Atherosclerosis is a process which results in atherosclerotic plaques forming in blood vessels. These plaques can occlude blood vessels, rupture leading to thrombrosis, and weaken the tunica media, leading to aneurysm.
When in peripheral vessels it is called Peripheral Artery Disease and when in the heart it leads to Coronary Artery Disease. Coronary Artery Disease can lead to angina, unstable angina and Myocardial infarction. Peripheral artery disease can lead to claudication and muscle infarcts. finishthis
Pathogenesis
1. Injury
Atherosclerosis is an arterial response to endothelial injury and the largest component of this is pressure. We so not see atherosclerosis in smaller arteries and veins, and this is because there isnt enough pressure. But there are other components which additionally lead to this. This includes but is not limited to, smoking, hyperlipidaemia, immune reactions, toxins, viruses, etc.
2. Dysfunction
This injury leads to dysfunction, such as increased vascular permeability and leukocyte and platelet adhesion. The increased permeability leads to lipoproteins to seep into the vessel wall where the attracted monocytes (attracted by cytokine release) turn to macrophages and engulf the lipids to turn into foam cells.
3. Plaque
The foam cells and activated endothelial cells lead to further cytokine and growth factor release. this triggers the Smooth msucle cells to be recruited from the media and these muscle cell proliferate and deposit ECM. They also engulf lipids and become foam cells. T cells are also recruited and this become a atherosclerotic plaque.
Complications
Atherosclerosis leads to mechanical obstruction of the vessel wall, which can lead to ischaemia (critical obstruction/stenosis is around 70%). Atherosclerotic plaques can also rupture leading to thrombosis forming and this can lead to unstable angina or an infarction.
The other outcome of the atherosclerotic plaque is that, as a result of the increased distance from the lumen to the media, there is degenerationa dn weakening of the media (from lack of resources diffused to it.) This weakening of the Media can lead to aneurysm formation, often in the abdominal aorta or the common iliac arteries.
Aneurysms can often be saccular (little pouch coming out of the vessel) or fusiform (the entire diameter blows up like a balloon,) and a real danger is that they can rupture with enough time. Often aneurysms can lead to clots forming due to its turbulent flow properties.