Cerebral vasomotor reactivity and apnea test in symptomatic and asymptomatic high-grade carotid stenosis

Abstract

Introduction. Cerebral vasomotor reactivity (VMR) represents an autoregulatory response of the arterial trunks on the specific vasoactive stimuli, most commonly CO2. Objective. The aim of this retrospective study was to compare VMR in high-grade symptomatic (SCAS) and asymptomatic carotid stenosis (ACAS), using the apnea test to evaluate the hemodynamic status. Methods. The study included 50 patients who were hospitalized at the neurology and vascular surgery departments as part of preparation for carotid endarterectomy. We evaluated VMR by calculating the breath holding index (BHI) in 34 patients with SCAS and 16 patients with ACAS, with isolated high-grade carotid stenosis. We evaluated the impact of risk factors and collateral circulation on BHI, as well as the correlation between the degree of carotid stenosis and BHI. Results. A pathological BHI was more frequent in the SCAS group (p<0.01). There was no difference in the range of BHI values between the groups, both ipsilaterally and contralaterally. Only male gender was associated with pathological BHI in both groups (p<0.05). Collateral circulation did not exist in over 60% of all subjects. We confirmed a negative correlation between the degree of carotid stenosis and BHI. Conclusion. SCAS and ACAS patients present with different hemodynamics. While ACAS patients have stable hemodynamics, combination of hemodynamic and thromboembolic effects is characteristic of SCAS patients.

Assessment of cerebral autoregulatory function and inter-hemispheric blood flow in older adults with internal carotid artery stenosis using transcranial Doppler sonography-based measurement of transient hyperemic response after carotid artery compression

“…The primary objective of this study was to investigate the impact of CAS on cerebral hemodynamics and autoregulation in both symptomatic and asymptomatic patients. Our results demonstrated that CAS was associated with impaired cerebral vascular reactivity, corroborating previous findings [ 88 – 90 ]. Notably, a larger proportion of symptomatic CAS patients exhibited incomplete CoW anatomy, which potentially contributed to their more severe clinical presentation.…”

Transcranial doppler methods in the assessment of cerebral vasomotor reactivity

“…Evaluation of VMR before and after carotid endarterectomy (CEA) is significant because of the evaluation of the revascularization effect on cerebral hemodynamics, as well as the increasingly important choice of the right time to perform it. The CEA contributes to the normalization of collateral circulation and restitution of cerebral hemodynamics in symptomatic [47,48,[52][53][54][55][56] and asymptomatic carotid disease [57][58][59][60][61]. Reduced VMR may encourage consideration of CEA or stenting in asymptomatic carotid disease or extra/intracranial bypass surgery in patients with recurrent hemodynamic stroke or TIA [3,4,52,62].…”

Correlation between Morphological and Hemodynamic Parameters of Carotid Arteries and Cerebral Vasomotor Reactivity

“…To our knowledge, there are no studies assessing VMR in early carotid disease, which is why the correlation between IMT and VMR is not investigated enough. Even though most of the studies focus on advanced or clinically significant carotid stenosis or even carotid occlusion and its correlation with VMR, it is only logical to assume that increased IMT as a marker of early atherosclerotic changes would correlate with small cerebral vessel function and VMR itself as they are both subjected to the same process, i.e., atherosclerosis [12,21,27]. Our study shows the possibility of this correlation, implicating that in patients with normal IMT, VMR is preserved.…”