Effects of Body Position on the Diagnosis of Right-to-Left Shunt and Standard Operations of Transcranial Doppler for Identification of Right-to-Left Shunt

摘要

Patent foramen ovale (PFO) is the most common cause of intracardiac right-to-left shunt (RLS) and is closely associated with paradoxical thrombotic embolism, crypto-genic stroke, transient ischemic attack, and migraine, regardless of early signs. Nonetheless, the role of PFO as a risk factor for stroke or migraine has always been controversial. Therefore, detection of RLS and research into the correlation between RLS and clinical events are necessary. At present, common methods used in clinical practice for the detection of intracardiac RLS include contrast transesophageal echocardiography, transthoracic echocar-diography, and contrast transcranial Doppler (TCD). Among these, transesophageal echocardiography is the gold standard. However, compared with other methods, sensitivity of TCD is higher due to extracardiac shunts. TCD has the additional advantages of low cost, noninvasiveness, and improved tolerability.