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

## TL;DR

This study finds that in patients with severe carotid artery stenosis, problems with blood flow regulation in the brain and blood pressure control are closely linked, increasing the risk of cerebral ischemia.

## Contribution

The study reveals a novel association between impaired cerebral vasoreactivity and cardiovascular autonomic nervous system dysfunction in patients with carotid stenosis.

## Key findings

- Cerebral vasoreactivity indices correlated significantly with cardiovascular autonomic nervous system indices in patients with carotid stenosis.
- Cerebrovascular resistance parameters showed significant associations with autonomic function metrics like Valsalva heart rate ratio and sympathetic index.
- Canonical correlation analysis confirmed a link between impaired cerebrovascular reactivity and autonomic nervous system dysfunction.

## Abstract

Background: 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. Methods: 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. Results: 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 (CARtimetomaxICAop) and VHRR (p = 0.041). A significant correlation was also found between the time elapsed until the CAR minimum value (CARtimetominICAop) and SI (p = 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 (CVARICAop) and PRT (p = 0.002). Canonical correlation analysis confirmed that impairments of CANS and CVR may be associated. Conclusions: In patients with severe ICAS, the potentially concomitant dysregulation of cerebrovascular reactivity and the cardiovascular autonomic nervous system can further increase cerebral ischemic risk.