Directory UMM :Data Elmu:jurnal:A:Atherosclerosis:Vol153.Issue1.Nov2000:

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Effect of hypertension and risk factors on diameters of abdominal

aorta and common iliac and femoral arteries in middle-aged

hypertensive and control subjects

A cross-sectional systematic study with duplex ultrasound

Markku J. Pa¨iva¨nsalo

_{*, Jukka Merikanto}

_{, Tapani Jerkkola}

b,c

_,

Markku J. Savolainen

b,c

_{, Asko O. Rantala}

b,c

_{, Heikki Kauma}

b,c

_{, Mauno Lilja}

b,c

_,

Antti Reunanen Y.

_{, Antero Kesa¨niemi}

b,c

_{, Ilkka Suramo}

a_{Departments of Diagnostic Radiology}_,_Uni₆_{ersity of Oulu}_,_FIN_-₉₀₂₂₀_,_Oulu_,_Finland b_{Department of Internal Medicine}_,_Uni₆_{ersity of Oulu}_,_FIN_-₉₀₂₂₀_,_Oulu_,_Finland

c_{Biocenter Oulu}_,_Uni₆_{ersity of Oulu}_,_FIN_-₉₀₂₂₀_,_Oulu_,_Finland

d_{Social Insurance Institution Research and De}₆_{elopment Unit}_,_FIN_-₀₀₃₈₁_Helsinki_,_Finland

Received 30 April 1999; received in revised form 22 November 1999; accepted 5 January 2000

Abstract

There is a general tendency towards atherosclerosis and arterial dilatation in older age, and high blood pressure also tends to increase arterial diameters. The purpose of this study was to examine the effect of hypertension and other cardiovascular risk factors on aortic, common iliac and common femoral artery diameters. The diameters of the abdominal aorta and the iliac and femoral arteries and the extent of echogenic plaques in the aorta and the iliac arteries down to groin level were evaluated with ultrasound in 1007 middle-aged (40 – 60 years) men (505) and women (502), 496 with arterial hypertension and 511 controls. Twenty-eight subjects were excluded because of poor visualization. Men had significantly larger diameters of the abdominal aorta (mean 21.392.8 vs. 17.891.3 mm) and the common iliac (13.492.0 vs. 12.291.2) and common femoral arteries (11.091.4 vs. 9.790.9) than women (Pfor all B0.001), but arterial diameter was also related to the subject’s size. Atherosclerotic plaques, age and height were associated with the diameter of the abdominal aorta in men, while high body mass index (BMI) had less significance. The diameter of the aorta was larger in hypertensive men aged 56 – 60 than in controls of the same age. In women, height, BMI and diastolic blood pressure (DBP) were associated with the diameter of the aorta, while systolic blood pressure (SBP) had less and age no effect. Age, plaques, height, BMI, DBP and SBP were associated with the diameters of the common iliac arteries in both genders, while smoking had an inverse correlation. The results on lipid values were inconsistent and an abnormal glucose tolerance test proved nonsignificant. In conclusion, arterial size measured as a diameter related to the subject’s size was larger in men. Age, arterial plaques and blood pressure increased arterial diameter significantly. However, the hypertensive disease itself had only a minimal effect. The changes were smaller in women than in men. © 2000 Elsevier Science Ireland Ltd. All rights reserved.

Keywords:Ultrasound; Aorta; Iliac arteries; Plaques; Diameters; Hypertension

www.elsevier.com/locate/atherosclerosis

1. Introduction

Ultrasound (US) often shows plaques in the abdomi-nal aorta and the iliac and femoral arteries as signs of atherosclerosis, which may sometimes result in arterial obliteration, dilation or aneurysm [1]. There is a general

tendency towards arterial dilation in older age [2 – 5]. The purpose here was to examine the effect of hyper-tension and other risk factors on the diameters of the aorta and the common iliac and common femoral arteries in a population-based series of randomly (age-stratified) selected 40- to 60-year-old men and women with an established diagnosis of arterial hypertension, and controls.

* Corresponding author. Fax: +358-8-3155420.

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2. Methods

2.1. Population

From the defined population of the City of Oulu, treated hypertensive patients of both sexes aged 40 – 60 years and age- and sex-matched controls were recruited for carotid [6] and abdominal ultrasound examinations as part of a survey on the cardiovascular risk factors (OPERA, Oulu Project Elucidating the Risk of Atherosclerosis). The treated hypertensives (300 men and 300 women) were randomly selected from the Social Insurance Institute’s register for the reimburse-ment of antihypertensive medication, and the controls from the same organization’s register of all inhabitants of the City of Oulu (about 100 000 persons) as de-scribed in detail previously [7]. The initial population consisted of 1200 subjects. The overall participation rate was 85.9%, and the aorta and the iliac arteries were examined in 1007 subjects, i.e. 505 men, 502 women, 496 with arterial hypertension and 511 controls.

The procedure for blood pressure measurement was in agreement with the American Society of Hyperten-sion [8]. All blood pressure measurements were recorded with an automatic oscillometric blood pres-sure recorder (Dinamap; Critikon, Ascot, UK). The resting blood pressure was measured three times at 1-min intervals on the right arm after patient had been seated for at least 5 min. The mean of the three sitting blood pressure measurements was used in the analysis. BMI was calculated as weight in kilograms divided by height in square meters. Details about the smoking habits, alcohol consumption, use of medications, and past medical history were sought in a questionnaire. A wide range of laboratory analyses were conducted. Af-ter the fasting blood had been drawn, the subjects were given a 75-g glucose load. Both 1- and 2-h glucose and insulin concentrations were determined. The glucose concentrations were measured with the glucose dehy-drogenase method (Diagnostica; Merck, Darmstadt, Germany). Plasma lipids and lipoproteins were ana-lyzed as described in the Lipid Research Clinic Pro-gram’sManual of Laboratory Operations [9].

The mean duration of hypertension was 6.9 years (SD 4.7 years, range 0.15 – 32.6 years). Of the hyperten-sive subjects, 262 were on selective b-blocking medica-tion, 210 on angiotensin-converting enzyme inhibitors, 190 on thiatzide diuretics, 125 on calcium channel blockers and 31 on non-selectiveb-blocking medication and loop diuretics, 294 women were postmenopausal.

2.2. Ultrasonography of aorta and iliac arteries

The data were collected over a period of 2 years. The ultrasound examination of the aorta and iliac arteries was carried out, using a duplex ultrasound system

(Toshiba Sonolayer SSD 270) with a scanning fre-quency of 5 MHz, by a single trained radiologist blinded to the presence or absence of hypertension and following the same protocol throughout. The abdomi-nal aorta and the common iliac and femoral arteries were imaged longitudinally and transversally. The whole scanning procedure was recorded on a Super-VHS video casette recorder (Panasonic). The videotapes were analyzed later. The same radiologist (MP) who performed the examinations made the mea-surements from the videotapes for the 380 successively youngest men, and another trained radiologist (JM) made the measurements for the other men and for all women. Twenty-eight of the 1007 subjects were ex-cluded because of poor visualization of the aorta and the iliac arteries.

All measurements were made about 4 years later from the video image on the monitor of the ultrasound device, using its electronic calipers. The maximal outer diameter (lumen plus wall thicknesses) of the lower abdominal aorta was measured in the sagittal and transverse planes and the maximal diameters of both common iliac arteries and both common femoral arter-ies in the groin in the sagittal plane. An arterial plaque was defined as a highly or moderately echodense struc-ture encroaching into the vessel lumen. Atherosclerosis was estimated on the basis of the plaques detected. The number of plaques was recorded and the length of each was measured as the maximal diameter from longitudi-nal ultrasound scans of the aorta and the iliac arteries between the level of the renal arteries and the inguinal ligament.

The moving mean technique [10] was used to assess the association of the diameters with increasing age, and the data on one third of the subjects in the overlap-ping subgroups were used to calculate the mean. Age was determined as of the day of the examination. The results were also calculated separately for the age classes of 40 – 45 years, 46 – 50 years, 51 – 55 years and 56 – 60 years. The diameters were correlated with sex, age and disease (hypertension/control) and other risk factors.

The method of Fleiss [11,12] was used to calculate interobserver variability. First, the variance of measure-ments in one plane by the two observers was calculated using the formula: (M1)

2₊₍_M 2)

2₋₍_M 1+M2)

2_/_2, where M1 and M2 are the diameters obtained by the two observers. The mean variance for all patients was then calculated. Interobserver variability was obtained by taking the square root of the mean interobserver variance. The variability percentage was obtained by dividing the variability with the mean diameter. The intrareader reproducibility of the measurements of ves-sel diameters was assessed in 40 subjects of this series with similar age and sex distribution as in the original series, and repeat measurements were performed from

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the videotapes 1 year after the subjects’ examinations, reader blinded to the original result. The intrareader variability/correlation coefficients (Pearson’s coeffi-cient) for the vessel diameters were: 3.7%/0.88 for the sagittal aortic diameter, 5.8%/0.72 for the transverse aortic diameter, 8.3%/0.78 for the iliac and 5.2%/0.86 for the femoral arterial diameters. The corresponding interreader values were: 4.5%/0.86 for the sagittal aortic diameter, 6.5%/0.71 for the transverse aortic diameter, 8.7%/0.76 for the iliac and 6.9%/0.89 for the femoral arterial diameters.

2.3. Statistical analyses

The data were analysed with the SystatTM _statistical program [13], which estimated the dependence of the diameters on age by means of correlation analysis. The data are presented as means9SD values, unless other-wise stated. Thex2test was used to test the differences in frequencies, and Student’s two-tailed t-test for inde-pendent samples to compare two groups. P-values B 0.05 were considered statistically significant. The arterial diameters were related to the risk factor vari-ables in multivariate stepwise linear regression analysis by backward elimination. Only the variables significant at P50.15 were retained in the equation.

3. Results

The clinical data are presented in Table 1. Table 2 shows the arterial diameters in the male and female cohorts. Men had significantly larger diameters of the aorta (mean sagittal diameter 20.392.8 vs. 17.291.3 mm) and the common iliac (13.392.0 vs. 12.291.3) and common femoral arteries (11.091.5 vs. 9.791.0) than women (P for all B0.001). The transversal aortic diameters were larger than the sagittal ones, the former being 22.293.0 mm for men and 18.491.4 mm for women (PB0.001). The arterial diameters were more

closely related to body height in women than in men. The diameters of the aorta in men and those of the common iliac and femoral arteries both in men and in women appeared to enlarge with age (Tables 2 and 3) (Fig. 1.). The aortic diameter was larger in hypertensive men aged 56 – 60 than in control men of the same age (Table 2) (Fig. 1). The mean aortic diameter was larger than the mean plus 2 SD (20.0 mm) in 2.5% of the control women aged 40 – 50 and, in 2.9% of those aged 51 – 60 years, and the corresponding percentages for hypertensive women were 3.0% and 1.5%. In the corre-sponding age groups of men, the aortic diameter ex-ceeded the mean plus 2 SD (25.4 mm) in 0.8% (40 – 50 years) and 3.9% (51 – 60 years) of the controls and in 0.8 and 7.0% of the corresponding hypertensives. In the common iliac arteries, the percentages for the same age groups were 1.3%/5.1% (mean+2 SD\14.6 mm) (con-trol women), 4.5%/8.0% (hypertensive women), 0.4%/ 5.8% (mean+2 SD\17.2 mm) (control men) and 1.6%/12.3% (hypertensive men). Hypertensive women in the age groups of 40 – 45 and 46 – 50 years had significantly larger common iliac and common femoral arteries than the controls. Obesity was significantly associated with arterial diameter and also with blood pressure (Table 3). The effect of lipid values, however, was nonsignificant. The diameters of the aorta in men and the diameters of the common iliac arteries in both men and women correlated well with the amount of plaques, which increased with age (Table 3) (Fig. 2). Hypertensive subjects had a larger plaque extent than controls, especially older women with a long duration of hypertension. The mean sum of plaque lengths in the aorto – iliac area was 79 mm in control and 107 mm in hypertensive women, and 100 mm in control and 104 mm in hypertensive men. Non-smoking men had sig-nificantly wider common iliac and common femoral arteries and slightly wider aortas than smoking men, and non-smoking women had only slightly wider com-mon iliac and comcom-mon femoral arteries than smoking women, but smoking women had wider aortas than non-smoking women (Fig. 3).

Table 1

Clinical data of the hypertensive and control subjectsa

Women

Variable Men

Controls HA P Controls HA P

255 233

Number 251 240

N.S. N.S.

51.995.9 51.896.0

Age (year) 50.996.1 50.595.9

27.994.6 B0.001

26.094.2

BMI (kg/m2₎ _B0.001 _26.693.6 _29.194.2

140920 154920 B0.001

SBP (mm Hg) 147920 159921 B0.001

83913 91911 B0.001

DBP (mm Hg) 89910 97910 B0.001

4.799.2 5.0910.6 N.S.

Smoking (pack- years) 16.1914.2 15.3913.6 N.S.

5.891.0 N.S. 5.791.1 N.S.

Total cholesterol (mmol/l) 5.591.0 5.891.1

HDL cholesterol (mmol/l) 1.5390.39 1.4590.38 0.016 1.2390.30 1.1990.32 N.S.

Triglycerides (mmol/l) 1.191.6 1.391.6 B0.001 1.491.6 1.791.6 B0.001

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Table 2

Sagittal artery diameters in the hypertensive and control women and mena

Age 40–45 46–50 51–55 56–60 All Pb

Aorta

Women 17.291.4

17.091.4 17.191.3 17.091.6

17.191.4 17.091.5

Control

17.391.5 17.391.3 17.291.3

HA 17.691.3 17.391.3 0.022

20.392.8 Men

19.991.7

Control 19.192.1 20.592.2 21.793.1 20.292.5

19.991.8 20.692.7 22.594.4

19.092.0 20.493.1

HA 0.574

Common iliac arteries

12.291.3 Women

11.591.0 12.191.0 12.591.4 12.091.3

Control 11.691.0

12.291.22 _12.4_91.33 _12.69_1.3

12.291.21 _12.491.4

HA B0.001

Men 13.392.0

12.891.6 13.291.9 14.791.7

12.291.6 13.292.0

Control

13.291.6 13.691.9 15.592.14 _13.692.2

HA 12.391.7 0.007

Common femoral arteries

Women 9.791.0

9.290.9

Control 9.491.0 9.690.8 9.991.0 9.691.0

9.890.96 _9.9_90.97 _9.99_0.8

9.990.95 _9.990.9

HA B0.001

Men 11.091.5 11.091.5

10.691.2 10.791.3 11.891.2

10.591.3 10.991.5

Control

10.891.2 11.191.2 12.191.6

HA 10.491.3 11.191.5 0.058

a_{Values are means9SD. Difference between hypertensives and controls}_t_-test.

b_{Significant differences between hypertensives and controls in subgroups:}1_P₌_0.004;2_P_B0.001;3_P₌_0.035;4_P₌_0.001;5_P₌_0.001;6_P_B0.001; 7_P₌_0.029.

4. Discussion

Duplex ultrasound is commonly used to diagnose aneurysms of the abdominal aorta by measuring its diameter. The variation in the measurements of the anteroposterior diameters of abdominal aortic aneu-ryms has been 2.2 – 8 mm [14,15]. In the series by Yucel et al. [11], the interobserver variability of the anteropos-terior measurement was 2.53 mm, which accounts for 7% of the mean diameter. In accordance with previous studies, interobserver variability was also larger for transverse measurements in our study, probably due to the superior axial compared to lateral resolution [11,14,15]. Our variability percentages were also com-parable to the previous results [11,16,17]. The in-trareader variabilities presented in millimeters in our series were 0.73 and 1.3 mm for the aortic sagittal and transverse measurements. The values are small because our series consisted of subjects with normal aortas compared to the series with aortic aneurysms [11]. The intra/interreader correlation coefficients were naturally poorer than in our carotid series [6], because of the smaller diameters of the aorta and the iliac vessels in relation to the ultrasound image, which leads to a poorer measurement accuracy compared to the carotid image.

The aortic diameter increases with age, being larger in men [18 – 20]. In a multivariate analysis, including age, height, body weight and sex, the distal aortic

diameter correlated only with age and sex in the series by Pedersen et al. (1993) [5]. According to our contra-dictory results, age had no effect on the female aortic diameter, but in men the diameter was significantly enlarged. However, the diameters of the common iliac and common femoral arteries slightly increased over age among women, while the corresponding increase in men was clearly higher.

The luminal diameter of the distal aorta was 16 mm in men and 13.7 mm in women, and the luminal diameters of the common iliac arteries were 9.9 and 8.8 mm in the series by Pedersen et al. [5]. Sonesson et al. [20] also measured the luminal diameters of the aorta, which were about 15.1/16.5 mm for women/men aged 40 years with body surface areas of 1.7 m2 _{and 16.2}_/ 18.2 mm for those aged 60 years. The aortic diameter was larger in males aged 25 years or more, though this difference decreased if corrected for differences in body surface area in the series by Sonesson et al. [20]. Our aortic diameters calculated from a regression equation for the same ages and body surfaces were 17.2/17.3 mm in women/men aged 40 years and 17.0/21.1 mm in subjects aged 60 years. Our values were higher, because we measured the outer diameters (vessel lumen plus wall thicknesses). In our series, the aortic diameters in females and males were the same at the age of 40 when corrected for differences in body surface area, while at the age of 50 years, men had 2 mm wider aortas than females, and the difference at the age of 60 years was 4

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Table 3 Diameter Variables Femoral artery Iliac artery Aorta

P ra _P _ra _P

A.Correlations of diameters of aorta,common iliac and femoral artery with the clinical 6ariables and plaquesb

Women

0.002 N.S. 0.239 B0.001 0.121 0.007

Age (years)

B0.001

0.236 0.110 0.015 0.198 B0.001

Height

0.348 B0.001 0.276

B0.001 B0.001

BMI 0.172

0.109 0.016 0.121

SBP 0.060 N.S. 0.007

0.173 B0.001 0.194

0.001 B0.001

DBP 0.149

N.S.

−0.025 0.050 N.S. −0.018 N.S.

Blood glucose

0.064 N.S. 0.013

N.S. N.S.

−0.057 Cholesterol

−0.141

−0.025 N.S. 0.002 −0.050 N.S.

HDL

0.092 0.043 −0.003

Triglycerides −0.014 N.S. N.S.

0.020 N.S. −0.015

0.018 N.S.

0.107 Smoking (pack-years)

−0.030 N.S. −0.029

Alcohol 0.029 N.S. N.S.

0.292 B0.001 0.093

N.S. 0.039

Aortic plaques 0.012

0.248 B0.001 0.061

Peripheral pl.1_s _0.020 _N.S. _N.S.

0.165c _0.181c

0.111c

Hypertensionc

Men

0.497 B0.001 0.360

B0.001 B0.001

Age (years) 0.358

Height 0.027 N.S. 0.025 N.S. 0.097 0.031

0.201 B0.001 0.234

0.002 B0.001

BMI 0.142

0.109 0.016 0.103

SBP 0.165 B0.001 0.023

0.103 0.023 0.1.32

0.009 0.003

DBP 0.117

N.S.

0.034 0.132 0.004 0.133 0.003

Blood glucose

−0.013 N.S. −0.001

N.S. N.S.

0.083 Cholesterol

N.S.

0.001 −0.053 N.S. −0.009 N.S.

HDL

Triglycerides 0.080 N.S. 0.106 0.019 0.057 N.S.

0.024 N.S. −0.075

0.006 N.S.

Smoking (pack-years) 0.124

−0.005 N.S. −0.004

Alcohol −0.025 N.S. N.S.

0.381 B0.001 0.173

B0.001 B0.001

Aortic plaques 0.427

0.444

Peripheral pl.1_s _0.383 _B0.001 _B0.001 _0.216 _B0.001

0.083c _0.060c

0.033c

Hypertensionc

B.Analysis of6ariance of sagittal 6essel diameters and independent6ariablesd

P F-ratio P F-ratio P

F-ratio

Women

8.3

Age 1.2 N.S. 0.004 9.8 0.002

23.2 B0.001 33.7

B0.001 B0.001

Height 37.2

52.7 B0.001 40.8

BMI 21.0 B0.001 B0.001

6.9 0.009 2.7

N.S. N.S.

SBP 2.6

0.001

11.6 12.0 0.001 11.4 0.001

DBP

0.8 N.S. 0.02

N.S. N.S.

0.08 Blood glucose

N.S.

0.000 0.01 N.S. 0.02 N.S.

Cholesterol

5.3 0.022 1.5 N.S.

HDL 0.2 N.S.

12.4 B0.001 11.7

0.016 0.001

5.8 Triglycerides

0.6 N.S. 0.3

Smoking 8.1 0.005 N.S.

0.02 N.S. 0.2

N.S. N.S.

Alcohol 0.2

1.3 N.S. 0.1

Aortic plaques 0.1 N.S. N.S.

3.4 N.S. 0.2

N.S. N.S.

0.05 Peripheral pl.

4.5 0.035 5.0

Hypertension 5.9 0.016 0.026

0.538 0.468

Multiple R 0.407

Men

84.0 B0.001 58.7

B0.001 B0.001

Age 15.7

22.5 B0.001 22.9

Height 11.0 0.001 B0.001

17.9 B0.001 22.0

0.013 B0.001

BMI 6.2

SBP 0.16 N.S. 8.8 0.003 11.8 0.001

6.6 0.010 12.9 B0.001

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Table 3 (Continued)

Variables Diameter

Iliac artery

Aorta Femoral artery

P ra

ra _P _ra _P

N.S. 0.02 N.S. 0.7 N.S.

Blood glucose 3.6

N.S. 1.8 N.S.

0.4 0.008

Cholesterol N.S.

0.9

HDL N.S. 0.002 N.S. 0.07 N.S.

N.S. 0.8 N.S.

Triglycerides 0.6 2.9 N.S.

N.S. 9.1 0.003

0.02 8.6

Smoking 0.004

1.8

Alcohol N.S. 0.2 N.S. 0.05 N.S.

B0.001 0.4 N.S. 0.3

Aortic plaques 23.7 N.S.

N.S. 35.6 B0.001

3.8 8.1

Peripheral pl. 0.005

0.15

Hypertension N.S. 1.1 N.S. 0.4 N.S.

Multiple R 0.543 0.642 0.522

a_{Correlation coefficient (Pearson).}

b_{Blood glucose: 2 h blood glucose.}1_{Peripheral pl., sum of plaque lengths in the common and external iliac arteries; aortic plaques}₌_{sum of}

plaque lengths in the aorta.

c_{Spearman’s coefficient.}

d_{Linear parameters: age, height, BMI, SBP, DBP, alcohol consumption, smoking (pack-years), cholesterol, HDL, triglycerides, 2 h blood}

glucose value at glucose tolerance test; categorical parameters: hypertension (0=no, 1=yes).

mm. When the mean aortic diameter was calculated in the control subjects, the diameter was larger than the mean plus 2 SD more often in hypertensives than in controls, especially in older subjects (50 – 60 years), in the iliac arteries of both genders and in the aortas of men. Human arteries dilate in response to progressive atherosclerosis, as was also seen in our series, where aortic dilatation was associated with aortic plaques and iliac and femoral dilatation with plaques in these vessels. This compensatory mechanism results in an increase in arterial size that is proportionate to the cross-sectional area of plaques that have accumulated in the vessel [21,22]. Atherosclerosis may also lead to obliteration or occlusion of arteries. Atherosclerosis is the etiopatho-logic cause of about 90% of the aortic aneurysms found in elderly subjects, in men, in smokers and in subjects in poor health (defined as concurrent hypertension, cardio-vascular disease or diabetes mellitus) [23 – 25]. The defi-nitions of abdominal aortic aneurysm based on the aortic diameter vary [3,26 – 30]. The most widely used definition is maximal sagittal diameter ]30 mm [26,27,31]. The reported prevalence of abdominal aortic aneurysms in subjects aged 50 years and older varies between 1.4 and 8.8% [32 – 34]. An aneurysm was found in 8.8% of men and in 2.1% of women]50 years referred for their first abdominal ultrasonography without any suspicion of aneurysm [32]. The prevalence in patients with symp-tomatic peripheral or cerebral arterial disease may be as high as 11.2% (men) and 6.4% (women) [35]. We found an aneurysm (diameter ]3.0 cm) in 1.4% of men aged 40 – 60 (2.4/1.2% in control men and 3.8/1.7% (dilatation/ aneurysm) in hypertensive men), but none in the women. Aneurysms in the iliac arteries are rare.

In multiple regression analysis, high blood pressure

increased arterial diameter. The diagnosis of hyperten-sion in regreshyperten-sion analysis had a nonsignificant effect on arterial diameter in men, even when SBP/DBP was ignored, and a minimal effect in women.

Long-term smoking is a primary risk factor for coro-nary and peripheral vascular disease causing endothelial dysfunction, an early stage of atherosclerosis [36]. Smoking may decrease endothelium-dependent

dilata-Fig. 1. Moving mean curves showing the sagittal diameters of the aorta (A) and the common iliac artery (B) in study subjects by gender and hypertensive status. FC, control females; FHT, hypertensive females; MC, control men; MHT, hypertensive men.

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Fig. 2. Moving mean curves showing the sagittal diameters of the aorta (A) and the common iliac artery (B); FNP, females without plaques; FP, females with plaques; MNP, men without plaques; MP, men with plaques.

common iliac and common femoral arteries were smaller in smokers compared to nonsmokers in our series. Lipid values did not have a significant effect on arterial diameters.

Arterial size, measured as a diameter related to the subject’s size, was higher in men. The significant risk factors increasing arterial diameter were age, atherosclerosis and blood pressure. However, hyperten-sive disease itself had only a minimal effect. The changes were smaller in women than in men.

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[13] Systat for Windows, Version 5, Statistics, Systat Inc., 1992 [14] Ellis M, Powell JT, Greenhalg RM. Limitations of

ultrasonogra-phy in surveillance of small abdominal aortic aneurysms. Br J Surg 1991;78:614 – 6.

[15] Akkersdijk GJM, Puylaert JBCM, de Vries AC. Accuracy of ultrasonographic measurement of infrarenal abdominal aortic aneurysm. Br J Surg 1994;81:376.

Fig. 3. Moving mean curves showing the sagittal diameters of the aorta (A) and the common iliac artery (B) according to smoking status and gender. FNS, non-smoking females; FS, smoking females; MNS, non-smoking men; MS, smoking men.

tion in active or passive smokers compared to non-smokers in the peripheral arteries, such the brachial artery measured with US [37]. The diameters of the

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[16] Persson J, Stavenow L, Wikstrand J, Israelsson B, Formgren J, Berglund G. Noninvasive quantification of atherosclerotic le-sions. Arterioscler Tromb 1992;12:261 – 6.

[17] Riley WA, Barnes RW, Applegate WB, Dempsey R, Hartwell T, Davis VG, et al. Reproducibility of noninvasive ultrasonic mea-surement of carotid atherosclerosis. Stroke 1992;23:1062 – 8. [18] Dixon AK, Lawrence JP, Mitchell JRA. Age-related changes in

the abdominal aorta shown by computed tomography. Clin Radiol 1984;35:33 – 7.

[19] Pearce WH, Slaughter MS, LeMaire S, Salyapongse AN, Fein-glass J, McCarthy WJ, Yao JST. Aortic diameter as a function of age, gender and body surface area. Surgery 1993;114:691 – 7. [20] Sonesson B, La¨nne T, Hansen F, Sandgren T. Infrarenal aortic

diameter in the healthy person. Eur J Vasc Surg 1994;8:89 – 95. [21] Losordo DW, Rosenfield K, Kaufman J, Pieczek A, Isner M.

Focal compensatory enlargement of human arteries in response to progressive atherosclerosis. In vivo documentation using in-travascular ultrasound. Circulation 1994;89:2570 – 0.

[22] Steinke W, Els T, Hennerici M. Compensatory carotid artery dilatation in early atherosclerosis. Circulation 1994;89:2578 – 81. [23] Amati G, Silver MD. Atherosclerosis of aorta and its complica-tions. In: Silver MD, editor. Cardiovascular Pathology. New York: Churchill Livingstone, 1991.

[24] Wolf YG, Otis SM, Schwend RB, Bernstein EF. Screening for abdominal aortic aneurysms during lower extremity arterial eval-uation in the vascular laboratory. J Vasc Surg 1995;22:417 – 23. [25] Krohn CD, Kullmann G, Kvernebo K, Rose´n L, Kroese A. Ultrasonographic screening for abdominal aortic aneurysm. Eur J Surg 1992;158:527 – 30.

[26] Scott RAP, Ashton HA, Kay DN. Abdominal aortic aneurysm in 4237 screened patients patients: prevalence, development and management over 6 years. Br J Surg 1991;78:1122 – 5.

[27] Holdsworth JD. Screening for abdominal aortic aneurysm in Northumberland. Br J Surg 1994;81:710 – 2.

[28] Johnston KW, Rutherford RB, Tilson MD, Shah DM, Hollier L, Stanley JC. Suggested standards for reporting on arterial aneurysms. J Vasc Surg 1991;13:452 – 8.

[29] Allardice JT, Allwright GJ, Wafula JMC, Wyatt AP. High prevalence of abdominal aortic aneurysm in men with peripheral vascular disease: screening by ultrasonography. Br J Surg 1988;75:240 – 2.

[30] Shapira OM, Psik S, Wasserman JP, Barzilai N, Mashiah A. Ultrasound screening for abdominal aortic aneurysms in patients with atherosclerotic peripheral vascular disease. J Cardiovasc Surg (Torino) 1990;31:170 – 2.

[31] The UK small aneurysm trial participants. The UK small aneu-rym trial: design, methods and progress. Eur J Vasc Endovasc Surg 1995;9:42 – 8.

[32] Akkersdijk GJM, Puylaert JBCM, deVries AC. Abdominal aor-tic aneurysm as an incidental finding in abdominal ultrasonogra-phy. Br J Surg 1991;78:1261 – 3.

[33] Pleumeekers HJCM, Hoes AW, vaderDoes E, VanUrk H, Grobbee DE. Epidemiology of abdominal aortic aneurysms. Eur J Vasc Surg 1994;8:119 – 28.

[34] Collin J, Araujo L, Walton J. A community detection program for abdominal aortic aneurysm. Angiology 1990;41:53 – 8. [35] MacSweeney STR, O’Meara M, Alexander C, O’Malley MK,

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[36] Heitzer T, Just H, Munzel T. Antioxidant vitamin C improves endothelial dysfunction in chronic smokers. Circulation 1996;94:6 – 9.

[37] Woo KS, Robinson JT, Chook P, Adams MR, Yip G, Mai ZJ, Lam CW, Sorensen KE, Deanfield JE, Celermajer DS. Differ-ences in the effect of cigarette smoking on endothelial function in Chinese and white adults. Ann Intern Med 1997;127:372 – 5.

(1)

the videotapes 1 year after the subjects’ examinations,

reader blinded to the original result. The intrareader

variability

/

correlation

coefficients

(Pearson’s

coeffi-cient) for the vessel diameters were: 3.7%

/

0.88 for the

sagittal aortic diameter, 5.8%

/

0.72 for the transverse

aortic diameter, 8.3%

/

0.78 for the iliac and 5.2%

/

0.86 for the femoral arterial diameters. The corresponding

interreader values were: 4.5%

/

0.86 for the sagittal aortic

diameter, 6.5%

/

0.71 for the transverse aortic diameter,

8.7%

/

0.76 for the iliac and 6.9%

/

0.89 for the femoral

arterial diameters.

2 .

3 .

Statistical analyses

The data were analysed with the Systat

_statistical

program [13], which estimated the dependence of the

diameters on age by means of correlation analysis. The

data are presented as means

9 SD values, unless

other-wise stated. The

x

test was used to test the differences

in frequencies, and Student’s two-tailed

t

-test for

inde-pendent samples to compare two groups.

P

-values

B

0.05 were considered statistically significant. The

arterial diameters were related to the risk factor

vari-ables in multivariate stepwise linear regression analysis

by backward elimination. Only the variables significant

at

P

5 0.15 were retained in the equation.

3. Results

The clinical data are presented in Table 1. Table 2

shows the arterial diameters in the male and female

cohorts. Men had significantly larger diameters of the

aorta (mean sagittal diameter 20.3

9 2.8 vs. 17.2

9

1.3 mm) and the common iliac (13.3

9 2.0 vs. 12.2

9 1.3)

and common femoral arteries (11.0

9 1.5 vs. 9.7

9 1.0)

than women (

P

for all

B

0.001). The transversal aortic

diameters were larger than the sagittal ones, the former

being 22.2

9 3.0 mm for men and 18.4

9 1.4 mm for

women (

P

B

0.001). The arterial diameters were more

closely related to body height in women than in men.

The diameters of the aorta in men and those of the

common iliac and femoral arteries both in men and in

women appeared to enlarge with age (Tables 2 and 3)

(Fig. 1.). The aortic diameter was larger in hypertensive

men aged 56 – 60 than in control men of the same age

(Table 2) (Fig. 1). The mean aortic diameter was larger

than the mean plus 2 SD (20.0 mm) in 2.5% of the

control women aged 40 – 50 and, in 2.9% of those aged

51 – 60 years, and the corresponding percentages for

hypertensive women were 3.0% and 1.5%. In the

corre-sponding age groups of men, the aortic diameter

ex-ceeded the mean plus 2 SD (25.4 mm) in 0.8% (40 – 50

years) and 3.9% (51 – 60 years) of the controls and in 0.8

and 7.0% of the corresponding hypertensives. In the

common iliac arteries, the percentages for the same age

groups were 1.3%

/

5.1% (mean

+

2 SD

\

14.6 mm)

(con-trol women), 4.5%

/

8.0% (hypertensive women), 0.4%

/

5.8% (mean

+

2 SD

\

17.2 mm) (control men) and

1.6%

/

12.3% (hypertensive men). Hypertensive women

in the age groups of 40 – 45 and 46 – 50 years had

significantly larger common iliac and common femoral

arteries than the controls. Obesity was significantly

associated with arterial diameter and also with blood

pressure (Table 3). The effect of lipid values, however,

was nonsignificant. The diameters of the aorta in men

and the diameters of the common iliac arteries in both

men and women correlated well with the amount of

plaques, which increased with age (Table 3) (Fig. 2).

Hypertensive subjects had a larger plaque extent than

controls, especially older women with a long duration

of hypertension. The mean sum of plaque lengths in the

aorto – iliac area was 79 mm in control and 107 mm in

hypertensive women, and 100 mm in control and 104

mm in hypertensive men. Non-smoking men had

sig-nificantly wider common iliac and common femoral

arteries and slightly wider aortas than smoking men,

and non-smoking women had only slightly wider

com-mon iliac and comcom-mon femoral arteries than smoking

women, but smoking women had wider aortas than

non-smoking women (Fig. 3).

Table 1

Clinical data of the hypertensive and control subjectsa

Women

Variable Men

Controls HA P Controls HA P

255 233

Number 251 240

N.S. N.S.

51.995.9 51.896.0

Age (year) 50.996.1 50.595.9

27.994.6 B0.001

26.094.2

BMI (kg/m2₎ _B_0.001 _26.6₉_3.6 _29.1₉_4.2

140920 154920 B0.001

SBP (mm Hg) 147920 159921 B0.001

83913 91911 B0.001

DBP (mm Hg) 89910 97910 B0.001

4.799.2 5.0910.6 N.S.

Smoking (pack- years) 16.1914.2 15.3913.6 N.S.

5.891.0 N.S. 5.791.1 N.S.

Total cholesterol (mmol/l) 5.591.0 5.891.1

HDL cholesterol (mmol/l) 1.5390.39 1.4590.38 0.016 1.2390.30 1.1990.32 N.S. Triglycerides (mmol/l) 1.191.6 1.391.6 B0.001 1.491.6 1.791.6 B0.001

(2)

Table 2

Sagittal artery diameters in the hypertensive and control women and mena

Age 40–45 46–50 51–55 56–60 All Pb

Aorta

Women 17.291.4

17.091.4 17.191.3 17.091.6

17.191.4 17.091.5

Control

17.391.5 17.391.3 17.291.3

HA 17.691.3 17.391.3 0.022

20.392.8 Men

19.991.7

Control 19.192.1 20.592.2 21.793.1 20.292.5

19.991.8 20.692.7 22.594.4

19.092.0 20.493.1

HA 0.574

Common iliac arteries

12.291.3 Women

11.591.0 12.191.0 12.591.4 12.091.3 Control 11.691.0

12.291.22 _12.4₉_1.33 _12.6₉_1.3

12.291.21 _12.4₉_1.4

HA B0.001

Men 13.392.0

12.891.6 13.291.9 14.791.7

12.291.6 13.292.0

Control

13.291.6 13.691.9 15.592.14 _13.6₉_2.2

HA 12.391.7 0.007

Common femoral arteries

Women 9.791.0

9.290.9

Control 9.491.0 9.690.8 9.991.0 9.691.0

9.890.96 _9.9₉_0.97 _9.9₉_0.8

9.990.95 _9.9₉_0.9

HA B0.001

Men 11.091.5 11.091.5

10.691.2 10.791.3 11.891.2

10.591.3 10.991.5

Control

10.891.2 11.191.2 12.191.6

HA 10.491.3 11.191.5 0.058

a_{Values are means}₉_{SD. Difference between hypertensives and controls}_t_-test.

b_{Significant differences between hypertensives and controls in subgroups:}1_P_=0.004;2_P_B_0.001;3_P_=0.035;4_P_=0.001;5_P_=0.001;6_P_B_0.001; 7_P_=0.029.

4. Discussion

Duplex ultrasound is commonly used to diagnose

aneurysms of the abdominal aorta by measuring its

diameter. The variation in the measurements of the

anteroposterior diameters of abdominal aortic

aneu-ryms has been 2.2 – 8 mm [14,15]. In the series by Yucel

et al. [11], the interobserver variability of the

anteropos-terior measurement was 2.53 mm, which accounts for

7% of the mean diameter. In accordance with previous

studies, interobserver variability was also larger for

transverse measurements in our study, probably due to

the superior axial compared to lateral resolution

[11,14,15]. Our variability percentages were also

com-parable to the previous results [11,16,17]. The

in-trareader variabilities presented in millimeters in our

series were 0.73 and 1.3 mm for the aortic sagittal and

transverse measurements. The values are small because

our series consisted of subjects with normal aortas

compared to the series with aortic aneurysms [11]. The

intra

/

interreader correlation coefficients were naturally

poorer than in our carotid series [6], because of the

smaller diameters of the aorta and the iliac vessels in

relation to the ultrasound image, which leads to a

poorer measurement accuracy compared to the carotid

image.

The aortic diameter increases with age, being larger

in men [18 – 20]. In a multivariate analysis, including

age, height, body weight and sex, the distal aortic

diameter correlated only with age and sex in the series

by Pedersen et al. (1993) [5]. According to our

contra-dictory results, age had no effect on the female aortic

diameter, but in men the diameter was significantly

enlarged. However, the diameters of the common iliac

and common femoral arteries slightly increased over

age among women, while the corresponding increase in

men was clearly higher.

The luminal diameter of the distal aorta was 16 mm

in men and 13.7 mm in women, and the luminal

diameters of the common iliac arteries were 9.9 and 8.8

mm in the series by Pedersen et al. [5]. Sonesson et al.

[20] also measured the luminal diameters of the aorta,

which were about 15.1

/

16.5 mm for women

/

men aged

40 years with body surface areas of 1.7 m

_{and 16.2}

_/

18.2 mm for those aged 60 years. The aortic diameter

was larger in males aged 25 years or more, though this

difference decreased if corrected for differences in body

surface area in the series by Sonesson et al. [20]. Our

aortic diameters calculated from a regression equation

for the same ages and body surfaces were 17.2

/

17.3 mm

in women

/

men aged 40 years and 17.0

/

21.1 mm in

subjects aged 60 years. Our values were higher, because

we measured the outer diameters (vessel lumen plus

wall thicknesses). In our series, the aortic diameters in

females and males were the same at the age of 40 when

corrected for differences in body surface area, while at

the age of 50 years, men had 2 mm wider aortas than

females, and the difference at the age of 60 years was 4

(3)

Table 3 Diameter Variables Femoral artery Iliac artery Aorta

P ra _P _ra _P

A.Correlations of diameters of aorta,common iliac and femoral artery with the clinical 6ariables and plaquesb Women

0.002 N.S. 0.239 B0.001 0.121 0.007

Age (years)

B0.001

0.236 0.110 0.015 0.198 B0.001

Height

0.348 B0.001 0.276

B0.001 B0.001

BMI 0.172

0.109 0.016 0.121

SBP 0.060 N.S. 0.007

0.173 B0.001 0.194

0.001 B0.001

DBP 0.149

N.S.

−0.025 0.050 N.S. −0.018 N.S.

Blood glucose

0.064 N.S. 0.013

N.S. N.S.

−0.057 Cholesterol

−0.141

−0.025 N.S. 0.002 −0.050 N.S.

HDL

0.092 0.043 −0.003

Triglycerides −0.014 N.S. N.S.

0.020 N.S. −0.015

0.018 N.S.

0.107 Smoking (pack-years)

−0.030 N.S. −0.029

Alcohol 0.029 N.S. N.S.

0.292 B0.001 0.093

N.S. 0.039

Aortic plaques 0.012

0.248 B0.001 0.061

Peripheral pl.1_s _0.020 _N.S. _N.S.

0.165c _0.181c

0.111c

Hypertensionc

Men

0.497 B0.001 0.360

B0.001 B0.001

Age (years) 0.358

Height 0.027 N.S. 0.025 N.S. 0.097 0.031

0.201 B0.001 0.234

0.002 B0.001

BMI 0.142

0.109 0.016 0.103

SBP 0.165 B0.001 0.023

0.103 0.023 0.1.32

0.009 0.003

DBP 0.117

N.S.

0.034 0.132 0.004 0.133 0.003

Blood glucose

−0.013 N.S. −0.001

N.S. N.S.

0.083 Cholesterol

N.S.

0.001 −0.053 N.S. −0.009 N.S.

HDL

Triglycerides 0.080 N.S. 0.106 0.019 0.057 N.S.

0.024 N.S. −0.075

0.006 N.S.

Smoking (pack-years) 0.124

−0.005 N.S. −0.004

Alcohol −0.025 N.S. N.S.

0.381 B0.001 0.173

B0.001 B0.001

Aortic plaques 0.427

0.444

Peripheral pl.1_s _0.383 _B_0.001 _B_0.001 _0.216 _B_0.001

0.083c _0.060c

0.033c

Hypertensionc

B.Analysis of6ariance of sagittal 6essel diameters and independent6ariablesd

P F-ratio P F-ratio P

F-ratio

Women

8.3

Age 1.2 N.S. 0.004 9.8 0.002

23.2 B0.001 33.7

B0.001 B0.001

Height 37.2

52.7 B0.001 40.8

BMI 21.0 B0.001 B0.001

6.9 0.009 2.7

N.S. N.S.

SBP 2.6

0.001

11.6 12.0 0.001 11.4 0.001

DBP

0.8 N.S. 0.02

N.S. N.S.

0.08 Blood glucose

N.S.

0.000 0.01 N.S. 0.02 N.S.

Cholesterol

5.3 0.022 1.5 N.S.

HDL 0.2 N.S.

12.4 B0.001 11.7

0.016 0.001

5.8 Triglycerides

0.6 N.S. 0.3

Smoking 8.1 0.005 N.S.

0.02 N.S. 0.2

N.S. N.S.

Alcohol 0.2

1.3 N.S. 0.1

Aortic plaques 0.1 N.S. N.S.

3.4 N.S. 0.2

N.S. N.S.

0.05 Peripheral pl.

4.5 0.035 5.0

Hypertension 5.9 0.016 0.026

0.538 0.468

Multiple R 0.407

Men

84.0 B0.001 58.7

B0.001 B0.001

Age 15.7

22.5 B0.001 22.9

Height 11.0 0.001 B0.001

17.9 B0.001 22.0

0.013 B0.001

BMI 6.2

SBP 0.16 N.S. 8.8 0.003 11.8 0.001

6.6 0.010 12.9 B0.001

(4)

Table 3 (Continued)

Variables Diameter

Iliac artery

Aorta Femoral artery

P ra

ra _P _ra _P

N.S. 0.02 N.S. 0.7 N.S.

Blood glucose 3.6

N.S. 1.8 N.S.

0.4 0.008

Cholesterol N.S.

0.9

HDL N.S. 0.002 N.S. 0.07 N.S.

N.S. 0.8 N.S.

Triglycerides 0.6 2.9 N.S.

N.S. 9.1 0.003

0.02 8.6

Smoking 0.004

1.8

Alcohol N.S. 0.2 N.S. 0.05 N.S.

B0.001 0.4 N.S. 0.3

Aortic plaques 23.7 N.S.

N.S. 35.6 B0.001

3.8 8.1

Peripheral pl. 0.005

0.15

Hypertension N.S. 1.1 N.S. 0.4 N.S.

Multiple R 0.543 0.642 0.522

a_{Correlation coefficient (Pearson).}

b_{Blood glucose: 2 h blood glucose.}1_{Peripheral pl., sum of plaque lengths in the common and external iliac arteries; aortic plaques=}_{sum of}

plaque lengths in the aorta.

c_{Spearman’s coefficient.}

d_{Linear parameters: age, height, BMI, SBP, DBP, alcohol consumption, smoking (pack-years), cholesterol, HDL, triglycerides, 2 h blood}

glucose value at glucose tolerance test; categorical parameters: hypertension (0=no, 1=yes).

mm. When the mean aortic diameter was calculated in

the control subjects, the diameter was larger than the

mean plus 2 SD more often in hypertensives than in

controls, especially in older subjects (50 – 60 years), in the

iliac arteries of both genders and in the aortas of men.

Human arteries dilate in response to progressive

atherosclerosis, as was also seen in our series, where

aortic dilatation was associated with aortic plaques and

iliac and femoral dilatation with plaques in these vessels.

This compensatory mechanism results in an increase in

arterial size that is proportionate to the cross-sectional

area of plaques that have accumulated in the vessel

[21,22]. Atherosclerosis may also lead to obliteration or

occlusion of arteries. Atherosclerosis is the

etiopatho-logic cause of about 90% of the aortic aneurysms found

in elderly subjects, in men, in smokers and in subjects in

poor health (defined as concurrent hypertension,

cardio-vascular disease or diabetes mellitus) [23 – 25]. The

defi-nitions of abdominal aortic aneurysm based on the aortic

diameter vary [3,26 – 30]. The most widely used definition

is maximal sagittal diameter

]

30 mm [26,27,31]. The

reported prevalence of abdominal aortic aneurysms in

subjects aged 50 years and older varies between 1.4 and

8.8% [32 – 34]. An aneurysm was found in 8.8% of men

and in 2.1% of women

]

50 years referred for their first

abdominal ultrasonography without any suspicion of

aneurysm [32]. The prevalence in patients with

symp-tomatic peripheral or cerebral arterial disease may be as

high as 11.2% (men) and 6.4% (women) [35]. We found

an aneurysm (diameter

]

3.0 cm) in 1.4% of men aged

40 – 60 (2.4

/

1.2% in control men and 3.8

/

1.7% (dilatation

/

aneurysm) in hypertensive men), but none in the women.

Aneurysms in the iliac arteries are rare.

In multiple regression analysis, high blood pressure

increased arterial diameter. The diagnosis of

hyperten-sion in regreshyperten-sion analysis had a nonsignificant effect on

arterial diameter in men, even when SBP

/

DBP was

ignored, and a minimal effect in women.

Long-term smoking is a primary risk factor for

coro-nary and peripheral vascular disease causing endothelial

dysfunction, an early stage of atherosclerosis [36].

Smoking may decrease endothelium-dependent

(5)

common iliac and common femoral arteries were

smaller in smokers compared to nonsmokers in our

series. Lipid values did not have a significant effect on

arterial diameters.

Arterial size, measured as a diameter related to the

subject’s size, was higher in men. The significant risk

factors

increasing

arterial

diameter

were

age,

atherosclerosis and blood pressure. However,

hyperten-sive disease itself had only a minimal effect. The

changes were smaller in women than in men.

References