Download Learning ECG with real-time interactive simulation

Learning ECG with
Real-time Interactive Simulation
Dr Vassilios Hurmusiadis - Primal Pictures Ltd ( contact: [email protected] )
Dr Malcolm Finlay - The Heart Hospital, London UK
Abstract
The Electrocardiogram (ECG) is a static 2D graphical
representation of the heart’s complex, dynamic 4-dimensional
electrical function. The work focuses on presenting the dynamic
electrical events of the heart in synchronization with simulated
normal and pathological ECG’s. The aim is to create a direct
visual link between pathology and ECG (“cause” and “effect”).
Validated simulations of normal rhythm, left/right bundle branch
blocks and Wolf-Parkinson-White syndrome with accessory
pathways have been implemented. We have created a novel
training method based on real-time simulation of
electrocardiography using interactive 3D computer graphics.
Objectives
The presented work is based on previous work by the author.
The work is focused on simulating the principles of
electrocardiography using a real-time interactive 3D simulation
model of cardiac electrophysiology. The developed generic
simulation model is capable of generating validated ECG’s
suitable for training in ECG diagnosis. It is not a patient-specific
predictive model. Advanced cardiac simulation, such as in the
Cardiome Project, focuses on developing computational models
of the excitation, metabolism and contraction of the heart with
view to making predictions about patient-specific interventions.
Methods
Results & Conclusion
Cardiac morphology is based on tomographic data from “The
Visible Human” project. All four cardiac chambers were equipped
with cell-nodes and myocardium fiber orientations. Ventricular
fibers were defined from canine DT-MRI datasets. Atrial fiber
orientations were constructed under guidance from cardiac
morphologists. An approximate model of specialized conduction
tissue was manually constructed, which includes the SA and AV
nodes, the bundle of His, left and right bundle branches and the
network of Purkinje fibers. Cardiac cell activation sequences
were constructed using the Luo-Rudy action potential model, and
formed the basis for the construction of the inter-cellular
activation propagation wave. A cellular automaton was
developed to simulate the propagation of electrical excitation
through the 3D cell-nodes based on local fiber orientations. Each
cell-node in the automaton possesses a rest state, an excitation
threshold, and a diffusive-type coupling to its nearest neighbors.
The mean electric axis is calculated and displayed over each
beat cycle. The simulated electric axis is projected onto the
standard lead vectors I, II, III, aVR, aVL and aVF of the Einthoven
triangle and the precordial lead vectors V1-V6. The respective
ECG signals are generated in real-time. Malfunctioning or
necrotic regions have been simulated by altering the cell
activation profiles in certain regions in the atria or ventricles.
Free online demo: http://staging.primalpictures.com/iecg
Validation of normal cardiac function, left and right bundle
branch blocks and pre-excitation through accessory pathways
on WPW syndrome, has been undertaken using the developed
prototype in collaboration with the Heart Hospital, UCLH. The
prototype is capable of real-time simulation of a whole heart
electrophysiology on a platform independent application
accessible online via the web and/or offline from disk. The
spatial and temporal relationships between the heart’s function
and ECG signal generation have been integrated in an elearning/assessment model. The application demonstrates the
spatial and temporal relationships between the heart’s
electrophysiology and 12-lead ECG generation. It allows endusers (medical students, trainee cardiologists, coronary care
nurses) to become intuitively aware by interacting with the
cardiac excitation process in real-time, in a bottom-up approach.
The work addresses the need for improved understanding of the
relationship between ECG tracings and the underlying
physiology/pathology of the heart. The interactive nature of realtime cardiac simulation allows a novel approach to teaching of
the 12-lead ECG. The 1 phase of the project which consists of
generating validated normal rhythm and two pathologies L/R
BBB and WPW syndrome has been completed. In the 2 phase
it is planned to validate a wide range of arrhythmias and pacing
procedures.
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