Coronary Artery Disease |
Angina Medical Treatment of Angina Heart Attack |
The heart is a muscular organ that pumps blood to the body at an average of
72 times per minute. Oxygen and nutrients serve as a fuel supply to the pump and
are carried to heart in the form of blood that flows through the coronary
arteries. Thus, the coronary arteries serve as fuel pipe lines to the heart
muscle.
The three major coronary arteries (Left Anterior Descending (LAD), Circumflex (Circ) and Right Coronary Artery (RCA)) and their respective branches each supply a designated portion of the heart, as follows: The LAD supplies blood to the front (anterior) portion of the heart and the septum (muscle partition that separates the Left Ventricle (LV) and Right Ventricle (RV)). The Circ supplies the back (posterior) portion of the LV. The RCA supplies the bottom (inferior) portion of the ventricle and also the RV in 90% of cases. In the other 10%, the Circ sends a branch to the inferior wall of the LV.
Coronary arteries have muscle fibers within their walls. By contracting the
muscle, the artery can reduce blood flow; relaxing the muscle increases flow. In
this way, the coronary arteries can regulate blood flow to different portions of
the heart. Occasionally, the muscle within a coronary artery may go into spasm
and markedly reduce blood flow to the heart muscle. This condition is known as
coronary spasm. Typically, the chest discomfort of coronary artery spasm occurs
at rest, and usually during the early morning hours. When the spasm is relieved
(spontaneously or with the use of medications), the blood vessel goes back to
its normal appearance and function. A temporary decrease in blood supply can
cause chest discomfort while a persistent decrease can result in permanent
muscle damage or a heart attack.
Atherosclerosis is by far the commonest cause
of coronary artery blockage. Unlike coronary spasm which creates a temporary
blockage, atherosclerosis results in a fixed blockage. Occasionally,
atherosclerosis may be accompanied by coronary spasm. The diagrams below show
the various stages of progression of atherosclerosis and development of coronary
artery blockages. The round picture on the left of each illustration is a
cross-sectional view of the coronary artery, while the picture on the right is a
longitudinal section at the same level.
The inner lining of the normal coronary
artery is smooth and free of blockages or obstructions.
Major risk factors for developing CAD include:
- Hyperlipidemia (high cholesterol level, particularly the "bad" component known as Low-Density Lipoprotein (LDL))
- High blood pressure
- Diabetes
- Cigarette smoking
- Strong family history of CAD
- Male gender, obesity, age above 50 years, lack of exercise, stress and tension can also predispose to the development of atherosclerosis
Significant atherosclerosis may be confined to the coronary arteries or may be associated with blockages within the arteries of the neck and those supplying blood to the lower limbs (legs)
The imbalance between the supply and demand of oxygen can cause chest discomfort (tightness, fullness, heaviness or pain) in the center of the chest and/or over the left breast). This is known as angina (pronounced an-ji-na) or angina pectoris. When the coronary artery blockage is severe enough to completely cut off the supply of oxygen and nutrients to the heart muscle, a heart attack can result. However, atherosclerosis may maintain a stable pattern for several years or even decades if the plaques grow slowly or remain relatively stationary. These patients may not notice worsening of angina during the time of stability and are said to have stable angina.
Coronary artery blockages and heart attacks may also be seen in patients who use "Crack" cocaine. This is becoming the commonest cause of heart attacks in young adults who are treated in emergency rooms in the USA.
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