The following section will walk you through the various phases of
atherosclerosis. The following "lecture" describes various phases of the
disease. The pictures will change automatically during the audio presentation.
You can play, stop, and rewind the animation/narration by clicking on the
buttons below.
Atherosclerosis begins with the deposition of fatty streaks on the inner
lining of the artery. Additional deposits lead to a bulky atheroma that begins
to encroach into the channel of the coronary artery. Fibers begin to grow into
the atheroma causing harder plaques. The plaque of atherosclerosis may develop a
crack on its surface. This is known as plaque rupture which can result in the
deposit of a blood clot at the site of the blockage. If the blood clot totally
blocks flow to the heart muscle, a heart attack usually results.
However, if the clot causes a partial blockage, the patient may develop
unstable angina. Such patients have prolonged, frequent and more severe episodes
of angina. The discomfort may be the patient's first symptom (in which case it
is called new onset angina). In other cases, stable angina gradually or suddenly
changes into a pattern of unstable angina.
The chest discomfort of unstable angina may become more frequent, last
longer, be more intense, be brought on by lesser degrees of exertion (compared
to prior symptoms), appear at rest or even awaken the patient from a sound
sleep. It is called unstable angina because many untreated patients end up
having a heart attack. Unstable angina may also occur in the absence of a blood
clot if the severity of the blockage (due to the atheroma and plaques) becomes
severe enough to cause a drastic decrease in blood supply to the heart
muscle.
