Arterial Intima-Media Thickness and its Relationship with Cardiovascular Disease and Atherosclerosis: A Possible Contribution of Medium-Sized Arteries

Association between popliteal artery wall thickness and structural progression in patients with symptomatic knee osteoarthritis

OBJECTIVE

There is increasing evidence for the involvement of vascular disease in the pathogenesis of knee osteoarthritis. Popliteal artery wall thickness can be used as a surrogate marker of atherosclerosis. We examined the association between popliteal artery wall thickness and knee cartilage volume in individuals with symptomatic knee osteoarthritis.

METHODS

This prospective cohort study analysed 176 participants from a randomised placebo-controlled trial examining the effect of atorvastatin on structural progression in knee osteoarthritis. The participants underwent magnetic resonance imaging (MRI) of the study knee at baseline and two-year follow-up. Popliteal artery wall thickness and tibial cartilage volume were measured from MRI using validated methods. The top quartile of the rate of tibial cartilage volume loss was defined as rapid progression.

RESULTS

At baseline, every 10% increase in popliteal artery wall thickness was associated with 120.8 mm3 (95% CI 5.4-236.2, p= 0.04) lower of medial tibial cartilage volume and 151.9 mm3 (95% CI 12.1-291.7, p= 0.03) lower of lateral tibial cartilage volume. Longitudinally, for every 10% increase in popliteal artery wall thickness, the annual rate of medial tibial cartilage volume loss was increased by 1.14% (95% CI 0.09%-2.20%, p= 0.03) and there was a 2.28-fold (95% CI 1.07-4.83, p= 0.03) risk of rapid progression of medial tibial cartilage loss, adjusted for age, sex, body mass index, tibial bone area, smoking, vigorous physical activity, and intervention group allocation.

CONCLUSION

The findings support a role for vascular pathology in the progression of knee osteoarthritis. Targeting atherosclerosis has the potential to improve outcomes in knee osteoarthritis.

Atherosclerotic Burden and Remodeling Patterns of the Popliteal Artery as Detected in the Magnetic Resonance Imaging Osteoarthritis Initiative Data Set

Background

An artificial intelligence vessel segmentation tool, Fully Automated and Robust Analysis Technique for Popliteal Artery Evaluation (FRAPPE), was used to analyze a large databank of popliteal arteries imaged through the OAI (Osteoarthritis Initiative) to study the impact of atherosclerosis risk factors on vessel dimensions and characterize remodeling patterns.

Methods and Results

Magnetic resonance images from 4668 subjects contributing 9189 popliteal arteries were analyzed using FRAPPE. Age ranged from 45 to 79 years (median, 61), and 58% were women. Mean lumen diameter, mean outer wall diameter, and mean wall thickness (MWT) were measured per artery. Their median values were 5.8 mm (interquartile range, 5.2–6.5 mm), 7.3 mm (interquartile range, 6.7–8.1 mm), and 0.78 mm (interquartile range, 0.73–0.84 mm) respectively. MWT was associated with multiple cardiovascular risk factors, with age (4.2% increase in MWT per 10‐year increase in age; 95% CI, 3.9%–4.5%) and sex (8.6% higher MWT in men than women; 95% CI, 7.7%–9.3%) being predominant. On average, lumen and outer wall diameters increased with increasing MWT until the thickness was 0.92 mm for men and 0.84 mm for women. After this point, lumen diameter decreased steadily, more rapidly in men than women (−7.9% versus −6.1% per 25% increase in MWT; P<0.001), with little change in outer wall diameter.

Conclusions

FRAPPE has enabled the analysis of the large OAI knee magnetic resonance imaging data set, successfully showing that popliteal atherosclerosis is predominantly associated with age and sex. The average vessel remodeling pattern consisted of an early phase of compensatory enlargement, followed by a negative remodeling, which is more pronounced in men.

Increased levels of platelet activation markers are positively associated with carotid wall thickness and other atherosclerotic risk factors in obese patients

The role of platelets in the development of atherosclerosis and obesity-related prothrombotic state is still under investigation. In this cross-sectional cohort study, we measured the levels of different platelet activation markers and evaluated their relationship with carotid intima-media thickness (IMT) along with other atherosclerotic risk factors in obese patients with or without atherosclerotic co-morbidities. We enrolled 154 obese patients, including 98 with either hypertension, type 2 diabetes mellitus or dyslipidaemia, 56 without these co-morbidities and 62 age- and sex-matched healthy controls. Platelet P-selectin expression and the number of platelet-derived microparticles (PMPs) were measured by flow cytometry; soluble P-selectin levels were analysed by ELISA and Thr715Pro P-selectin polymorphism was determined by PCR-RFLP. Carotid IMT was examined by ultrasonography. The levels of platelet activation parameters were significantly elevated in all obese subjects with increased carotid IMT compared to healthy controls. There was no effect of Thr715Pro genotype on soluble P-selectin levels in obese individuals contrary to normal subjects. Significant and positive association was revealed between carotid IMT and platelet P-selectin (p<0.0001), soluble P-selectin (p=0.039) and PMP (p=0.0001) levels. After adjusting for multiple variables, independent association was found between soluble P-selectin and fibrinogen (p=0.007), PMP levels and body mass index (p<0.0001) as well as platelet P-selectin and carotid IMT (p=0.012) plus plasminogen activator inhibitor-1 (p=0.009). In conclusion, P-selectin and PMP levels showed positive associations with abnormal carotid IMT and other risk factors in obesity suggesting a critical role of enhanced platelet reactivity in atherosclerotic wall alteration.

Type IIB von Willebrand Disease: Role of Qualitative Defects in Atherosclerosis and Endothelial Dysfunction

Objective. To verify whether a hereditary bleeding tendency, such as von Willebrand disease (vWD) type IIB, protects against the onset of atherosclerosis. Participants and Methods. Twenty-four patients with vWD type IIB and 24 healthy controls, matched for common atherosclerotic risk factors. All patients were evaluated by color Doppler ultrasound of the common carotid, carotid bifurcation, common femoral artery, brachial artery, and abdominal aorta, investigating intima-media thickness (IMT) and presence of plaques in each arterial district. Flow mediated dilation (FMD) of the brachial artery was used to test endothelial function. Results. vWD type IIB patients presented no significant difference in IMT in any arterial district. FMD showed no differences between the 2 groups. Conclusions. The quantitative clotting defect characteristic of vWD type IIB does not seem to protect against atherosclerosis.

Increased popliteal circumferential wall tension induced by orthostatic body posture is associated with local atherosclerotic plaques

OBJECTIVE

Lower limb arteries are exposed to higher hemodynamic burden in erectile posture. This study evaluated the effects of body posture on popliteal, carotid and brachial circumferential wall tension (CWT) and investigated the relationship between local CWT and atherosclerotic plaques in subjects with cardiovascular risk factors.

METHODS

Two hundred and three subjects (118 women and 85 men) with cardiovascular risk factors (smoking, hypertension or diabetes mellitus) underwent clinical and laboratory analysis and had their blood pressure measured in the arm and calf in supine and orthostatic positions. Arteries were evaluated by ultrasound analysis, while CWT was calculated according to Laplace's law.

RESULTS

Among the enrolled participants, 47%, 29% and none presented popliteal, carotid and brachial plaques, respectively. Carotid CWT measurements were not associated with local plaques after adjustment for potential confounders. Conversely, general linear model and logistic regression analyses adjusted for potential confounders demonstrated that peak orthostatic CWT was the only local hemodynamic parameter showing significant relationship with popliteal plaques in the whole sample. In gender-specific analyses, although positively correlated with popliteal plaques in both genders, local peak orthostatic CWT exhibited an independent association with popliteal plaques after adjustment for potential confounders only in women.

CONCLUSION

Popliteal CWT measured in orthostatic posture, rather than in supine position, is associated with popliteal atherosclerotic plaques, particularly in women. These findings suggest that erectile posture might play a role in the atherogenesis of leg arteries by modifying local hemodynamic forces and that there may be gender differences in this regard.

Flow-mediated dilation and intima-media thickness of the brachial and axillary arteries in individuals with and without inducible axillary artery compression

The presence of axillary artery aneurysm and/or thrombus in overhead throwing athletes has been linked, theoretically, with the finding of compression by the humeral head induced by a diagnostic arm maneuver. However, whether this intermittent compression is incidental or of pathological significance has yet to be determined. Flow-mediated vasodilation (FMD), intima-media thickness (IMT) and maximum vasodilatory capacity were measured locally (3rd portion of the axillary artery) and downstream (brachial artery) in individuals previously tested for inducible axillary artery compression (compressor group [COMP]: n=8, mean (SD) age: 23 (4) y; "noncompressor" control group [NONCOMP]: n=8, 26 (4) y). A high-resolution ultrasound machine recorded arterial diameter and blood flow velocity. A rapid inflation/deflation pneumatic cuff placed distal to the site of measurement induced reactive hyperemia. Custom-designed wall tracking software with synchronized Doppler waveform analysis detected changes in arterial diameter, blood flow velocity and shear rate from baseline to 3min after cuff deflation. Glyceryl trinitrate and/or ischemic hand grip exercises were administered to induce maximum vasodilation. No significant differences in FMD, IMT or maximum vasodilator capacity were observed between groups at the axillary artery. However, the downstream brachial FMD response was significantly diminished in the COMP group (6.38 [3.28]%) compared with the NONCOMP group (10.38 [2.74]%; p=0.006) despite a comparable shear rate between groups (COMP: 81.92 (44.55) s(-1); NONCOMP: 83.18 (40.02) s(-1); p=0.961). Pooled data revealed a significant negative relationship (r=-0.52, p=0.038) between the FMD response and degree of arterial compression. These results suggest a chronic change in downstream vascular function in individuals demonstrating clinically significant inducible axillary artery compression.

Postural changes may influence popliteal atherosclerosis by modifying local circumferential wall tension

Atherosclerosis of peripheral arteries typically affects vessels of the lower limbs, suggesting that local hemodynamic stimuli play a role in this process. Our study evaluated the effects of body postural changes on carotid and popliteal blood pressure, circumferential wall tension (CWT) and arterial strain, and investigated the relationship between such hemodynamic parameters and intima-media thickness (IMT) of these arteries. One hundred seventeen nondiabetic, nonhypertensive, nonsmoker subjects (48 men and 69 women) were enrolled and had their blood pressure measured in the arm and calf in supine and orthostatic positions. Echo-doppler analysis evaluated the common carotid and popliteal arteries after blood pressure measurements, while CWT was calculated according to Laplace's law. The results showed that changing from supine to orthostatic posture increased blood pressure and CWT in popliteal but not in carotid arteries. Partial correlation analysis adjusted for age and body mass index revealed no major relationship between IMT of the studied vessels and local blood pressure or arterial strain. Conversely, supine and orthostatic CWT exhibited comparable correlation coefficients with carotid IMT, while orthostatic CWT displayed a stronger relationship with popliteal IMT than with supine CWT. These results were confirmed by multiple linear regression analysis that included age, sex, body mass index, lipid fractions and glucose as independent variables. Overall, our results indicate that orthostatic CWT is a stronger hemodynamic predictor of popliteal IMT than supine CWT, suggesting that erectile posture may be a potential risk factor for popliteal atherosclerosis because it increases the local hemodynamic burden. (Hypertens Res 2008; 31: 2059-2064).

Arterial endothelial function in a porcine model of early stage atherosclerotic vascular disease

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the United States and is projected to become the leading cause of mortality in the world. Atherosclerosis is the most important single factor contributing to this disease burden. In this study, we characterize relationships between endothelial dysfunction and vascular disease in an animal model of diet-induced, early-stage atherosclerotic vascular disease. We tested the hypothesis that hypercholesterolaemia induces vascular disease and impairs endothelium-dependent relaxation (EDR) in conduit arteries of adult male Yucatan pigs. Pigs were fed a normal fat (NF) or high fat cholesterol (HFC) diet for 20-24 weeks. Results indicate that, while the HFC diet did not alter EDR in femoral or brachial arteries, EDR was significantly decreased in both carotid and coronary arteries. Sudanophilic fatty streaks were significantly present in the abdominal aorta and common carotid artery. Histopathology revealed increased intima-media thickness (IMT) and foam cell accumulation in Stary Stage I-III lesions in the abdominal aorta, common carotid artery and femoral arteries. In the coronary arteries, the accumulation of foam cells in Stary Stage I and II lesions resulted in a trend for increased IMT. There was no evidence of vascular disease in the brachial arteries. These results indicate that early stages of CVD (Stary Stage I-III) precede decreases in EDR induced by HFC diet, because femoral arteries exhibited foam cell accumulation and an increased IMT but no change in endothelial function.

Microalbuminuria in patients with previous myocardial infarction

Microalbuminuria (MA) is a cardiovascular risk factor. The aim of this study was to examine the relationship between MA and the intima-media complex of the carotid and brachial artery, endothelial function, glucose metabolism, haemostatic variables and cardiac hypertrophy in patients with coronary heart disease. A total of 123 patients, aged 31-80 years, with a history of previous myocardial infarction and without known diabetes mellitus were examined with B-mode ultrasound of common carotid and brachial arteries, flow-mediated dilatation of the brachial artery and echocardiography. A standard oral glucose tolerance test with 75 g of glucose was performed. MA was defined as excretion of 20-200 microg albumin/min. MA was present in 11% of patients. Patients with MA had significantly higher level of 2-h plasma glucose, a lower displacement of the atrioventricular plane, a thicker septum wall and a higher prevalence of impaired glucose tolerance test compared with patients with normoalbuminuria (P<0.05). Urinary albumin excretion (UAE) was significantly and positively associated with calculated intima-media area (cIMa) in both brachial and common carotid arteries as well as with age and interventricular septum thickness. In conclusion, UAE was significantly and positively associated with cIMa in both the common carotid and the brachial arteries as well as with left ventricular septum thickness and glucose intolerance in patients with a history of previous myocardial infarction without known diabetes mellitus.

Association of subclinical wall changes of carotid, femoral, and popliteal arteries with obstructive coronary artery disease in patients undergoing coronary angiography

STUDY OBJECTIVES

To examine the association of occult atherosclerosis of carotid, femoral, and popliteal arteries with the presence and severity of obstructive coronary artery disease (CAD) in patients without a history or presence of cerebrovascular or peripheral arterial disease using ultrasound examination of peripheral arteries.

PATIENTS/METHODS

One hundred eighty-four such individuals underwent routine coronary angiography. Obstructive CAD was found in 103 cases, which comprised the patient group. The remaining 81 individuals comprised the control group. All were blindly examined by duplex ultrasonography in order to assess occult atherosclerosis, as indicated by the estimation of intima-media thickness of the carotid artery (IMTC), intima-media thickness of the femoral artery (IMTF), intima-media thickness of the popliteal artery (IMTP), and ultrasonic biopsy (UB) of the carotid and femoral arteries. For the individuals with positive coronary angiography findings, the severity of CAD was estimated by the number of the diseased vessels.

RESULTS

IMTC, IMTF, IMTP, and UB showed significant correlation with the presence of obstructive CAD, but only IMTC and IMTF were independent predictive factors, with specificity of 74% and 60% and sensitivity of 76% and 70%, respectively. Additionally, our analysis yielded a regression model that, for a given value of IMTC and IMTF, may estimate the probability of CAD: p (CAD) = e((- 4.765 + 3.36 IMTC + 1.91 IMTF))/1 + e((- 4.765 + 13.36 IMTC + 1.91 IMTF)). Patients with one-vessel disease had significantly lower IMTC (p < 0.001) and UB (p = 0.011) and lower IMTF (p = 0.057) than those with three-vessel disease.

CONCLUSIONS

The assessment of occult atherosclerosis by duplex ultrasonography in both the carotid and the femoral arteries is significantly associated with the presence and severity of CAD.

Glucose clearance is higher in arm than leg muscle in type 2 diabetes

Insulin-mediated glucose clearance (GC) is diminished in type 2 diabetes. Skeletal muscle has been estimated to account for essentially all of the impairment. Such estimations were based on leg muscle and extrapolated to whole body muscle mass. However, skeletal muscle is not a uniform tissue and insulin resistance may not be evenly distributed. We measured basal and insulin-mediated (1 pmol min-1 kg-1) GC simultaneously in the arm and leg in type 2 diabetes patients (TYPE 2) and controls (CON) (n=6 for both). During the clamp arterio-venous glucose extraction was higher in CON versus TYPE 2 in the arm (6.9+/-1.0 versus 4.7+/-0.8%; mean+/-s.e.m.; P=0.029), but not in the leg (4.2+/-0.8 versus 3.1+/-0.6%). Blood flow was not different between CON and TYPE 2 but was higher (P<0.05) in arm versus leg (CON: 74+/-8 versus 56+/-5; TYPE 2: 87+/-9 versus 43+/-6 ml min-1 kg-1 muscle, respectively). At basal, CON had 84% higher arm GC (P=0.012) and 87% higher leg GC (P=0.016) compared with TYPE 2. During clamp, the difference between CON and TYPE 2 in arm GC was diminished to 54% but maintained at 80% in the leg. In conclusion, this study shows that glucose clearance is higher in arm than leg muscles, regardless of insulin resistance, which may indicate better preserved insulin sensitivity in arm than leg muscle in type 2 diabetes.

Intima???media complex of both the brachial artery and the common carotid artery are associated with left ventricular hypertrophy in patients with previous myocardial infarction

OBJECTIVES

Prospective trials have established intima-media thickness (IMT) of the carotid artery, flow-mediated dilation (FMD) of the brachial artery and cardiac left ventricular hypertrophy (LVH) as predictors of cardiovascular events. The aim of this study was to examine the relationship between intima-media complex of the brachial artery to FMD, intima-media complex of the common carotid artery and cardiac hypertrophy in patients with coronary heart disease.

METHODS AND PROCEDURES

Cross-sectional design. Procedures were undertaken within the Huddinge University Hospital, Karolinska Institute, Stockholm, Sweden. A total of 123 patients with a previous acute myocardial infarction (MI) were investigated. Calculated intima-media area (cIMa) of the brachial and common carotid arteries and FMD of the brachial artery and left ventricular dimensions were examined.

RESULTS

The brachial cIMa was significantly associated with age, p-triglycerides, common carotid cIMa, ejection fraction, septum thickness, posterior wall thickness and left ventricular mass index (P < 0.05). Brachial cIMa also tended to be associated with systolic blood pressure (P = 0.056). Common carotid cIMa was significantly associated with age, systolic blood pressure, brachial cIMa, FMD and septum thickness (P < 0.05). FMD was significantly associated with age and carotid cIMa (P < 0.05).

CONCLUSION

Both cIMa of the common carotid artery and the cIMa of the brachial artery were independently and significantly associated with ventricular septum thickness of the heart in patients with previous myocardial infarction.