Morphological Characteristics of Interatrial Septum and Its Clinical Relevance

The development of new trans-septal transcatheter interventions for patients with structural heart disease necessitates a precise and comprehensive understanding of the anatomy of the interatrial septum (IAS). The scarcity of gross anatomical studies has triggered our interest in exploring the morphometry and morphology of IAS.

To study the morphology, morphometry and variations of the interatrial septum in autopsied human hearts.

The study was conducted on 97 autopsied fresh human hearts, in which we observed the position and shape of fossa ovalis (FOv), along with prominence of the limbus and its location. The diameter of FOv, thickness of its floor, redundancy and any variation in the IAS were noted.

In most cases (72.9%), the FOv was situated toward the inferior vena cava and was oval shaped (69.8%), with mean horizontal and vertical diameters of 17.21 ± 4.11 mm and 12.74 ± 3.78 mm, respectively. The limbus was prominent in 72.2% specimens, most commonly prominent all around (36.6%), followed by antero-superior (28.2%), antero-inferior (16.9%) and anterior (8.5%) prominence. The mean thickness of the floor of FOv was 0.71 ± 0.98 mm, and redundancy was observed in 47% of samples. Probe patency was seen only in 10.3% specimens. The right surface of the IAS showed more variations (71.1%) compared to the left (44.3%), in form of recesses, atrial septal pouches, fibrous strands, retinacular-type fibrous networks and combination of more than one type.

Variations in the location of FOv, the prominence of limbus and the common occurrence of anatomical variants of the IAS mandate the preprocedural imaging of the region to reduce the failure rate and complications.