Neurovascular Coupling is Blunted in Atrial Fibrillation
Bibliographic record
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 .
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".