Atherosclerosis

Atherosclerosis is characterized by endothelial (lines the interior surface of blood vessels , forming an interface between circulating blood in the lumen and the rest of the vessel wall) dysfunction, vascular inflammation, and the buildup of lipids, cholesterol, calcium, and cellular debris within the intima (the innermost layer of an artery) of the vessel wall. 

This construction results in plaque formation accumulating on the inner walls of arteries, and as the artery walls thicken, the pathway for blood narrows, and this can decrease or block blood flow diminishing oxygen supply to target organs (Pic. 1, 2, 3, 4). Atherosclerosis represents a leading global cause of death and disability.

Atherosclerosis is a complex multifocal arterial disease of medium- and large-size arteries (Pic. 5, 6) involving interactions of multiple genetic and environmental factors. 

Although environmental factors such as diet or smoking play an important role in atherosclerosis development, genetic factors represent consequential determinant of atherosclerotic cardiovascular disease risk. Advances in techniques of molecular genetics have revealed that genetic disorders significantly influence susceptibility to atherosclerotic vascular diseases. 

The genetic risk of atherosclerosis is conferred in part through known metabolic risk factors such as hypertension (high blood pressure), dyslipidaemia (an abnormal amount of lipids in the blood), and diabetes mellitus, but together, the known risk features appear to be insufficient to explain the hereditary propensity to atherosclerosis. However, these risk factors alone do not account for the entire contribution to risk of atherosclerotic disease. 

Atherosclerosis is treated with drugs which are used to decrease high blood pressure and high levels of lipids. Surgical methods are performed in case of complications such as block of blood flow. 

Associated diseases 

Usually, atherosclerosis is an asymptomatic condition that might begin from childhood, whereas symptomatic organ-specific clinical manifestations often do not appear until 40 years of age or older when it is most commonly diagnosed.

Elevated blood pressure reflects the existence of atherosclerosis. There is irresistible evidence that high blood cholesterol increases the risk of developing atherosclerosis; but cholesterol is not the damaging mechanism. In fact, the risk of atherosclerosis is more precisely assessed by measuring the proportional association between lipoproteins of high density (HDL) cholesterol and LDL cholesterol.

Atherosclerosis is the primary cause of coronary heart disease (CHD), ischemic stroke, and peripheral arterial disease (a narrowing of the arteries other than those that supply the heart or the brain).

In the last decades a large amount of evidence linked rheumatoid arthritis (RA) (a long-term autoimmune disorder that primarily affects joints) to atherosclerosis. In fact, RA patients have an increased risk of cardiovascular events that is not fully explained by other classic cardiovascular risk factors. RA and atherosclerosis may share several common pathological mechanism and inflammation undoubtedly plays a primary role. 

Complications 

Atherosclerosis-related diseases often lead to serious outcomes such as sudden cardiac death, unstable angina pectoris (a type of chest pain that is irregular), acute myocardial infarction, stroke, and intermittent claudication (a symptom that describes muscle pain on mild exertion, classically in the calf muscle, which occurs during exercise, such as walking, and is relieved by a short period of rest) due to vessel obliteration (the occlusion of the lumen of the blood vessel) or plaque rupture with subsequent thrombosis (the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system) (Pic. 7). 

Risk factors 

Age

Atherosclerosis is a multifactorial disease (having many factors). The pathology of atherosclerosis is a progressive process with increasing age that is related to some risk factors such as hypertension (high blood pressure), hyperlipidemia (abnormally elevated levels of any or all lipids or lipoproteins in the blood), diabetes mellitus, obesity, and cigarette smoking. Genetic factors represent consequential determinant of atherosclerotic cardiovascular disease risk.

Infection

Epidemiological studies further indicate that infection by various types of bacteria and the presence of products of these bacteria in serum contributed to the development of atherosclerosis.

Stress and cardiovascular disease

Cardiovascular disease has a number of behavioral risk factors, some of which are related to chronic stress. Medical researchers are not sure exactly how stress increases the risk of heart disease. However, it could be that high levels of stress make other risk factors (such as high cholesterol or high blood pressure) worse. Many researchers argue that the relationship between stress and cardiovascular disease is a combination of these factors.

Heart transplantation

Syndrome of accelerated atherosclerosis (faster development) has been classically described in patients undergoing heart transplantation.

With advanced age, men experience decreases in important health indicators (muscle amount, muscle power, physical activity, bone density, blood generation, and sexual drive). Doctors think of atherosclerosis to be the main cause of erectile dysfunction (ED). With ED, man is not able to deliver sperms into woman’s body, where the fertilization takes place. 

The thought was driven from the hypothesis that small arteries will be clotted before the large or medium ones. Since erection depends mainly on the amount of delivered blood to the penis, normal arteries thought to have no problem in supporting the process of blood delivering. In contrast, if the arteries become stiffen due to the deposition of atherosclerosis (which in turn will reduce their compliance as a result of the increment in arteries walls resistance), the amount of delivered blood will be declined which affects the process of erection. 

In these cases, there are methods of assisted reproduction, which are able to fertilize eggs outside the body, and than insert embryo to the woman’s womb.

Women’s fertility is not strictly affected by atherosclerosis.

Atherosclerosis treatment usually begins with lifestyle changes such as a low cholesterol diet, regular exercise, and quitting smoking.

In some cases the atherosclerosis is caused by familial hypercholesterolemia (FH) (high LDL cholesterol levels). In this case the disease leads to atherosclerotic plaque deposition in the coronary arteries and aorta at an early age. Thanks to prenatal testing called preimplantation genetic diagnosis (PGD) it is possible to detect the embryo with familial hypercholesterolemia.

Depending on which part of blood stream is damaged several signs and symptoms occur. The most prone to atherosclerosis are heart arteries, cerebral arteries and retinal arteries.

Heart atherosclerosis

For most people, the first symptoms result from atheroma progression within the heart arteries, most commonly resulting in a heart attack. It is plaque ruptures, showing debris & clots which obstruct blood flow downstream, sometime also locally, which reduce/stop blood flow. 

However, the heart arteries, because they are small (from about 5 mm down to microscopic), they are hidden deep within the chest and they never stop moving, have been a difficult target organ to track, especially clinically in individuals who are still asymptomatic. 

Cerebral atherosclerosis

Cerebral atherosclerosis is a type of atherosclerosis where build-up of plaque in the blood vessels of the brain occurs. Diseases associated with cerebral atherosclerosis include:

Alzheimer's disease

Alzheimer's disease is a form of dementia that entails brain atrophy. The most common early symptom is difficulty in remembering recent events (short-term memory loss). As the disease advances, symptoms can include problems with language, disorientation (including easily getting lost), mood swings, loss of motivation, not managing self care, and behavioural issues.

Cerebral microbleeds (CMB)

Cerebral microbleeds have been observed during recent studies on dementia sufferers using MRI (magnetic resonance imaging). Microbleeds does not have to cause any symptoms, but if they did, the manifestation depend on which part of brain is damaged.

Stroke

Strokes occur from the sudden loss of blood flow to an area of the brain. The loss of flow is generally either from a blockage or hemorrhage. Studies of postmortem stroke cases have shown that intracranial atherosclerotic plaque build up occurred in over half of the individuals and over one third of the overall cases had stenotic build up. 

Sudden-onset face weakness, arm drift (i.e., if a person, when asked to raise both arms, involuntarily lets one arm drift downward) and abnormal speech are the findings most likely to lead to the correct identification of a case of stroke.

Retinal atherosclerosis

Central retinal artery occlusion is a disease of the eye where the flow of blood through the central retinal artery is blocked (occluded). There are several different causes of this occlusion; the most common is carotid artery atherosclerosis. Central retinal artery occlusions cause sudden, acute, and painless loss of vision in one eye.