Vulnerable plaque is not a every day term that people hear about. In fact many people who are fortunate enough not to have heart problems may never ever hear the term but it is a serious one. Vulnerable plaque is a collection of white blood cells and lipids (including cholesterol) in the wall of an artery. This can result in sudden serious problems such as a heart attack. Vulnerable plaque is believed to be cause by inflammation in the arteries which leads to the development of soft or vulnerable plaque.