153 Ventricular pacing along individual branches of the coronary sinus using a quadripolar LV pacing lead
Bibliographic record
Abstract
Introduction Cardiac resynchronisation therapy (CRT) usually involves placing the left ventricular (LV) pacing lead in the postero-lateral or lateral region of the LV epicardial surface as this is thought likely to re-coordinate myocardial contraction most effectively. The LV lead is standardly placed in a position with the best pacing parameters and satisfactory stability. It is not known, however, whether there is a significant difference in haemodynamic response to LV pacing in different regions of the same coronary sinus (CS) vein. In this study we aimed to evaluate the difference in acute haemodynamic response to pacing along individual branches of the CS. Methods 16 patients underwent an acute haemodynamic study during their CRT-defibrillator implant. We used a high fidelity pressure wire to assess the acute haemodynamic response (AHR) to pacing in different branches of the coronary sinus. We used a novel quadripolar lead (Quartet, St Jude Medical, Sylmar, California, USA) that has four poles on the LV lead―distal tip and 3 ring electrodes. The 3 ring electrodes are spaced 20 mm, 30 mm and 47 mm from the distal tip electrode and the four poles allow bipolar pacing between them. It was thus possible for us to test pacing parameters and AHR along a significant proportion of a CS branch without having to reposition the LV lead. Results DDDLV pacing was attempted in as many different CS branches as possible in each patient (total 56 different positions used). The mean overall percentage difference in AHR (measured by change in +dP/dt compared to baseline AAI pacing or VVI pacing in AF patients) between an individual CS branch bipole with the lowest +dP/dt and that with the highest was 6.6±5.6%. Much larger differences in change in +dP/dt were seen, however, between different branches of the CS in the same patient with a mean difference in change in +dP/dt in the best CS vein compared to the worst CS vein of 16.7±6.3%. Although the difference in AHR seen between different bipoles within the same vein were not large, we did find that in some cases no pacing capture was found with one bipole but was found with another. Furthermore, differences in whether phrenic nerve stimulation (PNS) occurred were seen when using different LV lead bipoles within the same branch of the CS. Conclusion Our data suggest that only a small difference in AHR is seen when pacing along the same branch of the CS compared to pacing within different branches of the CS within the same patient. This means that although the site of LV lead placement is important, a proximal or distal position within a CS branch is much less important than choosing the right branch in terms of acute haemodynamic response. A choice of bipoles on the LV lead may mean, however, that problems with capture thresholds or PNS can be overcome without the need to reposition the LV lead.
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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 | 0.000 | 0.000 |
| 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) | 0.000 | 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".