Chronic total occlusion (CTO) is a complete or nearly complete blockage of one or more coronary arteries. The blockage, typically present for at least three months, is caused by a buildup of plaque within a coronary artery. When this happens, blood flow to the heart is compromised.

Robert, what is it you are asking? Maybe I can help what is Cto? I am guessing it is not the Chief technical officer. 😉