Atherosclerosis

Introduction to atherosclerosis Atherosclerosis is the most common and important group of vascular diseases called arteriosclerosis. It is characterized by thickening and hardening of the arterial wall, loss of elasticity and shrinkage of the lumen. The appearance of lipids accumulated on the intima of the artery is yellow atheroma, which is called atherosclerosis. Mainly involving large and medium-sized arteries, its clinical manifestations are mainly based on the disease of the affected organs. The cause of the disease is not completely clear, but through extensive and in-depth etiological investigations, the disease is a multi-disease disease, and its risk factors include: dyslipidemia, hypertension, smoking, diabetes and impaired glucose tolerance, age factors, Gender factors, genetic factors, etc. Surgical treatment includes surgery such as recanalization or reconstruction or bypass grafting of stenotic or occluded blood vessels, particularly coronary, renal, and extremity arteries to restore arterial blood supply. basic knowledge The proportion of illness: 30% Susceptible population: the older you are, the more likely you are sick Mode of infection: non-infectious Complications: coronary heart disease, angina pectoris, cerebral embolism

Atherosclerosis etiology

Causes

The cause of the disease is not completely clear, but through extensive and in-depth etiological investigations, the disease is a multi-disease disease, and its risk factors include: dyslipidemia, hypertension, smoking, diabetes and impaired glucose tolerance, age factors, Gender factors, genetic factors, etc.

High blood pressure (25%):

Clinical and autopsy data indicate that the incidence of atherosclerosis is significantly increased in patients with hypertension. This may be due to the high pressure of the arterial wall, the damage of the intimal layer and the endothelial cell layer, the low density lipoprotein easily enters the arterial wall, and stimulates the proliferation of smooth muscle cells, causing atherosclerosis.

Hyperlipidemia (25%):

Clinical data suggest that atherosclerosis is common in hypercholesterolemia. Experimental animals given high cholesterol diet can cause atherosclerosis. Recent studies have found that the increase of low density lipoprotein and extreme density lipoprotein and the decrease of high density lipoprotein are related to atherosclerosis. The increase in blood triglycerides is also related to the occurrence of atherosclerosis. Recent studies have found that lipoprotein a [Lp(a)] is closely related to the occurrence of atherosclerosis.

Smoking (15%):

The concentration of carboxyhemoglobin in the blood of smokers can reach 10-20%, the oxygenation in the arterial wall is insufficient, the synthesis of fatty acids in the intimal layer is increased, the release of prostacyclin is reduced, and platelets are easily adhered to the arterial wall. In addition, smoking can also reduce the amount of pro-protein of high-density lipoprotein in the blood, and increase the serum cholesterol level, so that it is prone to atherosclerosis. In addition, the nicotine contained in the smoke during smoking can directly affect the arteries and myocardial damage caused by the heart and coronary arteries.

Diabetes (15%):

People with diabetes are often associated with hypertriglyceridemia or hypercholesterolemia. If accompanied by hypertension, the incidence of atherosclerosis is significantly increased. People with diabetes often have elevated blood factor VIII and increased platelet activity. Factor VIII is produced by cells in the arterial wall. The increase in this factor indicates lesions of the intima. Increased platelet activity makes it easy to accumulate on the arterial wall, accelerate atherothrombotic thrombosis and cause occlusion of the arterial lumen. In recent years, studies have concluded that insulin resistance is closely related to the occurrence of atherosclerosis. Patients with type 2 diabetes often have insulin resistance and hyperinsulinemia associated with coronary heart disease.

Obesity (10%):

It is also a predisposing factor for atherosclerosis. Obesity can lead to increased levels of plasma triglycerides and cholesterol. Obese people are often associated with hypertension or diabetes. In recent years, obesity patients often have insulin resistance, and the incidence of atherosclerosis is significantly increased.

Pathogenesis

There are various theories on the pathogenesis of this disease from different angles, including lipid infiltration theory, thrombosis theory, and smooth muscle cell cloning theory. In recent years, most scholars have supported the "endothelial injury response theory." It is believed that the main risk factors of this disease eventually damage the intima of the artery, and the formation of atherosclerotic lesions is the result of the inflammation-fibrotic proliferative response of the artery to the intimal injury. Based on his theory of injury response in 1999, Ross clearly stated that atherosclerosis is an inflammatory disease, pointing out that atherosclerosis is a pathological process characterized by chronic inflammatory response, and its development is always accompanied by an inflammatory response. The theory of atherosclerosis inflammation is essentially a summary and inspiration for the study of the pathogenesis of atherosclerosis.

Pathophysiology

The pathological changes of atherosclerosis mainly involve large muscle-elastic arteries (such as aorta) and medium-muscle elastic arteries in the systemic circulatory system (the most common in coronary and cerebral arteries, followed by arteries, renal arteries and mesenteric arteries). The lower extremities are more than the upper limbs, and the pulmonary arteries are rarely involved.

In atherosclerosis, there are three types of changes in lipid intima and streaks, atheroma and fibroid plaques, and complex lesions in the arterial intima. The American College of Cardiology has subdivided it into type 6 based on its pathological development: type I lipid spots, type II lipid streaks, type III plaques, type IV plaques, and V-type atherosclerotic plaques. , type VI composite lesions.

From a clinical point of view, atherosclerotic plaques can be basically divided into two categories: one is stable, that is, the fibrous cap is thicker and the lipid pool is smaller; the other is unstable. (also known as vulnerable type) plaque, its fibrous cap is thin, and the lipid pool is large and easy to rupture. It is the rupture of this plaque that causes an acute cardiovascular event.

Atherosclerosis prevention

The disease is a lifestyle-related disease to a certain extent, so establishing a good living habit is an important measure to prevent this disease. Reasonable diet, moderate exercise, smoking-free alcohol, regular life, maintaining a relaxed mood, and actively treating the primary disease can all play a role in preventing this disease.

Atherosclerotic complications Complications, coronary heart disease, angina pectoris, cerebral embolism

From the chronic passage of atherosclerosis, the affected arteries have weakened elasticity, increased fragility, and the lumen is gradually narrowed or even completely occluded, and can be expanded to form an aneurysm. Depending on the condition of the affected arteries and collateral circulation, it can cause dysfunction of the entire circulatory system or individual organs.

The disease can cause damage and disease of the corresponding organs according to the location of the disease. Among them, coronary heart disease, angina pectoris and cerebral embolism are the most serious and common.

Symptoms of atherosclerosis Common symptoms High blood pressure, hypertrophy, hyperlipidemia, vascular damage, shortness of breath, high homocysteinemia

Mainly after the involvement of related organs:

Staging and classification:

1. Classification according to the stage of the disease: The development process of the disease can be divided into 4 stages, but the clinical stages are not strictly in order, and may occur alternately or simultaneously.

(1) Asymptomatic or subclinical: The length of the process varies from early pathological changes until atherosclerosis has developed, but there is no clinical manifestation of organ or tissue involvement.

(2) Ischemic phase: Symptoms of organ ischemia due to stenosis of blood vessels.

(3) Necrotic phase: The manifestation of organ tissue necrosis due to occlusion of the lumen due to acute thrombosis in the blood vessel.

(4) Fibrosis period: long-term ischemia, atrophy of organ tissue fibrosis and cause symptoms.

2. According to the different parts of the affected artery, the disease includes: aorta and its main branches, coronary artery, carotid artery, cerebral artery, renal artery, mesenteric artery and atherosclerosis of extremities.

(1) General performance

There may be mental and physical decline.

(two) aortic atherosclerosis

Most have no specific symptoms. The main consequence of aortic atherosclerosis is the formation of an aortic aneurysm, which is most common in the abdominal aorta below the renal artery opening, followed by the aortic arch and descending aorta. Abdominal aortic aneurysm often found a pulsatile mass in the abdomen during physical examination, and it was found that the corresponding part of the abdominal wall could hear murmur, and the femoral artery pulsation could be weakened. Thoracic aortic aneurysm can cause chest pain, shortness of breath, difficulty swallowing, hemoptysis, vocal cords due to pressure on the recurrent laryngeal nerve, paralysis caused by hoarseness, tracheal displacement or obstruction, compression of the superior vena cava or pulmonary artery. Once the aortic aneurysm ruptures, it can be fatal. Arterial dissection can also occur on the basis of atherosclerosis.

(C) coronary atherosclerosis

Coronary atherosclerosis causes vascular stenosis or obstruction, or (and) heart disease caused by myocardial ischemia, hypoxia or necrosis due to functional changes in the coronary arteries (). Coronary atherosclerotic heart disease is the most common type of organ disease caused by atherosclerosis, and is also a common disease that seriously endangers human health.

(four) craniocerebral atherosclerosis

Cranial atherosclerosis most frequently invades the internal carotid artery, basilar artery and spinal artery. The internal carotid artery enters the brain as a particularly good area, and the lesions are concentrated in the vascular bifurcation. Atherosclerotic plaque causes vascular stenosis, insufficient blood supply to the brain or local thrombosis or plaque rupture, debris from cerebral vascular accidents such as cerebral embolism (ischemic stroke); long-term chronic cerebral ischemia causes brain atrophy, can develop into Vascular dementia.

(5) Renal atherosclerosis

Can cause refractory hypertension, those who are over 55 years old and suddenly have high blood pressure, should consider the possibility of this disease. If renal artery thrombosis occurs, it can cause pain in the kidney area, urinary closure and fever. Long-term renal ischemia can cause kidney atrophy and develop into renal failure.

(6) Mesenteric atherosclerosis

May cause symptoms such as indigestion, decreased intestinal tension, constipation and abdominal pain. When the thrombus is formed, there is severe abdominal pain, bloating and fever. When the intestinal wall is necrotic, it can cause symptoms such as blood in the stool, paralytic ileus and shock.

(7) Extremity atherosclerosis

The lower extremities are more common, resulting in cold, numbness and typical intermittent claudication of the lower extremities due to blood supply disorders, ie numbness, pain and even convulsions of the gastrocnemius during walking, disappearing after rest, and appearing again when walking; serious sustainability Pain, the lower extremity arteries, especially the dorsal artery, pulsation weakened or disappeared. Gangrene can occur when the arterial lumen is completely occluded.

Atherosclerosis examination

1, patients often have elevated blood cholesterol, triglycerides, high-density lipoprotein decreased, lipoprotein electrophoresis pattern abnormalities, most patients with type III or type IV hyperlipoproteinemia.

2, X-ray examination shows aortic elongation, expansion and distortion, sometimes visible calcium deposition.

3, angiography can show the stenosis, lesions and extent of the quadriple artery, renal artery and coronary artery caused by atherosclerosis.

4, Doppler ultrasound examination helps to determine the blood flow of the arteries and renal arteries of the extremities.

Diagnostic diagnosis of atherosclerosis

Diagnostic criteria

The disease has developed to a considerable extent, especially when there are obvious lesions in the organs, the diagnosis is not difficult, but early diagnosis is not easy. Elderly patients with dyslipidemia, X-ray, ultrasound and angiography found vascular stenosis or sexual lesions should first consider the diagnosis of this disease.

Differential diagnosis

Aortic atherosclerosis caused by aortic changes and aortic aneurysm, need to be differentiated from syphilitic aortitis and aortic aneurysm and mediastinal tumor; coronary atherosclerosis caused by angina and myocardial infarction, and other coronary lesions Identification of the cause; myocardial fibrosis needs to be differentiated from other heart diseases, especially primary dilated cardiomyopathy; cerebrovascular accidents caused by cerebral atherosclerosis need to be differentiated from cerebrovascular accidents caused by other causes; Hypertension caused by renal atherosclerosis needs to be differentiated from other causes of hypertension; renal artery thrombosis needs to be differentiated from kidney stones; symptoms caused by atherosclerosis of the extremities need to be caused by arterial lesions of other causes Identification.

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