Azygos reflux: a CT sign of cardiac tamponade.

Three patients who were investigated with dynamic contrast medium enhanced computed tomography (CT) of the thorax were noted to have pericardial effusions with reflux of contrast medium back along the azygos vein. The diagnosis of cardiac tamponade was not made clinically, but in each case was suggested from the CT findings. Confirmation of the diagnosis was made in all three cases, two patients with echocardiography and one at post mortem. One patient made a rapid recovery following the insertion of a pericardial drain, another made a temporary recovery after pericardiocentesis but the third died. Thirty CT scans performed with similar protocol were reviewed and none of these demonstrated reflux along the azygos vein. The presence of contrast medium refluxing into the azygos vein implies significant haemodynamic disturbance, and in the presence of a pericardial effusion suggests the diagnosis of cardiac tamponade.