Coronary Artery Disease
Angina, unstable angina and heart attack
A healthy heart is a hollow muscle that performs the
critical function of pumping blood to all the organs and tissues of the body. The heart, too, needs blood
and its oxygen to function. The blood supply to the heart is carried through the coronary arteries.
Coronary artery disease refers to the build-up of cholesterol on the walls of the coronary arteries. If
left untreated, it can trigger a series of events: angina, unstable angina and heart attack.
What is artherosclerosis?
Atherosclerosis is the process of cholesterol building up on the coronary
arteries and becoming plaque.
What is angina?
Angina is a medical condition caused by the thickening of plaque to the point where
it restricts the flow of blood through the coronary artery. In this condition, adequate blood to supply the
heart's needs may flow through the artery at rest, but when the heart's need for oxygen increases, such as
when the heart rate increases in response to exercise, blood flow through the partially blocked artery is
insufficient to supply the heart muscle with enough oxygen. In most patients, this is perceived as a
pressure-like sensation in the middle of the chest (or the neck or the left arm) which is provoked by
exertion and relieved by rest. This is called angina pectoris (Latin for pain of the chest).
Exercise testing, with ECG or with echo or nuclear images of the heart, can detect the presence of these
coronary narrowings. Cardiac catheterization with angiography of the coronary arteries can locate them
precisely.
Treatment options for stable angina include medication, angioplasty and stent placement, or coronary
bypass surgery.
What is unstable angina?
Unstable angina is usually caused by the development of a small blood clot
at the site of coronary plaque that has ruptured through the inner lining of the coronary artery into the
bloodstream. This clot can partly occlude (block) the artery, and small fragments of the clot can migrate
downstream in the system and block smaller branches. Patients with unstable angina experience an abrupt
change in their angina threshold (the amount of effort required to produce angina) or have angina at rest.
What is a heart attack?
A heart attack is a plaque rupture accompanied by the development of a large
blood clot which leads to the complete obstruction of a large coronary artery and a complete interruption
of blood supply to a large part of the heart muscle. This event is usually very painful and can be
accompanied by sweating, nausea, or vomiting. The electrocardiogram often shows typical changes reflecting
heart muscle injury. The blockage can be treated with clot-dissolving drugs (lytic therapy), angioplasty,
or both. If symptoms of a heart attack occur, it is extremely important to seek medical help urgently,
because a heart attack is a life-threatening situation, but one in which prompt recognition and treatment
can minimize or reverse injury to the heart muscle.
