Fig. 2.

Interatrial shunt in a mechanically ventilated patient with acute cor pulmonale. Interatrial shunt in a mechanically ventilated patient with acute cor pulmonale due to COVID-19. a Labeled 2-D subcostal 4-chamber transthoracic echocardiographic (TTE) view of the heart demonstrating dilatation of the right atrium (RA) and right ventricle (RV). LA, left atrium; LV, left ventricle. b 2-D subcostal 4-chamber TTE view of the heart after i.v. injection of saline microbubble contrast showing the arrival of the contrast in the RA and RV. c Labeled 2-D subcostal 4-chamber TTE view of the heart after i.v. injection of saline microbubble contrast demonstrating grade 4 shunt (opacification of left atrium). Bubbles appeared in the LA within 3 cardiac cycles of opacification of the RA demonstrating the presence of an interatrial shunt