the atrioventricular junction is crucial for accurate diagnosis and surgical repair.

Purpose of the Study:

• To elucidate the morphological characteristics of specific breaches within atrioventricular septal defects.
• To determine whether traditionally described "clefts" in these defects function as commissures by comparing them to normal valve structures.

Main Methods:

• Comparative morphological analysis of leaflet tissue breaches in atrioventricular septal defects.
• Examination of commissures in normal atrioventricular and arterial valves.
• Evaluation of an isolated cleft in the mitral valve aortic leaflet.

Main Results:

• The gap between bridging leaflets in ASDs functions as a commissure, despite lacking papillary muscle support.
• The anterior gap in Rastelli type A malformations is also identified as a commissure, supported by the right ventricle's medial papillary muscle.
• Surgical division of the superior bridging leaflet in Rastelli type C repair is considered a division, not a commissure.

Conclusions:

• Morphological re-evaluation suggests that certain "clefts" in atrioventricular septal defects are functionally commissures.
• This understanding refines the description of atrioventricular canal malformations and aids in surgical planning.
• Distinguishing between commissures and divisions is vital for accurate interpretation of ASD morphology.