Diastolic right-to-left shunting in a patient with atrial septal defect and pericardial tamponade.

We present the case of a patient with an atrial septal defect who presented with hypotension, hypoxia, and cyanosis as a result of pericardial tamponade. The classic findings of pulsus paradoxus and low measured right heart output were not present. Echocardiography demonstrated the atrial septal defect, pericardial effusion, and diastolic chamber collapse. Furthermore, Doppler study showed not only a large left-to-right shunt but also a diastolic right-to-left shunt, which explained the patient's hypoxia.