Eur J Cardiothorac Surg 2002;21:580-581
© 2002 Elsevier Science NL
Intermittent cyanosis: unusual diagnosis of an ascending aortic aneurysm
Jean-Michel Grinda*,
Emmanuel Lansac,
Alain Berrebi,
Alain Deloche
Cardiac Surgery Department, Hopital Europeen Georges Pompidou, 21 rue Leblanc, 75908, Paris cedex 15, France
Received 11 October 2001;
received in revised form 11 December 2001;
accepted 17 December 2001.
* Corresponding author. Tel.: +33-1-56-09-36-24; fax: +33-1-56-09-22-19
e-mail: jean-michelgrinda{at}egp.ap-hop-paris.fr
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Abstract
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The authors report here an unusual case of an ascending aorta aneurysm diagnosed in the event of a check-up for a dyspnea with cyanosis. The right atrium compression by the aneurysm initiated a right-to-left shunt through a patent foramen ovale.
Key Words: Ascending aortic aneurysm • Foramen ovale • Intermittent cyanosis
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1. Introduction
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The prevalence of a patent foramen ovale (FO) within the global population is about 20–25% [1]. Usually asympytomatic, the FO can become re-permeable and induce a right-to-left shunt in all pathologies leading to increased pressures within the right cavities. This phenomena has been described in acquired pulmonary pathologies with pulmonary arterial hypertension as well as in patients with normal or sub-normal pulmonary arterial pressures. We report here a case of a right atrium compression by an ascending aorta aneurysm initiating a right-to-left symptomatic shunt.
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2. Case report
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A 64-year-old female patient, recently diagnosed as hypertensive consulted for cyanosis episodes of extremities. Clinical examination was of no special nature. Facing a severe rest hypoxemia (PaO2 53 mmHg), a first pneumologic check-up (pulmonary X-rays, respiratory functional tests, thoracic scanning, pulmonary scintigraphy) did not reveal any pulmonary pathologies but detected a 53 mm diameter ascending aorta aneurysm. The proximal part of the ascending aorta, the sinus of Vasalva and notably the non-coronary sinus were involved by the aneurismal dilatation. A hyperoxia test was carried out revealing a true right-to-left shunt estimated at 25% of blood flow (under FiO2 100%, PaO2 measured at 82 mmHg for a theoretical PaO2 at 687 mmHg).
While investigating for a cardiac etiology, a transthoracic echography did not reveal any abnormal atrial or ventricular communication, but showed a right atrium compression and an interatrial septal forcing by the ascending aortic aneurysm (Fig. 1
). During a right catheterization, right atrium pressure was at 7 mmHg and at 5 mmHg in the pulmonary capillary without any pulmonary arterial hypertension. Trans-oesophageal cardiac echography with contrast test brought out a positional right-to-left shunt, increased by a lateral decubitus, through a patent foramen ovale.
The patient underwent surgery for ascending aorta and aortic valve replacement (Bentall procedure) with direct closing of the foramen ovale. Postoperative course was uneventful and her symptoms resolved.
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3. Discussion
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The interest of this case lies in the circumstances during which the ascending aorta aneurysm was discovered. Actually dyspnea and cyanosis being the only symptoms, investigations were primarily directed towards a pulmonary etiology. In view of the normal results obtained after examinations, hyperoxia test was the key test, since it allowed us to bring out a shunt and its cardiac output-related quantization. Cardiac echography with contrast test thus appears to be the most rational and less invasive examination to locate the abnormal communication site.
FO accounts for valvular formation only allowing a right-to-left blood flow. Left pressures usually higher than right ones account for the lack of physiological shunt. Apart from true pulmonary artery hypertension, some pathological cases can generate a FO re-permeabilization.
This phenomenon is well known in ICU or during cardiac surgery postoperative course in ventilated patients suffering from severe hypoxia not related to pulmonary condition. A shunt results from the increase of pulmonary resistance induced by positive expiratory pressure related to a right ventricular (RV) compliance defect, as well as to modified pressure regimen [1–3].
In other observations, we notice an obstructive mechanism as for right atrium (RA) myxoma obstructing the tricuspid valve [2] or as for obstructive cardiomyopathy with a septal buffer over the RV [4]. FO re-permeabilization can be compared to this mechanism, related to RV compliance defect as for infarction or RV calcifications [4,5]. In patients who have undergone lobectomy, the right atrium and the inferior vena cava anatomical changes are to be involved, generating a preferential flow or inferior cava venous blood through the FO [6].
In the reported case, there are two mechanisms to explain a shunt re-permeabilization whilst pulmonary artery pressures are normal. First, the right atrium compression by the aneurysm induces a right atrial pressure increase associated with a FO relative opening caused by the interatrial septal defect and secondly the anatomical changes of the right atrium which would encourage inferior cava venous return within the FO axis [7].
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References
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Abstract
1. Introduction
