Neurovascular coupling and cerebral autoregulation in atrial fibrillation

Abstract

People with atrial fibrillation are at an increased risk of stroke, cognitive decline and dementia. We recently identified that individuals with atrial fibrillation exhibit a reduced cerebrovascular reactivity to carbon dioxide, indicative of a diminished cerebral vasodilatory reserve. In this study we sought to determine whether neurovascular coupling (NVC) is blunted in atrial fibrillation in comparison with age‐matched, hypertensive and healthy control participants. Posterior (PCA) and middle cerebral artery (MCA) flow velocity (Vm), along with beat‐to‐beat mean arterial pressure (MAP), were measured during a NVC assessment consisting of five cycles of visual stimulation (reading) for 30 s followed by 30 s with both eyes‐closed in 12 patients with atrial fibrillation (69 [7] yr; mean [SD], 3 women), 13 patients with hypertension (67 [5] yr, 4 women) and 12 healthy control participants (63 [10] yr, 4 women). Cerebrovascular conductance indices (CVCi) were calculated as PCA Vm/MAP and MCA Vm/MAP. NVC was denoted by the peak response observed during visual stimulation and is expressed as a percentage change from the eyes‐closed period. Resting PCA Vm and MCA Vm were not different between the atrial fibrillation (31 [7] and 49 [12] cm/s), hypertension (33 [8] and 55 [12] cm/s), and healthy control (36 [8] and 55 [12] cm/s) groups (P>0.05). Visual stimulation evoked an increase in PCA CVCi in all groups, but the magnitude of the hyperemic response was blunted in patients with atrial fibrillation (18 [8] %) and hypertension (17 [8] %), in comparison with healthy controls (26 [9] %) (P<0.05). Visual stimulation evoked a greater increase in MCA CVCi in the atrial fibrillation group (17 [6] %), than patients with hypertension (10 [4] %) and healthy controls (13 [6] %) (P<0.05). Thus, when peak PCA CVCi responses were considered following subtraction of the peak MCA CVCi responses (i.e., the “non‐selective” effect of the NVC test), a significantly diminished response was observed in the atrial fibrillation group (1 [8] %) compared the hypertension (7 [9] %) and healthy control groups (13 [9] %) (P<0.01). In summary, individuals with atrial fibrillation exhibit a blunted NVC response to visual stimulation when compared to age‐matched, healthy control and hypertensive participants. Additional studies are required to identify the mechanisms for the attenuated cerebral perfusion response of the occipital lobe to visual stimulation in atrial fibrillation (e.g., attenuated neuronal activation, altered cerebrovascular vasodilatory signaling). Support or Funding Information Funded by BHF project grant PG/15/45/31579. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Neurovascular Coupling Impairment in Heart Failure with Reduction Ejection Fraction

“…However, white matter lesions and cognitive decline are also present in HFrecEF, highlighting the importance of other aspects like vascular risk factors to cortical damage [ 2 ]. Decreased NVC is also present in other cardiovascular diseases associated with HF such as hypertension and atrial fibrillation [ 22 , 23 ]. Furthermore, oxidative stress impairs NVC.…”

Cerebrovascular Dysfunction in Atrial Fibrillation

“… Junejo et al (2019a) assessed cerebral autoregulation in AF patients [ n = 30, 69 (63,72) years], primary hypertensives [ n = 29, 68 (65,72) years], and healthy controls [ n = 24, 68 (66,70) years]. Cerebral autoregulation was determined using transfer-function analysis of the MCA Vm and blood pressure (finger photoplethysmography) responses to repeated squat-to-stand maneuver.…”

“… Junejo et al (2019a , c ) investigated whether neurovascular coupling is blunted in AF patients [ n = 12, 71 (66,72) years] compared to primary hypertensives [ n = 13, 66 (65,69) years] and healthy controls [ n = 12, 69 (57,70) years]. Beat-to-beat posterior cerebral artery (PCA), MCA Vm (temporal transcranial Doppler ultrasonography), and vascular conductance (calculated as Vm/mean blood pressure) responses to repeated visual-stimuli (30 s eyes-open, 30 s eyes-closed for 5 min) were spline interpolated and then averages and percentage changes calculated ( Phillips et al, 2016 ).…”

“…* p < 0.05 vs. HC. Modified from Junejo et al (2019a ; open access article published under CC-BY 4.0 license).…”

“…Evidence exists for age‐ and hypertension-associated decline in neurovascular coupling response ( Girouard and Iadecola, 2006 ; Lipecz et al, 2019 ), alongside some conflicting reports ( Stefanidis et al, 2019 ). However, mechanistic studies in humans are limited and it remains to be investigated whether the attenuated neurovascular coupling responses reported in AF patients ( Junejo et al, 2019a , c ) reflect neurodegenerative blunting or disrupted coupling between neurons and vasculature. Moreover, to our knowledge, to date, neurovascular coupling has only been assessed in AF patients using visual stimulation (i.e., reading) and whether this diminished response persists during other stimuli (e.g., finger tapping) is unknown.…”