Ambulatory Monitoring of Cerebrovascular Responses to Upright Posture and Walking in Older Adults With Heart Failure
Bibliographic record
Abstract
Background Insufficient cardiac output (Q) in individuals with heart failure (HF) limits daily functioning and reduces quality of life. While lower cerebral perfusion, secondary to limitations in Q, has been observed during moderate-intensity efforts, individuals with HF may also be at risk for lower perfusion during even low-intensity ambulatory activities. Methods We determined whether HF is associated with an altered cerebrovascular response to low-intensity activities representative of typical challenges of daily living. In this study, we monitored central hemodynamics and middle cerebral blood velocity (MCAv) and cerebral tissue oxygenation (near-infrared spectroscopy) in 10 individuals with HF (78±4 years; left ventricular ejection fraction (LVEF) 20-61%) and 13 similar aged controls (79±8 years; LVEF 52-73%) during three randomized transitions: 1) supine-to-standing; 2) sitting-to-slow-paced over-ground walking; and 3) sitting-to-normal-paced over-ground walking. Results Throughout supine, sitting, standing, and both walking conditions, individuals with HF had lower cardiac index (Qi) and cerebral tissue oxygenation than controls ( P <0.05), and MCAv was lower across the range of blood pressure in HF (P=0.051) and during walking only (P=0.011). Individuals with HF had an attenuated increase in stroke volume index and Qi during normal-paced walking compared to controls ( P <0.01). Conclusion The indices of cerebral perfusion from MCAv and cerebral oxygenation were lower during ambulatory activities in individuals with HF; however, relationships between MCAv and blood pressure were not different between HF and controls indicating no difference in static cerebral autoregulation.
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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".