Does the Intraventricular Pressure Gradient Increase following Acute High Intensity Interval Exercise in Heart Failure?
Bibliographic record
Abstract
An increase in the diastolic intraventricular pressure gradient (IVPG) is an important mechanism that aids in left ventricular filling during exercise. Prior work has shown that individuals with severe heart failure have impairment in IVPG at peak exercise (Am J Physiol Heart Circ Physiol 2005; 289: H2081-H2088). We have previously shown in the present study cohort (J Appl Physiol 2011; 110: 398-406) that left ventricular peak twist reserve is blunted, but that left ventricular peak untwisting rate, due to an increase in peak basal rotation rate and not peak apical rotation rate, is enhanced following acute high intensity interval (HIT) exercise in patients with mild heart failure. It is unclear whether regional differences in rotational properties of the ventricle in heart failure (i.e., base versus apex) that we have observed affect the IVPG post-HIT. PURPOSE: To determine if the IVPG immediately following acute HIT would be increased despite impaired apical contribution to left ventricular untwisting. METHODS: Nine patients (49 ± 16 years; 6 male) with mild heart failure (NYHA Class I/II = 7/2; left ventricular ejection fraction = 36 ± 7%; peak VO2 = 27 ± 9 ml/kg/min) performed 1 session of HIT (4 × 4 min at 96 ± 10% peak heart rate with a 3 min recovery period between bouts). Cardiac MRI (1.5 T scanner) was performed at rest prior to HIT and 6 ± 2 min following HIT. Rotational mechanics and IVPG were analyzed using in-house techniques with custom software. Analyses were performed using 2-tailed paired t-testing with p<0.05 being significant. RESULTS: Our novel finding is that the IVPG from pre-HIT (1.8 ± 1.0 mmHg) to post-HIT (1.6 ± 0.7 mmHg) remained effectively unchanged (p>0.05), despite a significant 24% increase in untwisting rate (p<0.05) that was modulated primarily by an increase in peak basal and not peak apical rotation rate. CONCLUSION: The maintenance of, but not the increase in, IVPG may aid in diastolic filling following HIT in patients with mild heart failure. Impairment in apical rotational mechanics likely account for the poor IVPG reserve of the left ventricle in mild heart failure.
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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 | 0.001 | 0.001 |
| 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".