Find in Library

Background: We anticipate that in vascular outpatients followed over time, measured changes in arterial stiffness will be the multifactorial result of pressure-dependence, ageing- related degeneration, wall stress homeostasis, and medical treatment. Carotid ultrasound enables assessment of carotid pulse wave velocity (cPWV, via Bramwell- Hill), geometry (relative wall thickness, RWT = 2*IMT/diameter), and intrinsic material stiffness (Young’s-modulus, via Moens-Korteweg). We investigated changes in these carotid properties over time, and their interrelationship. To check whether the change in measured cPWV could be merely due to pressure-dependence, we calculated based on the stiffness index β0 [2] the theoretical pressure-dependent change in cPWV [3]. Methods: Hypertensive outpatients (n = 147) were assessed at baseline and 3.5±1.1 year follow- up, and were stratified according to baseline-to-follow-up change in diastolic blood pressure (ΔDBP) into three groups: decreasedDBP (ΔDBP < −7 mmHg), constantDBP (−7 mmHg ≤ ΔDBP≤7 mmHg) and increasedDBP (ΔDBP > 7 mmHg), with the cut-off being twice the typical DBP measurement error [1]. Results: The theoretical pressure-dependent change in cPWV was 0.4±1.3 m/s lower (p < 0.001, n = 147), corroborating the anticipated multifactorial conditions. Table 1 shows no changes in cPWV, RWT and Young’s-modulus for decreasedDBP. For constantDBP, both cPWV and Young’s-modulus were increased at follow-up. IncreasedDBP showed increases in cPWV and Young’s-modulus and a decreased RWT. The latter implies a 9.2±10.7 kPa increase in circumferential wall stress (p < 0.001), in contrast to a 5.3±6.9 kPa decrease (p < 0.001) in decreasedDBP (p < 0.05 for between groups). n = 147 ΔcPWV [m/s] ΔRWT [−] ΔYoung’s-modulus [MPa] Mean±sd p Mean±sd p Mean±sd p DecreasedDBP (n = 53) −0.1±1.4 0.72 0.00±0.04 0.38 −0.01±0.32 0.87 ConstantDBP (n = 67) +0.6*±1.4 <0.001 0.00±0.04 0.18 +0.10*±0.26 <0.001 IncreasedDBP (n = 27) +0.5*±1.5 0.029 −0.02*,**±0.04 0.002 +0.19*±0.35 <0.001 Δs calculated as follow-up – baseline. *:p < 0.05 compared to decreasedDBP. **:p < 0.05 compared to constantDBP. The bold indicates that there is a statistically significant difference between follow-up and baseline. Table 1.Changes in measure carotid properties with 3.5-year follow-up. Conclusions: In this outpatient cohort, with clear DBP reduction, there is a discontinuation of carotid stiffening, but no reversal. In patients with increased DBP, progressive carotid stiffening appears driven by impaired wall stress homeostasis.