Objective: The purpose of this study was to investigate the effects of cervical rotatory manipulation (CRM) on hemodynamics and plaque stability of atherosclerotic internal carotid artery (ICA) in rabbits.

Methods: Forty rabbits were randomly divided into 4 groups: (1) internal carotid atherosclerosis (ICAS) rabbits treated with CRM (ICAS-CRM group); (2) ICAS rabbits treated without CRM (ICAS group), (3) Normal-CRM group (normal rabbits treated with CRM), and (4) blank control group. In the ICAS-CRM group and ICAS group, the ICAS model was induced by ICA balloon injury combined with a high-fat diet for 12 weeks. CRM was applied to rabbits in the ICAS-CRM and the Normal-CRM groups. During the study, an ultrasonography examination was performed for detecting plaque and hemodynamics on the ICAs. At the end of the study, all atherosclerotic ICAs were removed for histological and immunohistochemical detection.

Results: The hemodynamics (especially end-diastolic velocity, resistance index, and pulsatility index) through the ICAs were adversely affected by atherosclerosis while not adversely affected by CRM. Compared with the ICAS group, the micro-vessel density and average integrated optical densities of macrophages in the ICAS-CRM group were significantly increased. Compared to the ICAS group, in the ICAS-CRM group, the atherosclerosis was more serious, and the tunica intima was more unstable.

Conclusions: Although CRM did not affect the hemodynamic index of ICA, it was observed to decrease the stability of severe ICAS plaques in rabbits, which may increase the plaque vulnerability.

Author keywords: Artherosclerosis; Cartoid Artery; Internal; Hemodynamics; Histology; Immunohistochemistry

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