9.10 STRUCTURAL AND FUNCTIONAL ARTERIAL ABNORMALITIES IN FIBROMUSCULAR DYSPLASIA ARE IN THE CONTINUUM OF HYPERTENSION: AN IMAGING AND BIOMECHANICAL STUDY

Abstract

Fibromuscular dysplasia (FMD) is a non-atherosclerotic non-inflammatory arterial disease of unknown origin. We previously showed the presence of triple signal (TS) at ultrasound within common carotid artery (CCA) wall. We aimed at coupling TS presence with microconstituents of the vessel wall. We included 50 patients with multifocal FMD, 50 essential hypertensive (HT) patients and 50 healthy subjects (HS) matched for age, sex, ethnicity and BP (HT and FMD). TS score from the right and left CCA were assessed from 15-MHz echotracking system coupled with aplanation tonometry. 14 microconstituents of the CCA, representing geometry, perivascular tethering, and wall material coefficients were derived from fitting of the pressure-diameter curve. In multivariate analysis, age, hypercholesterolemia and IMT were significantly associated with TS, explaining 9.5% of its variance. TS was more frequent in FMD than HS (49% vs 16%, p<0.01), and HT (32%, p=0.08). When considering the whole population (n=150), several microconstituents appeared correlated with age and BP: particularly, residual stress was higher, and collagen fibers were stiffer with increasing age and BP (p<0.01). TS was positively associated with circular collagen mediated-stiffness (p<0.01), independently of age and BP. We confirmed that FMD is associated with higher frequency of TS, but with overlap with matched HT and HS. The strong association between TS and carotid remodeling, independently of age and BP, suggests that it corresponds to the muscular transition of an elastic artery [1]. The association of TS with circular collagen stiffness suggests that TS has subtle but measurable mechanical consequences.