Identification and Morphogenesis of Vestibular Atrial Septal Defects

Area of Science:

• Cardiovascular Pathology
• Developmental Biology
• Congenital Heart Defects

Background:

• Vestibular atrial septal defects are rare interatrial communications in the antero-inferior septum.
• They may result from developmental issues like inadequate muscularization or excessive apoptosis.
• This study investigates their frequency and potential origins.

Purpose of the Study:

• To determine the frequency of vestibular atrial septal defects in human necropsy specimens.
• To identify associated cardiac malformations.
• To explore the potential morphogenesis of these defects using developing mouse hearts.

Main Methods:

• Analysis of 2100 necropsy specimens from three cardiac archives.
• Identification of vestibular atrial septal defects and associated intracardiac malformations.
• Assessment of 450 developing mouse heart datasets using episcopic microscopy.

Main Results:

• A total of 68 (3%) vestibular atrial septal defects were identified in the human specimens.
• Similar defects were observed in mouse embryos at embryonic day 15.5.
• The defects are located in the muscular antero-inferior rim of the oval fossa.

Conclusions:

• Vestibular atrial septal defects may be more common than previously recognized.
• Increased clinical awareness of their location can improve identification.
• Embryonic developmental failure in septal component fusion is a likely cause.