What is atherosclerosis?
We often mention atherosclerosis, but what exactly is atherosclerosis? First let’s understand what arteries are. Arteries are blood vessels responsible for transporting the blood pumped by the heart to the whole body. They pulsate with the beating of the heart, so they are called "arteries."
The normal arterial wall has a three-layer structure of intima, middle and adventitia. The intima is covered by a layer of endothelial cells . The surface is very smooth, which can prevent harmful substances in the blood from damaging the blood vessel wall and play a protective role in the blood vessels. When the endothelial cells of arteries are damaged or aged, the lipid components in the blood (mainly cholesterol ) can easily enter the subintima, causing local fibrous tissue hyperplasia. In the early stage, some lipids will appear on the surface of the blood vessel intima. quality stripes.
As lipid deposition increases, the lipid core wrapped in fibrous tissue gradually increases, forming protruding plaques, which thickens and hardens the arterial wall and makes the lumen smaller. These plaque lesions in the arteries are mostly yellow granular and look like millet porridge, so they are called atherosclerosis.
As the narrowing of the arterial lumen caused by atherosclerotic lesions worsens, the blood flow at the distal end of the artery can be reduced, eventually causing ischemia and hypoxia in the organs and tissues that supply blood, such as myocardial ischemia or insufficient blood supply to the brain . In the process of enlargement of atherosclerotic plaques, it can also cause a local inflammatory reaction. At this time, the atherosclerotic plaques become unstable and ulcers or breaks are prone to appear on the surface of the plaques.
As we all know, when we are injured and bleeding somewhere on our body, blood clots will soon appear in the injured area. These blood clots can stop bleeding. Once the plaque in the artery ruptures, the platelets in the blood will quickly gather to the breach like an injury and bleeding, forming a blood clot or "thrombus".
Platelet aggregation can activate a large number of coagulation factors in the blood, prompting the formation of some fibrous substances in the blood. They network red blood cells together to form larger thrombus, eventually causing complete occlusion of the artery and interrupting the distal blood flow, thus Causes ischemic necrosis of the organs and tissues that supply blood, leading to serious consequences such as myocardial infarction or cerebral infarction .
It can be seen that atherosclerosis is a chronic and progressive disease. The inflammatory reaction caused by the disease can promote the rupture of atherosclerotic plaques, and the thrombosis triggered by the latter is responsible for acute thrombotic events (such as acute myocardial infarction). or cerebral infarction) the main cause.
What are the dangers of atherosclerosis?
Arteries are spread throughout the body, and the harm of atherosclerosis is also systemic. When the coronary arteries responsible for the heart's own blood supply develop atherosclerotic stenosis or occlusion, it can cause myocardial ischemia and hypoxia. Patients may suffer from angina pectoris, myocardial infarction, arrhythmia, and/or heart failure, or even sudden Cardiac arrest (sudden death) occurs. Cerebral arteries or the carotid arteries and vertebral arteries that supply blood to the brain. If atherosclerosis causes severe stenosis or occlusion of blood vessels, it can cause insufficient blood supply to the brain or cerebral infarction. If intracranial atherosclerotic blood vessels rupture, cerebral hemorrhage may occur.
Patients who suffer from cerebral infarction or cerebral hemorrhage (collectively referred to as cerebrovascular accidents) may present with headache, dizziness, hemiplegia, aphasia, dysphagia, unsteady walking, dementia, disturbance of consciousness, etc. Severe cases are life-threatening. Renal atherosclerotic stenosis can cause refractory hypertension , and in severe cases, renal insufficiency may occur. Mesenteric atherosclerotic stenosis can cause intestinal ischemic necrosis, and patients may experience abdominal distension, abdominal pain, blood in the stool, or even intestinal necrosis, which is life-threatening. Patients with severe atherosclerotic stenosis of the lower limbs may experience lower limb pain, intermittent claudication , and even acral necrosis.
What causes atherosclerosis?
Through a large number of epidemiological surveys , animal experiments and clinical studies, it has been found that atherosclerosis is often not caused by a single cause, but is the result of the interaction of genetic factors and environmental factors.In medicine, these factors that can cause or accelerate atherosclerosis are called "risk factors." The currently recognized risk factors for atherosclerosis can be divided into pathogenic factors such as hyperlipidemia or other related factors, and can also be divided into the following two categories.
(1) Unchangeable risk factors: mainly age, gender and family genetic history. Atherosclerosis is more common in middle-aged and elderly people over 50 years old, which is related to vascular aging. Compared with men, the onset of atherosclerosis in women is delayed by 10 years. This may be due to the fact that estrogen has a certain protective effect on blood vessels before menopause, but as estrogen levels decrease after menopause, atherosclerosis develops in women. The incidence of sclerosis gradually approaches that of men. People with a family history of early-onset atherosclerotic disease (i.e., first-degree relatives develop age at age 55 for men and age 65 for women) are at increased risk.
(2) Modifiable risk factors: including hyperlipidemia, hypertension, diabetes , smoking, obesity, lack of physical activity, etc. Hyperlipidemia, hypertension, diabetes and smoking are currently recognized as major risk factors. They all have a direct damaging effect on vascular endothelial cells , causing cholesterol in the blood to be more easily deposited under the endothelium and promoting atherosclerosis. occurrence and development.
For an individual, the more risk factors there are, the earlier the age of onset, and the greater the degree of vascular damage.
