Atrial Fibrillation

What this page documents

This page details the bioelectrical architecture, mathematical constants of chaotic atrial depolarization, and atrioventricular node behavior parameterized in the MioAtlas three-dimensional cardiac simulator for atrial fibrillation. The sole purpose of this document is to provide transparency regarding computational modeling and its biophysical foundations; it does not constitute clinical practice guidelines, emergency protocols, or a medical diagnostic tool. For an in-depth description of the mathematical integration of the 12 leads, refer to the technical methodology section.

Model parameters

The quantitative values governing atrial excitation kinematics and ventricular response in the simulation engine derive from the AFIB entity configuration in the conduction system catalog:

Source of each parameter value

The bioelectrical parameterization implemented in MioAtlas is grounded in the following peer-reviewed scientific sources:

1. Anatomical localization of ectopic trigger (FOCUS_LA_PV): Assignment of the initial focus to myocardial sleeves of the pulmonary veins matches classic atrial microanatomy described by Anderson et al. (2009).
2. 12-lead ECG tracing generation and calibration standards: Recording speed at 25 mm/s, voltage calibration at 10 mm/mV, and narrow QRS complex morphology (90 ms) follow AHA/ACCF/HRS standardization guidelines in Kligfield et al. (2007).
3. Dipole dynamics and 3D ECG synthesis: Wavefront propagation using multiple spatial dipoles projected onto a synthetic torso is based on the whole-heart electrical activity model by Sovilj et al. (2013).
4. Dynamic QT interval adaptation: Despite R-R cycle irregularity, theoretical ventricular repolarization duration dynamically adjusts cycle-by-cycle using the cubic formula of Fridericia (1920).

How it is modeled

In the interactive coronal cut of the heart, the simulator decouples sinus activity from the SA node and instantiates a multifrequency noise generator across the left and right atria. This generator decomposes atrial activity into 7 micro-reentrant wavelets (waveletCount = 7) propagating across the myocardial mesh with heterogeneous conduction velocity.

At the atrioventricular junction, the AV node is modeled as a probabilistic refractory state filter. When a wavelet reaches the node, the algorithm evaluates the elapsed time since the preceding ventricular depolarization; if the node is in its absolute refractory phase, the impulse is blocked; if in the relative refractory phase, a variable latency is introduced before propagating the action potential down the bundle of His. The resulting 12-lead ECG demonstrates an absence of P waves, replaced by low-amplitude f waves (0.05 – 0.15 mV) and completely irregular R-R intervals with up to 40% dispersion.

What is NOT reproduced

To maintain smooth rendering at 120 frames per second in the browser without excessive CPU overhead, the model incorporates deliberate biophysical simplifications:

• Intracavity hemodynamics and loss of atrial kick: The simulator does not calculate real-time reductions in cardiac output or left ventricular end-diastolic pressure variations resulting from the loss of coordinated mechanical atrial systole.
• Thrombogenesis and blood stasis risk: Computational fluid dynamics (CFD) of left atrial appendage stasis and automated embolic risk scoring are not implemented.
• Adaptive autonomic tone: Sympathetic and parasympathetic tone fluctuations are not dynamically recalculated for postural changes or stress, remaining within static user-selected bounds.
• Beat-to-beat Ashman phenomenon: Although R-R intervals are irregular, the simulator does not automatically generate transient right bundle aberrancy following a long-short cycle sequence unless explicitly configured.
• Detailed cellular electrophysiology: Individual membrane ionic currents (IKur, INa, ICaL) via high-density Hodgkin-Huxley formulations are omitted.

Interactive variants

You can inspect different bioelectrical setups and associated conditions directly in the simulator via these deep links:

• Classic Atrial Fibrillation (uncontrolled ventricular response, 125 bpm): standard baseline with fine f waves and narrow QRS complexes.
• Preexcited Atrial Fibrillation (accessory pathway conduction): rapid, wide, irregular ventricular activation via an extranodal bypass tract.
• Typical Atrial Flutter (cavotricuspid isthmus macro-reentry): organized sawtooth flutter waves at 300 bpm with 2:1 AV block to contrast with AF disorganization.

Related entities to compare in the simulator

To explore supraventricular rhythm disturbances and activation pathways in the 3D environment:

• Typical Atrial Flutter in 3D Simulator: Organized atrial macro-reentry with regular F waves at 300 bpm and constant AV conduction.
• AV Nodal Reentrant Tachycardia (AVNRT) in 3D Simulator: Dual AV nodal pathway circuit in Koch’s triangle with narrow regular QRS at 180 bpm.
• Multifocal Atrial Tachycardia (MAT) in 3D Simulator: Three or more distinct P-wave morphologies with variable PR intervals.
• Respiratory Sinus Arrhythmia in 3D Simulator: Physiological P-P interval variability modulated by respiration with normal P waves and PR intervals.