Essential for the proper functioning of our body, the excess of “bad” cholesterol represents a risk factor for the occurrence of cardiovascular disease.
Cardiovascular diseases are the first cause of death in the world, and in France, they represent the second cause of death after cancer according to Santé Publique France.
Sometimes of genetic origin, hypercholesterolemia contributes to the formation of the atherosclerotic plaque associated with cardiovascular disease.
Cardiovascular disease is not a fatality, it is possible to prevent it with the daily respect of hygiene-dietetic rules.
Lipid is an essential fat for our bodies. Present in excess, it can contribute to the occurrence of cardiovascular diseases.
What is cholesterol?
The liver mainly produces fat, accounting for about 70% of its production, while food contributes to a lesser extent, providing approximately 30% of cholesterin intake.
It belongs to the sterol family.
There is only one type of lipid: we speak of good and bad cholesterin depending on the nature of the protein which ensures its transport in the blood (lipoprotein HDL or LDL).
Cholesterol plays a vital role in the proper functioning of the body as it serves as a component of the cell membrane and participates in the synthesis of various hormones and vitamins.
Having lipids is normal, but having too much is not.
Difference between good and bad cholesterol
Cholesterol is of only one type
Lipoproteins, which are proteins, transport cholesterin in the blood, and healthcare professionals primarily distinguish two types of lipoproteins: High-Density Lipoproteins (HDL) and Low-Density Lipoproteins (LDL).
LDLs are lipoproteins that transport lipids synthesized by the liver or ingested in food to cells in the body. Attached to cholesterol, we speak of LDL-cholesterol, commonly called “bad cholesterol”.
They call these lipoproteins so because their excess presence causes an excessive influx of cholesterol into the cells that constitute the blood vessels.
This intake can contribute to the formation of atherosclerotic plaques responsible for cardiovascular diseases.
Conversely, HDLs are lipoproteins that transport sterol from the cells to the liver to be eliminated there in the form of bile salts. Attached to cholesterol, we speak of HDL-cholesterol commonly called “good cholesterol”.
How cholesterol level is defined?
The cholesterol level is expressed in grams per liter of blood (g/L) or mmol per liter of blood (mmol/L).
There is no defined standard for sterol but recommendations that take into account the risk factors associated with the occurrence of cardiovascular disease (diabetes, history of cardiovascular disease, arterial hypertension, etc.).
The recommended total sterol level will not be the same for a diabetic patient who smokes as for a patient who is not.
In addition, it is important to consider the ratio of HDL-cholesterol to LDL-cholesterol.
Doctors and researchers consider a high level of HDL cholesterol to be a protective factor against cardiovascular disease, whereas they view both a low level of HDL cholesterol and an excess of LDL sterol as risk factors for the development of cardiovascular disease.
It is the ratio between good and bad cholesterin that must be taken into account.
For example, an individual A with a total cholesterol level of 2.30 g/L (5.93 mmol/L) without risk factors and presenting an excess of HDL-cholesterol (good cholesterol) greater than 0.60 g/L (1.55 mmol/L) will have less risk of having a cardiovascular accident than an individual B, diabetic and smoker, with a total cholesterol level of 1.90 g/L (4.90 mmol/L) and with low HDL-cholesterol.
Currently, in France, the recommendations of the French Agency for the Safety of Health Products (Affrays) are as follows:
- Total cholesterol: less than 2.00 g/L (or 5.0 mmol/L).
- HDL-cholesterol: between 0.40 g/L and 0.60 g/L (or between 1.0 mmol/L and 1.5 mmol/L).
- Sterol-LDL: the expected value takes into account the risk factors.
- Considering an HDL-cholesterin level below 0.40 g/L (or 1.0 mmol/L) as a risk factor for the onset of cardiovascular disease is common practice.
- An HDL-cholesterol level greater than or equal to 0.60 g/L (or 1.5 mmol/L) is considered a protective factor against the onset of cardiovascular disease.
How lipid is produced?
Cholesterol is produced mainly by the liver and about a third comes from our diet.
Diet, therefore, influences our cholesterin levels. By modifying it, it is possible to modify the LDL-cholesterol level even if this is not always sufficient.
Foods of animal origin rich in saturated fats (eggs, meats, shellfish, fatty derivatives of milk, etc.) contribute to the increase in LDL-cholesterol.
Conversely, a diet based on fruits, vegetables, cereals, vegetable oils (rapeseed, peanuts, olive oil), and fish can lower the LDL-cholesterol level. This diet constitutes what is known as the “Mediterranean diet”.
In general, it is important to have a balanced diet: you have to vary the food. It is not recommended to significantly reduce the intake of this or that food because this can lead to creating vitamin deficiencies.
Other factors can alter cholesterin levels. This is the case for familial hypercholesterolemia (genetic origin), for certain chronic diseases (hypothyroidism, Cushing, etc.), and for certain medications such as oral contraceptives, cortisone, etc. which increase cholesterol levels.
Cholesterol and cardiovascular diseases
An excess of Cholesterol-LDL is responsible for an accumulation of cholesterol at the level of the cells with an accumulation on the wall of the vessels. This deposit is partly responsible for the atheroma plaque which is a fatty plaque that as it grows, obstructs the vessels, reduces the diameter of the latter, and therefore decreases the blood flow which brings the necessary oxygen. To the cells for proper function.
Risks associated with hypercholesterolemia
Hypercholesterolemia is an excess of bad cholesterol in the blood.
Excess cholesterin, which contributes to the formation of atherosclerotic plaque, can lead to the development of various cardiovascular diseases, including angina pectoris, myocardial infarction, cerebrovascular accident (CVA), or arteritis of the lower limbs.
Similarly, atherosclerosis is a degenerative disease of the arteries for which hypercholesterolemia also represents a risk factor.
Hypercholesterolemia alone is not responsible for these diseases. Other risk factors may be associated or be the cause without excess cholesterol being associated.
These risk factors are mainly:
- Smoking.
- Diabetes.
- Overweight and obese.
- High blood pressure.
- Lack of physical activity.
- Familial hypercholesterolemia or hypercholesterolemia.
Hypercholesterolemia contributes to the formation of atherosclerotic plaque responsible for the thickening of the walls of blood vessels (arteries). The organs are less irrigated: a muscle like the heart will be less oxygenated (angina pectoris) or not at all oxygenated (myocardial infarction).
Familial hypercholesterolemia
Familial hypercholesterolemia, a genetic disease, is transmitted within the same family from generation to generation.
Depending on the number of genes affected, we speak of a heterozygous or homozygous form.
The homozygous form is the most severe but also the rarest with 1 case per 1,000,000 in France. The LDL-cholesterol level can exceed 5 g/L (12.90 mmol/L) in the absence of treatment.
The heterozygous form is less severe and more common. It affects 1 in 500 people in France. The LDL-cholesterol level rarely exceeds 3 g/L (7.74 mmol/L).
It corresponds to the accumulation of bad cholesterol in the body. Symptoms vary with age and the level of LDL cholesterol.
Cholesterol deposits can relate to:
- The arteries: we speak of atherosclerosis. The presence of lipoproteins in excess causes an excessive influx of cholesterol into the cells that make up the blood vessels, which results in the development of cardiovascular diseases, the most serious risk.
- The cornea with the appearance of corneal arches.
- The eyelids: we speak of xanthelasmas which correspond to the appearance of yellowish fatty deposits on the eyelids.
- The Achilles tendon or hand tendons form fatty deposits. This is xanthoma.
- Familial hypercholesterolemia is an indication for treatment with statins whose action is to lower the level of LDL-cholesterol in the blood.
- Without treatment, the homozygous form of the disease increases the risk of infarction, particularly in young individuals.
What is an atherosclerotic plaque?
Atheroma plaque does not appear in a day. It results from a complex process in which cholesterin intervenes but not only.
It all starts with a fatty deposit in a vessel. The cells that make up the wall assimilate cholesterin, which thickens it.
The formation of the atherosclerotic plaque occurs as a result of a local inflammatory reaction, which creates a fibrous tissue that traps a nucleus composed of cell debris, cholesterol, and other substances.
It is estimated that cholesterol only makes up 10% of an atherosclerotic plaque. Cellular debris, calcium, and fibrous layers (collagen among others) provide most of their composition.
The inflammatory reaction will intensify and lead to a risk of cracking in the vessel wall. The blood platelets then intervene to plug the breach. Clot forms obstructing a little more vessel, see the mouth: it is a cardiovascular accident.
An atheroma plaque may have no consequences, however, the risk of cracking the vessel wall exists. It is rare before the age of 40 and occurs rather beyond the age of 50.
What analyzes to measure cholesterol?
Healthcare professionals perform cholesterol testing by taking a blood sample after 12 hours of fasting. Which is referred to as cholesterolemia.
Typically, the doctor will prescribe either:
- The dosage of total cholesterin or.
- Exploration of a lipid abnormality (EAL) or lipid profile.
- The assessment may request or add other parameters depending on the measured levels of HDL-cholesterol and LDL-cholesterol. Apolipoproteins A and/or B.
- Healthcare providers often associate the measurement of triglyceride levels with that of total cholesterol levels. Food contains another type of fat called glycerides.
Total cholesterol
These are all the circulating forms of cholesterin without distinguishing between HDL-cholesterol and LDL-cholesterol.
Healthcare providers frequently measure levels of cholesterin along with triglycerides, which belong to a separate group of lipids known as glycerides.
Exploration of a lipid abnormality or EAL
This is a dosage of total cholesterol with the dosage of HDL-sterol and LDL-sterol. In an EAL, the laboratory also performs a triglyceride test.
Healthcare providers measure total cholesterol, HDL-cholesterol, and triglycerides, while they calculate LDL-cholesterol using Friedewald’s formula.
In the case of hypertriglyceridemia greater than 3.4 g/L (or 3.9 mmol/L). One measures LDL-cholesterol or apolipoprotein B due to the interference caused by excess triglycerides.
The appearance of the serum is also noted.
Apolipoproteins
- Apolipoproteins are proteins present in the HDL or LDL lipoproteins necessary for the transport of cholesterol in the body.
- The dosage of these markers confirms or rules out the association between cardiovascular risk and high levels of LDL-sterol or low levels of HDL-cholesterol.
- If rare genetic diseases (dyslipidemia of genetic origin) are present, healthcare providers may indicate measuring the dosage of apolipoproteins A1 and/or B.
Extreme forms of complex dyslipidemia.
The biologist can initiate the apolipoprotein A1 test if the lipid abnormality exploration (EAL) shows a C-HDL concentration of less than 0.30 g/L (0.77 mmol/L). And/or if there is suspicion of interference during the analysis of the lipid profile.
The biologist can initiate the apolipoprotein B test if the lipid abnormality exploration (EAL) shows a triglyceride concentration greater than 3.4 g/L (3.9 mmol/L).
What are the treatments?
Doctors use hypocholesterolemia agents as treatments to lower lipid levels.
Their goal is to reduce mortality and the occurrence of cardiovascular disease by reducing the level of bad cholesterol, or LDL-cholesterol.
Current recommendations from the French National Authority for Health (HAS) recommend the use of statins. The most prescribed in France are pravastatin and simvastatin.
Healthcare professionals reserve the use of statins for patients at cardiovascular risk. In France, the French Agency for the Safety of Health Products (Affrays) defines several risk factors that determine the level of risk. Depending on the patient’s level of risk. Healthcare professionals will prescribe different types of statins and dosages to achieve the target LDL-lipid level.
In all cases, healthcare professionals must implement rules of hygiene and diet before or in conjunction with drug treatment. If healthcare professionals cannot achieve the target LDL-cholesterol value through lifestyle and dietary changes. They will start treatment for primary prevention (patients at cardiovascular risk but without a confirmed diagnosis) three months after the implementation of these rules.
Nowadays, the use of statins is controversial because of the many associated side effects and the latest scientific publications.
Surgery
Atherosclerotic plaque blocking a coronary artery reduces the flow of oxygen-laden blood.
The heart, which is a muscle, suffers from this lack of oxygen.
To remedy this, it is possible to perform coronary angioplasty. This is a non-painful intervention that consists of passing a probe through an artery. Most often femoral (in the groin) or humeral (in the arm).
At the end of the procedure, the surgeon uses a balloon to reach the obstructed area of the vessels, inflates it to push aside the vessel walls, and then removes it.
The dilation caused by this operation lasts an average of 6 months.
On the occasion of an angioplasty, it is possible to set up a stent. It is a medical device that comes in the form of a small tube, most often metallic. It keeps the walls of the coronary arteries dilated, ensuring correct blood flow and therefore oxygenation of the heart muscles.
The advantage of placing a stent is to prevent the atherosclerotic plaque from returning to its original shape and obstructing the artery again.
A coronary bypass can also be performed. It consists of grafting an artery or a vein onto the coronary artery. Upstream of the obstructed area and branching it downstream. The interest is to ensure the blood flow and therefore the supply of oxygen to the heart.
The arteries used are mammary arteries or the internal saphenous vein (legs). The lifespan of a bypass exceeds 15 years.
