Reproducibility of arterial stiffness indices at different vascular territories

Transcription

1 Reproducibility of arterial stiffness indices at different vascular territories Simova I., Katova M., Kostova V., Hristova K., Dimitrov N. Department of Noninvasive Cardiovascular Imaging and Functional Diagnostics National Heart Hospital, Sofia, Bulgaria

2 Background

3 1 Claridge MW et al. Ultrasound Med Biol 2008; 2 Matsui Y et al. Hypertens Res 2004; 3 Frimodt-Møller M et al. Nephrol Dial Transplant 2008; 4 Kawasaki T et al. Cardiovasc Res 1987; 5 Buntin CM et al. Ann Biomed Eng 1990 Background There is a controversy in the literature about the reproducibility and prognostic value of AS indices in different vascular territories Arterial stiffness indices measured at the common carotid atrery generally show good inter- and intraobserver and intersession variability 1,2,3 ; the variability of these indices has not been evaluated in different vascular territories; β stiffness index values varied considerably in the peripheral muscular arteries (brachial and femoral) in 39 healthy subjects and are influenced by vasoactive stimuli 4 ; In 42 healthy male subjects the authors evaluated the carotid, brachial, femoral, popliteal and tibial arteries and prove that pressure strain elastic modulus Ер and the circumferential elastic modulus increase with aging in all vascular territories except in the brachial artery 5.

4 Purpose Proceeding from the assumption that visco-elastic properties differ along the arterial tree we set ourselves the following tasks: To evaluate the level of agreement between AS indices measured at different peripheral arteries; To estimate the interobserver variability of AS indices in different vascular beds.

5 Methods 75 patients Inter-vessel agreement; 36 patients interobserver inter-vessel variability common carotid brachial superficial femoral

6 Evaluation of AS Standard conditions: according to the Expert consensus document on arterial stiffness Scanner: Aloka Prosound SDD- α 10; linear array 7.5 to 12 MHz transducer Analytical instrument: Echo-tracking (ET)

7 ET derived AS indices (stiffness parameter): index of arterial stiffness β = In (Ps / Pd) / [(Ds Dd) / Dd] Calculated from changes in vessel diameter and BP Arterial stiffness value Ep (pressure-strain elasticity modulus): index of vessel elasticity Ep = (Ps Pd) / [(Ds Dd) / Dd ] Calculated from changes in vessel diameter and BP Arterial elasticity Ep AC (arterial compliance): index of blood vessel compliance AC = π(ds Ds - Dd Dd) / [4 (Ps Pd)] Calculated from changes in blood vessel cross-sectional area and BP Arterial compliance AC PWVβ (One Point Pulse wave velocity): index of vessel elasticity PWVβ = (βp / 2ρ) ρ:blood density (1050 Kg/m3) Arterial stiffness PWVβ AI (augmentation index): influenced by Ao PWV and related to Ao stiffness and extend of wave reflection AI - % of Pulse Pressure: what % of PP represents reflected wave Arterial stiffness AI

8 Statistics Distribution of variables: Kolmogorov-Smirnov; Inter-site agreement: one-way analysis of variance (ANOVA); Interobserver variability: intraclass correlation coefficients (ICC); between groups comparison: independentsamples T test; SPSS statistical software for Windows version 13.0.

9 Results Clinical variable Distribution n = 75 Distribution n = 36 Age mean ± SD 40 (± 14.5) 30 (± 7.3) Female n (%) 41 (55%) 24 (67%) Body mass index mean ± SD 24 (± 4) 23 (± 4) Arterial hypertension n (%) 30 (40%) 0 Diabetes mellitus n (%) 0 0 Dyslipidemy n (%) Total cholesterol mmol/l HDL cholesterol mmol/l 18 (24%) Present smokers n (%) 20 (27%) 13 (36%) Former smokers n (%) 8 (11%) 6 (17%) Degenerative aortic stenosis n (%) 0 0 Framingham risk score Women Men 1% 6,5% 1% 1%

10 Inter-vessel agreement: ANOVA Parameter Common carotid artery Brachial artery Femoral artery β 6.3 ± ± ± 7.6 Ер (kpa) 87 (45 129) 250 ± ± 99 АС (mm 2 /kpa) 1.01 ± ( ) 0.94 ± 0.61 АІ (%) 11.3 ± ± ± 13.8 PWVβ (m/s) 5.5 ± ± ± 2.3 p < 0.01 p < 0.01

11 Interobserver variability: intraclass correlation coefficients β Ep AC AI PWVβ Carotid 0.8** 0.83** 0.85** 0.72** 0.69** Brachial Femoral 0.56** 0.60** 0.68** 0.41* 0.64** ** p < * p < 0.05

12 Subgroup analysis: AH Parameter Common carotid artery Brachial artery Femoral artery AH no AH AH no AH AH no AH β 7.3** 5.6** * 7.8* (± 3.6) (± 2) (± 9.9) (± 9.1) (± 6.2) (± 2.3) Ер (kpa) 109* (± 57) 72* (± 27) 238 (± 150) 258 (± 123) 163* (± 89) 112* (± 28) АС (mm 2 /kpa) 0.9* (± 0.45) 1.08* (± 0.38) 0.17 (± 0.11) 0.14 (± 0.13) 0.87* (± 0.5) 1.04* (± 0.64) АІ (%) 15.2* 8.7* * 15.3* (± 11) (± 7.2) (± 14.8) (± 11.3) (± 8.7) (± 10.2) PWVβ (m/s) 6.1* 5.1* * 6.5* (± 1.4) (± 0.9) (± 2.8) (± 2.2) (± 2.3) (± 1.4) ** p < * p < 0.05

13 Subgroup analysis: dyslipidemy Parameter Common carotid artery Brachial artery Femoral artery DLP no DLP DLP no DLP DLP no DLP β 8.1* 6* * 7.4* (± 3.3) (± 2.7) (± 7) (± 9.6) (± 7) (± 4.6) Ер (kpa) 102* (± 44) 82* (± 38) 191 (± 99) 270 (± 134) 167* (± 80) 104* (± 62) АС (mm 2 /kpa) 0.8* (± 0.4) 1.06* (± 0.41) 0.17 (± 0.14) 0.16 (± 0.12) 0.82* (± 0.49) 1.33* (± 0.67) АІ (%) 16.5* 9.6* (± 9.7) (± 7.6) (± 14) (± 12.5) (± 8.3) (± 9.2) PWVβ (m/s) 6.6* 5.3* * 5.9* (± 1.4) (± 1.2) (± 2.2) (± 2.4) (± 2.2) (± 1.9) * p < 0.05

14 Conclusion In a study group of 75 patients we found that the level of agreement of ET derived AS indices was good when they were measured at the common carotid and femoral arteries; In a subgroup of 36 patients reproducibility of AS parameters was clinically acceptable when the evaluation was performed on the common carotid and femoral arteries.

15 Conclusion AS indices measured at the brachial artery differed significantly from those measured at the common carotid and femoral arteries and the interobserver variability of these parameters was high when measured at the brachial artery; On the basis of these results we do not recommend AS measurement at the brachial artery.

16 THANK YOU FOR YOUR ATTENTION