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

Abstract

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.

Intra-arrest transesophageal echocardiography during cardiopulmonary resuscitation

“…Intra-arrest TEE is performed to explore the mechanism of blood flow during CPR, diagnose the possible cause of CA, monitor the presence of cardiac contraction, assess the effectiveness of chest compression, guide catheter cannulation, and evaluate the complications of CPR. Table 1 summarizes the indications and objectives of intra-arrest TEE and the echocardiographic findings of intra-arrest TEE in the literature [ 5 - 47 ].…”

“…Kinetic analysis of chest compressions can be performed by measuring the excursions of the free wall of the RV [ 34 ]. An intracardiac shunt or paradoxical embolism can be detected during intra-arrest TEE [ 41 , 47 ].…”