A 25 year old man presents with history of breathlessness. A transthoracic echo reveals a patent foramen ovale. What diagnostic inv would you do for a patent foramen ovale?

The key is A. Transesophageal echo. [Bubble study can be done in conjunction with both trans-thoracic echocardiogram and trans-oesophageal echocardiogram. The presence of a patent foramen ovale may be difficult to confirm by a transthoracic echocardiogram. So trans-oesophageal echocardiogram is generally the most accurate available test for doctors to see a patent foramen ovale by using the ultrasound in combination with color flow Doppler or a saline contrast study].