Abstract
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.