The effects of whole body vibration on pulse wave velocity in men with chronic spinal cord injury.

OBJECTIVE: A pilot study to evaluate the therapeutic potential of 40 weeks of passive standing with whole body vibration (PS-WBV) on central and peripheral arterial stiffness among men with chronic spinal cord injury (SCI). METHODS: Consenting participants were pre-screened to ensure safe participation. Fifteen individuals with chronic SCI were enrolled to participate in PS-WBV sessions three times per week for 40 weeks on a modified WAVE platform custom-fitted with an EASYStand 5000. Knee angle was set at 160°, and vibration parameters were 45Hz frequency and 0.7mm displacement. Each 45-minute session of PS-WBV training was intermittent (60 seconds on and 120 seconds off). Aortic and leg pulse wave velocity (PWV) was measured at baseline, mid-point (20 weeks) and exit (40 weeks). RESULTS: Nine males (age 41±11 years, American Spinal Injury Association Impairment Scale A-D, neurological level of injury T4-T10, years post-injury 12±8 years) completed the intervention. Aortic PWV was collected on n=7 at exit, and leg PWV was collected on n=6 at exit. No changes over time were found for either aortic PWV (P = 0.46) or leg PWV (P = 0.54). One possible study-related serious adverse event occurred during study intervention: the development of a grade III pressure sore on the right proximal anterior shin (n=1). CONCLUSION: Forty weeks of PS-WBV in adults with SCI did not result in an observable change in arterial stiffness.

Association between abnormal arterial stiffness and cardiovascular risk factors in people with chronic spinal cord injury.

Aims To describe the association between cardiovascular risk factors and abnormal arterial stiffness, defined by a carotid-femoral pulse wave velocity ≥ 10 m/s, in patients with chronic spinal cord injury (SCI). Methods Ninety consenting adults with chronic SCI (C1-T10 ASIA Impairment Scale A-D) participated in this cross-sectional study. The cardiovascular risk factors considered included age, sex, duration of injury, neurological level of injury (C1-T1, tetraplegia; T2-T12, paraplegia), age at injury, impairment scale category, supine resting systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, leisure time physical activity, treated hypertension, treated hyperlipidemia, diabetes, lipid profiles, fasting blood glucose, glycated hemoglobin, and C reactive protein. Logistic regression analysis was used to determine the association between abnormal arterial stiffness and dichotomized cardiovascular risk factors. Results Dichotomized variables significantly associated with increased arterial stiffness were: age ≥ 52 years (OR 22.1, CI 4.28-113.99); systolic blood pressure ≥ 130 mmHg (OR 11.76, CI 2.89-47.88); heart rate ≥ 62 bpm (OR 6.62, CI 1.33-33.03); and paraplegia (OR 4.26, CI 1.00-18.33). The area under the receiver operating characteristic curve for probability of arterial stiffness was 0.920 (95% CI 0.861-0.978, p < 0.001). Conclusions Age, resting systolic blood pressure, resting heart rate, and neurological level of injury can identify patients at high risk of elevated arterial stiffness in the population with chronic SCI.

Exploring the associations between arterial stiffness and spinal cord impairment: A cross-sectional study.

BACKGROUND/OBJECTIVE: Elevated aortic arterial stiffness (aortic pulse wave velocity: aPWV) is an independent coronary artery disease predictor among the general population. The purpose of this study was to: (1) report aPWV values in a representative cohort of patients with spinal cord injury (SCI); (2) to compare aPWV values in people with SCI based on neurological level of injury; and (3) to contrast the reported aPWV values with available normal values for the general population. METHODS: Adults with chronic SCI (n = 87) were divided into two groups (TETRA group, n = 37 and PARA group, n = 50). aPWV and potential confounders of aPWV were assessed. Analysis of covariance was used for comparisons between groups and adjusted for the confounders. Subjects' aPWV values were contrasted with reference values for general population determined by "The Reference value for arterial stiffness' collaboration" and prevalence of abnormal aPWV defined as greater than or equal to the age-specific 90th percentile was reported. RESULTS: Prevalence of abnormal aPWV in the cohort was 25.3%. After adjusting for covariates, the mean aPWV values were significantly different between two groups (TETRA: 8.0 (95% confidence interval (CI): 7.5-8.6) m/second, PARA: 9.0 (95% CI: 8.5-9.4) m/second, P = 0.010). The prevalence of abnormal aPWV was significantly higher in the PARA group (36%) compared to the TETRA group (11%) (P = 0.012). CONCLUSIONS: One-quarter of the total cohort had an abnormal aPWV. Subjects with paraplegia had higher aPWV values and a higher frequency of abnormal aPWV than subjects with tetraplegia. Elevated aPWV in people with SCI, particularly those with paraplegia, may impart significant adverse cardiovascular consequences.

Test-retest reliability of pulse wave velocity in individuals with chronic spinal cord injury.

BACKGROUND: Pulse wave velocity (PWV), which reflects arterial stiffness, is an important predictor of future coronary artery disease. The test-retest reliability of PWV has not been investigated in people with spinal cord injury (SCI). PURPOSE: To report the test-retest (day-to-day) reliability of PWV measurements among people with SCI, and to determine the smallest real difference (SRD) of PWV values. PARTICIPANTS: Twenty men (n = 19) and a woman (n = 1) with SCI (C4-T10; AIS A-D; ≥ 1-year post-injury; 10 with paraplegia and 10 with tetraplegia; time post-injury: 11.8 ± 8.7 years; age: 43.0 ± 12.6 years). METHODS: On two occasions within a 2-week period, aortic PWV (between the common carotid and femoral artery), arm PWV (between the brachial and radial artery), and leg PWV (between femoral and posterior tibial artery) were assessed at the same time of day using Doppler flowmeters. RESULTS: No statistically significant differences were found between days 1 and 2 in aortic PWV (day 1: 941 ± 185 cm/seconds, day 2: 917 ± 160 cm/seconds, P = 0.257), leg PWV (day 1: 1088 ± 141 cm/seconds, day 2: 1122 ± 165 cm/seconds, P = 0.099) and arm PWV (day 1: 1283 ± 185 cm/seconds, day 2: 1358 ± 256 cm/seconds, P = 0.180). The aortic and leg PWVs had high test-retest reliability (intraclass correlation coefficient: ICC = 0.920 and 0.913, respectively; P < 0.001 for both) and arm PWV had moderate test-retest reliability (ICC = 0.598, P = 0.03). SRDs for each PWV were 104 cm/seconds (aortic PWV), 97 cm/seconds (leg PWV) and 143 cm/seconds (arm PWV). CONCLUSION: The test-retest reliability of PWV assessment is high among patients with chronic SCI. Changes in aortic PWV values above 104 cm/seconds with repeated testing like represent true changes in health status.