Value of adding blood to agitated saline for detection of right-to-left shunt by contrast transcranial Doppler ultrasound

AIM To compare the efficacy of two contrast agents (CAs), namely, agitated saline (AS) and AS with blood (ASb), in the diagnosis of right-to-left shunt (RLS) by contrast-enhanced transcranial Doppler (c-TCD). METHODS The study was conducted in 521 consecutive patients with patent foramen ovale (PFO), who suffered from cryptogenic stroke and/or migraine. For each patient, we performed c-TCD both at rest and during Valsalva maneuver using two different contrast agents: AS and ASb and compared the results. RESULTS RLS was detected respectively in 30% at rest and in 45% during Valsalva maneuver using ASb, and in 14% and in 33% using AS (P<0.01). The positive rates of both ASb and AS during Valsalva maneuver were obviously higher than those at rest. The positive rate and the number of micro-embolic signals using ASb were statistically higher than those using AS. CONCLUSION SASb can significantly increase the efficacy of c-TCD contrast agent in the diagnosis of right-to-left shunt and clinically can be widely used as a standard contrast agent.