Non-invasive strain imaging in normotensive and hypertensive patients

Literature shows that arterial stiffness is related to age and degree of atherosclerosis. It has been hypothesized that there is no difference in arterial stiffness between normotensive (NT) and hypertensive (HT) patients of same sex and age. This was demonstrated in a previous study by analysing pressure diameter curve data and estimating the incremental Youngs modulus [1]. In this study, 2D strain imaging was used to investigate possible differences in carotid stiffness by quantifying the response to pressure, i.e., strain, in a group of NT and HT subjects, matched for both age and sex. Radio-frequency data of the common carotid artery were acquired in 18 NT and 18 HT patients, with a mean age of 52 ± 11, using the Mylab 70 (Esaote, NL). Displacements and strains were estimated using a 2D strain imaging algorithm [2]. Strain analysis was performed and on the far wall data at end-systole. One-way ANOVA indicates significant lower strains in the HT groups throughout the vessel wall (NT = 6.3%±5.6%; HT = 4.8%±3.9%). The lower strain and distensibility can be explained by the higher mean arterial pressure and non-linear behaviour of the vascular tissue. These results confirm the hypothesis that the stiffness in HT patients is not necessarily higher compared to NT patients.