Echocardiographic diagnosis of right-to-left shunt using transoesophageal and transthoracic echocardiography.

Compared with TOE using shunt visualisation, TTE accurately diagnosed large PFO using criteria of cardiac cycles ≤3 and shunt grade ≥III. TTE possibly diagnosed pulmonary shunt using criteria of cardiac cycles >3 and shunt grade ≥III. Both modalities showed limitations in diagnosing small amount of RLS.