Effect of cardiac resynchronization therapy on regional left ventricular function: a speckle tracking strain analysis
Bibliographic record
Abstract
AIMS: The mechanisms associated with cardiac resynchronization therapy (CRT) benefits have been elucidated in part, however little is known about the effects of biventricular pacing (BVP) on regional myocardial contractility. METHODS AND RESULTS: Twenty patients with conventional CRT criteria were studied before and after device implantation. Speckle tracking strain analysis was performed from standard bidimensional acquisitions during different pacing configurations. Longitudinal and transverse strains were measured for the six basal left ventricular (LV) segments. Acute CRT improved LV end-diastolic and end-systolic volumes without significantly modifying LV ejection fraction. Moreover, CRT produced significant changes in regional strain. When compared with spontaneous rhythm, simultaneous BVP caused a significant increase in longitudinal septal strain (-4.8 vs. -7.3%, P = 0.003) and a significant decrease in longitudinal lateral strain (-8.2 vs. -5.9%, P = 0.03). Simultaneous BVP also induced a significant decrease in transverse lateral strain from 17.9 to 10.9% (P = 0.004). CONCLUSION: In this acute echocardiographic study, BVP decreased lateral wall deformation while improving septal wall contraction, thus potentially improving LV contractile pattern.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.001 | 0.002 |
| 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) | 0.000 | 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 teacher head, 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".