Causes of Coronary artery Disease
Why does your coronary artery block?
Heart attack is usually due to
blocking of a least one coronary artery. This block in the layman term is
called coronary thrombosis. Formation of an atheroma is the precursor of coronary
thrombosis. The process of formation of atheroma is called atherosclerosis. The
term “atherosclerosis” is derived from the Greek words “athero” (Gruel or
porridge) and “sclerosis” (hardening) (1). So atherosclerosis means hardening
of arteries. Why some people develops atheroma and others do not is clear.
Deposition of cholesterol (fat) inside coronary artery is the initial stage of
heart attack. The artery in our body has got three coatings, inner coating is
called intima, middle one is called media and outer coating is known as
adventitious. Deposition of fat in the inner coating of artery, intima is the
initial event. The initial lesion is called fatty streak, which is yellow in
color. The yellow discoloration gradually increases in size and ultimately
forms fibrous plaque. This fibrous plaque is white in appearance and elevated
and causes obstruction to the blood flow inside coronary artery. This elevated
plaque consists primarily of smooth muscle cells and fatty substances
cholesterol and cholesteryl ester. Cholesterol starts depositing inside the
coronary arteries due to the response of injury inside the coronary arteries. The final event of coronary thrombosis is initiated by the blood cell
platelets. Blood contain three types of cells red blood cells (RBC), white
blood cells (WBC) and platelets. RBC carries oxygen; WBC is a part of body’s defense mechanism and platelets helps in clotting (solidification of blood).
If the cholesterol gruel (atheroma) ruptures then platelets aggregate on it and
cause thrombosis and this thrombosis leads to heart attack.
Can the progress of fat Deposition be halted?
There are some statistical evidences
that the process of atherosclerosis (fat deposition) can be halted if you
control your diet and take medicines which reduce your blood cholesterol level.
In a recently published trial (CLAS trial) documented that niacin and
colestipol groups of drug can cause regression of fat ball (atheroma) in 16.2%
cases and in 45% cases the size of the fat ball remained stationary . Brown
and colleagues have demonstrated statistically significant regression in the
atheroma with decrease in the blood cholesterol and LDL level. This
provides clear evidence that the lesions of atherosclerosis are able to regress
at apparently all states of lesion development.
A
number of investigators have proved that the fish oils, which contain omega-3
fatty acids decrease the blood fat level and reduce the size of fat ball
(atheroma ) inside the coronary artery .
Reference:
1. Ross R. The
pathogenesis of atherosclerosis. Heart disease by Braunwald E. 4th
Ed, 1992, p 1106-1122.
2. Ross R, Glomset J.
atherosclerosis and arterial smooth muscle cell. Science 1973; 180:1332.
3. Ross R, Glomest J. The
pathogenesis of atherosclerosis. N Engl J Med 1976; 195 : 369
4. Cashin HL, Mack WJ,
Pogoda JM et al. Beneficial effects of colestipol-niacin on coronary
atherosclerosis : A 4 year follow-up. JAMA 1990; 164 : 3031
5. Cannon PJ. Eicosanoids
and the blood vessel wall. Circulation 1984; 70 :100
