Jennifer L. Olive

Vascular remodeling after spinal cord injury.

PURPOSE Our purpose was to determine whether spinal cord injured (SCI) subjects have decreased femoral artery diameter and maximal hyperemic blood flow when expressed per unit of muscle volume compared with able-bodied (AB) individuals. A secondary purpose was to determine whether blood flow recovery rates were similar between groups. METHODS Blood flow was measured in the femoral artery using Doppler ultrasound after distal thigh cuff occlusion of 4 and 10 min. Muscle mass of the lower leg was determined by magnetic resonance imaging (MRI). RESULTS SCI individuals had smaller muscle cross-sectional areas (37%, P = 0.001) and volumes (38%, P = 0.001) than AB individuals. Furthermore, femoral artery diameter (0.76 +/- 0.14 vs 0.48 +/- 0.06 cm, AB vs SCI, P < 0.001) and femoral artery maximal blood flow (2050 +/- 520 vs 1220 +/- 240 mL x min-1, AB vs SCI, P < 0.001) were lower in SCI than AB individuals. Femoral artery diameter and maximal blood flow per unit muscle volume did not differ between SCI and AB individuals (P = 0.418 and P = 0.891, respectively). Blood flow recovery after ischemia was prolonged in SCI compared with AB individuals for both cuff durations (P = 0.048). CONCLUSIONS In summary, femoral artery diameter and maximal hyperemic blood flow response per unit muscle volume are not different between SCI and AB individuals. Vascular atrophy after SCI appears to be closely linked to muscle atrophy. Furthermore, the SCI compared with AB individuals had a prolonged time to recovery, which may suggest decreased vessel reactivity.

The effects of aging and activity on muscle blood flow

BackgroundOur purpose was to determine if aging had an influence on muscle blood flow independent of habitual physical activity levels.MethodsBlood flow was measured in the femoral artery by Doppler ultrasound after cuff occlusion of 10 minutes. Active and inactive older subjects (73 ± 7 years) were compared to active and inactive young subjects (26 ± 6 years).ResultsPeak blood flow capacity when normalized to lean muscle mass was related to activity level (p < 0.001), but not to age. Specifically, the young active group had higher peak blood flows than the young inactive (p = 0.031) or older inactive (p = 0.005) groups. Resting blood flow and conductance were not significantly different between groups. Mean arterial pressure was significantly higher in the older compared to young group (p = 0.002). Conductance was related to both activity (p = 0.002) and age (p = 0.003). A prolonged time for blood flow to recover was found in the older compared to the young group (p = 0.038) independent of activity status.ConclusionsThe prolonged recovery time in the older subjects may suggest a reduced vascular reactivity associated with increased cardiovascular disease risk. Peak blood flow capacity is maintained in older subjects by physical activity. In summary, maximal flow capacity and prolonged recovery of blood flow are influenced by different mechanisms in young and older active and inactive subjects.

Blood flow response to a postural challenge in older men and women

BackgroundThe purpose of this study was to measure blood flow in the carotid and femoral arteries, heart rate and blood pressure in response to postural challenge in older adults. A second purpose was to determine if older men and women have different cardiovascular responses to a postural challenge such as tilt.MethodsThirty-seven healthy elderly men and women participated in this study (69–82 years old). All subjects had similar physical activity levels. Postural challenge was induced by a 60° tilt at the level of the waist. Continuous carotid blood flow and femoral blood flow was measured with Doppler ultrasound.ResultsCarotid blood flow was significantly reduced 17% in both men and women immediately after tilt (p < 0.001), and by 3.2% two minutes after tilt (p < 0.001). Femoral blood flow decreased 59.4% in men and 61% in women immediately after tilt (p < 0.001), and remained significantly decreased two minutes after tilt by 21% (p <0.001). Heart rate increased by 15% in men (p < 0.001), and 26% in women immediately after the tilt (p < 0.001). Heart rate returned to resting values within two minutes in both men and women. Response to tilt was not significantly related to self-report physical activity levels or to six-minute walk time.ConclusionA postural challenge induced larger changes in the femoral artery compared to the carotid artery. There were no differences between men and women to a tilt table test except for differences in heart rate response. There was no difference in the blood flow responses to postural challenge with physical activity level or between healthy older men and women.

Correction: The effects of aging and activity on muscle blood flow

Correction After publication of our paper [1], we discovered that our normalized blood velocity and compliance numbers were 60 times higher than they should have been. The revised Figure 1 and Figure 2, along with Table 1 are shown here with the correct values. Heart rate, blood pressure, and half time to recovery of blood flow and oxygen saturation from the original article are all correct. The statistical analysis and interpretation of the data remain unchanged. We apologize for the error. Published: 08 July 2003