Atherosclerosis (AS) is the most common and important type of atherosclerosis. The disease mainly involves large and medium-sized myoelastic arteries, mostly aorta, coronary arteries and cerebral arteries, and often leads to occlusion of the lumen or rupture and bleeding of the wall, causing damage to various important organs such as heart, brain and kidney, which is extremely harmful to people’s health and is one of the main causes of death in the elderly.
Atherosclerotic cardiovascular disease (ACVD) is the number one killer in developed countries and is becoming increasingly common in developing countries. In recent years, China’s rapid economic development, people’s living standards have improved significantly, and the lifestyle is undergoing profound changes. The pace of work and life is accelerating, and the caloric diet is increasing but physical activity is decreasing. Obesity and other cardiovascular disease risk factors caused by poor lifestyles have increased significantly, and the incidence of cardiovascular and cerebrovascular diseases is thus rising rapidly. In addition, diseases such as stroke and myocardial infarction can lead to severe disability, reduced quality of life, and a heavy medical burden. The high morbidity, mortality and disability rates make cardiovascular and cerebrovascular diseases a major public health problem in China in this century.
ACVD mainly includes coronary heart disease (CHD), stroke and peripheral artery disease, and the causes of ACVD are multifaceted, and many of the associated factors are related to lifestyle, including smoking, atherogenic diet, overweight or obesity, and sedentary and physical inactivity. In response to the grim situation that the incidence of ACVD is gradually increasing worldwide, the International Society for Atherosclerosis proposes to strengthen prevention in three aspects.
(1) Risk assessment for patients selected for clinical intervention;
(2) Clinical management of ACVD risk factors;
(3) Special issues of ACVD prevention.
The aim is to reduce the occurrence of atherosclerotic cardiovascular and cerebrovascular events as much as possible to improve the quality of life and prolong human lifespan, and the LAS considers that some of the general population are at high risk of developing ACVD and need clinical intervention to reduce the prevalence and mortality of ACVD. Early clinical management of these individuals can significantly reduce their likelihood of developing the disease. Such interventions involve an organic combination of therapeutic lifestyle changes and pharmacological treatment.
The main feature of atherosclerosis is subintimal lipid deposition in certain parts of the artery with proliferation of smooth muscle cells and fibrous matrix components, which progressively develop into atherosclerotic plaques. The arterial wall at the site of the plaque thickens and hardens, reducing or blocking blood flow. However, damage to the vessel wall is a gradual developmental process, and early on it is only functional changes that eventually lead to acute vascular events as the damage to the vessel wall continues to worsen.
Therefore, early detection of structural and functional lesions of the arterial vasculature and timely and effective intervention are fundamental measures to prevent the occurrence of these serious and lethal diseases.
Currently, the main methods used to evaluate structural and functional lesions of the arteries are.
1, Pulse wave velocity (Pulse Wav;Velocity, PWV) of arteries;
2, Calculation of the reflected wave gain index (Augmentation Index, AI) by performing pulse waveform analysis;
3. Calculate the Ankle-Brachial Index (ABI) by measuring the blood pressure in the upper arm and ankle;
4.Using ultrasound imaging to directly detect the dilatability and compliance of the wall of a specific artery (Compliance).
Pulse Wave Velocity – PWV
The PWV is related to the biomechanical properties of the arterial wall, the geometry of the vessel and the density of the blood, and its magnitude is an early and sensitive indicator of arterial stiffness. The larger the value, the stiffer the vessel wall.
The baseline value of PWV is 35,000 px/sec. PWV can be obtained by measuring the conduction time and distance of the pulse wave between two arterial recording sites and is calculated as follows: PWV(cm/s)=L(La-Lb)/t. t is the time difference between the two waveforms, i.e., propagation time, and L is the distance between the two probes, i.e., distance. an increase in PWV indicates increased arterial stiffness and poor compliance . Conversely, the vascular stiffness is low and compliance is good. It has been demonstrated by pathology that carotid artery compliance measured by noninvasive methods correlates closely with carotid atherosclerosis seen at postmortem examination of patients.
PWV is measured by the following methods: PWV measurement can be done with pressure receptors or Doppler signal methods to pick up the pulse wave at different sites. Currently, automatic pulse wave velocity meters are used to measure the PWV of the carotid-femoral artery (catroid-femoral artery PWV, cfPWV), carotid-radial artery (catroid-radial artery PWV, crPWV) and brachial-ankle artery (brachial-ankle artery PWV, baPWV). Pulsewave velocity.
Increased cfPWV indicates increased aortic stiffness; increased crPWV indicates increased stiffness of peripheral muscular arteries; increased baPWV reflects the elastic state of the large and middle arterial systems. Studies have shown that baPWV is closely related to cardiovascular disease and is one of the independent factors in predicting the occurrence and development of cardiovascular disease.
PWV measurement is suitable for the following groups.
1.People who have reached the age of 14 years;
2.People diagnosed with hypertension (including critical hypertension), hyperlipidemia, diabetes mellitus (including elevated fasting glucose and reduced glucose tolerance), obesity, smoking, high-fat diet and lack of exercise;
3.People with a family history of cardiovascular disease;
4.Persons with long-term dizziness and discomfort, but no clear diagnosis;
5, after activity or resting state with chest tightness, palpitations and other precordial discomfort, not clearly diagnosed;
6, those with a clear diagnosis of coronary artery disease, unstable angina or myocardial infarction (acute or old).
Li B et al. reported that baPWV was significantly and positively correlated with systolic blood pressure, mean arterial pressure, diastolic blood pressure, age, and heart rate; it was also found that baPWV was significantly and negatively correlated with large artery elasticity index C1 and small artery elasticity index C2. Tomiyama H et al. reported that baPWV increased significantly with increasing blood pressure at all ages. In diabetic patients, baPWV, was significantly greater than that of the normoglycemic population at the same age.
Aso K et al. reported that baPWV was significantly associated with diabetic complications such as proteinuria, peripheral neuropathy and retinopathy after adjusting for age, systolic blood pressure level and duration of diabetes. saKuragi S et al. studied baPWV and brain natriuretic peptide (BNP) levels in 134 patients with coronary artery disease and found that baPWV and BNP levels were significantly elevated in patients with coronary artery disease, and baPWV levels were significantly correlated with BNP levels.
Our recent study also found that endothelial dysfunction was highly positively correlated with baPWV in patients with coronary artery disease. baPWV can be used as a valid indicator to evaluate arterial vascular injury. Also, because baPWV is easy to measure and reproducible, it is more suitable for rapid clinical detection of stiffness of the entire arterial system.
Therefore, conducting arterial elastography is beneficial for early detection of arterial vascular lesions. This is important for reducing the occurrence of cardiovascular events and improving people’s health care. To achieve early intervention, the key lies in the ability to detect early signs of vascular stiffening. If coronary heart disease or stroke has already occurred, it is too late to start “paying attention” to your blood vessels.
Therefore, it is necessary to regularly check the structure and function of blood vessels, measure blood pressure, and test blood lipids and blood sugar when there are no obvious symptoms of atherosclerosis. Currently, vascular ultrasonography is mainly used to examine the structure of the carotid, femoral and brachial arteries for the appearance of plaque and to measure the thickness of the carotid intima. There are many methods to examine vascular function, and the main ones that have been recognized are pulse wave conduction velocity, reflection wave enhancement index, arm-ankle blood pressure ratio, and vascular endothelial function.
Among them, pulse wave velocity is considered to be the gold standard for detecting atherosclerosis. If the artery is hardened, the pulse wave conduction velocity is accelerated. There are various instruments for measuring pulse wave conduction velocity, but most of them are complex and require trained professionals to operate, so they are mostly used in clinical studies and have not been fully extended to the clinic. Among the many methods for testing arterial elasticity, baPWV has the advantages of convenience and ease of use, high reproducibility and good subject compliance, and is suitable for rapid and accurate clinical evaluation of the stiffness of the entire arterial system, which is conducive to the early intervention and control of vascular lesions.
Reflex Wave Gain Index – AI
Central arterial pressure generally refers to the systolic pressure at the root of the ascending aorta. After cardiac ejection, intravascular luminal pressure is transmitted from the heart to the periphery as a pressure wave along the arterial wall. The antegrade pressure wave is reflected at the site of resistance small arteries, and this reflected pressure wave is rapidly reversed and overlapped and fused with the antegrade pressure wave in late systole or early diastole to become the actual state pressure wave.
Central arterial blood pressure is a better predictor of cardiovascular events than brachial blood pressure and is more closely associated with the occurrence of endpoint events. Studies have demonstrated that central arterial pressure obtained using the reflectance gain index (AI) test is a better predictor of cardiovascular events than peripheral arterial (brachial) pressure, and the ASCOT study has shown that the effect of different antihypertensive therapies on central arterial pressure varies even when endpoint blood pressure is reduced to the same degree, indicating that central arterial pressure is a better predictor of the onset and progression of cardiovascular disease.
The reflected wave gain index (AI) is usually defined as the reflected wave height (augmentation pressure) divided by the entire systolic pressure wave height (i.e., pulse pressure). And by detecting the pulse wave, the central arterial blood pressure is calculated using the conversion equation based on the brachial artery blood pressure.
In arteriosclerosis, arterial compliance decreases and wave reflection speeds up, bringing forward the reflected wave that should fall in the diastolic phase of the central artery to late systole, resulting in an increase in the central artery systolic unstressed pressure and gain index. AI quantitatively reflects the overall elasticity of the entire arterial system and sensitively shows the status of pressure wave reflection due to changes in the elasticity of large and small arteries, which are determinants of left ventricular afterload.
The AI is a combination of pressure wave reflection point, intensity and velocity changes; the greater the AI, the stronger the role of pressure reflection waves in the increase of systolic and pulse pressure.
It has been found that both PWV and AI, indicators of stiffness of large arteries, are negatively correlated with the onset of cardiac ischemia, i.e., the greater the PWV and AI, the more likely the heart is to be ischemic. Advanced end-stage renal disease is at increasing risk of cardiovascular disease. Epidemiology and clinical trials have shown that large artery injury is a major cause of increased cardiovascular morbidity and mortality in patients with advanced end-stage renal disease and that increased AI is an independent predictor of death.
In conclusion, as cardiovascular disease risk factors increase, large arteries stiffen, diastolic pressure decreases, reflected pressure waves from peripheral vessels increase, and AI increases, leading to increased central pulse pressure, wasted energy in the left ventricle, and reduced pulse pressure amplification, allowing AI to predict cardiovascular events and death independently of cardiovascular risk factors
Ankle-Arm Blood Pressure Index – ABI
The ankle-arm blood pressure index (ABI) is the ratio of the systolic pressure of the posterior tibial or dorsalis pedis artery to the systolic pressure of the brachial artery. The measurement of ABI is mainly to assess arterial stenosis and obstruction in the lower extremities. Its sensitivity for the diagnosis of lower extremity arterial disease is 95% and its specificity is close to 100%. In addition, by observing the difference in blood pressure between the left and right upper arms, abnormalities in the upper extremity arteries such as inflammation of the great arteries and stenosis of the subclavian artery can be detected. Its judgment criteria are: 0.9