Fig. 1

A-1,2: Grade 1—< 5 bubbles within LV only after Valsalva maneuver (yellow arrows: bubbles within LA and LV) LA: left atrium, LV: left ventricle. B-1,2: Grade 2—5 to 25 bubbles within LV both resting and after Valsalva maneuver. C-1,2: Grade 3—> 25 bubbles or opacification within LV