5.1 Assessment of the Arterial Wall Behavior along the Common Carotid Artery at the Level of a Plaque According to Arterial Stiffness Gradient

Abstract

Background

We previously described longitudinal strain gradient named bending strain (BS), along the common carotid artery (CCA) with two distinct patterns (Paini, Stroke 2007, Beaussier, Hypertension 2008): Pattern A (larger radial strain at the plaque level than at adjacent CCA) and its opposite, Pattern B.

Aim:

To assess the role of change in CCA thickness (IMT) and medial diameter (D) during the cardiac cycle at the level of plaques according to functional patterns of BS.

Method:

45 CCA were analysed at the level of the plaque in 26 patients. Mechanical parameters were measured at 128 sites on a 4 cm long CCA segment by an echotracking system (ArtLab®). Plaque composition was determined by magnetic resonance imaging (MRI). For each plaque, systolo(s)-diastolic(d) variation of IMT and D were calculated. We obtained DIMT ((IMTs - IMTd)/IMTd), DDiameter ((Ds - Dd)/Dd) and ratio R (DIMT/DD). Results: R did not significantly differ according to remodeling pattern neither to plaque composition. Plaques exhibiting Pattern B (n = 25) were characterized by an R 73 % higher than plaques exhibiting Pattern A (n = 20) (5.9 ± 3.0 versus 3.4 ± 1.6, p<0.005). In other words, IMT strain is disproportionately larger than diameter strain among Pattern B than among pattern A.

Conclusion:

The arterial stiffness gradient at the level of the plaque may influence the arterial wall behavior: an inward BS may be associated with exaggerated compressibility and local stresses within the wall in comparison to an outward BS with reduced local stresses.