HEART SPECIALISTS IN YELAHANKA NEW TOWN BANGALORE
The causes of coronary symptoms
The symptoms of coronary artery disease are caused by the reduction of myocardial perfusion
that results from narrowing of the lumen of one or more of the coronary arteries. This narrowing
is most often the result of atherosclerosis. Other much less common causes include:
1 coronary artery spasm (often in an already diseased segment of artery but sometimes
as a result of the use of cocaine)
2 thrombosis (usually on an already diseased, or occasionally aneurismal, segment)
3 embolism (e.g. from an infected aortic valve)
4 congenital coronary abnormality
Numerous other cardiac symptoms and problems can be the eventual result of atheromatous
coronary disease. These include myocardial infarction , cardiac failure cardiac
arrhythmias and some cardiac valve problems.
Risk factor mechanisms of action
Atherosclerosis is thought to result primarily from a disturbance of the vascular endothelium.
The final common pathway for the effects of endothelial dysfunction is largely through abnormalities
of nitric oxide (NO) production. This chemical, released by a healthy endothelium, is
a potent vasodilator and has anti-inflammatory and other favourable actions on the arteries.
Causes of this disturbance can be:
n mechanical (hypertension)
n chemical (oxidised lipids, components of cigarette smoke, hyperinsulinaemia) or
n due to immunological injury.
The damaged endothelium attracts inflammatory mediators, platelets and circulating lipids
and promotes fibroblast and smooth muscle proliferation. This results in the formation of a
plaque, which may narrow the arterial lumen.
Plaques can remain stable (or sometimes regress), enlarge, rupture or erode (more common
in diabetics). Most acute ischaemic events (acute coronary syndromes or acute myocardial
infarctions) are thought to be the result of further luminal narrowing caused by the formation
of partly or fully occlusive thrombus on a ruptured or eroded plaque. Coronary risk factors
may therefore operate because they are atherogenic or thrombogenic.
Plaque rupture may be at least partly an inflammatory process involving inflammatory cells,
cytokines and even bacteria. This may explain the association between inflammatory markers
such as high-sensitivity C reactive protein (hsCRP) and a risk of acute coronary events. Although
this association seems well established, there is still uncertainty about its role in overall risk
Plaques at risk of rupture are called vulnerable plaques. They typically have a thin fibrous
cap. The shoulde of these caps are at risk of rupturing and allowing
material from within the plaque to come