Heart muscle is supplied with oxygenated blood by the coronary arteries which branch off the aorta shortly after it leaves the heart.The coronary arteries wrap around the entire heart and form many branches which grow into the heart to supply the cardiac muscle with oxygen and nutrients.Any blockage of these arteries results in insufficient oxygen being delivered to the heart muscles. The heart is unable to pump blood effectively to the rest of the body.This may lead to a heart attack or myocardial infarction.Heart muscle cells that are unable to respire die.