CORONARY ARTERY DISEASE (CAD)

Normally coronary circulation is made up of two main arteries, right and left. Left main artery divides into two large arteries, left anterior descending (LAD) and left circumflex (LCX). So we can say that there are three main arteries of the heart, right coronary artery (RCA), left anterior descending artery (LAD) and left circumflex artery (LCX). 

(Ref. Fig  Blausen.com staff (29 August 2014). "Medical gallery of Blausen Medical 2014" )

CAD is a disease of coronary artery where there is compromise in the blood flow of artery due to fatty deposits, atherosclerosis or calcium deposits in the native coronary artery or arteries.

(Ref. Fig  Blausen.com staff (29 August 2014). "Medical gallery of Blausen Medical 2014" )

ANGINA is the state of CAD where there is compromise in the flow of the blood in coronary artery but not complete. There is demand and supply mismatch of the blood flow to the heart.  Till this stage usually there occur no or minimal damage to the heart muscle and heart function is usually preserved.

(Ref. Fig  Blausen.com staff (29 August 2014). "Medical gallery of Blausen Medical 2014" )

In heart attack or myocardial infarct, there occur complete block of one or more coronary artery. There is definite damage to the heart muscle depending on the how many arteries are completely blocked. 

(Ref. Fig  Blausen.com staff (29 August 2014). "Medical gallery of Blausen Medical 2014" )