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

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

Extrinsic compression of popliteal artery in asymptomatic athlete and non-athlete individuals. A comparative study using duplex scan (color duplex sonography).

AIM: Extrinsic compression of the popliteal artery and absence of surrounding anatomical abnormalities characterize the functional popliteal artery entrapment syndrome (PAES). The diagnosis is confirmed to individuals who have typical symptoms of popliteal entrapment and occlusion or important stenosis of the popliteal artery with color duplex sonography (CDS), magnetic resonance imaging (MRI) or arteriography during active plantar flexion-extension maneuvers. However, variable result findings in normal asymptomatic subjects have raised doubts as to the validity of these tests. The purpose of this study was to compare the frequency of popliteal artery compression in 2 groups of asymptomatic subjects, athletes and non-athletes. METHODS: Forty-two individuals were studied. Twenty-one subjects were indoor soccer players, and 21 were sedentary individuals. Physical activity was evaluated through questionnaires, anthropometric measurements, and cardiopulmonary exercise test. Evaluation of popliteal artery compression was performed in lower limbs with CDS, ankle-brachial index (ABI) measurements and continuous wave Doppler of the posterior tibial artery. RESULTS: The athletes studied fulfilled the criteria of high level of physical activity whereas sedentary subjects met the criteria of low level of activity. Popliteal artery compression was observed with CDS in 6 (14.2%) studied subjects; 2 of whom (4.7%) were athletes and 4 (9.5%) were non-athletes. This difference was not statistically significant (p=0.21). Doppler of the tibial arteries and ABI measurements gave good specificity and sensibility in the identification of popliteal artery compression. CONCLUSIONS: The frequency of popliteal artery compression during maneuvers in normal subjects was 14.2% irrespective of whether or not they performed regular physical activities. Both Doppler and ABI showed good agreement with CDS and should be considered in screening popliteal arteries in individuals suspected of PAES.

Evaluation of tibolone effect on arterial resistance in postmenopausal women.

OBJECTIVE: The aim of this study was to evaluate the effect of tibolone on peripheral vascular resistance in postmenopausal women, by determination of the pulsatility index (PI) of the common carotid, radial and popliteal arteries using Doppler ultrasonography. METHODS: Twenty-nine patients were studied in a longitudinal, prospective, before and after study, for 7 months. The patients did not suffer from cardiovascular disease or any other conditions that would interfere with vascular resistance, and had no contraindications for hormone replacement therapy (HRT). Tibolone was used in a dose of 2.5 mg, orally, continuously for 6 months. Color duplex Doppler ultrasonography of the right and left common carotid, radial and popliteal arteries was carried out to determine PI, using the average value found in both sides at baseline (before administration of the drug), 3 and 6 months after initiating medication and 1 month after discontinuation of the drug. PI was determined by means of spectral analysis of the best arterial blood flow waveform, and pretreatment values (baseline) were used as control. RESULTS: In the common carotid artery, no significant differences in PI were observed at 3 and 6 months, in comparison with baseline. A significant decrease in PI was noted in the radial artery at 6 months as compared with baseline (decrease of 51.5%). PI in the popliteal artery also presented a significant decrease at 6 months in relation to baseline (decrease of 28.6%). The results were statistically assessed by ANOVA (analysis of variance). CONCLUSION: There was no significant variance in PI in the common carotid artery; however, in the radial and popliteal arteries there was significant variance, and their resistance decreased after use of tibolone for 6 months but returned to the pretreatment values 1 month after discontinuation of the drug.