Right-to-Left Shunts Occur During Cardiopulmonary Resuscitation: Echocardiographic Observations.

OBJECTIVES

A significant proportion of the population has a patent foramen ovale (PFO). The intracardiac pressure during cardiopulmonary resuscitation (CPR) may differ from that of normal circulation, which may result in a right-to-left shunt in the presence of a PFO. In this study, transesophageal echocardiography (TEE) was conducted to evaluate whether CPR carried out in patients after cardiac arrest causes right-to-left shunt.

DESIGN

A retrospective observational study.

SETTING

One academic medical center from January 2017 to April 2020.

PATIENTS: Patients older than 20 years who suffered from nontraumatic out-of-hospital cardiac arrest (OHCA) and underwent intra-arrest TEE.

MEASUREMENT AND MAIN

RESULTS

Patients who had microbubbles resulting from fluid injection in the right atrium, as indicated on TEE imaging, were included in the analysis. The presence of right-to-left shunt was defined as the appearance of microbubbles in the systemic circulation, including the left atrium, left ventricle, or aorta. A total of 97 patients were included in the final analysis. A right-to-left shunt was observed in 21 patients (21.6%), and no shunt was found in 76 patients (78.4%). The degree of the right-to-left shunt, determined by the number of microbubbles, was mild in 11 patients (52.4%), moderate in eight (38.0%), and severe in two (9.6%). Multivariate analysis showed that no factors were associated with the presence of right-to-left shunt during CPR.

CONCLUSIONS

Right-to-left shunts can be appreciated during CPR in patients who experience OHCA. Further studies are needed to verify its clinical significance.