How to Interpret Bubbles After Three to Eight Heartbeats

The TTE does demonstrate a delayed appearance of bubbles going from right to left atrium. If the bubbles show up early, meaning fewer than four cycles, this indicates an intracardiac shunt. Those occurring after four beats indicate an interpulmonary shunt. In normal subjects, these micro bubbles would be seen in the right heart and then would flow into the pulmonary circulation where they are stopped by ECHO. However, in patients with right to left shunting, these bubbles can pass into the left side of the heart.