M1
- Mathematical Model
M4
- Assignment of cardiac tissue types
D2
- Parameter values of the experiment
Introduction
Cardiac contraction is a complex spatial-temporal phenomenon; it is activated by the temporal changes of potential value in each cardiac cell. During contraction there is also a torsion of the heart. These considerations emphasize the complexity of the phenomenon, that may not be simply described as a temporal change of the scale factor of the heart volume. Several are the cardiopathologies due to conduction diseases; the "Myocardial infarction", the "Tachycardia" and the "Atrial or Ventricular fibrillation" are some examples. Complexity and importance of this phenomenon justify the interest and the studies that affect it.
The aim of this work is the visualization of the results of a simulation of cardiac potential propagation; the Visible Human Dataset is a start point for a simulation made in an ambient of cardiac anatomy characterized by truly real data. The work is based on a model developed at the Chair of Medical Informatics of the "Politecnico di Milano", named "Simul-Prop-El-Cardio". Is our opinion that good results are achievable with the employ of a valid propagation model and an accurate description of heart anatomy. The VHD describes completely the whole anatomy of the heart. Image processing has been done to translate the informations of the Dataset into the format required by the model we employ. The best way to understand potential propagation in the heart is the observation of cardiac contraction. Since we have not yet developed an electro-mechanical model, based on an impulse-deformation relationship, we make use of a potential-color relationship: each cell of the cardiac volume reflects a color, depending of its potential value.
Cardiac cells are grouped in slices, corresponding to heart images of the VHD. We want to visualize the entire external surface and the internal structure of the cardiac volume, that can describe heart anatomy, as well as potential distribution. We propose also a so called "Decumulated-view" and a "Temporal-view", in order to have a better comprehension of the spatial and temporal characteristics of this phenomenon.
The "Decumulated-view" is a global image in which we visualize a spatial series of images, that report, at a fixed time instant, potential distribution in different layers ( a layer is a subset of contiguous slices); these layer are built starting from the layer "From-To", removing step by step a slice, in order to reach the layer "To-To".
The "Temporal-view" is a global image in which we visualize a temporal series of images that describe potential distribution in a fixed layer "(From-i,To)".
Data, Methods and Results
The architecture of the project is described in this flow-chart. The right side of the diagram shows the elaborations of the VHD images, that have been made to extract from the Dataset the informations needed. The left side shows the data flow, in input and in output of the simulation program. The display permits the visualization of a set of slices, that can describe heart anatomy, as well as potential distribution. Potential distribution is obtained superimposing (AND) simulation results to anatomical data. Links to each component of the schema that describe data are labeled with "D", links that describe methods are labeled with "M" and links that describe results are labeled with "R". Links (at the left side of the schema) are organized in order to have the best comprehension of the work.
Project's architecture
|
|
M1
- Mathematical Model
|
Conclusions
Our goals have been reached. The work has required firstly a deduction of the cardiac morphology from the VHD, secondly a conversion of these images in the electrical model format and finally the project and the implementation of the software aimed at the visualization of simulation results. The software developed permits an appropriate interpretation of the spatial and temporal characteristics of the phenomenon, it is completely freeware, and has an adequate number of window interfaces, that made it simple and intuitive, easy to use, also for people with no familiarity with computers. The employ of a real anatomy for heart electrical activity simulation and new visualization modalities represent work's originality. Future developments are the simulation of pathologies, the development of a contraction model, based on an impulse-deformation relationship, and also the diffusion of the software via INTERNET.