The Sinus Venosus Veno-Venous Bridge: Not a septal defect

Area of Science:

• Cardiology
• Anatomy
• Medical Morphology

Background:

• Sinus venosus defects (SVDs) were previously thought to involve a 'common wall' between right pulmonary veins and the superior caval vein.
• This review updates the understanding of SVD morphology, challenging earlier concepts.

Purpose of the Study:

• To provide an updated morphological description of sinus venosus defects.
• To differentiate SVDs from other types of atrial septal defects based on anatomical features.

Main Methods:

• Review of current anatomical and embryological evidence.
• Comparative morphological analysis of different atrial septal defects.

Main Results:

• The superior rim of the oval fossa is an infolding, not a common wall or second septum.
• SVDs result from anomalous pulmonary venous connections creating a veno-venous bridge outside the oval fossa.
• SVDs, ostium defects, and coronary sinus defects are morphologically distinct from true atrial septal defects within the oval fossa.

Conclusions:

• The understanding of sinus venosus defect morphology has evolved.
• Accurate morphological differentiation is crucial for diagnosing and managing congenital heart defects.