P.18 Carotid Stiffness Parameters and Cerebral Blood Flow Pulsatility in Young Healthy Individuals across Races

Abstract

Background Higher cerebral blood flow (CBF) pulsatility was found to be associated with severer brain white matter lesions in the elderly [1]. It was hypothesized that the central/elastic arterial stiffness/compliance may directly affect CBF pulsatility. However, it is still unclear which carotid stiffness parameters may better reflect this impact, and whether race and sex differences are present. Methods To study the correlations among those parameters with comparisons between different races and sexes, we enrolled 35 young healthy subjects (19 females), aged 29 ± 5 (18~40) years, with three races of comparable age and sex ratio, i.e. White (n = 16), Black (n = 7), and Asian (n = 12). All subjects were in resting seated position, with continuous transcranial Doppler recording of CBF velocity at middle cerebral artery (MCA), simultaneous 1-min ultrasound echo-tracking on bilateral common carotid arteries, and multiple measurements of brachial blood pressure (BP). Results All derived parameters [2], including MCA pulsatility index (PI), showed no significant racial differences but with significantly (p < 0.05) higher carotid stiffness index (β), Peterson’s pressure modulus (Ep), BP pulsatility index (mostly driven by higher systolic BP but similar diastolic BP), and lower arterial compliance (AC, p = 0.07) in males than in females. Only AC (but not β and Ep) showed a significant correlation with PI (r = 0.49, p = 0.004) even after controlling for BP pulsatility index, which negatively correlated with AC (β = −0.35, p = 0.038). Conclusions Higher carotid AC (i.e. decreased stiffness) seems to enhance CBF pulsatility in young healthy populations, which might differ from the elderly.