apid and Extensive Arterial Adaptations After Spinal ord Injury

Objective: To assess the time course of adaptations in leg ascular dimension and function within the first 6 weeks after spinal cord injury (SCI). Design: Longitudinal study design. Setting: University medical center and rehabilitation clinic. Participants: Six men were studied serially at 1, 2, 3, 4, and weeks after SCI. Interventions: Not applicable. Main Outcome Measures: Diameter, blood flow, and shear ate levels of the common femoral artery (CFA), superficial emoral artery (SFA), brachial artery, and carotid artery were easured with echo Doppler ultrasound (diameter, blood flow, hear rate). Endothelial function in the SFA was measured with ow-mediated dilation (FMD). In addition, leg volume and lood pressure measurements were performed. Results: Femoral artery diameter (CFA, 25%; SFA, 16%; .01) and leg volume (22%, P .01) decreased simultaeously, and these reductions were largely accomplished within 3 eeks postinjury. Significant increases were observed for basal hear rate levels (64% increase at week 3; 117% increase at eek 6; P .01), absolute FMD responses (8% increase at eek 3, 23% increase at week 6; P .05) and relative FMD esponses (26% increase at week 3, 44% increase at week 6; .001). Conclusions: Our findings show a rapid onset of adaptations n arterial dimension and function to extreme inactivity in umans. Vascular adaptations include extensive reductions in emoral diameter and leg volume, as well as increased basal hear rate levels and FMD responses, which all appear to be argely accomplished within 3 weeks after an SCI.