LAFB
Technical documentation
Left Anterior Fascicular Block
Block in the thin anterior fascicle of the left bundle branch. Activation of the left ventricle proceeds first through the posterior fascicle (inferior and rightward) and then anteriorly and leftward. Results in marked left axis deviation (between -45° and -90°), qR complexes in I and aVL, and rS complexes in II, III, and aVF with normal or slightly prolonged QRS (< 120 ms).
Also known as: Left Anterior Fascicular Block · hemibloqueo anterior izquierdo · HBAI · bloqueo fascicular anterior izquierdo · bloqueo de subdivision anterior izquierda · left anterior fascicular block · left anterior hemiblock · LAFB
What parameters does the model use?
The following values are applied by the simulation engine to this entity. They govern activation kinematics in the 3D model and the real-time synthesis of the 12-lead electrocardiogram.
What parameters does the model use?
| Parameter | Model value |
|---|---|
| Mechanism | Bloqueo |
| Impulse origin | Sinoatrial node (SA node) |
| Modeled rate | 60–100 bpm (default 75) |
| Regularity | Regular |
| P wave | Sinus (upright in I, II, aVF) |
| PR interval | 120–200 ms (default 160) |
| QRS duration | 105 ms |
| QRS morphology | Left anterior fascicular block |
| AV conduction | 1:1 AV conduction |
| Severity | Benign |
Which leads should be evaluated?
The catalog marks as primary diagnostic leads I, aVL, II, III, aVF. qR pattern in I and aVL, rS in II, III, aVF with marked left axis deviation (-45° to -90°).
In the simulator, these leads are highlighted on the 12-channel tracing and corresponding vectors are rendered on the 3D model, displaying electrical changes and anatomical origin simultaneously.
Frequently asked clinical questions
How is Left Anterior Fascicular Block identified on the 12-lead ECG?
Block in the thin anterior fascicle of the left bundle branch. Activation of the left ventricle proceeds first through the posterior fascicle (inferior and rightward) and then anteriorly and leftward. Results in marked left axis deviation (between -45° and -90°), qR complexes in I and aVL, and rS complexes in II, III, and aVF with normal or slightly prolonged QRS (< 120 ms). The characteristic diagnostic waveforms are generated in real time across the simulated 12-lead tracing.
Which leads are critical for diagnostic confirmation?
The primary diagnostic leads are I, aVL, II, III, aVF. qR pattern in I and aVL, rS in II, III, aVF with marked left axis deviation (-45° to -90°). In the simulator, these channels highlight the correlation with anatomical vectors.
What is the underlying electrophysiological or anatomical mechanism?
It originates from altered conduction in the SA_NODE, mediated by bloqueo.
How can this condition be explored in the 3D simulator?
MioAtlas offers direct deep-link reproducibility with preconfigured parameters, allowing full 3D cardiac rotation and lead vector inspection.
How do you open this configuration?
The simulator encodes its full state in the query string, providing a stable and reproducible URL:
https://mioatlas.com/simulador/en/?mode=conduction&arr=LAFB
Related entities
Other entities in the same category within the catalog:
Sources and bibliographic references
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Surawicz B, Childers R, Deal BJ, et al. (2009). "AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: Part III: Intraventricular conduction disturbances". Circulation.
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Anderson RH, Yanni J, Boyett MR, Chandler NJ, Dobrzynski H (2009). "The anatomy of the cardiac conduction system". Clin Anat.
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Kligfield P, Gettes LS, Bailey JJ, et al. (2007). "Recommendations for the standardization and interpretation of the electrocardiogram: Part I: The electrocardiogram and its technology". Circulation.