Electrovectorcardiographic Diagnosis of Left Septal Fascicular Block: Anatomic and Clinical Considerations
Bibliographic record
Abstract
Several publications considering anatomical, histological, pathological, electrocardiographic, vectorcardiographic, and electrophysiologic studies have shown that the left bundle branch splits into three fascicles or in a "fan-like interconnected network" in the vast majority of human hearts. The left His system is trifascicular with a left anterior, a left posterior, and a left septal fascicle (LSF). Consequently, the classic term "hemiblock," to describe the block of one of the fascicles, established several decades ago by the Rosembaum's school, should be updated. Electrovectorcardiographic changes resulting from conduction abnormalities of the left anterior and left posterior fascicles are commonly diagnosed, mainly by their changes in the frontal plane. However, the existence of conduction defects of the LSF remains controversial. The ECG/VCG hallmark of LSF block is prominent anterior QRS forces (PAF) on the horizontal plane. This ECG/VCG phenomena should be distinguished from other conditions that also produce anterior QRS shift in the HP as: normal variants, right ventricular enlargement, misplaced precordial leads, lateral myocardial infarction, right bundle branch block, Wolff-Parkinson-White, obstructive and nonobstructive forms of hypertrophic cardiomyopahty, diastolic left ventricular enlargement, endomiocardial fibrosis, Duchenne muscular dystrophy, and dextroposition. The two highly frequent etiologies of LSFB are ischemia (coronary artery disease (CAD) with critical proximal obstruction of the left anterior descending coronary artery) and, in Latin America, Chagas' cardiomyopathy. The aims of this review are to revise the evidence of the existence of a trifascicular left Hissian system and to help in the ECG/VCG recognition of the LSFB.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".