Peripheral arterial disease in spinal cord injury

Jeffrey Wayne Bell, Purdue University

Abstract

Spinal cord injury leads to a variety of sequelae that are determinental to the health of the individual incurring the injury including reduced physical activity, altered body composition, metabolic abnormalities, and increased cardiovascular disease risk. Arterial structure, function, and hemodynamics below the neurological injury level also are altered within weeks of the injury providing evidence that spinal cord injured individuals (SCI) may be predisposed to higher rates of lower-extremity peripheral arterial disease (PAD) compared to able-bodied controls. The purpose of this study was to investigate whether SCI have greater rates of PAD compared to controls and further to determine whether individuals meeting current physical activity recommendations have less PAD. Additionally, we sought to determine whether hemodynamics were altered and to investigate whether altered hemodynamics were associated with measures of PAD. We hypothesized that SCI would have greater rates of PAD, exercise would improve these measures, hemodynamics would be altered in SCI and would be related to PAD measures. To test these hypotheses we utilized an ankle brachial index (ABI) and vascular ultrasonography to determine intima media thickness (IMT) as well as hemodynamic environment in four arteries including the brachial (BA), carotid (CA), superficial femoral (SFA), and popliteal (PA). An ABI and ultrasonography was performed in 105 SCI and 156 able-bodied controls with groups further sub-divided into physically active and sedentary. ABIs were significantly lower in SCI versus controls (0.96 ± 0.12 vs. 1.06 ± 0.07, p < 0.001). Physical activity grouping demonstrated a trend for larger ABI in active compared to sedentary controls (1.08 ± 0.07 vs. 1.05 ± 0.07, p = 0.06), whereas no differences were seen in ABI measurements for active versus sedentary SCI (0.94 ± 0.11 vs. 0.97 ± 0.10, p = 0.28). Upper-body BA and CA IMTs were similar in controls versus SCI. Lower extremity IMTs revealed similar thicknesses for both SFA and PA, but when normalized for artery diameter, individuals with SCI had greater IMT than controls in the SFA (0.094 ± 0.03 vs. 0.073 ± 0.02 mm/mm lumen diameter, p < 0.01) and PA (0.117 ± 0.04 vs. 0.091 ± 0.02 mm/mm lumen diameter, p < 0.01). Lower-extremity artery hemodynamics were altered in SCI in a direction of atheroprotection including increased resting mean shear and reduced resting oscillatory shear index (OSI). OSI was lower in SCI compared to controls for SFA (0.16 ± 0.009 vs. 0.26 ± 0.005, p < 0.01) and PA (0.20 ± 0.011 vs. 0.26 ± 0.004, p < 0.01). Mean shear rate was higher in SCI compared to controls for SFA (43.54 ± 2.79 vs. 20.48 ± 1.09 s-1, p < 0.01) and PA (30.43 ± 2.79 vs. 11.68 ± 0.79 s-1 , p < 0.01). The evidence of a greater burden of PAD in the lower-extremities of SCI should prompt physicians providing care for these individuals to utilize these methods to screen for PAD.

Degree

Ph.D.

Advisors

Newcomer, Purdue University.

Subject Area

Kinesiology|Physiology

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