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Right-to-left shunt (RLS) may be the cause of marked hypoxemia, a respiratory insufficiency which is usually difficult to diagnose by respiratory physicians as it develops in the absence of an intrinsic lung disease.
We report a case of RLS in a patient with a hepatopulmonary syndrome caused by chronic autoimmune cholangitis. RLS was suspected clinically by physical examination and by standard CT imaging and MIP reconstruction of the pulmonary vascular bed. Repeated previous transthoracic echocardiography (TTE) studies did not reveal shunts or any cardiac defect. The final diagnosis was made by means of a minimally invasive transcranial Doppler examination with the use of saline agitated with 0.5ml of patient’s blood as contrast solution.
Transcranial Colour-Coded Duplex Sonography (TCCS) with saline contrast medium injection is described to have a higher sensitivity than TTE and comparable to transesophageal echocardiography (TEE) in RLS diagnosis. The collaboration of neurologists in diagnosing respiratory insufficiency is very important as the examination is simple, well tolerated in comparison with the discomfort associated with transesophageal echocardiography, and minimally invasive in comparison with angiography, which is the last diagnostic procedure in this clinical scenario. In order to confirm RLS, TCCS with blood-saline contrast medium injection should be performed for the diagnosis of chronic hypoxemia for which causes are not detected with routine clinical examinations.