Abstract
A program to accomplish simulation of the propagation process of the ventricular excitation in a digital computer was devised and succesfully executed. The comparison of the simulated propagation process by this program with that observed in animal experiments may give a newer knowledge in regard to the spread of excitation in the ventricles. Combination of this simulation scheme and the reconstruction method of the electrocardiographic QRS patterns to be reported elsewhere will give a newer clue to interpretation of genesis of QRS pattern. Further, there is a good possibility that the present study will be utilized as a new scheme for computer diagnosis of electrocardiogram in the near future.
On the basis of the horizontal cross-sections of the human heart, a model for the ventricles of the heart was assumed as a cluster of 3 mm cubic blocks. The specialized conduction system was also set in this model. The model was fed into the computer in such a way that each of the blocks provided a memory address in the computer.
Referring to the physiological evidence in regard to conduction of the excitation in cardiac muscle, three principles were postulated : 1) the excitation being to spread radially with a uniform velocity, 2) no repeated firing of a block in virtue of refractoriness mechanism and 3) higher conduction velocity in the specialized conduction system than in the proper cardiac muscle. In order to simulate the propagation of excitation so as to fulfill the above principles, a program was written and executed. The excitation was let to spread imaginarily in the model stored in the computer memory.
The simulated propagation process thus obtained of the ventricles in a normal mode was found consistent in principle with that observed in animal experiments. This meant that the simulation program was largely justifiable and applicable to the intended purpose mentioned above.
Modification of the program in the aspects found to be inadequate is under way. The next step will naturally be application of this simulation program to the abnormal conductions such as ventricular extrasystole, bundle branch block and myocardial infarction. An example in case of ventricular extrasystole was demonstrated.
