4.2 THE INHOMOGENEITY OF DIASTOLIC-SYSTOLIC RISE TIME OF THE DISTENSION WAVEFORM DISTRIBUTION IN THE COMMON CAROTID ARTERY IS ASSOCIATED WITH LIPID PRESENCE OF DISTAL PLAQUES

Abstract

Objectives: Diastolic-systolic rise time characteristics of the distension waveform distribution, i.e., mean and inhomogeneity, might be modified by wave reflections from distal plaques. The aim of this study is to investigate the association between rise time characteristics for the common carotid artery (CCA) and composition of distal plaques. Methods: Longitudinal B-mode ultrasound (US) registrations of the CCA of 129 patients (age 69 ± 9) were performed with a Philips IU22 scanner. All patients had a plaque in the ipsilateral bifurcation and recently experienced a cerebrovascular accident. Distension waveforms were extracted by edge tracking and the diastolic-systolic rise time and its inhomogeneity, defined as standard deviation of systolic-diastolic rise time distribution for an artery segment, were derived. Plaque composition was extracted from 3T-MRI measurements (N = 125). Results: 118 subjects had both an adequate MRI and US registration. 58% of the plaques had a lipid-rich necrotic core (LRNC) of which 68% had a thin fibrous cap (FC). Lipids were demonstrated in the proximal part in 51 plaques (43%). Mean CCA diastolic-systolic rise time (162 ± 26 ms) did not vary with plaque composition (Student t-test, p-value > 0.2). The inhomogeneity, however, was significantly lower for vulnerable distal plaques (mean difference LRNC: 8ms, FC: 11ms, Student t-test, p-value < 0.02) and, more specifically, when lipids were present in the proximal part of the plaque (mean difference 12ms, Student t-test, p-value < 0.001). Conclusion: Diastolic-systolic rise time inhomogeneity of CCA distension is associated with the lipid presence of distal plaques. This research was supported by the Center for Translational Molecular Medicine and the Dutch Heart Foundation.