Arterial properties of the carotid and femoral artery in endurance-trained and paraplegic subjects

Abstract

In humans, the relationships of blood flow changes to structure, function, and shear rate of conducting arteries have not been thoroughly examined. Therefore, the purpose of this study was to investigate these parameters of the elastic-type, common carotid artery (CCA) and the muscular-type, common femoral artery (CFA) in long-term highly active and extremely inactive individuals, assuming that the impact of activity-induced blood flow changes on conduit arteries, if any, should be seen in these subjects. We examined 21 highly endurance-trained athletes (A), 10 paraplegic subjects (P), and 20 sedentary subjects (S) by means of noninvasive ultrasound. As a result, the CFA diameter and compliance were highest in A (9.7+/-0.81 mm; 1.84 +/-0.54 mm(2)/kPa) and lowest in P (5.9+/-0.7 mm; 0.54+/-0.27 mm(2)/kPa) compared with S (8.3+/-1.0 mm; 0.92+/-0.48 mm(2)/kPa) with P <0.01 among the groups. Both parameters correlated with each other (r = 0.62; P<0.01). Compared with A (378+/-84 s(-1); 37+/-15 s(-1)) and S (356+/-113 s(-1); 36+/-20 s(-1)), the peak and mean shear rates of the CFA were almost or more than doubled in P (588+/-120 s(-1); 89+/-26 s(-1)). In the CCA, only the compliance and peak shear rate showed significant differences among the groups (A: 1.28+/-0.47 mm(2)/kPa, 660+/-138 s(-1); S: 1.04+/-0.27 mm(2)/kPa, 588+/-109 s(-1); P: 0.65+/- 0.22 mm(2)/kPa, 490+/-149 s(-1); P<0.05). In conclusion, the results suggest a structural and functional adaptation in the CFA and a predominantly functional adaptation of the arterial wall properties to differences in the physical activity level and associated exercise-induced blood flow changes in the CCA. The results for humans confirm those from animal experiments. Similar shear rate values of S and P in the CFA support the hypothesis of constant shear stress regulation due to local blood flow changes in humans. On the other hand, the increased shear rate in the CFA in P indicates an at least partially nonphysiological response of the arterial wall in long-term chronic sympathectomy due to a change in local blood flow.

Peripheral vascular function in spinal cord injury: a systematic review

“…54,55 Compared with the inactive lower limbs, the active upper limb vasculature is relatively well preserved. For example, the diameters of the common carotid artery 51,53 and brachial artery 50 are similar between SCI and AB. Thus, it appears the structural adaptations below the injury are primarily an adaptation to the reduced metabolic demands of the lower limb vasculature.…”

“…However, shear stress and shear rate in the common femoral artery in individuals with SCI are Peripheral vascular function in spinal cord injury CR West et al 50-100% greater than in AB individuals. 51,53,54 The almost doubled shear rate appears to be a consequence of the inactivity rather than loss of supraspinal sympathetic control, as both tetraplegics (decreased sympathetic tone to a nearly all of the vasculature) and low paraplegics (decreased sympathetic tone to approximately half of the vasculature) demonstrate similar increases in shear stress compared with AB controls. 51 It should be noted that shear stress is inversely proportional to arterial diameter cubed at constant flow and viscosity.…”

“…Acute alterations are mediated primarily by changes in sympathetic activity to the smooth muscle, whereas chronic changes are mediated primarily by changes in blood flow and pressure, which alters shear stress and consequently the number of smooth muscle cells in vessel walls. 48 Remodeling of peripheral arteries in paralyzed limbs occurs soon after SCI; within weeks there is a significant reduction in systemic blood volume 49 and a consequent inward remodeling of the arterial wall, 50 such that the diameter of the common femoral artery is 30-50% smaller [51][52][53][54] and resting blood flow in the leg is 30-40% lower than in AB individuals. 54,55 Compared with the inactive lower limbs, the active upper limb vasculature is relatively well preserved.…”

The effects of body-weight supported treadmill training on cardiovascular regulation in individuals with motor-complete SCI

“…Regarding the former, recent research has shown that individuals with complete SCI exhibit peripheral vascular changes that likely contribute to their increased cardiovascular risk. Specifically, studies have found the luminal diameter to be significantly reduced 20 and the vascular resistance to be significantly increased 6,21 in the femoral artery of individuals with complete SCI, and accordingly, resting femoral artery blood flow may be reduced by approximately 50% compared to that of able-bodied individuals. 4 Clinically, this reduction in blood flow has been hypothesized to contribute to thrombus formation, 3,4 delayed wound healing 21 and an increased risk of pressure sore formation.…”

Relationship between Large and Small Arterial Compliance and Regional Body Composition in Middle-Aged and Elderly Adults

“…The findings of this study suggest that decreased compliance of peripheral small arteries may partly reduce peripheral blood flow, resulting in reduction in muscle volume in middle-aged and elderly individuals. On the other hand, recent studies have shown that moderate or high-intensity physical training induced an increase in the diameter of the femoral artery [29][30][31] , whereas femoral arterial compliance did not change in contrast with carotid arterial compliance 32) . Also, a previous study indicated that resistance training increased blood flow and vascular conductance of the femoral artery in middle-aged and elderly adults 33) .…”