Atrial fibrillation and cardiac sympathetic reflexes in heart failureThe opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology.
Bibliographic record
Abstract
This editorial refers to ‘Atrial fibrillation impairs cardiac sympathetic response to baroreceptor unloading in congestive heart failure’† by P.A. Gould et al., on page 2562 Why do heart failure patients with atrial fibrillation progress more rapidly to pump failure and death than those who remain in sinus rhythm?1 There are many conceivable mechanisms: adverse ventricular remodelling and synchronization; higher filling pressures, yet loss of atrial contraction and lower stroke volume; atrial remodelling; a greater risk of atrial thrombus and embolic stroke; an increased likelihood of central sleep apnoea, which increases the risk of premature death; loss of vagal and sympathetic modulation of heart rate variability; adrenergic augmentation of atrioventricular nodal conduction; adverse effects of rate and rhythm modifying drugs; and altered neural regulation of the heart and circulation by reflexes arising specifically from the atria. Gould et al.,2 from Melbourne, take up the latter theme, using a radiotracer method Esler developed to quantify the release rate of norepinephrine into plasma. A series of publications from this laboratory has transformed our understanding of the time course, magnitude, and organ specificity of sympathetic nervous system activation in heart failure. It is now evident that sympathetic activation is first directed at the failing heart in proportion to the increase in filling pressure; that the relative increase in cardiac norepinephrine spillover (CNES) is far greater than that of any other organ;3 that the prognosis of patients with end-stage heart failure can be predicted by their rate of CNES;4 and that the mode of death from heart failure can be anticipated from kinetic-based calculations of catecholamine release and storage rates.5 Important to the present study is their observation, in nine heart failure patients with secondary pulmonary hypertension, that a simultaneous reduction in both pre-load and systemic blood pressure, caused by an infusion of sodium nitroprusside (SNP), increases total body norepinephrine spillover (TNES), yet at the same time decreases CNES.6 Four of these patients had atrial fibrillation. Azevedo et al.7 resolved this apparent paradox, instead using non-hypotensive and hypotensive lower body negative pressure (LBNP) as their experimental intervention. All of their patients had sinus rhythm. Reductions in cardiac filling pressure during non-hypotensive LBNP had no effect on CNES in subjects with normal left ventricular systolic function, but lowered CNES in those with heart failure. Hypotensive LBNP increased CNES significantly in control subjects, but had no effect in the group with heart failure. These and related findings led to the proposal that elevated left atrial pressure elicits a sympatho-excitatory reflex, ordinarily quiescent, and with an afferent limb directed specifically to the heart. Such a reflex would account for the early and selective increase in CNES present in patients with mild heart failure.8 Does atrial fibrillation perturbs this putative reflex?
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.012 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.026 | 0.017 |
| Insufficient payload (model declined to judge) | 0.004 | 0.003 |
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".