Peak oxygen uptake is not determined by cardiac noradrenaline spillover in heart failure
Bibliographic record
Abstract
AIMS: We recently found that resting muscle sympathetic nerve activity is inversely related to peak oxygen uptake (VO(2) peak) in patients with heart failure, suggesting a peripheral neurogenic limit to exercise in heart failure. No such relationship was observed in healthy controls. To determine whether this observation is specific to sympathetic discharge to skeletal muscle, we tested the null hypothesis that VO(2) peak would not relate to resting cardiac noradrenaline spillover, which is also elevated in heart failure. METHODS AND RESULTS: We measured cardiac noradrenaline spillover at rest by a radiotracer technique and VO(2) peak, during cycle ergometry, by open circuit spirometry in 49 heart failure patients (mean age 54.4+/-1.4 (SE)). There was a significant relationship between age and peak VO(2) (P=0.022). There was no significant relationship between cardiac noradrenaline spillover and either absolute or relative VO(2) peak (P=0.136), with age included in a multiple linear regression model, and none between cardiac noradrenaline spillover and the percent predicted VO2) peak achieved (P=0.34). CONCLUSIONS: Reduced exercise capacity in heart failure relates more closely to sympathetic traffic to skeletal muscle than to cardiac sympathetic outflow, as assessed by noradrenaline spillover. This finding lends further support to the concept of a predominantly peripheral neurogenic limit to exercise.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.002 |
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; both teacher heads agree on what is shown here.
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".