Septum secundum and septum primum

The septum primum and septum secundum are two distinct embryonic membranes that grow to partition the primitive atrium into the left and right chambers (StatPearls, 2023). The septum primum is a thin, crescent-shaped fold that grows from the roof of the atrium toward the endocardial cushions, while the septum secundum is a thicker, more rigid structure that develops to the right of the septum primum (NCBI, 2022). Together, they form the foramen ovale, a critical physiological shunt that allows oxygenated blood from the placenta to bypass the fetal lungs (Wikipedia, 2024). At birth, the increase in left atrial pressure forces the septum primum against the septum secundum, leading to functional closure and eventual anatomical fusion into the interatrial septum (NIH, 2023). Failure of this fusion or improper development of these septa results in congenital heart defects such as atrial septal defects (ASD) or a patent foramen ovale (PFO) (PubMed, 2021). These defects are clinically significant as they can lead to paradoxical embolism, cryptogenic stroke, and right-sided heart failure (Mayo Clinic, 2023). These structures are anatomical features and do not serve as molecular targets for drug therapy (StatPearls, 2023). Instead, clinical management of septal abnormalities typically involves surgical repair or transcatheter device closure (PubMed, 2021). Understanding the morphology of these septa is essential for diagnosing and treating structural heart diseases (NCBI, 2022).

Other names

Interatrial septumAtrial septumSeptum atriorumSeptum primumSeptum secundum

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