[Postural effect in patients with patent foramen ovale: evaluation of right-to-left shunt with transcranial Doppler and transthoracic echocardiography and correlation with arterial oxygen saturation]

Background. Transcranial Doppler echocardiography and transthoracic echocardiography may detect with high accuracy right-to-left shunt (RLS) due to patent foramen ovale (PFO). However, a standardized diagnostic protocol has never been established. It has been suggested that standing or sitting positions may improve sensitivity of transcranial Doppler due to increased LRS in such positions. We aimed to test efficacy of the sitting position in addition to the supine position in the grading of RLS in patients with PFO. We have also evaluated whether an increase in RLS is associated with a fall in oxygen saturation (SaO2). Methods. From September 2015 to February 2016, 70 consecutive patients with suspected PFO underwent transcranial Doppler echocardiography and transthoracic echocardiography with microbubble count and evaluation of SaO2. Results. RLS due to PFO was diagnosed in 58 patients (82.9%). An increase in RLS grade in the sitting position was observed in 28 out of 58 patients (48.3%) (group 1), whereas no increase was detected in 30 patients (51.7%) (group 2). Among the clinical and echocardiographic variables considered, group 1 and group 2 differed only in the prevalence of atrial septal aneurysm (35.7 vs 3.3%, p=0.002). Postural changes were not associated with a fall in SaO2. Conclusions. RLS increases in about half of patients with PFO in the sitting position compared with the supine position, whereas no changes occur in SaO2.