Differentiation between patent foramen ovale and pulmonary arteriovenous malformations via simultaneous contrast transthoracic echocardiography and transcranial doppler

The objective is to differentiate between patent foramen ovale (PFO) and pulmonary arteriovenous malformations (PAVM) using simultaneous contrast transthoracic echocardiography (cTTE) and contrast transcranial cerebral Doppler (cTCD). A total of 193 patients suspected of having a right-to-left shunt were classified into four groups based on the reference standard, including PFO (n = 102), PAVM (n = 18), negative subjects (n = 53), and indeterminate group (n = 20). Simultaneous cTTE and cTCD were performed in all patients. The comparison between PFO and PAVM was as follows: (1) The cut-off for cardiac cycles was set at ≤ 3 for PFO and ≥ 4 for PAVM. (2) Regarding the quantity of left atrial (LA) bubbles at rest, less than 30 bubbles were observed in 76.4% of patients with PFO, while more than 30 bubbles were found in 94.4% of patients with PAVM. (3) The cut-off of incremental bubbles during modified Valsalva were set at ≥ 10 bubbles for PFO and ≤ 1 bubble for PAVM. (4) The percentages of observed bubbles crossing either interatrial septum or pulmonary vein were 11.8% and 72.2% in the PFO and PAVM groups, respectively. In PFO group, the simultaneous use of cTTE and cTCD demonstrated a high area under the curve (AUC) of 0.973 using incremental bubbles. The successful application of cTCD-guide Valsalva maneuver resulted in a higher quantity of LA bubbles observed in cTTE findings. Simultaneous use of cTTE and cTCD enables differential diagnosis between PFO and PAVM. Moreover, the use of cTCD-guide Valsalva maneuver is recommended for PFO diagnosis.