“Aquarium Sign” Observed in All Four Cardiac Chambers During Mechanical Ventilation in a Heart Failure Patient

of 5 cmH2O.Follow-up TTE before weaning from the ventilator scattered (so-called "aquarium sign" 1 ) in all 4 cardiac chambers (Figure A,B; Supplementary Movies 1,2).An immediate imaging with abdominal contrast-enhanced computed tomography (CECT) scan revealed hepatic portal venous gas (HPVG).Gastric wall thickening and poor contrast enhancement were also observed (Figure C,D).Emergency upper gastrointestinal revealed multiple gastric ulcers for which conservative management was initiated.On the following day, repeat echocardiography showed resolution of the microbubbles in all cardiac chambers.We hypothesize that the use of PEEP during mechanical ventilation may have exacerbated right-to-left shunting through a patent foramen ovale, thereby contributing to the appearance of microbubbles in all 4 cardiac chambers, though the presence of a potential internal shunt cannot be ruled out.When the aquarium sign is observed in a cardiac chamber, acute mesenteric ischemia, gastric ischemia, or air embolism, which are associated with HPVG, should be considered, and immediate abdominal CECT should be performed.