Anatomical bases of the surgical dissection of the interatrial septum: a morphological and histological study.

BACKGROUND

The interatrial septum (IAS) can be dissected to resect pulmonary tumors invading the left atrium. The aim of this study was to describe the dissected structures, and to expose the benefits, the limits, and the embryologic reasons of such dissection.

METHODS

We dissected the IAS of 11 fresh, non-embalmed human hearts. The dissected structures were described and the length and depth of the dissection were measured. A histological study was performed in four other fresh hearts to identify and differentiate between dissectible and non-dissectible structures.

RESULTS

The dissection was performed through a fatty tissue located between two muscular walls. The depth limit of the IAS dissection was identified as the limbus of the fossa ovalis and the muscular roof of the atria. The section of the latter doubles the depth of the dissection at the level of the upper pulmonary veins. Mean length of the dissected IAS was 77 mm (55-90). Mean depths of the IAS were 41 mm (35-50) at the level of the left upper pulmonary vein, 27 mm (12-35) between the upper and lower pulmonary veins, and 14 mm (8-20) at the level of the left inferior pulmonary vein

CONCLUSION

The surgical dissection of the IAS is performed through the septum secundum that appears as an infold of the atrial wall. The length of the resectable left atrial cuff reaches a mean of 40 mm at the level of the upper pulmonary vein.