Venous air embolism in CT coronary angiography

Venous air embolization (VAE) from IV lines is a risk with IV contrast administration. The incidence of VAE ranges from 7% to 23%. While life-threatening VAE is rare, there is the potential risk of serious cerebrovascular events from paradoxical systemic air embolization (SAE) in patients with congenital intracardiac shunts. CT coronary angiogram (CTCA) hypothetically carries a higher risk of VAE as it requires dual injections as compared to single bolus dose contrast used in CT chest (CTC). The aim of this study was to assess the risk of VAE using CTCA as compared to conventional CTC. The incidence of cardiac shunts and their association with paradoxical SAE were also investigated.

A retrospective study was conducted at a tertiary hospital. Adult patients undergoing CTCA and CTC over a 6-month period in 2017 were included. Images were reviewed on PACS for the presence of VAE. Electronic medical records were interrogated for evidence of neurological sequelae or requiring neurological imaging (CTB/MRIB) within 1 month of the initial imaging.

508 patients were included, 408 underwent CTCA and 100 underwent CTC. The VAE incidence in CTCA was 24% (94 patients) and 10% in the CTC (10 patients). This was statistically significant. Among the CTCA group, 36% (108 patients) had an intracardiac shunt. No statistically significant difference in VAE incidence was identified in CTCA patients with shunts vs without shunts. There was no incidence of SAE in both groups.

VAE is more common with CTCA than conventional CTC. There were no cases of paradoxical SAE found.