Porcine heart interatrial septum anatomy

The left-sided atrial septal pouch (SP), a recently re-discovered anatomical structure within the human interatrial septum, has emerged as a possible source of thrombi formation and a trigger for atrial fibrillation, thereby potentially increasing the risk for ischemic stroke. In many studies, the swine interatrial septum has been used as model of the human heart. Also, possible new strategies and devices for management of the SPs may first be tested in this pig model. Therefore, in this study, we aimed to evaluate swine interatrial septum morphology and to compare it with the human analog, especially in the light of SP occurrence.

A total of 75 swine (Sus scrofa f. domestica) hearts were examined. The interatrial septum morphology was assessed, and SPs were measured.

The most common variant of the interatrial septum was smooth septum (26.6%) followed by the patent foramen ovale channel and right SP (both 22.7%). No left or double SPs were observed. In 28.0% of all cases the fold of tissue (left septal ridge) was observed on the left side of the interatrial septum in the location where the left-sided SP should be expected. The mean length of the patent foramen ovale channel was 7.1±1.5mm. The mean right SP depth was 6.3±2.2mm, and its ostium width and height were 5.8±1.2 and 5.3±1.6mm, respectively.

There are significant differences between human and porcine interatrial septum morphology that should be taken into account during experimental studies. The absence of the left SP in swine results in the inability to use porcine heart as an experimental model for left-sided SP management.