Ask your cardiologist about monitoring with an event recorder to try and capture the heart rhythm during an episode to help decide the nature of the problem
Shunts can be intermittent at times and are best evaluated by using various manuovers to change intracardiac pressures (like Valsalva) during TEE with bubble study
Bubbles seen in the left side of the heart after the 5th cardiac cycle can be from the natural passage of blood through the lung blood vessels and may not represent a residual shunt