Evaluation of cerebral hemodynamic status in patients with unilateral symptomatic carotid artery stenosis during motor tasks, through use of transcranial Doppler sonography

ABSTRACT Background: Carotid artery stenosis increases cerebral ischemic event risk through changing different cerebral hemodynamic parameters. Objective: To investigate how cerebral hemodynamics in the M1 segment of middle cerebral artery change in patients with carotid artery stenosis, after motor tasks using transcranial Doppler sonography (TCD). Methods: Thirty-two healthy subjects and 30 patients with unilateral symptomatic carotid artery stenosis were recruited. The patient population was divided into three groups according to the degree of stenosis (group 1: ≥50 to 69%, group 2: 70 to 89% and group 3: ≥90 to 99%). TCD was used to measure the pulsatility index (PI) and cerebral vasomotor reactivity (CVR). Results: In the patient group, significant differences for symptomatic side PI values (p=0.01) and mean CVR increases (p=0.05) were observed, compared with the healthy controls. However, the difference was not statistically significant for asymptomatic side PI values and mean CVR increases. The results from the intergroup comparison showed significantly higher percentages of symptomatic and asymptomatic side CVR increases in group 1, compared with groups 2 and 3 (p=0.001 and p=0.002, respectively). Conclusions: Our study showed that cerebral autoregulation and hemodynamic mechanisms are impaired in patients with carotid artery stenosis. Furthermore, the impairment of PI and CVR tends to get worse with increasing degrees of stenosis. In addition, this study demonstrated that assessment of these two hemodynamic parameters in clinical practice might be helpful for monitoring the progress of carotid artery stenosis.

Study on the Radial Sectional Velocity Distribution and Wall Shear Stress Associated With Carotid Artery Stenosis

BackgroundAtherosclerosis is an important cause of cardiovascular disease. The wall shear stress (WSS) is one of the key factors of plaque formation and dislodgement. Currently, WSS estimation is based on measurement of the blood velocity gradient. However, due to the lack of flow field measurements in carotid stenosis vessels, the two distribution forms (parabolic and non-parabolic) commonly considered in numerical simulations could cause WSS estimates to differ by more than 40%, which could seriously affect the accuracy of mechanical analysis. MethodsThis study was the first to apply 3D printing technology to create an experimental model of real-structure carotid arteries. Microparticle image velocimetry (micro-PIV) was adopted to comprehensively measure blood velocity field data at the stenosis location, providing experimental validation of numerical simulation (Fluent; finite volume method) results. Then, the flow field was simulated at a normal human heart rate (45-120 beats per minute). ResultsThis study revealed that when blood flowed across the carotid artery stenosis location, the velocity distribution was not parabolic but rather a plateau-shaped distribution, with a similar flow velocity in the central area (more than 65% of the total flow path). The WSS values calculated based on a parabolic velocity distribution and the maximum velocity were nearly 60% lower.ConclusionThis study provides a reliable method for WSS determination to better understand the vascular stenosis location and facilitate flow and shear force field research. In the future, it is necessary to carry out in-depth research on the relationship between the plaque shape, flow field distribution and WSS, and amendments to the calculated WSS for clinical stenosis should be proposed.

In-Hospital Outcomes of Urgent, Early, or Late Revascularization for Symptomatic Carotid Artery Stenosis

Background and Purpose: Advancements in carotid revascularization have produced promising outcomes in patients with symptomatic carotid artery stenosis. However, the optimal timing of revascularization procedures after symptomatic presentation remains unclear. The purpose of this study is to compare in-hospital outcomes of transcarotid artery revascularization (TCAR), transfemoral carotid stenting (TFCAS), or carotid endarterectomy (CEA) performed within different time intervals after most recent symptoms. Methods: This is a retrospective cohort study of United States patients in the vascular quality initiative. All carotid revascularizations performed for symptomatic carotid artery stenosis between September 2016 and November 2019 were included. Procedures were categorized as urgent (0–2 days after most recent symptom), early (3–14 days), or late (15–180 days). The primary outcome of interest was in-hospital stroke and death. Secondary outcomes include in-hospital stroke, death, and transient ischemic attacks. Multivariable logistic regression was used to compare outcomes. Results: A total of 18 643 revascularizations were included: 2006 (10.8%) urgent, 7423 (39.8%) early, and 9214 (49.42%) late. Patients with TFCAS had the highest rates of stroke/death at all timing cohorts (urgent: 4.0% CEA, 6.9% TFCAS, 6.5% TCAR, P =0.018; early: 2.5% CEA, 3.8% TFCAS, 2.9% TCAR, P =0.054; late: 1.6% CEA, 2.8% TFCAS, 2.3% TCAR, P =0.003). TFCAS also had increased odds of in-hospital stroke/death compared with CEA in all 3 groups (urgent adjusted odds ratio [aOR], 1.7 [95% CI, 1.0–2.9] P =0.03; early aOR, 1.6 [95% CI, 1.1–2.4] P =0.01; and late aOR, 1.9 [95% CI, 1.2–3.0] P =0.01). TCAR and CEA had comparable odds of in-hospital stroke/death in all 3 groups (urgent aOR, 1.9 [95% CI, 0.9–4], P =0.10), (early aOR, 1.1 [95% CI, 0.7–1.7], P =0.66), (late aOR, 1.5 [95% CI, 0.9–2.3], P =0.08). Conclusions: CEA remains the safest method of revascularization within the urgent period. Among revascularization performed outside of the 48 hours, TCAR and CEA have comparable outcomes.