Femoral Artery Compliance Research Articles

Influence of physical inactivity on arterial compliance during a glucose challenge.

What is the central question of this study? To understand better the effects of acute hyperglycaemia on arterial stiffness in healthy young individuals, we assessed arterial stiffness in physically active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. What is the main finding and its importance? During an oral glucose tolerance test, we identified an increase in leg arterial stiffness (i.e. reduced femoral artery compliance) only when subjects were inactive for 5days (<5000stepsday-1 ) and not when they were engaging in regular physical activity (>10,000stepsday-1 ). These results demonstrate the deleterious consequence of acute reductions in daily physical activity on the response of the peripheral vasculature to acute hyperglycaemia. Acute hyperglycaemia has been shown to augment indices of arterial stiffness in patients with insulin resistance and other co-morbidities; however, conflicting results exist in healthy young individuals. We examined whether acute hyperglycaemia after an oral glucose tolerance test (OGTT) increases arterial stiffness in healthy active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. High-resolution arterial diameter traces acquired from Doppler ultrasound allowed an arterial blood pressure (BP) waveform to be obtained from the diameter trace within a cardiac cycle. In 24 subjects, this method demonstrated sufficient agreement with the traditional approach for assessing arterial compliance using applanation tonometry. In 10men, continuous recordings of femoral and brachial artery diameter and beat-to-beat BP (Finometer) were acquired at rest, 60 and 120min of an OGTT before and after 5days of reduced activity (from >10,000 to<5000stepsday-1 ). Compliance and β-stiffness were quantified. Before the reduction in activity, the OGTT had no effect on arterial compliance or β-stiffness. However, after the reduction in activity, femoral compliance was decreased (rest, 0.10±0.03mm2 mmHg-1 versus 120min OGTT, 0.06±0.02mm2 mmHg-1 ; P<0.001) and femoral β-stiffness increased (rest, 8.7±2.7a.u. versus 120min OGTT, 15.3±6.5a.u.; P<0.001) during OGTT, whereas no changes occurred in brachial artery compliance (P=0.182) or stiffness (P=0.892). Insulin sensitivity (Matsuda index) was decreased after the reduction in activity (P=0.002). In summary, in young healthy men the femoral artery becomes susceptible to acute hyperglycaemia after 5days of reduced activity and the resultant decrease in insulin sensitivity, highlighting the strong influence of daily physical activity levels on vascular physiology.

All‐Extremity Aerobic Exercise Training Improves Carotid Artery Compliance in Older Adults

Advancing age is associated with decreased arterial compliance and increased arterial wall intima‐media thickness (IMT), both independent predictors of cardiovascular disease. Aerobic exercise training is a recognized strategy for reducing the risk of cardiovascular disease, however, optimal exercise prescription in older adults remains unknown. The purpose of this study was to examine the effect of all‐extremity aerobic exercise training on central and peripheral vascular structure and function in older adults. Twenty two sedentary older men and postmenopausal women (age 55 to 76 yrs, 64±1yrs; mean±SE), free of major clinical disease (e.g., diabetes, cardiovascular, renal and liver disease) were randomized to 8 weeks of all‐extremity aerobic exercise training (EX; n=12) or non‐exercise control condition (CON; n=10). Aerobic training was performed 4 days/week under supervision and consisted of 47 min of exercise on an air‐braked all‐extremity ergometer (Airdyne, Schwinn) at 70% of maximal heart rate. Central and peripheral vascular structure was assessed by measuring carotid and femoral artery diameter and IMT using high resolution ultrasonography. Vascular function was evaluated by calculating arterial compliance using simultaneous measures of diameter and pressure via applanation tonometry. In response to the exercise intervention, carotid artery compliance improved (EX: 0.12±0.01 vs. 0.14±0.02 mm2/mmHg, P=0.01 and CON: 0.12±0.02 vs. 0.12±0.02 mm2/mmHg, P=0.8; pre‐ vs. post‐intervention). However, carotid artery diameter (EX: 7.1±0.2 vs. 7.1±0.2 mm and CON: 6.8±0.2 vs. 6.8±0.2 mm; P&gt;0.05) and IMT normalized for lumen diameter (EX: 0.09±0.005 vs. 0.08±0.003 and CON: 0.09±0.005 vs. 0.09±0.004; P&gt;0.05) remained unchanged. Femoral artery compliance did not improve with the intervention (EX: 0.17±0.02 vs. 0.16±0.02 mm2/mmHg and CON: 0.17±0.03 vs. 0.14±0.03 mm2/mmHg; P&gt;0.05). Similarly, femoral artery diameter (EX: 8.6±0.4 vs. 8.8±0.4 mm, and CON: 8.5±0.5 vs. 8.6±0.5 mm; P&gt;0.05) and IMT/diameter (EX: 0.07±0.009 vs. 0.07±0.008 and CON: 0.09±0.009 vs. 0.08±0.008; P&gt;0.05) did not change following the intervention. In conclusion, eight weeks of aerobic exercise training performed on an all‐extremity ergometer improves carotid artery compliance in healthy older adults. This finding may have important implications for reducing the risk of cardiovascular disease in older adults.

ALTERED ARTERIAL FUNCTION IN MIGRAINE OF RECENT ONSET

Objective: Migraine is associated with cardiovascular disorders but the underlying mechanisms are unknown. Arterial structure and function are important determinants of cardiovascular morbidity and mortality. The aim of the present study was to assess arterial properties in patients with migraine of recent onset. Methods: In a cross-sectional study, structural and functional arterial properties were assessed using ultrasound and applanation tonometry in 50 patients with a history of migraine >1 and Results: Brachial artery diameter (4.82 ± 0.93 mm vs 5.39 ± 0.89 mm, p = 0.01) and compliance (0.30 ± 0.17 mm 2 /kPa vs 0.37 ± 0.19 mm 2 /kPa, p = 0.02) were decreased in migraine patients compared with controls. Femoral artery compliance was decreased in migraine patients (1.19 ± 0.55 mm 2 /kPa vs 1.42 ± 0.59 mm 2 /kPa, p = 0.04). Carotid arterial wall properties were similar between groups. Aortic augmentation index was increased in migraine patients (4 ± 10% vs −1 ± 10%, adjusted p = 0.04). Flow-mediated vasodilation of the brachial artery (normalized to peak shear rate) was decreased in patients with migraine (29 ± 15 vs 37 ± 15 10 −3 %. sec, p = 0.006). Conclusion: Functional arterial properties are altered in patients with migraine of recent onset.

Altered arterial function in migraine of recent onset

Migraine is associated with cardiovascular disorders but the underlying mechanisms are unknown. Arterial structure and function are important determinants of cardiovascular morbidity and mortality. The aim of the present study was to assess arterial properties in patients with migraine of recent onset. In a cross-sectional study, structural and functional arterial properties were assessed using ultrasound and applanation tonometry in 50 patients with a history of migraine >1 and <6 years during a headache-free interval and 50 age- and gender-matched subjects without a history of migraine. Brachial artery diameter (4.82 +/- 0.93 mm vs 5.39 +/- 0.89 mm, p = 0.01) and compliance (0.30 +/- 0.17 mm(2)/kPa vs 0.37 +/- 0.19 mm(2)/kPa, p = 0.02) were decreased in migraine patients compared with controls. Femoral artery compliance was decreased in migraine patients (1.19 +/- 0.55 mm(2)/kPa vs 1.42 +/- 0.59 mm(2)/kPa, p = 0.04). Carotid arterial wall properties were similar between groups. Aortic augmentation index was increased in migraine patients (4 +/- 10% vs -1 +/- 10%, adjusted p = 0.04). Flow-mediated vasodilation of the brachial artery (normalized to peak shear rate) was decreased in patients with migraine (29 +/- 15 vs 37 +/- 15 10(-3)%. sec, p = 0.006). Functional arterial properties are altered in patients with migraine of recent onset.

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

Four-month longitudinal within-subject exercise training study. Although body-weight supported treadmill training (BWSTT) has not shown promise as a means of improving ambulation in individuals with motor-complete spinal cord injury (SCI), it may still improve cardiovascular health and function in this population. The purpose of this study was to (i) investigate the effects of BWSTT on peripheral muscular and elastic artery dimension and function and measures of heart rate variability (HRV) and blood pressure variability (BPV) in individuals with motor-complete SCI, and (ii) to make a preliminary examination of what factors may predict favourable cardiovascular outcomes following BWSTT in this population. Centre for Health Promotion and Rehabilitation, McMaster University, Hamilton, Ontario, Canada. Six individuals (four male, two female; age 37.7+/-15.4 years) with chronic SCI (C4-T12; ASIA A-B; 7.6+/-9.4 years post-injury) were included in the present investigation. Doppler ultrasound was used to determine femoral (exercising; muscular), carotid (elastic) and brachial (non-exercising control; muscular) artery dimension and function before and after 4 months of BWSTT. Continuous heart rate and blood pressure were also recorded before and after 4-months of BWSTT to determine frequency domain measures of HRV and BPV; clinically valuable indices of neurocardiac and neurovascular control, respectively. Two-way ANOVA (vessel x time) revealed no exercise-induced change in femoral or carotid artery cross-sectional area, blood flow or resistance and no change in carotid artery compliance following the 4 months of BWSTT compared to the non-exercising control brachial artery. However, there was a significant exercise-induced increase in femoral artery compliance. There were no exercise-induced changes in HRV or BPV when all participants were considered together. However, the results suggest that the subgroup of individuals who had a substantial heart rate response to BWSTT (n=3), experienced exercise-training induced changes in HRV reflective of a relative shift toward cardiac vagal predominance and reductions in BPV. BWSTT may cause an increase in femoral artery compliance in individuals with motor-complete SCI and therefore, should be encouraged as a means of improving cardiovascular health in this population. BWSTT may also cause modest improvements in measures of HRV and BPV in a select subgroup of individuals who respond to ambulation with moderate to large increases in HR. In the present study, factors associated with a substantial HR response to BWSTT were a propensity to orthostatic intolerance and muscular spasticity.

GREATER AGE-RELATED REDUCTIONS IN CENTRAL ARTERIAL COMPLIANCE IN RESISTANCE-TRAINED MEN

PURPOSE Reductions in the compliance of central arteries exert a number of adverse effects on systemic cardiovascular function and disease risk. Using a cross-sectional study design, we determined the relation between chronic resistance training and carotid arterial compliance. METHODS A total of 62 healthy normotensive men aged 20–39 (young) and 40–60 years (middle-aged) who were either sedentary or resistance trained were studied. RESULTS Regardless of resistance-trained status, carotid arterial compliance was lower (P < .05) in the middle-aged compared with the young men. There was no significant difference between young sedentary (.19 ± .01 mm2/mmHg) and resistance-trained men (.16 ± .01 mm2/mmHg). In the middle-aged group, carotid arterial compliance in the resistance- trained men (.11 ± .01 mm2/mmHg) was ∼30% lower (P < .05) than their sedentary peers (.15 ± .01 mm2/mmHg). Femoral artery compliance and arm pulse wave velocity were not different among any groups. Left ventricular hypertrophy index was greater (P < .05) in resistance-trained compared with sedentary men and was associated with carotid arterial compliance (r= −.35; P < .01). CONCLUSIONS We concluded that 1) age-related reductions in central arterial compliance are greater in resistance-trained than sedentary men; 2) the effect of resistance training only pertains to central arteries whose cushioning function dampens fluctuations in pressure and flow; and 3) the lower arterial compliance in the resistance- trained men is associated with left ventricular concentric hypertrophy. In marked contrast to the beneficial effect of regular aerobic exercise, the present findings are not consistent with the idea that resistance training exerts beneficial influences on arterial wall buffering functions.

Associations of metabolic variables with arterial stiffness in type 2 diabetes mellitus: focus on insulin sensitivity and postprandial triglyceridaemia.

Type 2 diabetes mellitus is associated with an increased risk of atherothrombotic disease, which may in part be mediated through increased arterial stiffness. We investigated to what extent increased arterial stiffness is associated with cardiovascular risk factors that commonly cluster in type 2 diabetes. In this cross-sectional, observational study we assessed, in 81 subjects with type 2 diabetes, local distensibility and compliance of the common carotid and femoral arteries, and carotido-femoral transit time. We subsequently investigated whether these measures of arterial stiffness were determined by diabetes duration, blood pressure, lipid levels (including fasting and postprandial triglyceridaemia), hyperglycaemia, BMI, waist-to-hip ratio, insulin resistance (as measured by a euglycaemic, hyperinsulinaemic clamp), hyperinsulinaemia, cigarette smoking, or the use of alcohol. In multivariate analysis, insulin-mediated glucose uptake was positively [standardized beta, 0.21 (P = 0.05)] associated with the carotid artery compliance coefficient, and the use of alcohol was negatively associated with the femoral artery compliance coefficient [standardized beta, -0.25 (P = 0.03)]. Except for mean arterial pressure, which was negatively associated with all outcome variables, the other cardiovascular risk factors that we investigated were not significantly associated with the distensibility coefficients of both the carotid and femoral artery, or with the carotido-femoral transit time. In subjects with type 2 diabetes mellitus, insulin resistance and the use of alcohol were associated with increased arterial stiffness, which supports the hypothesis that increased arterial stiffness can act as a mediating factor in the association between type 2 diabetes mellitus and increased risk of atherothrombotic disease. We found no evidence for an association between fasting or postprandial triglyceridaemia and arterial stiffness.

The effect of pregnancy on the compliance of large arteries and veins in healthy parous control subjects and women with a history of preeclampsia

Objective: Early pregnancy is characterized by a fall in total peripheral vascular resistance. In this study we tested the hypothesis that this phenomenon is accompanied by rising compliances of the large arteries and veins. Study Design: In 42 women with a history of preeclampsia and 10 healthy parous control subjects we measured the following variables in the midfollicular phase and the midluteal phase during the menstrual cycle and again at 5 and at 7 weeks of amenorrhea: cardiac output, mean arterial pressure, carotid and femoral artery compliances, and venous compliance. The total peripheral vascular resistance was determined as the ratio of mean arterial pressure and cardiac output. After screening for thrombophilia and hypertension, women with a history of preeclampsia were divided into subgroups with hypertension, thrombophilic disorders, and no underlying abnormalities. Results: In parallel with the fall in total peripheral vascular resistance during early pregnancy, femoral artery compliance and venous compliance increased in the control group. Except for venous compliance, these changes were also observed in the women with thrombophilia and a history of preeclampsia. In the subgroups of the women with a history of preeclampsia with hypertension and with no underlying disorder both arterial and venous compliance failed to increase despite a drop in total peripheral vascular resistance. Conclusion: These data support the concept that during normal pregnancy the fall in total peripheral vascular resistance is paralleled by improved macrovascular compliance. The latter adaptive change did not occur in women with a history of preeclampsia with hypertension or without an underlying disorder. (Am J Obstet Gynecol 2000;183:1278-86.)

Assessing arterial stenoses by tracking turbulence with Doppler ultrasound

When a stenosis, or narrowing, causes a significant area reduction of a blood vessel, turbulence in the post-stenotic jet can be detected with Doppler ultrasound distal to the stenosis. A technique is investigated for assessing the severity of a stenosis, defined as the pressure drop across the lesion, by extracting the streamwise turbulence intensity (or the normalized square root of the velocity variance) from the Doppler ultrasound in an arterial flow model. The model consists of an optically and acoustically transparent polyurethane tube that mimics femoral artery compliance, a pump capable of continuous and pulsatile flow, 10-μm glass spheres as an ultrasound and laser scatterer, and both blunt and rounded inlet stenoses. The flow field through three axisymmetric, Plexiglas stenoses with diameter reductions from 60% to 95% mH were investigated with an ATL HDI 3000 using the L7-4 linear array in Doppler mode (1.0-mm spatial pulse length) and a Dantec two-color 55X laser Doppler anemometer (0.7-mm major axis). To validate the ultrasound technique, correlation of Doppler ultrasound and laser Doppler anemometry flow measurements was examined. The correlation of the peak velocity, the maximum turbulence intensity, and the pressure drop across each stenosis was also investigated. This Doppler ultrasound technique could be sensitive to more subtle alterations in hemodynamics and therefore could aid early detection of atherosclerosis.

Reproducibility of ultrasound assessment of common carotid and femoral artery compliance and distensibility in the anesthetized rat

To validate ultrasound assessment of common carotid and femoral artery compliance and distensibility in the anesthetized rat. A reproducibility study was performed by taking measurements twice on two different days in anesthetized Wistar-Kyoto (WKY) rats. The common carotid or femoral arterial diameter on one side and the contralateral arterial blood pressure were measured using a 10-MHz probe echo-Doppler device and an arterial catheter, respectively. The pressure and diameter data were stored in a computer programmed to calculate the arterial compliance and distensibility coefficients (Reneman formulas) and compliance and distensibility indices (arctangent model of Langewouters). A second experimental session was repeated 1 day later, and mean values, day-to-day mean differences and repeatability coefficients were calculated for each parameter. For both the common carotid and the femoral artery, the mean values for heart rate, mean arterial pressure, arterial diameter, arterial compliance and arterial distensibility were similar on the first and second days; mean day-to-day differences were small and repeatability coefficients were in the range 5-10% of the mean value for diameter and mean arterial pressure and 10-20% of the mean value for compliance and distensibility. In the anesthetized rat, ultrasound evaluation of the mechanical properties of the common carotid and femoral arteries is a reliable and reproducible technique.

A New Device for the Measurement of the Arterial Compliance Using Implantable Sensors

To determine the compliance of experimental arterial grafts and its chronic adaptation after implantation, a new device for measurements was developed which is combined with implantable sensors. The system is based on the physical induction phenomenon. Each sensor comprises two small coils of copper wire which are sutured opposite to each other to the arterial vessel. Up to 3 sensors are adapted to one electrical connector which can be covered subcutaneously. The device is able to read pulsatile diameter excursions of arterial vessels down to 0.02 mm. It was applied first to evaluate the elastic properties of a 4-mm dialdehyde-starch-preserved bovine internal mammary artery implanted in the canine femoral artery position. For comparison an ePTFE graft was used. At implantation the compliance of the biograft was calculated to be 0.028 +/- 0.009% mm Hg-1, which was half of the compliance of the native femoral artery (0.06 +/- 0.0025% mm Hg-1), but superior if compared to the PTFE (0.008 +/- 0.005% mm Hg-1). Within 6 months the compliance of the femoral artery decreased to 0.039 +/- 0.013% mm Hg-1, which was well matched now to the compliance of the biograft (0.027 +/- 0.005% mm Hg-1).

Correlation of noninvasive arterial compliance with anatomic pathology of atherosclerotic nonhuman primates

Fifteen cynomolgus monkeys were fed a control ( n = 3) or cholesterol-containing diet ( n = 12) for 26 months. An impedance plethysmograph and a calibrated volume plethysmograph were used to determine femoral arterial volume change, ΔV, from femoral arteries. Abdominal aorta pulse pressure was measured directly. The ratio of ΔV to pulse pressure, Δ P, defined femoral artery compliance. At necropsy, sections of pressure fixed common iliac, external iliac, femoral and carotid arteries were obtained for measurements. The site of the largest atherosclerotic lesion was chosen for histologic measurement. The percentage intima in arterial tissue (PIAT) was determined at the site of the largest atherosclerotic lesions in iliac arteries and averaged. Peak compliance was inversely correlated with the PIAT (Pearson correlation −0.39, P < 0.10, n = 21) which improved to r = −0.52, P < 0.01 ( n = 27) when the PIAT also included the carotid atherosclerosis. The correlation coefficients were comparable to those obtained for total plasma cholesterol concentration, and direct systolic and diastolic blood pressure. Peak compliance and α-cholesterol concentrations provided the best multiple linear regression fit for the prediction of PIAT.

Transcutaneous measurement of arterial wall properties as a potential method of estimating aging.

ABSTRACT:The visco‐elastic properties of arterial walls vary with the structural alterations which occur secondary to aging. An ultrasonic echo‐tracking device developed in this laboratory was used for noninvasive estimation of these properties. Femoral artery compliance (% Δ V/V) and pressure strain elastic modulus (Ep) were estimated in 36 normal subjects (68 vessels). The subjects were divided into three groups according to age: &lt;35, 35–60, &gt;60. The femoral arterial diameter and changes in diameter with each pulse beat were measured transcutaneously with the echo‐tracking device. Brachial arterial blood pressure was obtained by means of a cuff and stethoscope. The results showed a progressive increase in Ep and a complementary decrease in % Δ V/V with increasing age. Ep varied from 2.64 dynes/cm2 ± 0.26 SEM in the young group to 6.28 dynes/cm2 ± 1.03 SEM in the old group. % Δ V/V varied from 6.0% ± 0.5 SEM in the young group to 3.3% ± 10.5 SEM in the old group. Statistical comparisons of Ep showed significant differences between the groups, indicating that arterial stiffness increases with age. % Δ V/V was significantly lower in the old group than in the young. Variation within groups increased markedly with advancing age, and values for Ep and % Δ V/V overlapped in all groups.