[Right-left auricular shunt caused by patent foramen ovale at a multi-purpose intensive care unit. Apropos of 3 cases].

Three cases of symptomatic right-to-left interatrial shunt through a patent foramen ovale were detected in the course of a case of paradoxical embolism related to a massive pulmonary embolism, a case of refractory hypoxemia after cardiopulmonary bypass and a case of refractory hypoxemia in a patient with tricuspid endocarditis. According to anatomic studies, the incidence of patent foramen ovale is 25-30% in healthy people. In that case any pathological event generating an increase in the right atrial pressure higher than the left atrial pressure may induce a right-to-left shunt with systemic arterial desaturation and possible paradoxical embolization. The reported cases emphasize the advantage of ultrasonic examinations (contrast sonocardiography, pulsated or coloured Doppler) to show the right-to-left atrial shunt. The demonstration of this acquired shunt requires appropriate measures in order to reverse the atrial gradient. Sometimes a specific therapy is required such as caval filter insertion in case of pulmonary embolization or surgical closure of foramen ovale in some patients.