Abstract 1355: Determining Wavefront Size during Ventricular Fibrillation: Optical Mapping Study from Human Langendorff Hearts
Bibliographic record
Abstract
Background: We had recently established a model for the study of VF in humans using an optical mapping technique in Langendorff perfused human hearts. The optical mapping technique allows for the unequivocal evaluation of wavefront identification, the origin of wavefronts and their directional spread. Objective: The objective of this study was to measure wavefront sizes from different regions during human VF to determine the minimal spatial resolution required to study human VF in-vitro. Methods: The hearts were explanted from seven cardiomyopathic patients who underwent transplantation. The hearts were Langendorff perfused with Tyrode’s solution (95%O 2 +5%CO 2 ) and the potentiometric dye (0.2 mg Di-4-ANEPPS dissolved in 20mg of perfusate) was injected as a bolus into the coronary circulation. The imaged region was physically immobilized to minimize motion. The fluorescence was excited at 530 nm with a HL 150 W halogen lamp, the emission signal was longpass filtered at 610 nm and recorded with a CCD and CMOS camera (MiCAM02, Ultima, BrainVision Inc., Japan). The spatial resolution depending on the mapping window was 0.65–0.85 mm and the temporal resolution was 1 kHz. The heart was paced at a cycle length of 600 ms and the VF was induced by briefly touching the heart with the two poles of a 9V battery. The changes in dye signal were recorded over 1887 ms and analyzed using BV-analyzer software (BrainVision Inc, Japan). Wavefronts were identified using high-pass filter (0.01 Hz) on the fluorescence data. Recordings were performed at 4 sites: LV Septum (LVS), Right Ventricle Endocardium (RV), Left Ventricle Endocardium (LVendo) and Left Ventricle Epicardium (LVepi). Results: 16 episodes of VF were recorded and a total of 54 wavefronts were identified. Average wavefront size was 23.6 mm. By region, the average wavefront sizes were: LVS = 26.3 mm; RV = 22.4 mm; LVendo = 29.7 mm; LVepi = 19.3 mm. Conclusion: These results show that different regions on the human ventricle during VF show different wavefront size suggesting that propensity for wavebreak maybe spatially differentially distributed. To study human VF with multi-electrode mapping tools using inter-electrode spacing of less than 1–2 cm should provide sufficient resolution.
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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 | 0.000 |
| 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) | 0.002 | 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".