Hypoxaemia associated with an enlarged aortic root: a new syndrome?

Jean-Christophe Eicher ^1*, Philippe Bonniaud ², Nicolas Baudouin ², Annie Petit ¹, Géraldine Bertaux ¹, Erwan Donal ³, Jean-François Piechaud ⁴, Michel David ⁵, Pierre Louis ¹ and Jean-Eric Wolf ⁶

¹ Department of Cardiology, Centre Hospitalo-Universitaire, Dijon, France
² Department of Pneumology, Centre Hospitalo-Universitaire, Dijon, France
³ Deprtment of Cardiology, Centre Hospitalo-Universitaire, Poitiers, France
⁴ Jacques Cartier Institute, Massy, France
⁵ Department of Cardiovascular Surgery, Centre Hospitalo-Universitaire, Dijon, France
⁶ Depatment of Cardiology, Centre Hospitalo-Universitaire, Dijon, France

^* To whom correspondence should be addressed. E-mail: jean-christophe.eicher{at}chu-dijon.fr.

Accepted 29 November 2004

Abstract

Background: Right-to-left interatrial shunting associated with an aortic aneurysm has been incidentally reported.

Objective: To assess the mechanisms through which an enlarged aortic root may facilitate right-to-left shunting through a patent foramen ovale.

Patients: Nineteen patients with platypnea- orthodeoxia syndrome were compared to thirty control patients without platypnea.

Interventions: Multiplane transesophageal echocardiography.

Main outcome measures: The aortic root diameter, the atrial septal dimension behind the aortic root, and the amplitude of the phasic oscillation of the septum were measured. Four groups of patients were compared : 12 platypneic patients with a dilated aortic root (POS- D), 7 platypneic patients with a normal aorta (POS-N), 15 control patients with a dilated aortic root (CONT-D), and 15 control patients with a normal aorta (CONT-N).

Results: In POS-D and CONT-D patients, the apparent atrial septal dimension was 16.3 (2.7) mm and 17.4 (5.9) mm respectively, compared to 24.4 (5.2) in POS-N patients and 25 (4) in CONT-N (p<0.005). Furthermore, the amplitude of septal oscillation was 14.7 (2.5) mm in the POS-D group v 5.8 (2.4) in CONT-N (p<0,001), compared to 23.3 (3) in 7 patients with an atrial septal aneurysm (p<0.001).

Conclusion: In patients with an enlarged aorta, an apparent smaller dimension and an increased mobility of the atrial septum are seen. These findings appear to be the result of a compression by the aortic root and decreased septal tautness. Consequently, a "spinnaker effect" with the inferior vena caval flow may take place, opening the foramen ovale, and leading to sustained right-to left shunting.

Keywords: aortic root, echocardiography, intracardiac shunt, patent foramen ovale

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• Pemberton, J., Irvine, T., Stewart, M. J., Antunes, G., Gibson, G. J. (2007). Platypnoea orthodeoxia in a patient with aortic root dilatation and a patent foramen ovale. Eur J Echocardiogr 8: 151-154 [Abstract] [Full Text]