Types of ischemic heart disease constituted of causal chains. This figure shows a couple of causal chain-constituted ischemic heart disease. Each node shows the abnormal states, and each link indicates the causal relation between the abnormal states. A core causal chain of each disease is colored differently: ischemic heart disease is orange, and the subclasses of the ischemic heart disease, myocardial infarction are yellow. Prinzmetal angina is also a subclass of the ischemic heart disease consists of a pink core causal chain, and by an upstream extension smoking is added in the derived causal chain. Organic angina pectoris is green and the accumulation of cholesterol is added to the derived causal chain, which is a possible cause of arterial sclerosis.