Carotid Artery Stiffness in Patients With Neurally Mediated Syncope

Abstract

Neurally mediated syncope is defined as a transient loss of blood flow to the brain, resulting in vasodilatation, bradycardia, or both. The pathophysiologic mechanisms of neurally mediated syncope are not clear. In this study, we investigated carotid artery elasticity parameters in patients with neurally mediated syncope. The study was conducted on 41 patients who were examined by the tilt table test. Group 1 constituted of 21 patients who had a positive response to the tilt table test. Clinical and hemodynamic parameters were compared with patients in a negative tilt table test group (group 2). The systolic and diastolic diameters of the carotid arteries, carotid distensibility, carotid strain, carotid stiffness index, and carotid elastic modulus of the left carotid arteries were calculated by a high-resolution ultrasound device. No differences in hemodynamic variables or clinical parameters were detected between the groups. Carotid distensibility (mean ± SD, 1.6 ± 0.6 versus 2.2 ± 0.8 cm(2) × dyne(-1) × 10(-6); P = .044) and strain (6.8% ± 1.7% versus 8.2% ± 1.9%; P = .026) were lower in group 1 than in group 2. The carotid elastic modulus (0.88 ± 0.33 versus 0.74 ± 0.25 cm(2) × dyne(-1) × 10(-6); P = .002) and stiffness index (6.7 ± 0.4 versus 6.2 ± 0.5; P = .038) were higher in group 1. In this study, we concluded that elastic properties of the carotid artery are impaired in patients with neurally mediated syncope. This finding suggests that impaired carotid arterial elasticity may be a factor in the pathophysiologic mechanisms of neurally mediated syncope.