Study of the endo-epi flow ratio by using an electronic circuit model of the coronary vessel

An electronic circuit model of the coronary vessel using field effect transistor (FET) was used to perform dynamic simulation of the left coronary circulation and to study the changes in the endo-epi flow ratio of the myocardium in order to demonstrate the vulnerability of the subendocardial layer of the intramyocardium to various coronary arterial diseases and the way the coronary arterial blood flow is effected by the occurrence of abnormality in the heart. Under normal condition, the simulated endo-epi flow ratio was found to be 0.68. The changes in the flow ratio were observed while varying the septal arterial resistance, mean arterial pressure and intramyocardial pressure individually. The mean flow in the subendocardium was found to decrease at a rate faster than that in the subepicardium with the increase in the septal arterial resistance and the intramyocardial pressure. The same tendency was also observed while the arterial pressure was lowered. From all these observations, it can be concluded that the subendocardium is more vulnerable to ischemic heart diseases than the subepicardium.