Carotid and Femoral Artery Intima-Media Thickness During 6 Months of Spaceflight

Abstract

Introduction: The objective was to determine the effects of 6 mo of microgravity exposure on conduit artery diameter and wall thickness.

Methods: Diagnostic images of the common carotid artery (CC) and superficial femoral artery (FA) were obtained using echography which astronauts performed on themselves after receiving minimal training in the use of ultrasound imaging. Echographic video was recorded using a volume capture method directed by a trained sonographer on the ground through videoconferencing. Vessel properties were later assessed by processing the downlinked video. Data were collected from 10 astronauts who performed the echographic video capture at the beginning of the spaceflight (day 15) and near the end of the spaceflight (day 115 to 165). In-flight and postflight measurements were compared to preflight assessments.

Results: No significant changes with spaceflight were found for CC and FA diameter. Intima-media thickness (IMT) of the CC was found to be significantly increased (12% ± 4) in all astronauts during the spaceflight (early and late flight) and remained elevated 4 d after returning to Earth. Similarly, FA IMT was increased during the flight but returned to preflight levels 4 d postflight.

Conclusion: The experiment demonstrated that, using the volume capture method of echography, untrained astronauts were able to capture enough echographic data to display vessel images of good quality for analysis. The increase in both CC and FA IMT during the flight suggest an adaptation to microgravity and to the confined environment of spaceflight which deserves further investigation.