Diagnostic criteria for determining the type of the right-to-left shunt using contrast-enhanced transcranial Doppler ultrasound in young patients with ischemic stroke/transient ischemic attack

Objective. To determine specific diagnostic criteria for detecting the type of the right-to-left shunt by contrast-enhanced transcranial Doppler ultrasound (cTCD) in young patients with paradoxical embolism and ischemic stroke/TIA. Material and methods. The study included 64 ischemic stroke or transient ischemic attack patients (age 28–44 years) with patent foramen ovale (PFO), atrial septal defect (ASD) or pulmonary arteriovenous malformation (PAVM). cTCD was used to assess the degree of shunting, its change during the Valsalva maneuver (VM), time to the fi rst microembolic signal (MES) detection, and the duration of MES registration. Results. According to cTCD data, 20% of patients with PFO had no shunt at rest, and 80% had a mild to moderate right-to-left shunt. After VM, a severe shunt was detected in 75% of patients in this group and a moderate shunt in 25%. All patients with ASD and PAVM had a marked shunt at rest. The difference in time to first MES detection from the start of contrast administration was not statistically significant for all groups. The duration of MES registration that indicated shunting was shorter in patients with PFO compared to those with ASD (p < 0.001) or with PAVM (p < 0.001) and it was significantly longer in patients with PAVM compared to those with ASD (p < 0.001). Conclusion. The key diagnostic criteria to defi ne the right-to-left shunt type are the functional shunt degree at rest and the duration of MES registration. Severe shunting at rest can suggest the presence of ASD or PAVM, while the duration of MES registration > 2 min suggests a PAVM.