[Severe hypoxemia due to a right-to-left shunt at the atrial level caused by an infarction of the right ventricle].

The authors report the case of a biventricular inferior myocardial infarction complicated in the acute phase by massive tricuspid regurgitation and a right-to-left interatrial shunt through a patent foramen ovale; this resulted in severe hypoxaemia. The diagnosis was made by contrast 2D echocardiography which showed ventriculo-atrial regurgitation and the passage of microbubbles from the right to the left atrium leading to opacification of the left ventricule: right heart catheterisation with oxymetry and selective right ventriculography confirmed the diagnosis. The hypoxaemia became less severe as the haemodynamic conditions improved. This is one possible mechanism of severe hypoxaemia in the acute phase of myocardial infarction and should be excluded routinely in this situation as it can have important prognostic and therapeutid implications.