Anotomic interaction between the aortic root and the atrial septum: a prospective echocardiographic study.

Background: We recently demonstrated that patients with platypnea-orthodeoxia syndrome and an enlarged aortic root had a smaller and hypermobile atrial septum (AS) compared with those with a normal aortic root. However, this was a partly retrospective study.

Methods: In all, 72 patients underwent transesophageal echocardiography and cardiac catheterization. The aortic root diameter, AS dimension, AS oscillation amplitude (ASo), and atrial pressure gradient were measured.

Results: Significant correlations were found: aortic root diameter and AS dimension (r = -0.5, P < .001), aortic root diameter and ASo (r = +0.3, P = .014), AS dimension and ASo (r = -0.28, P = .02), and ASo and atrial pressure gradient (r = -0.36, P = .003). Nineteen patients presented with patent foramen ovale; those with grade 3 shunting had significantly higher mobility of the AS and larger aortic roots.

Conclusion: These results confirm that an increasing aortic size affects the AS by decreasing its apparent size and increasing its mobility. In case of a patent foramen ovale, increased AS mobility is associated with greater shunting.