Building the ventricles and conduction system
Created by Arun Mahtani
Building the ventricles and conduction system
Click the tracing to jump the heart to that moment.
The layers button on the heart adds anatomy labels, a cutaway, glass atria and a textbook colour scheme. The sun and moon button switches between light and dark mode. For teaching, not for clinical use.
The ventricles are a procedural model: a prolate left ventricle, a crescent right ventricle with its infundibulum, papillary muscles, the moderator band and the His–Purkinje system, placed in the chest at standard fluoroscopic orientation. For each site the activation time of every 1.5 mm voxel is solved as a shortest-path (eikonal) problem, with faster conduction on the Purkinje-rich mid and apical endocardium, slower conduction across the wall, and blocked or slowed conduction in scar. Reentrant circuits add a narrow isthmus whose slow diastolic conduction contributes almost nothing to the surface ECG.
The 12-lead ECG is computed from that activation: every voxel's activation and repolarisation gradient acts as a current dipole in a uniform conductor, the precordial leads sit at their chest positions and the limb leads use the Einthoven lead vectors. For all 18 sites the simulated ECG matches the published pattern tags shown in the library (V1 pattern, polarity of the inferior leads, lead I, precordial transition and QRS width); amplitudes, notching and finer criteria such as pseudo-delta wave or maximum deflection index are not modelled reliably. Use it to build intuition, not to localise a patient's arrhythmia.
The displayed surface adds epicardial fat, coronary arteries and veins, valve annuli, the atria and great vessels for orientation. These are drawn for teaching and do not change the simulated activation or ECG.
C-arm angles: positive values are LAO and cranial, negative values are RAO and caudal.
What helps, what is wrong, what you would like to see. Your feedback goes only to the creator of SimVT.