A new automated computerized analyzing system simplifies readings and reduces the variability in ultrasound measurement of intima-media thickness

The metabolic syndrome in middle-aged men according to different definitions and related changes in carotid artery intima-media thickness (IMT) during 3 years of follow-up

OBJECTIVES

To examine the occurrence over time of the metabolic syndrome (MetS) according to different definitions and the relation to change during follow-up in carotid artery intima-media thickness (IMT), measured by ultrasound.

DESIGN

A cohort of 316, originally 58-year-old men, initially free of diabetes and cardiovascular disease, was followed for 3.2 +/- 0.2 years. IMT was measured bilaterally by high-resolution B-mode ultrasound at baseline and follow-up. The MetS was classified according to slightly modified World Health Organization (WHO) and National Cholesterol Education Program (NCEP) criteria.

RESULTS

In 88% WHO and NCEP definitions resulted in identical classifications. IMT was larger both at baseline and after 3 years in men fulfilling the criteria for the MetS, according to either of the definitions, compared to those without factors in the syndrome. Men who fulfilled the WHO criteria for the MetS, at the initial and final examination showed a statistically significant increase in carotid artery IMT during the study [76 (95% CI: 14-130) microm, n = 37]. Men fulfilling the WHO criteria for the MetS at baseline tended to have a larger annual increase in IMT than those not fulfilling the criteria or having no risk factors in the syndrome.

CONCLUSIONS

More than 10% of the men had the MetS both at baseline and after 3 years, and this was associated with an increase in IMT using the WHO definition. Several of the components included in the MetS deteriorated during follow-up, i.e. body mass index (BMI), waist-to-hip ratio (WHR), waist circumference, blood glucose and blood pressure.

Morphological changes rather than flow-mediated dilatation in the brachial artery are better indicators of the extent and severity of coronary artery disease

OBJECTIVES

The aim of this study was to examine the relationship between morphological and functional parameters of the brachial and carotid arteries and the angiographic extent and severity of coronary artery stenosis in patients with severe coronary artery disease (CAD).

DESIGN

A cross-sectional study.

SETTING

University hospital.

MAIN OUTCOME MEASURES

Flow-mediated dilatation (FMD), intima-media thickness (IMT) in the brachial artery and atherosclerotic wall changes in the carotid arteries were measured by B-mode high-resolution ultrasound in 58 patients who had undergone coronary angiography.

RESULTS

A significant correlation was seen between the extent of coronary artery stenosis defined as the coronary angiographic score and both the mean brachial artery IMT and intima-media area (IMa; P = 0.01 and P = 0.04, respectively). There was no significant correlation between FMD and the extent of coronary artery stenosis. A significant correlation was seen between the mean carotid artery IMT and the mean brachial artery IMT (r = 0.30, P = 0.03). However, there was no significant correlation between FMD and the mean carotid artery IMT or IMa (r = 0.16, P = 0.23 and r = 0.17, P = 0.24, respectively).

CONCLUSIONS

Morphological but not functional parameters of the brachial artery are associated with the extent of coronary artery stenosis and atherosclerotic wall changes in the carotid arteries in patients with severe CAD. These findings indicate a potential of B-mode ultrasonography of morphological parameters in the brachial artery in the diagnostic and prognostic evaluation of patients with suspected CAD.

Endothelial function in conduit and resistance arteries in men with coronary disease

The aims of this study were to determine whether non-invasive measurement of endothelial function in conduit arteries reflects that of subcutaneous resistance arteries measured in vitro and to examine whether there is an endothelial dysfunction also in resistance arteries in patients with a previous myocardial infarction. The brachial artery diameter responses to a hyperemic flow stimulus and an in vitro method, pressure myography, to directly evaluate flow-mediated responses in arteries obtained from biopsies of subcutaneous fat were measured in 25 patients with a previous myocardial infarction and in 8 aged matched healthy subjects. Flow-mediated dilatation of the brachial artery was more pronounced in the healthy group compared with the group with coronary disease, 5.1 +/- 2.5% and 2.6 +/- 2.1%, respectively (p < 0.05). The flow-mediated dilatation in subcutaneous arteries from CHD patients was significantly reduced compared to control subjects (e.g. percent change from initial preconstriction at maximum flow rate of 204 microl/min: 42 +/- 7% CHD (n = 25) versus 84 +/- 24% control (n = 8), ANOVA, p = 0.03). There was a significant correlation between flow-mediated dilatation of the brachial artery and maximum flow-mediated dilatation at microvascular level, (p < 0.01). In conclusion this study demonstrates endothelial dysfunction in both conduit and resistance circulation in patients after myocardial infarction compared to an aged-matched healthy control group. Furthermore, a significant and independent relationship between endothelial function by means of flow-mediated dilatation in large conduit arteries and resistance arteries was observed.

Fluvastatin and lifestyle modification for reduction of carotid intima-media thickness and left ventricular mass progression in drug-treated hypertensives

OBJECTIVES

The Hypertension High Risk Management trial (HYRIM) investigated the effect of fluvastatin treatment and lifestyle intervention on development of carotid intima-media thickness (IMT) in drug-treated hypertensive patients.

METHODS AND RESULTS

HYRIM was a placebo-controlled, 2 x 2 factorial trial in which 568 drug-treated hypertensive men aged 40-74 years with total cholesterol 4.5-8.0 mmol/L, triglycerides <4.5 mmol/L, body mass index 25-35 kg/m2, and a sedentary lifestyle were randomized to receive either fluvastatin, 40 mg daily, or placebo, and either intensive lifestyle intervention (physical activity and diet) or usual care (treatment of hypertension and other disorders by own private physician). Carotid IMT was assessed by B-mode ultrasound vasculography and left ventricular (LV) mass was calculated from ultrasound recordings of the heart. Fluvastatin alone reduced the primary study endpoint of 4-year development of IMT in the common carotid artery (CCA) compared with placebo (p=0.0297). Carotid bulb IMT progression over 4 years was also significantly (p=0.0214) reduced by fluvastatin compared with placebo. Fluvastatin significantly lowered LDL-C levels (mean net difference through 4 years, 0.6 mmol/L; p<0.0001), and reduced the 2-year development of LV mass (p=0.0144) compared with placebo. Lifestyle intervention had no significant effect on LDL-C, carotid IMT or LV mass, and did not increase the effects of fluvastatin.

CONCLUSIONS

In drug-treated hypertensive patients in a usual care setting, fluvastatin treatment reduces progression of carotid IMT and LV mass.

Interrelation between the extent of atherosclerosis in the thoracic aorta, carotid intima-media thickness and the extent of coronary artery disease

Intima-media thickness (IMT) of the common carotid artery and atherosclerosis of the thoracic aorta have been shown to correlate with coronary artery disease (CAD). This study compares the relation between wall changes in the thoracic aorta and the carotid arteries and the angiographic severity and extent of atherosclerotic lesions in the coronary arteries in patients with verified CAD. Atherosclerotic wall changes in the carotid arteries and the thoracic aorta were measured by B-mode ultrasonography and transesophageal echocardiography (TEE), respectively, in 37 subjects aged 65+/-10 years with angiographically verified CAD. The mean value of the common carotid IMT of the right and left sides was 0.87+/-0.21 mm. All subjects had carotid plaques. TEE detected grades II-IV atherosclerotic plaques in the thoracic aorta in 32 of the 37 (86%) patients. A significant correlation was seen between the extent of coronary artery stenosis and aortic plaques score (r=0.46, p=0.008). Mean carotid IMT was also significantly correlated with coronary artery stenosis extent score (r=0.44, p=0.007). Moreover, a significant correlation was seen between the aortic plaque score and the mean carotid IMT (r=0.39, p=0.02). In conclusion, we found a clear and significant relationship between wall changes in the thoracic aorta, common carotid IMT and the angiographic extent of coronary artery stenosis in patients with severe CAD. These findings indicate a potential of B-mode ultrasonography of the carotid arteries and transesophageal echocardiographic aortic examination in the diagnostic and prognostic evaluation of patients with suspected CAD.

A semiautomated ultrasound border detection program that facilitates clinical measurement of ultrasound carotid intima-media thickness

We have developed a novel, semiautomated carotid intima-media thickness (CIMT) border detection program (AUTO) and evaluated its measurement reproducibility and accuracy. Images from 6 carotid segments were acquired in 50 subjects, for a total of 300 segments. Mean and maximum CIMT values were measured blindly at a reference (REF) lab and in duplicate by experienced (EXP) and novice (NOV) readers using manual (MAN) and AUTO methods. Coefficients of variation for AUTO measurements of mean (3.2%) and maximum (4.1%) CIMT were low, and the AUTO method improved the NOV reader's reproducibility. Compared with the REF lab, mean (0.012 +/- 0.006 mm) and maximum (0.144 +/- 0.006 mm) CIMT biases were small and equivalent to those of the REF lab ( P < .001). The AUTO method shortened reading times by 35% to 46% ( P < .001). We conclude that our novel AUTO CIMT measurement program improved reproducibility and was accurate. Compared with MAN tracing, the AUTO method agreed better with the REF lab and decreased reading time.

Persistent endothelial dysfunction is related to elevated C-reactive protein (CRP) levels in Type II diabetic patients after acute myocardial infarction

The atherosclerotic process is an ongoing dynamic and progressive state arising from endothelial dysfunction and inflammation. Although suffering from an acute coronary artery disease, patients with Type II diabetes have a poor outcome compared with non-diabetic patients, which may only partly be explained by traditional risk factors. Our purpose was to compare non-traditional risk factors, such as endothelial function, C-reactive protein (CRP) and adiponectin, in Type II diabetic and non-diabetic patients following AMI (acute myocardial infarction). Twenty Type II diabetic patients were compared with 25 non-diabetic patients at baseline (1-3 days from the onset of chest pain) and at 60 days follow-up after an AMI. Using high-resolution ultrasound, brachial artery responses to FMD (flow-mediated vasodilatation; endothelium-dependent vasodilatation) and NTG (nitroglycerine-induced vasodilatation; endothelium-independent vasodilatation) were measured. Plasma levels of CRP and adiponectin were measured by ELISA. At baseline, FMD (1.9 compared with 3.2%; P=0.22) and CRP levels (6.95 compared with. 5.51 mg/l; P=0.40) did not differ between Type II diabetic and non-diabetic patients, whereas adiponectin levels were lower in Type II diabetic patients (2.8 compared with 5.0 ng/ml; P<0.05). At 60 days follow-up, there were significant differences in FMD (1.5 compared with 4.1%; P<0.02), CRP (4.23 compared with 1.46 mg/ml; P<0.01) and adiponectin (3.3 compared with 5.3 ng/ml; P<0.05) levels between Type II diabetic and non-diabetic patients. In contrast, NTG responses improved in both groups between baseline and follow-up (Type II diabetic patients, 9.7 compared with 13.2% respectively, P<0.05; non-diabetic patients, 7.9 compared with 12.4% respectively, P<0.01). These results show a persistent endothelium-dependent dysfunction and inflammatory activity in patients with Type II diabetes, but not in non-diabetic patients, after AMI. These findings may, in part explain, the poor outcome in coronary artery disease seen in Type II 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.

Comparison between three-dimensional volume-selective turbo spin-echo imaging and two-dimensional ultrasound for assessing carotid artery structure and function

PURPOSE

To compare a volume-selective three-dimensional turbo spin echo (TSE) technique with ultrasound (US) for assessing carotid artery wall structure and function.

MATERIALS AND METHODS

A three-dimensional volume-selective TSE technique was used to image the carotid artery in 10 healthy subjects and five hypertensive subjects (each of whom were scanned three times while they received different hypertension treatments). Lumen and wall area were measured on MR images. Two-dimensional US measurements of the intima-media thickness (IMT) and lumen diameter were taken in three orientations through a single cross section. The lumen area change over the cardiac cycle was used to determine distension. For validation, a Bland-Altman analysis was used to compare the vessel wall and lumen areas measured by three-dimensional MRI volumes with those obtained by US scans.

RESULTS

Agreement between the two methods was found. The mean difference in distension between US and MRI was 1.2% (+/-5.1%). For the wall area measurements, good agreement was shown, but there was a systematic difference due to the visualization of the adventitia by MRI. Both techniques offer an easy way to objectively measure lumen indices. MRI can provide the complete circumference over the length of a vessel, while US is flexible and relatively inexpensive. The application of US is limited, however, when subjects are poorly echogenic. A difference between hypertensive and healthy subjects was found.

CONCLUSION

There was a good agreement between MRI and the clinically established two-dimensional US method. The MRI method has the advantage of providing increased vessel coverage, which permits one to assess localized abnormalities without assuming vessel uniformity.

Effects of glucagon-like peptide-1 on endothelial function in type 2 diabetes patients with stable coronary artery disease

GLP-1 stimulates insulin secretion, suppresses glucagon secretion, delays gastric emptying, and inhibits small bowel motility, all actions contributing to the anti-diabetogenic peptide effect. Endothelial dysfunction is strongly associated with insulin resistance and type 2 diabetes mellitus and may cause the angiopathy typifying this debilitating disease. Therefore, interventions affecting both endothelial dysfunction and insulin resistance may prove useful in improving survival in type 2 diabetes patients. We investigated GLP-1's effect on endothelial function and insulin sensitivity (S(I)) in two groups: 1) 12 type 2 diabetes patients with stable coronary artery disease and 2) 10 healthy subjects with normal endothelial function and S(I). Subjects underwent infusion of recombinant GLP-1 or saline in a random crossover study. Endothelial function was measured by postischemic FMD of brachial artery, using ultrasonography. S(I) [in (10(-4) dl.kg(-1).min(-1))/(muU/ml)] was measured by hyperinsulinemic isoglycemic clamp technique. In type 2 diabetic subjects, GLP-1 infusion significantly increased relative changes in brachial artery diameter from baseline FMD(%) (3.1 +/- 0.6 vs. 6.6 +/- 1.0%, P < 0.05), with no significant effects on S(I) (4.5 +/- 0.8 vs. 5.2 +/- 0.9, P = NS). In healthy subjects, GLP-1 infusion affected neither FMD(%) (11.9 +/- 0.9 vs. 10.3 +/- 1.0%, P = NS) nor S(I) (14.8 +/- 1.8 vs. 11.6 +/- 2.0, P = NS). We conclude that GLP-1 improves endothelial dysfunction but not insulin resistance in type 2 diabetic patients with coronary heart disease. This beneficial vascular effect of GLP-1 adds yet another salutary property of the peptide useful in diabetes treatment.

Oxidized low-density lipoprotein in plasma is a prognostic marker of subclinical atherosclerosis development in clinically healthy men

OBJECTIVE

To investigate the association between plasma oxidized low-density lipoprotein (OxLDL) and the progress of clinically silent atherosclerosis, as measured by ultrasound in the carotid arteries.

DESIGN

Prospective, observational study with more than 3 years of follow-up.

SETTING

One-centre study at university hospital.

MATERIAL AND METHODS

The subjects (n = 326) were obtained by stratified sampling from a population sample of men who were 58 years old at baseline. Carotid artery intima-media thickness (IMT) was measured bilaterally by high-resolution B-mode ultrasound at baseline and after follow-up. Plasma OxLDL cholesterol concentrations and conventional cardiovascular risk factors were measured at study entry. Automated measurements of IMT were performed. Plaque occurrence and size were assessed (plaque status). Plasma OxLDL at entry was measured by a specific monoclonal antibody, mAb-4E6.

RESULTS

OxLDL at entry, but not LDL cholesterol, was associated with the number and size of plaques at follow-up (P = 0.008), also after adjustment for plaque status at entry (P = 0.033). The plasma OxLDL concentration at entry was associated with change in carotid artery IMT (r = 0.17; P = 0.002) and in a stepwise multiple regression analysis this association remained after adjustment for other cardiovascular risk factors (P = 0.005).

CONCLUSIONS

These results provide new information, supporting the concept that circulating OxLDL was associated with the silent phase of atherosclerosis progression in clinically healthy men independently of conventional risk factors.

Tetrahydrobiopterin increases insulin sensitivity in patients with type 2 diabetes and coronary heart disease

Tetrahydrobiopterin (BH(4)) is an essential cofactor of nitric oxide synthase that improves endothelial function in diabetics, smokers, and patients with hypercholesterolemia. Insulin resistance has been suggested as a contributing factor in the development of endothelial dysfunction via an abnormal pteridine metabolism. We hypothesized that BH(4) would restore flow-mediated vasodilation (FMD, endothelial-dependent vasodilation), which may affect insulin resistance in type 2 diabetic patients. Thirty-two subjects (12 type 2 diabetic subjects, 10 matched nondiabetic subjects, and 10 healthy unmatched subjects) underwent infusion of BH(4) or saline in a random crossover study. Insulin sensitivity index (S(I)) was measured by hyperinsulinemic isoglycemic clamp. FMD was measured using ultrasonography. BH(4) significantly increased S(I) in the type 2 diabetics [3.6 +/- 0.6 vs. 4.9 +/- 0.7 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P < 0.05], while having no effects in nondiabetics [8.9 +/- 1.1 vs. 9.0 +/- 0.9 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P = 0.92] or in healthy subjects [17.5 +/- 1.6 vs. 18 +/- 1.8 x 10(-4) dl.kg(-1).min(-1)/(microU/ml), P = 0.87]. BH(4) did not affect the relative changes in brachial artery diameter from baseline FMD (%) in type 2 diabetic subjects (2.3 +/- 0.8 vs. 1.8 +/- 1.0%, P = 0.42), nondiabetic subjects (5.3 +/- 1.1 vs. 6.6 +/- 0.9%, P = 0.32), or healthy subjects (11.9 +/- 0.6 vs. 11.0 +/- 1.0%, P = 0.48). In conclusion, BH(4) significantly increases insulin sensitivity in type 2 diabetic patients without any discernible improvement in endothelial function.

Degree of atherosclerosis predicts short-term commitment for smoking cessation therapy

BACKGROUND

Only little is known about factors that influence the smokers' propensity to start smoking cessation therapy and stay within such programs.

METHODS

One hundred fifteen subjects that were current smokers and presented at the angiologic outpatient unit were enrolled in a prospective cohort study. All patients were invited to take part in a smoking cessation program. Patients' history, noninvasive vascular, cardiac, and pulmonary parameters, state of atherosclerotic disease (SMART-score), smoking history, and Fagerström index were obtained and the carbon monoxide breathing test was performed.

RESULTS

Lower age and heavy smoking were associated with less propensity to start smoking cessation therapy. The degree of atherosclerosis significantly predicted short-term commitment to smoking cessation therapy (relative risk for discontinuation: 0.82; 95% CI: 0.70-0.96). Single factors predictive for staying within the therapy were peripheral arterial occlusive disease and hyperlipidemia, while neither prior myocardial infarction nor pulmonary function was associated with compliance. Fifty-four percent of patients that completed 3 months of therapy quit smoking.

CONCLUSIONS

Counseling in smokers with preexistent or newly diagnosed atherosclerotic diseases or risk factors should include their specific vascular condition and information on positive consequences on the progress of these conditions. Counseling for initiation of smoking cessation therapy should apply different strategies as used in the maintenance phase of therapy.

Preclinical atherosclerosis and inflammation in 61-year-old men with newly diagnosed diabetes and established diabetes

OBJECTIVE

The aim of this study was to investigate the occurrence of subclinical atherosclerosis and underlying mechanisms in men with newly diagnosed diabetes and established diabetes compared with healthy control subjects.

RESEARCH DESIGN AND METHODS

In a population-based study of 61-year-old Caucasian men (n = 271) with established diabetes (n = 50) and newly diagnosed diabetes (n = 24) and healthy control subjects (n = 197), standard risk factors and highly sensitive (hs) C-reactive protein (CRP) were measured. Ultrasound measurements of intima-media thickness (IMT) were performed bilaterally in the common carotid artery, and a composite measure was calculated from common carotid and carotid bulb IMT (composite IMT). The plaque status was assessed.

RESULTS

Composite IMT and carotid plaque size increased gradually among the healthy control subjects, newly diagnosed diabetic patients, and established diabetic patients (P for trend < or =0.001, respectively). CRP was higher in newly and established diabetes (NS between diabetes groups) compared with healthy control subjects (P < 0.001). Total cholesterol levels were lower in newly diagnosed diabetes (5.51 +/- 1.13 mmol/l, P < 0.05) and established diabetes (5.45 +/- 1.15 mmol/l, P < 0.01) compared with those of healthy control subjects (5.77 +/- 1.03 mmol/l). In men with diabetes (n = 74), diabetes onset status (newly diagnosed versus established), waist-to-hip ratio (WHR), and serum triglycerides, but not CRP, explained 16% of the variance in composite IMT.

CONCLUSIONS

This is the first study to show increased preclinical atherosclerotic changes (IMT and plaque size) and increased inflammation (hs-CRP) in men with newly diagnosed diabetes as well as in patients with established diabetes compared with healthy control subjects. WHR, diabetes onset status (newly diagnosed versus established), and triglycerides, but not CRP, were independent correlates of carotid artery IMT in men with diabetes.

Oral snuff impairs endothelial function in healthy snuff users

AIMS

Oral snuff is a less dangerous drug and therefore a good substitute for cigarette smoking. The aim of this study was to determine whether oral moist snuff induces acute endothelial dysfunction. Previous studies have shown that endothelial dysfunction predicts cardiovascular morbidity.

METHODS AND RESULTS

Twenty healthy middle-aged snuff users underwent ultrasound assessment of endothelial-dependent flow-mediated dilatation (FMD) of the brachial artery. FMD measurements were performed in duplicate at baseline and then 20 and 35 min after the administration of 1 g portion-bag-packed moist snuff or placebo. Ten of the subjects were examined twice according to a randomized cross-over procedure, once with snuff and once with placebo. All images were arbitrarily analysed off-line by a single blinded observer. FMD values declined significantly from 3.4 +/- 2.0% to 2.3 +/- 1.3% (P < 0.05) 35 min after the administration of 1 g oral moist snuff. Heart rate, systolic and diastolic blood pressure increased significantly (P < 0.05) after snuff administration. All parameters remained unchanged after placebo.

CONCLUSIONS

Oral moist snuff significantly impaired FMD of the brachial artery. As endothelial dysfunction predicts cardiovascular morbidity, use of oral snuff should be discouraged.

Increased Interleukin-6 levels in pituitary-deficient patients are independently related to their carotid intima-media thickness

OBJECTIVE

Increased cardiovascular morbidity and mortality has been observed in patients with pituitary deficiency and untreated growth hormone deficiency (GHD). We investigated peripheral inflammatory and fibrinolytic markers and their associations with arterial intima-media thickness (IMT) in GHD.

DESIGN

Cross-sectional study.

PATIENTS

Thirty-four patients with GHD, but without cardiovascular disease, were compared to healthy controls matched for age, sex, body mass index (BMI) and smoking habits.

MEASUREMENTS

IMT of the common carotid artery, C-reactive protein (CRP), interleukin-6 (IL-6), fibrinogen, plasminogen activator inhibitor-1 (PAI-1) activity and tissue plasminogen activator antigen (tPA-ag) were measured.

RESULTS

Median IL-6 concentrations were increased by 208% and 248% in GHD patients compared to BMI-matched and nonobese controls, respectively. Median CRP and tPA-ag levels were increased by 237% and 167% in patients compared to nonobese controls, but not significantly different compared to BMI-matched controls. Plasma levels of fibrinogen and PAI-1 activity did not differ between groups. Age, low-density lipoprotein (LDL) cholesterol, tPA-ag and IL-6 were positively correlated, and IGF-I was negatively correlated to IMT in the patient group, but only age and IL-6 were independently related to IMT.

CONCLUSIONS

IL-6 concentrations were increased in GHD patients compared to controls and independently related to IMT in patients. This finding may help to explain the variance in IMT and the increased vascular morbidity and mortality in hypopituitary patients with GHD.

A novel cellular marker of insulin resistance and early atherosclerosis in humans is related to impaired fat cell differentiation and low adiponectin

The epidemic increase in type 2 diabetes can be prevented only if markers of risk can be identified and used for early intervention. We examined the clinical phenotype of individuals characterized by normal or low IRS-1 protein expression in fat cells as well as the potential molecular mechanisms related to the adipose tissue. Twenty-five non-obese individuals with low or normal IRS-1 expression in subcutaneous abdominal fat cells were extensively characterized and the results compared with 71 carefully matched subjects with or without a known genetic predisposition for type 2 diabetes. In contrast to the commonly used risk marker, known heredity for diabetes, low cellular IRS-1 identified individuals who were markedly insulin resistant, had high proinsulin and insulin levels, and exhibited evidence of early atherosclerosis measured as increased intima media thickness in the carotid artery bulb. Circulating levels of adiponectin were also significantly reduced. Gene analyses of fat cells in a parallel study showed attenuated expression of several genes related to fat cell differentiation (adiponectin, aP2, PPARgamma, and lipoprotein lipase) in the group of individuals characterized by a low IRS-1 expression and insulin resistance. A low IRS-1 expression in fat cells is a marker of insulin resistance and risk for type 2 diabetes and is associated with evidence of early vascular complications. Impaired adipocyte differentiation, including low gene expression and circulating levels of adiponectin, can provide a link between the cellular marker and the in vivo phenotype.

Cardiovascular autonomic neuropathy associated with carotid atherosclerosis in Type 2 diabetic patients

AIMS

To clarify if cardiovascular autonomic neuropathy is associated with carotid artery atherosclerotic plaques in Type 2 diabetic patients.

METHODS

Cardiovascular autonomic nerve function was related to carotid artery ultrasound in 61 Type 2 diabetic patients 5-6 years after diagnosis of diabetes.

RESULTS

Cardiovascular autonomic neuropathy [abnormal age corrected expiration/inspiration (E/I) ratio or acceleration index (AI)] was found in 13/61 (21%) patients. Patients with cardiovascular autonomic neuropathy showed increased degree of stenosis in the common carotid artery (24.6 +/- 13.2% vs. 14.7 +/- 9.2%; P = 0.014) and a tendency towards a higher plaque score (4.0 +/- 1.7 vs. 3.2 +/- 1.6; P = 0.064). Controlled for age, AI correlated inversely with degree of stenosis (r = -0.39; P = 0.005), plaque score (r = -0.39; P = 0.005), and mean (r = -0.33; P = 0.018) and maximum (r = -0.39; P = 0.004) intima-media thickness in the common carotid artery. In contrast, E/I ratio correlated only slightly with mean intima-media thickness in the common carotid artery (r = -0.28; P = 0.049).

CONCLUSIONS

Cardiovascular autonomic neuropathy was associated with carotid atherosclerosis in Type 2 diabetic patients. Abnormal E/I ratios reflect efferent structural damage to parasympathetic nerves whereas abnormal AI reflects afferent autonomic dysfunction possibly due to impaired baroreceptor sensitivity secondary to carotid atherosclerosis.

Bezafibrate-induced improvement in glucose uptake and endothelial function in protease inhibitor-associated insulin resistance

Protease inhibitors used as therapy for HIV-1 infection have been associated with metabolic side-effects such as peripheral fat wasting, central adiposity, hyperlipidaemia and insulin resistance. This metabolic disorder is known as the lipodystrophy syndrome. This syndrome can be recognized by the early appearance of an increase in serum triglyceride, cholesterol and plasma-free fatty acid levels. Here, we describe an HIV-1 positive patient with the lipodystrophy syndrome in whom a decline in serum triglycerides was seen along with a significant improvement in glucose uptake following treatment with bezafibrate for 3 months. This improvement may be a consequence of the Randle effect, i.e. increased availability of plasma-free fatty acids is negatively correlated to glucose uptake. We also noted a significant improvement in endothelial-dependent flow-mediated dilatation after treatment with bezafibrate. This effect could result from the increased glucose uptake observed and a decrease in insulin resistance secondary to the lowered triglyceride levels by bezafibrate. We conclude that bezafibrate may be of clinical utility in the lipodystrophy syndrome, through its beneficial effects on insulin resistance, glucose uptake and endothelial dysfunction.

Intima-media thickness in cardiovascularly asymptomatic hypopituitary adults with growth hormone deficiency: relation to body mass index, gender, and other cardiovascular risk factors

OBJECTIVE

Increased cardiovascular mortality and carotid atherosclerosis have been observed in hypopituitary patients with untreated GH deficiency (GHD), but results are contradictory and relations to cardiovascular risk factors are not clear. The aim of this study was to investigate intima-media thickness (IMT) in relation to cardiovascular risk factors in adults with GHD.

DESIGN

Cross-sectional observational study of 21 men and 13 women with GHD, but without cardiovascular disease, compared to two healthy control groups matched for age, sex and smoking habits. One control group was matched for body mass index (BMI) and the other group was nonobese.

MEASUREMENTS

IMT of the carotid and femoral arteries, blood pressure, blood samples and anthropometric data.

RESULTS

Patients had 12% thicker composite carotid IMT [(IMT of common carotid artery + IMT of bulb)/2] compared to nonobese controls (P = 0.022), but IMT was not different compared to BMI-matched controls. Femoral IMT did not differ between patients and controls. Patients had higher waist : hip ratio (WHR), heart rate, serum triglycerides and fasting insulin concentrations in combination with lower high-density lipoprotein (HDL) cholesterol and smaller low-density lipoprotein (LDL) peak particle size compared to both nonobese and to BMI-matched controls. This cardiovascular risk pattern was more pronounced in female patients than in male patients compared to their gender controls. Carotid IMT was related to age, serum cholesterol, LDL cholesterol and smoking in the patient group. Only age was independently related to carotid IMT in multivariate analysis.

CONCLUSIONS

These results indicate that high BMI in GH-deficient patients contribute to their increased intima-media thickness. However, several cardiovascular risk factors are present in this patient group independent of their increased BMI, especially in women.

Endothelium-dependent flow-mediated vasodilatation, insulin resistance and the metabolic syndrome in 60-year-old men

OBJECTIVES

To evaluate the endothelium-dependent flow-mediated vasodilatation (FMD) in the brachial artery and to study the relationship to insulin sensitivity and to the metabolic syndrome in 60-year-old clinically healthy men.

SUBJECTS

The men were randomly selected from the general population (n = 55). The subjects with the metabolic syndrome were defined according to a definition proposed by a working group associated with the World Health Organization (WHO).

METHODS

Ultrasound images for measurement of lumen diameter of the brachial artery were recorded before and after reactive hyperaemia induced by occlusion of the artery, both with and without ischaemic hand exercise during the occlusion. Insulin-mediated glucose uptake was determined by euglycaemic hyperinsulinaemic clamp as a measure of insulin sensitivity.

RESULTS

The FMD was in the total group 3.2% when hyperaemia was induced by occlusion only and 8.7% after occlusion plus ischaemic hand exercise (P < 0.001, n = 51). However, no relationship was observed between any measure of FMD and insulin-mediated glucose uptake (r = -0.05 and r = 0.06, n = 47, P > 0.30). Furthermore, subjects with the metabolic syndrome (n = 13) did not differ in any measure of FMD compared with those with no risk factors (n = 11).

CONCLUSION

In this study the ultrasound method to evaluate endothelial function did not show that low insulin sensitivity or the metabolic syndrome were associated with impaired FMD in otherwise clinically healthy 60-year-old men.

The early effect of lipid-lowering treatment on carotid and femoral intima media thickness (IMT)

OBJECTIVES

an increased intima media thickness (IMT) is an early indicator of the atherosclerotic process. We investigated the early effect of atorvastatin on the common carotid artery (CCA) and common femoral artery (CFA) IMT.

METHODS

the IMT was measured in the CCA and the CFA of hyperlipidaemic patients referred with peripheral vascular disease. The measurements were performed using an automated radio frequency IMT technique pre-treatment and at 4 and 8 weeks post-treatment with 20 mg/day atorvastatin.

RESULTS

patients (14 men; 11 women), median age 69 years (range: 48-81) had a CCA-IMT mean (SD) of 0.79 (0.21) mm pre-treatment, 0.75 (0.22) mm after 4 weeks, and 0.64 (0.15) mm after 8 weeks. The ANOVA test was significant (p=0.024) for the CCA-IMT trend. The corresponding CFA-IMT readings were 0.83 (0.13) mm, 0.80 (0.09) mm and 0.69 (0.14) mm (p=0.0003). After 8 weeks of treatment there was a significant reduction in total cholesterol 6.0 (0.3) to 4.3 (0.8) mmol/l, p=0.0004 and low-density lipoprotein cholesterol 3.7 (0.2) to 2.2 (0.5), p=0.0001. There was a significant decrease in median serum creatinine levels after 8 weeks treatment: 87 micromol/l (range 67-114) to 84 micromol/l (range: 64-112), p=0.007.

CONCLUSIONS

cholesterol-lowering with atorvastatin 20 mg/day leads to a decrease in CCA-IMT and CFA-IMT. This difference achieved significance after 8 weeks of treatment, but a trend was visible at 4 weeks. These rapid changes in IMT may be attributable to an anti-inflammatory effect. IMT measurement may be a useful tool to rapidly assess the effect of drug treatment on the atherosclerotic process.

Elevated interleukin-6 predicts progressive carotid artery atherosclerosis in dialysis patients: association with Chlamydia pneumoniae seropositivity

The cardiovascular mortality rate is unacceptably high in patients with end-stage renal disease (ESRD), which suggests an accelerated atherogenic process. The cause(s) of the accelerated atherogenesis in ESRD patients are not known, though recent studies suggest that persistent infection, such as Chlamydia pneumoniae, and proinflammatory cytokines may contribute. Forty-five ESRD patients (26 men) aged 51 +/- 2 years was studied at a time-point close to start of dialysis treatment and again after about 12 months of dialysis treatment. By using noninvasive B-mode ultrasonography, we evaluated changes in a surrogate marker of atherosclerosis, calculated intima media (cIM) area, in the common carotid artery. C-reactive protein (CRP), S-albumin, and interleukin-6 (IL-6) assessed the presence of an inflammatory reaction. We also measured C pneumoniae antibodies by microimmunofluorescence, nutritional status by subjective global assessment, lipid parameters, smoking habits, and the presence of comorbidity close to the start of dialysis. No significant changes in the prevalence of carotid plaques or the mean cIM area were observed during the first 12 months of dialysis. However, because some patients showed marked increases in the cIM area during only 12 months of dialysis we divided the patients into 2 groups: 23 nonprogressors ((delta)cIM area -2.7 +/- 0.4 mm2) and 22 progressors ((delta)cIM area 3.6 +/- 0.7 mm2). Sex, age, body mass index, comorbidity, blood lipid levels, S-albumin, and CRP levels did not differ significantly between the 2 groups. On the other hand, progressors had a significantly elevated basal median level of IL-6 (5.7 versus 3.1 pg/mL; P < 0.05) and an increased prevalence of positive (> or 1/64) immunoglobulin (Ig) A antichlamydia antibodies (59% versus 17%; P < 0.01) compared with nonprogressors. A significant positive (R = 0.41; P < 0.01) correlation was found between Log IL-6 and changes in the cIM area during 12 months of dialysis. In a stepwise multiple regression model, Log IL-6 did predict, independently (P < 0.01) of traditional risk factors and C pneumoniae antibodies, changes in the cIM area. These data suggest that a persistent chlamydial infection stimulates IL-6 levels, which in turn may be involved in the pathogenesis of accelerated carotid atherosclerosis in dialysis patients.

Using snakes to detect the intimal and adventitial layers of the common carotid artery wall in sonographic images

This study presents an innovative automatic system for detecting the intima-media complex of the far wall of the common carotid artery by applying the snake techniques. Cohen's snake was modified and some criteria were added for our applications. In addition, the oscillating problem of using snakes was solved by properly choosing the time step from analysis of the frequency response of the filters. A time-diminishing gravity window, external forces, and a cost function assist the snake in selecting the optimal shape of intimal and adventitia layers. We compared the proposed snake and ziplock snake with respect to the manual extraction contour. The results show that the system can automatically detect the intimal and adventitial layers without any manual correction.

Post-occlusion brachial artery vasodilatation after ischaemic handgrip exercise is nitric oxide mediated

Flow-mediated vasodilatation (FMD) of the brachial artery is used as a measure to quantify endothelial dysfunction. However, FMD after occlusion only is small in healthy people over middle age, but can be increased after handgrip exercise. The aim of this study was to evaluate whether postocclusion vasodilatation after handgrip exercise is mediated by nitric oxide (NO). High frequency ultrasound was used to measure brachial artery diameter at rest and after reactive hyperaemia with and without handgrip exercise during NaCl or NG-monomethyl-L-arginine (L-NMMA) infusion in healthy 60-year-old men. Postocclusion vasodilation was significantly larger after handgrip exercise compared with occlusion only (P=0.0078). Postocclusion vasodilatation was significantly lower after ischaemic handgrip exercise during intra-arterial infusion of L-NMMA compared with infusion of NaCl (P = 0.039). It may be concluded that the increased postocclusion brachial artery vasodilatation observed after ischaemic handgrip exercise is at least partly NO mediated. This modification of the investigation procedure may improve our ability to quantify FMD in subjects with and without vascular disease.

Carotid and femoral atherosclerosis, cardiovascular risk factors and C-reactive protein in relation to smokeless tobacco use or smoking in 58-year-old men

Objectives. To examine the associations between smokeless tobacco use, smoking, cardiovascular risk factors, inflammation and ultrasound-assessed measures of atherosclerosis in the carotid and femoral arteries. Subjects. The study was performed in a population-based sample of clinically healthy men (n = 391) all 58 years old. Exclusion criteria were cardiovascular or other clinically overt diseases or continuous medication with cardiovascular drugs. Methods. The habits of smoking and oral moist snuff use were assessed by questionnaires. C-reactive protein (CRP) was assessed by high sensitive enzyme-linked immunosorbent assay (ELISA). Intima-media thickness (IMT) in the carotid bulb, the common carotid artery and the common femoral artery and plaque occurrence were measured by ultrasound. Results. The use of oral moist snuff was associated with serum triglycerides and waist-hip ratio (WHR), but not with CRP or ultrasound-assessed measures of subclinical atherosclerosis. Smoking, on the other hand, was associated with CRP, the components in the metabolic syndrome and IMT as well as plaques in the carotid and femoral arteries. In comparison to never-smokers the current smokers had higher values of WHR, triglycerides, C-reactive protein and IMT in carotid bulb and femoral artery. Ex-smokers were in general more obese and had a femoral IMT that was in-between that of never-smokers and current smokers. Conclusions. Tobacco smoking, but not oral moist snuff use, was associated with carotid and femoral artery IMT, and increased levels of CRP. Current smoking was also associated with abdominal obesity. Ex-smokers though, are generally more obese. Smoking was also associated with hyperinsulinaemia, dyslipidaemia and high blood pressure, i.e. the metabolic syndrome. The inhaled smoke from the combustion of tobacco seems to be an important aetiological factor in the atherosclerotic process.

Computerized analysing system using the active contour in ultrasound measurement of carotid artery intima-media thickness

BACKGROUND AND PURPOSE

B-mode measurement of the carotid intima-media (IM) thickness (T) based on manual tracing (MT) procedures are dependent on the subjectivity of the reader and the existing automatic tracing procedures often fail to detect the IM boundaries accurately. The purpose of this study was to compare the tracing results of the IM boundaries of the carotid wall with a new automatic identification (AI) procedure, based on an active contour model, and computer-assisted manual tracing (MT).

METHODS

The detection of the IM boundaries was performed with both procedures in 126 ultrasound images [63 each of the common carotid artery (CCA) and carotid bulb] along the far wall of the distal CCA and the carotid bulb. Intra- and inter-reader variability for mean and maximum IMT with AI and MT and accuracy of identification of both IM boundaries were evaluated.

RESULTS

Using MT the intra- and inter-reader variability amounted to 0.01-0.03 and 0.03-0.07 mm, respectively. The variability was slightly higher in the carotid bulb than in the CCA. Using AI the variability was almost eliminated. Mean and maximum IMT were measured systematically lower by AI compared with MT in all regions by 0.01 mm. The accuracy of identification was similar for both IM boundaries, but lower in the carotid bulb region than in the CCA.

CONCLUSIONS

The new AI procedure identifies both IM boundaries in the region of the far wall of the CCA and carotid bulb with high precision, and eliminates most of the intra- and inter-reader variability of the IMT measurement using MT.

Improved analysis of brachial artery ultrasound using a novel edge-detection software system

Brachial artery ultrasound is commonly employed for noninvasive assessment of endothelial function. However, analysis is observer dependent and susceptible to errors. We describe studies on a computerized edge-detection and wall-tracking software program to allow more accurate and reproducible measurement. In study 1, three purpose-built Perspex phantom arteries, 3.00, 4.00, and 6.00 mm in diameter, were measured with the software. There was a mean bias of 11 microm (P < 0.001 at each level) between known and measured values; the mean resolving power of the software was estimated as 8.3 microm. In study 2, the mean intraobserver coefficient of variation of repeated measures of flow-mediated dilation (FMD) using the software (6.7%) was significantly lower than that for traditional manual measurements using the intima-lumen interfaces (24.8%, P < 0.05) and intima-media interfaces (32.5%, P < 0.05). In study 3, 24 healthy volunteers underwent repeat testing twice within 1 wk; the coefficients of variation for between-visit reproducibility of FMD and response to glyceryl trinitrate using the software were 14.7 and 17.6%, respectively. Assuming 80% power and an alpha of 0.05, eight subjects with matched controls would be required, in a parallel designed study, to detect an absolute 2.5% change in FMD. In summary, we have developed a semiautomated computerized vascular ultrasound analysis system that will improve the power of clinical intervention studies to detect small changes in arterial diameter.

Mild-to-moderate hypertriglyceridemia in young men is associated with endothelial dysfunction and increased plasma concentrations of asymmetric dimethylarginine

OBJECTIVES

The aim of this study was to investigate endothelial function and common carotid intima-media thickness (IMT) in healthy young men with mild-to-moderate hypertriglyceridemia. Plasma asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, was measured to further elucidate the mechanisms involved.

BACKGROUND

Hypertriglyceridemia is a risk factor for coronary heart disease although the mechanisms behind the increased risk remain to be defined. Acute elevation of plasma triglycerides induced by an intravenous fat load is associated with impaired endothelial function. The results of studies examining acute effects induced by a high-fat meal or effects of chronic hypertriglyceridemia on endothelial function are more inconsistent.

METHODS

Flow-mediated vasodilation and nitroglycerin-induced vasodilation of the brachial artery and common carotid IMT were measured noninvasively by ultrasound technique in 15 hypertriglyceridemic (HTG) subjects and 15 matched controls, mean age 34 years. Plasma concentrations of ADMA were measured by high-performance liquid chromatography.

RESULTS

Flow-mediated vasodilation was decreased in the HTG group (p < 0.0001), whereas nitroglycerin-induced vasodilation and carotid IMT did not differ significantly. Asymmetric dimethylarginine concentrations were higher in the HTG group (p < 0.05).

CONCLUSIONS

Hypertriglyceridemia in young men is associated with endothelial dysfunction and increased plasma concentration of ADMA but not with increased IMT of the common carotid artery. The corollary is that chronic hypertriglyceridemia results in endothelial dysfunction, possibly due to increased ADMA concentration, and that endothelial dysfunction might precede increased IMT among the early manifestations of atherosclerosis.

Cell adhesion molecules and secretory type II phospholipase A2 in relation to carotid atherosclerosis in patients with hypercholesterolaemia

OBJECTIVE

There has been no previous study investigating the relationship between subclinical atherosclerosis, as measured by ultrasound, and circulating levels of cell-adhesion molecules and snpPLA2 in patients with hypercholesterolaemia. The main aims of the present study were therefore to investigate the relationship between subclinical atherosclerosis, cell-adhesion molecules and snpPLA2 in a group of subjects with hypercholesterolaemia and also in a healthy control group; and to investigate the relationship between conventional risk factors, cell-adhesion molecules and snpPLA2 in these groups.

METHODS

Study subjects were recruited from the general population (50 subjects with hypercholesterolaemia and all 105 controls) and from the lipid clinic of Sahlgrens Hospital, Gothenburg (55 subjects with hypercholesterolaemia). Cell-adhesion molecules and snpPLA2 were analyzed by ELISA.

RESULTS

The levels of sICAM turned out to be positively and significantly associated with plaque occurrence and plaque size in the carotid artery in the patient group, but not in the control group. There were no significant relationships between sVCAM, sE-selectin or snpPLA2 and atherosclerosis, as measured by ultrasound. However, sICAM was significantly associated with sVCAM, sE-selectin and snpPLA2 both in the patient and in the control groups. In the patient group sICAM was positively and significantly associated with triglyceride levels and also negatively associated with high density lipoprotein (HDL) levels.

CONCLUSIONS

The present study showed that sICAM-1 was significantly associated with atherosclerosis, as measured by ultrasound, in the carotid artery in patients with hypercholesterolaemia. Furthermore, sICAM-1 levels were associated with plasma levels of snpPLA2 (r=0.44, P < 0.001), which recently have been shown to predict coronary events. Finally, high sICAM-1 levels were associated with an atherogenic lipid profile including high triglyceride levels and low HDL levels.

Multiple risk intervention trial in high risk hypertensive men: comparison of ultrasound intima-media thickness and clinical outcome during 6 years of follow-up

OBJECTIVES

The objective was to analyse whether a favourable change in risk factors, caused by a comprehensive risk factor modification programme, affected intima-media thickness (IMT) in the common carotid artery, and whether any such change was associated with a change in cardiovascular events during a 6-year follow-up.

DESIGN

Patients were randomized 1 : 1 to special intervention or usual care.

SETTING

Hypertension Unit at university hospital.

SUBJECTS

A total of 164 patients were randomized. Inclusion criteria were male, aged 50-72 years (at randomization) and one or more of the following: Serum cholesterol level > 6.5 mmol L(-1), smoking or diabetes mellitus. All patients were prescribed antihypertensive treatment since many years. In 142 men good quality ultrasound recording of the common carotid IMT were achieved at baseline, 119 were re-examined after 3.3 years, and 97 patients were available for examination after mean follow-up time of 6.2 years. Cardiovascular events were available for all randomized patients.

INTERVENTIONS

The nonpharmacological special intervention programme was based on one information meeting followed by five weekly 2-h sessions with participation of patients and spouses. The diet recommendations were similar to established guidelines. Overweight patients were instructed to lose weight, and diabetic patients were systematically taught self-monitoring of blood glucose. Smokers were invited to a smoking cessation programme with five weekly meetings. Follow-up visits were thereafter scheduled every 6 months. Lipid lowering drugs were recommended in the intervention group if the treatment goals using nonpharmacological measures were not achieved. Patients in the usual care group were told to quit smoking and to lower their consumption of fat and glucose. Antihypertensive treatment (i.e., selection of drugs) was on purpose kept similar in the two groups.

MAIN OUTCOME MEASURES

The IMT of the common carotid artery as measured by ultrasound. Cardiovascular events during follow-up.

RESULTS

Significant net reductions were seen for serum cholesterol, triglycerides, fasting glucose and smoking. No difference in change in IMT was observed during follow-up between the two randomization groups. The explanation was that patients with positive plaque status at baseline had a much larger increase in IMT over time than patients with negative plaque status, and that patients with positive plaque status more often survived and were available for re-examination after 6 years in the intervention group than in the usual care group. Total mortality was lower in the intervention group, compared with the usual care group, 13 and 29%, respectively (P=0.028).

CONCLUSIONS

In high risk populations, long-term studies with surrogate endpoints may be misleading because of missing data in patients where a large increase in IMT would have been observed, had they been re-examined. Another important conclusion from our study was that the gloomy prognosis for this patient category may be improved by a dedicated risk factor intervention programme. The improved prognosis was observed mainly in those patients at highest risk judged from history of cardiovascular disease or positive ultrasound plaque status at baseline.

Does renal failure cause an atherosclerotic milieu in patients with end-stage renal disease?

PURPOSE

Atherosclerotic vascular disease is the main cause of morbidity and mortality in patients with end-stage renal disease, but the independent contribution of renal failure rather than associated risk factors is unclear. We sought to examine the relative contribution of these factors to the severity of atherosclerosis by measuring intima-medial thickness and brachial artery reactivity in uremic patients and controls.

SUBJECTS AND METHODS

Cardiovascular risk factors, including lipid and homocysteine levels, were evaluated in 213 patients (69 on hemodialysis, 60 on peritoneal dialysis, and 82 nonuremic controls). High-resolution B-mode ultrasonography with automated off-line analysis was used to measure the intima-medial thickness in the common carotid artery and to measure the lumen diameter of the brachial artery at rest, during reactive hyperemia, and after sublingual nitroglycerine. The correlations of risk factors with intima-medial thickness and brachial reactivity were examined using a general linear regression model.

RESULTS

Patients with renal failure had a greater mean (+/- SEM) maximum intima-medial thickness than controls (0.83 +/- 0.02 mm versus 0.70 +/- 0.02 mm, P < 0.05), but the brachial artery response to reactive hyperemia was not significantly different between the renal failure patients and the control group (4.7% +/- 6.1% versus 6.1% +/- 8.6% dilatation, P > 0.05). The uremic state was an independent predictor of intima-medial thickness (r2 = 0.16, P < 0.001) but not of brachial artery reactivity (P = 0.99).

CONCLUSION

The atherosclerotic burden in patients with renal failure, as indicated by an increased intima-medial thickness, may reflect effects of uremia that are independent of cardiovascular risk factors.

LDL particle size in relation to intima-media thickness and plaque occurrence in the carotid and femoral arteries in patients with hypercholesterolaemia

OBJECTIVES

Small LDL particle size has been shown to be associated with coronary artery disease. However, no previous study has been performed relating LDL particle size to ultrasound measurement of atherosclerosis in hypercholesterolaemic subjects. The main aims of the present study were therefore: (i) to investigate the relationship between intima-media thickness (IMT) of the carotid bulb and LDL particle size in patients with primary hypercholesterolaemia (n = 102) and in matched normocholesterolaemic controls (n = 102); and (ii) to investigate the relationship between plaque occurrence in the carotid and femoral arteries and LDL particle size. LDL particle size was determined by subjecting serum to 2-16% polyacrylamide gradient gel electrophoresis.

RESULTS

The results showed that patients with primary hypercholesterolaemia had smaller LDL peak particle size compared with healthy control subjects (P < 0.001 for men, P = 0.006 for women). However, the difference in LDL peak particle size between patients with hypercholesterolaemia and controls disappeared when adjusting for serum triglycerides. There was no association between increasing IMT of the carotid bulb and decreasing LDL peak particle size or between the occurrence of moderate to large plaques in the carotid and femoral arteries and small LDL peak particle size. However, metabolic variables such as serum triglycerides, HDL, blood glucose, body mass index, and also systolic blood pressure were associated with LDL peak particle size.

CONCLUSION

The lack of an association between atherosclerosis, as measured by ultrasound, and small LDL particle size in patients with hypercholesterolaemia implies that other risk factors, such as hypercholesterolaemia and high blood pressure, may overshadow any importance of small LDL particle size.

Granularity of the carotid artery intima-medial layer: reproducibility of quantification by a computer-based program

Ultrasound of the carotid artery identifies the hypoechoic intima-medial layer (IML). Increased granularity of the IML has been associated with early atherosclerosis. The aim of the study was to assess the reproducibility and observer agreement of a computer-based program measure of IML granularity. Ten healthy adult volunteers (median age 32 years, range 18-34 years) were examined twice, 2 weeks apart, with a 7 MHz linear transducer using standardized imaging settings, by two observers. Images of both common carotid arteries were digitized and analysed on a customized computer program. The ratio (averaged over a 1 cm length of arterial wall) of the lowest pixel brightness in the IML to the maximum pixel brightness in the intima-medial interface was determined. Overall mean intima-medial reflectivity (IMR) indices for the two observers were 0.761 +/- 0.101 and 0.707 +/- 0.103, with single determination standard deviation values of 0.090 and 0.073, respectively. For interobserver calculations, the overall mean IMR index for both sessions was 0.734 +/- 0.107, with a single determination standard deviation of 0.067. Comparison with the intima-medial thickness (IMT) showed an inverse correlation (r = -0.72). This method of quantifying the reflectivity of the IML demonstrates good reproducibility in subjects with normal IMT measurements. The technique may be of value in identifying subjects at high risk of atherosclerosis but with IMT still within the normal range.

A multiscale dynamic programming procedure for boundary detection in ultrasonic artery images

Ultrasonic measurements of human carotid and femoral artery walls are conventionally obtained by manually tracing interfaces between tissue layers. The drawbacks of this method are the interobserver variability and inefficiency. In this paper, we present a new automated method which reduces these problems. By applying a multiscale dynamic programming (DP) algorithm, approximate vessel wall positions are first estimated in a coarse-scale image, which then guide the detection of the boundaries in a fine-scale image. In both cases, DP is used for finding a global optimum for a cost function. The cost function is a weighted sum of terms, in fuzzy expression forms, representing image features and geometrical characteristics of the vessel interfaces. The weights are adjusted by a training procedure using human expert tracings. Operator interventions, if needed, also take effect under the framework of global optimality. This reduces the amount of human intervention and, hence, variability due to subjectiveness. By incorporating human knowledge and experience, the algorithm becomes more robust. A thorough evaluation of the method in the clinical environment shows that interobserver variability is evidently decreased and so is the overall analysis time. We conclude that the automated procedure can replace the manual procedure and leads to an improved performance.

Computerized measurement of LDL particle size in human serum. Reproducibility studies and evaluation of LDL particle size in relation to metabolic variables and the occurrence of atherosclerosis

OBJECTIVES

The main aims of the present research project were to develop and evaluate a new software program for evaluation of LDL particle size applied to the gradient gel electrophoresis methodology without the use of previous ultracentrifugation, and to investigate the relationships among LDL particle size, metabolic variables and atherosclerosis, as measured by ultrasound, in subjects with different degrees of insulin resistance.

METHODS

LDL particle size was determined by polyacrylamide gradient gel electrophoresis.

RESULTS

Coefficient of variation for between-assay experiments was 0.3% (r = 0.99) for measurement of LDL peak particle size. LDL peak particle size was negatively correlated to serum triglycerides, apolipoprotein B, fasting insulin, BMI and diastolic blood pressure and positively correlated to HDL. Furthermore, subjects with moderate to large plaques in the carotid artery had smaller LDL particles compared to subjects without plaques.

CONCLUSIONS

This project resulted in a highly reproducible, computerized method for the analysis of LDL particle size. The data suggest that it is possible to assess LDL particle size in serum without the use of previous ultra-centrifugation. LDL particle size was associated with metabolic variables and the occurrence of moderate to large plaques in the carotid artery.

Second manifestations of ARTerial disease (SMART) study: rationale and design

The Second Manifestations of ARTerial disease (SMART) study is a single-centre prospective cohort study among patients, newly referred to the hospital with (1) clinically manifest atherosclerotic vessel disease, or (2) marked risk factors for atherosclerosis. The first objectives of the SMART study are to determine the prevalence of concomitant arterial disease at other sites, and risk factors in patients presenting with a manifestation of arterial disease or vascular risk factor and to study the incidence of future cardiovascular events and its predictors in these high-risk patients. At least 1000 patients, aged 18 to 80 years, will undergo baseline examinations, including a questionnaire on cardiovascular disease, height, weight and blood pressure measurements, blood tests for glucose, lipids, creatinine and homocysteine, urinary tests for microproteinuria, resting twelve-lead electrocardiogram, ultrasound scanning of the abdominal aorta, kidneys and the carotid arteries, measurements of common carotid intima-media thickness and arterial stiffness, and a treadmill test to assess atherosclerosis of the leg arteries. Abnormal findings are reported to the treating specialist and general practitioner with a treatment suggestion according to current practice guidelines. Recruitment and baseline examinations began in September 1996. All cohort members will be followed for clinical cardiovascular events for a minimum of three years. In the scope of secondary prevention, the study is expected to support the design of solid based screening and treatment programmes and evidence-based cardiovascular medicine to reduce morbidity and mortality, and improve quality of life, in high-risk patients.

Adding ischaemic hand exercise during occlusion of the brachial artery increases the flow-mediated vasodilation in ultrasound studies of endothelial function

A non-invasive method has been introduced to study endothelial function by evaluating flow-mediated, endothelium-dependent vasodilation of the brachial artery. One weakness of this method is that the post-occlusion vasodilation response is very small in subjects above the age of 60 years, which is a problem when quantifying endothelial dysfunction above this age. We have therefore evaluated whether a higher post-occlusion flow stimulus and a larger vasodilation response can be achieved by adding ischaemic hand exercise during the occlusion of the brachial artery. The subject population was men (n = 12), aged 60 years, free from cardiovascular disease. B-mode ultrasound images for the measurement of lumen diameter of the brachial artery were recorded before and after reactive hyperaemia induced by occlusion of the artery. Blood flow velocity was recorded intermittently using a Doppler technique. Hyperaemia was induced in two different ways: first by occlusion only and then by adding ischaemic hand exercise during the occlusion. The results showed that flow velocity was higher and the duration of flow increase was longer after ischaemic hand exercise compared with occlusion only. Two minutes after cuff pressure release, the increase in blood flow velocity was significantly higher after ischaemic hand work compared with occlusion only (P < 0.01). The corresponding maximal lumen diameters after cuff pressure release were 4.63 +/- 0.35 and 4.45 +/- 0.34 respectively (P < 0.01). The flow-mediated vasodilation increased significantly from 2.24 +/- 2.00% after occlusion only to 7.42 +/- 3.32% after occlusion plus ischaemic hand exercise (P < 0.01). In conclusion, this study showed that a maximal endothelial-dependent vasodilation was not achieved after occlusion only in these 60-year-old men. Adding ischaemic hand exercise may therefore be of value when quantifying endothelial dysfunction in this age group.

Evaluation of off-line automated intima-media thickness detection of the common carotid artery based on M-line signal processing

Intima-media thickness (IMT) measurements have gained increasing attention, because IMT is assumed to represent the endothelial adaptive response to physiological and pathophysiological processes. The main aim of the present study was to assess the intrasubject intrasession variability of a new off-line automated radio frequency (RF) IMT method in comparison with an already established off-line manual B-mode IMT method. IMT also was assessed by means of an on-line manual B-mode and an on-line manual RF IMT method. We investigated posterior wall IMT 0-1 cm proximal to the bulb in both common carotid arteries of 16 young (20-31 y; mean 25 y) female and male and 13 elderly (51-65 y; mean 56 y) female volunteers. Two commercially available ultrasound devices (Pie Medical Scanner 200 and Ultramark 9) were used to assess the effects of signal processing on the off-line automated RF IMT method. Intrasubject intrasession variability was determined using the standard deviation to evaluate and compare the various methods. Spearman rank correlation coefficients and Bland and Altman bias and limits of agreement were calculated to objectivate the comparability between the various methods. Intrasubject intrasession variation of IMT estimates was not statistically different between any of the methods. We observed a good comparability between the commonly used off-line manual B-mode IMT method and the off-line automated RF IMT method at the level of the common carotid artery.

How can the variability in ultrasound measurement of intima-media thickness be reduced? Studies of interobserver variability in carotid and femoral arteries

A critical component in scientific studies of most biological variables is the variation or error in measurements which leads to non-identical results of repeated measurements from the same subject. The aim of this study was to investigate whether the interobserver error (s) in measurement of intima-media thickness (IMT) in carotid and femoral arteries could be decreased if the mean value obtained using two ultrasound images from each of the right and left arteries was used in the analyses instead of the mean value obtained using images from only the right artery. In addition, we wished to evaluate two different reading procedures, one based on manual tracing of echo interfaces and the other on automated edge detection. In a methodological study, 50 subjects were examined with ultrasound twice in the same day by two independent laboratory technologists. The ultrasound images were analysed in two ways: using a computerized manual tracing analysing system and an automated analysing system. When both right and left carotid arteries were examined (manual reading), the interobserver error was smaller than that determined for the examination of only the right artery, for IMTmean in both the common carotid artery (P = 0.06) and the carotid artery bulb (P < 0.05). The interobserver error was also significantly smaller for double-sided vs. one-sided examination with automated reading of IMTmean in the common carotid artery (P < 0.01) and in the carotid artery bulb (P < 0.01). The coefficient of variation (CV) for measurement in the common carotid artery decreased from 8.6% (one-sided, manual reading) to 5.3% (double-sided, automated reading). The interobserver error in measurement of IMT in the common femoral artery did not improve by examination of both right and left arteries. The results from this study show that the interobserver errors in measurement of IMT can be decreased by using ultrasound images from both the right and the left carotid arteries, and that the use of an automated analysing system greatly simplifies the reading of ultrasound images with sustained low variability.