Concomitant Dysregulation of Cerebral Vasoreactivity and Arterial Blood Pressure Is Closely Related in Patients with Carotid Stenosis

<b>Background:</b> In patients with severe atherosclerotic internal carotid artery stenosis (ICAS), the capacity of cerebral vasoreactivity (CVR)-an independent risk factor for cerebral ischemia-is reduced, and dysregulation of arterial blood pressure (ABP) may also be present. Thus, this study assessed the relationship between changes in cerebral blood flow velocity (BFV) in response to vasoactive stimuli (as measured by transcranial Doppler (TCD)), characterizing CVR and cardiovascular autonomic nervous system (CANS) function. <b>Methods:</b> Common carotid artery compression (CCC n = 26), hyperventilation (HV) and breath-holding (BH) tests (n = 31), and the Valsalva maneuver (VM n = 34) were used to assess CVR in patients with ICAS. In the middle cerebral arteries, BFV was monitored by TCD, whereas ABP was registered non-invasively. For statistical analysis, validated indices describing CANS function-namely, sympathetic index (SI), pressure recovery time (PRT), and Valsalva heart rate ratio (VHRR)-were selected based on the VM response. Several parameters were defined in order to evaluate CVR responses, including cerebral arterial resistance (CAR = ABP/BFV), which was correlated with the CVR indices using Spearman's pairwise correlation and canonical correlation. <b>Results</b>: A significant correlation was found between several CVR indices of the HV-BH and VM tests and CANS indices of VM using Spearman's pairwise correlation test. Regarding the HV-BH CVR and CANS indices of VM, a significant correlation was found between CAR values until it reached its maximum on the to-be-operated side (CAR_{timetomaxICAop}) and VHRR (<i>p</i> = 0.041). A significant correlation was also found between the time elapsed until the CAR minimum value (CAR_{timetominICAop}) and SI (<i>p</i> = 0.019). Concerning the CVR and CANS indices of the VM, a significant correlation was found between cerebrovascular Valsalva ratio on the to-be-operated side (CVAR_ICAop) and PRT (<i>p</i> = 0.002). Canonical correlation analysis confirmed that impairments of CANS and CVR may be associated. <b>Conclusions</b>: In patients with severe ICAS, the potentially concomitant dysregulation of cerebrovascular reactivity and the cardiovascular autonomic nervous system can further increase cerebral ischemic risk.