[Patency of the foramen ovale in paradoxical embolism. Detection by contrast echocardiography and the cough provocation test].

Five patients with suspected paradoxical embolism were investigated for patent foramen ovale by contrast echocardiography. Right-to-left shunting was demonstrated in 3 patients: during a Valsalva manoeuvre in one and during coughing fits in all three. Patency of the foramen ovale was confirmed by cardiac catheterization in these 3 patients. In 2 patients the foramen was not patent and the diagnosis of paradoxical embolism was not confirmed. In two other patients, the right and left atrial pressures were measured simultaneously during a Valsalva manoeuvre and during coughing. The normal pressure gradient between the two atria was suppressed during the relaxation stage, resulting in decreased curvature of the interatrial septum which facilitated the flow of blood from the inferior vena cava into the left atrium. Coughing appears to be a simpler and more sensitive test than the Valsalva manoeuvre to induce transient right-to-left atrial shunting.