Myocardial ischemia
Introduction
Introduction to myocardial ischemia Myocardial ischemia refers to a decrease in blood perfusion of the heart, resulting in a decrease in oxygen supply to the heart, abnormal myocardial energy metabolism, and a pathological condition that does not support the normal functioning of the heart. Coronary stenosis or occlusion caused by coronary atherosclerosis is the most common and most common cause of myocardial ischemia, which leads to myocardial ischemia and hypoxia. The resulting heart disease is commonly known as "coronary heart disease". Coronary heart disease is the "culprit" of myocardial ischemia. Myocardial ischemia seriously harms the health of middle-aged and elderly people. In recent years, with the improvement of living standards, coronary atherosclerosis has become younger, and some young people aged 20-30 also have myocardial ischemia. basic knowledge Sickness ratio: 0.0012% Susceptible people: no special people Mode of infection: non-infectious Complications: arrhythmia
Cause
Cause of myocardial ischemia
Coronary heart disease (70%)
The common cause of myocardial ischemia is coronary atherosclerosis. Coronary atherosclerotic heart disease is an atherosclerotic lesion of coronary artery angiogenesis that causes stenosis or obstruction of the vascular lumen, resulting in myocardial ischemia, hypoxia or necrosis. Heart disease, often referred to as "coronary heart disease." However, the scope of coronary heart disease may be more extensive, including inflammation, embolism, etc. leading to stenosis or occlusion of the lumen. The World Health Organization classifies coronary heart disease into five broad categories: asymptomatic myocardial ischemia (occult coronary heart disease), angina pectoris, myocardial infarction, ischemic heart failure (ischemic heart disease), and sudden death. Clinically, it is often divided into stable coronary heart disease and acute coronary syndrome.
Age factor (10%)
Older patients with vascular aging or thickening of blood vessel walls, especially the capillaries or arteries of the heart, cause poor blood flow, cause insufficient blood supply to the heart, and easily induce cardiac ischemia.
Other reasons (15%)
Secondly, there are various factors such as inflammation (rheumatism, syphilis, Kawasaki disease and vascular occlusive vasculitis), sputum, embolism, connective tissue disease, trauma and congenital malformation. Epidemiological studies have found that important risk factors associated with atherosclerosis such as hyperlipidemia, hypertension, diabetes, smoking, obesity, increased homocysteine, less physical activity, and men also induce myocardial deficiency blood.
Prevention
Myocardial ischemia prevention
Prevention method
First, the diet of patients with myocardial ischemia: patients with myocardial ischemia have several principles in the diet, pay attention to low-salt, low-fat, light diet, eat more sweet potatoes, tomatoes, carrots and other vegetables, which can improve the body's resistance food. Drink some green tea, tea contains a small amount of theophylline, has a certain diuretic effect, has a certain help to the patient's myocardial ischemia treatment, there is vitamin C in the tea, can play a good role in prevention and treatment of arteriosclerosis, But not too thick. Sticking to black fungus every day can help reduce blood viscosity and improve myocardial ischemia.
Second, patients with myocardial ischemia should be careful not to be overjoyed and to maintain adequate sleep. Develop good habits, regular bowel movements, and not overwork.
Third, moderate exercise should be promoted to promote the establishment of myocardial collateral circulation.
Fourth, if the condition changes, it is necessary to seek treatment in time.
Preventive drug
ABCDE for primary prevention of coronary heart disease: The primary prevention program for coronary heart disease includes a summary of ABCDE.
A. Aspirin.
B. beta blockers.
C. Calcium ion antagonist.
D. Statins, lipid-regulating drugs.
E. Angiotensin-converting enzyme inhibitors.
Complication
Myocardial ischemia complications Complications arrhythmia
Common complications of myocardial ischemia are:
1. Arrhythmia and cardiovascular accidents. The occurrence of arrhythmia is closely related to the onset of transient myocardial ischemia and is an important factor influencing fatal arrhythmias. Meissner et al reported that 450,000 people die each year in the United States, 20% to 50% of which die from bradyarrhythmia. Before or at the same time, complications of myocardial ischemia are often accompanied by asymptomatic myocardial ischemia.
2. Ischemic cardiomyopathy. Slow and long-lasting myocardial ischemia can cause extensive diffuse fibrosis of the myocardium, forming a congestive ischemic cardiomyopathy. This is a common complication of myocardial ischemia.
3. Asymptomatic myocardial infarction. SMI patients are prone to asymptomatic myocardial infarction, and about 20% to 25% of patients with myocardial infarction are asymptomatic. The onset often occurs in the form of complications of myocardial ischemia. Complications of myocardial ischemia such as arrhythmia, heart failure, cardiogenic shock, etc., mortality is significantly higher than patients with painful myocardial infarction. This is also a common complication of myocardial ischemia.
Symptom
Myocardial ischemic symptoms Common symptoms High and symmetrical T wave limbs, chest, back pain, shortness of breath, dyspnea, tiredness, chest pain, flustered, tiredness, chest tightness, bradycardia, shortness of breath
Myocardial ischemia occurs after the age of 40, and the average prevalence is about 6.49%. With the improvement of people's living standards, the prevalence of myocardial ischemia in China is increasing year by year. Myocardial ischemia is a common and frequently-occurring disease in middle-aged and elderly people. In daily life, if you have any of the following conditions, you should seek medical advice promptly and check as soon as possible.
(1) When tired or mentally stressed, there is pain in the back of the sternum or in the anterior region, or tightness in the contraction, and it is radiated to the left shoulder and the left upper arm for 3 to 5 minutes. After the rest, the self-remission is accompanied by sweating.
(2) Chest tightness, palpitations, shortness of breath, and self-relief during rest.
(3) There are sore throats and burning sensations associated with exercise, tightness, and toothache.
(4) Chest pain and chest tightness after eating, cold, drinking.
(5) When the sleep pillow is low at night, feel chest tightness and suffocation. If you need high pillow and comfortable position, you may feel chest pain, palpitations and difficulty breathing when you are sleeping or lying in the daytime. You need to sit up or stand immediately to relieve.
(6) Pain, chest tightness, shortness of breath or chest pain discomfort during sexual life or forced bowel movements.
(7) Sudden bradycardia, decreased blood pressure or syncope.
Examine
Myocardial ischemia
1. Examination of risk factors related to coronary heart disease.
In order to detect myocardial ischemia as early as possible, people over the age of 40 should have regular physical examinations to understand whether there are risk factors associated with coronary heart disease, such as blood lipids, blood pressure, blood sugar, cervical vascular ultrasound, cardiac ultrasound, and electrocardiogram.
Second, subject to load test.
If you are at high risk of myocardial ischemia, ask your doctor if you have typical symptoms of coronary heart disease and decide whether you need to undergo a load test, such as active plate electrocardiogram, adenosine stress echocardiography, and coronary multi-slice CT.
Third, coronary angiography.
Through the evaluation of non-invasive examination to determine whether the need to further use the gold standard for coronary heart disease diagnosis - coronary angiography to confirm the diagnosis to determine the extent and extent of coronary lesions.
Diagnosis
Diagnosis of myocardial ischemia
Diagnostic identification
The most common cause of ischemic cardiomyopathy is coronary heart disease, which is mainly caused by coronary atherosclerotic stenosis, occlusion, spasm and other diseases. A small number is due to congenital anomalies of the coronary arteries, coronary arteritis and other diseases.
Myocardial lesions that need to be differentiated from ischemic cardiomyopathy (ICM) are mainly dilated cardiomyopathy, alcoholic cardiomyopathy, and Keshan disease.
(a) dilated cardiomyopathy
Dilated cardiomyopathy is an unexplained cardiomyopathy. The main features are unilateral or bilateral heart chamber enlargement, myocardial contractile function, clinical manifestations of recurrent congestive heart failure and arrhythmia. Its clinical features are very similar to ICM, and differential diagnosis is also very difficult, especially in patients over 50 years old, if accompanied by angina, it is easily misdiagnosed as ICM. Because dilated cardiomyopathy and ICM treatment principles are very different, it is of great clinical significance to correctly identify the two. The following points are helpful to identify the two.
1. The age of onset of dilated cardiomyopathy is relatively mild, often with a history of myocarditis; while ICM is older, most have a history of angina or myocardial infarction, often accompanied by hypertension, hyperlipidemia and diabetes.
2. Electrocardiogram examination: Electrocardiogram of patients with dilated cardiomyopathy and ICM can be expressed as left ventricular hypertrophy with strain, abnormal Q wave and arrhythmia, etc., which is difficult to identify. However, dilated cardiomyopathy is often accompanied by complete left bundle branch block, and ECG ST-T changes are mostly non-specific and have no diagnostic value for localization.
3. Chest X-ray examination: the heart shadow of patients with dilated cardiomyopathy is large, the ratio of cardiothoracic to more than 0.6. In the perspective of fluoroscopy, the heart beat is obviously weakened. In the late stage, there are signs of pleural effusion, pericardial effusion or pulmonary embolism. Although ICM patients have a significant increase in heart shadow, most of them have aortic heart, accompanied by ascending aorta widening and aortic calcification.
4. Cardiac ultrasound examination of dilated cardiomyopathy and ICM identification points: (1) cardiac morphological comparison: dilated cardiomyopathy due to extensive myocardial involvement, often manifested as a general expansion of 4 heart chambers; and ICM often left The atrium and left ventricle are mainly enlarged, and often accompanied by thickening and calcification of the aortic valve and annulus. (2) Comparison of wall thickness and movement status: the wall thickness of patients with dilated cardiomyopathy is diffusely thinned, and the wall motion is diffusely weakened; while the myocardial ischemia site of ICM patients is closely related to the distribution of coronary artery lesions, severe ischemic At the site, the wall of the chamber is thinned and the movement is weakened. Therefore, the thickness of the common wall is limited and the wall motion is weakened or disappeared. (3) Hemodynamic changes: patients with dilated cardiomyopathy have a generalized enlargement of the heart, often secondary to changes in the structure of the valve and valve support, resulting in significant regurgitation of multiple valves; and ICM patients with left atrium and The left ventricle is enlarged, often accompanied by mitral valve regurgitation. (4) patients with dilated cardiomyopathy have a wide range of myocardial lesions, left ventricular enlargement and myocardial contraction, so the cardiac systolic function is significantly reduced; while ICM patients have reduced left ventricular ejection fraction and short axis shortening rate, but The degree is relatively lighter than dilated cardiomyopathy.
5. Peripheral artery ultrasound exploration: It is currently believed that the use of peripheral arterial ultrasound to explore the carotid artery and femoral artery can be used as a window to reveal coronary lesions, and can help differential diagnosis of dilated cardiomyopathy and ICM. Studies have shown that only a small number of patients with dilated cardiomyopathy have positive carotid and femoral plaques; in ICM patients, carotid and femoral plaques are all positive. Although carotid and femoral plaques are not absolutely negative in patients with dilated cardiomyopathy, carotid and femoral plaque negative can be used as an important condition to rule out ICM diagnosis.
6. Radionuclide examination: The distribution of nuclide in the myocardium is not only related to blood flow, but also closely related to the function and fibrosis of cardiomyocytes. ICM is considered to be more severe and has a higher degree of fibrosis than patients with dilated cardiomyopathy. Therefore, 99m Tc-methoxyisobutyl isocyanide (M IB I) myocardial perfusion imaging examination, dilated cardiomyopathy mostly showed a non-segmented, scattered sparse area, a small range, a small degree, performance For more small piece defects or variegated changes; while ICM patients are mostly segmental perfusion abnormalities distributed by coronary artery, myocardial perfusion damage is heavy and large; when the perfusion defect is larger than the left ventricular wall 40 When it is %, it has a higher value for the diagnosis of ICM.
7. Cardiac catheterization and cardiovascular angiography: Cardiac catheterization in patients with dilated cardiomyopathy shows increased left ventricular end-diastolic pressure, left atrial pressure, and pulmonary capillary wedge pressure, reduced cardiac output and stroke volume, and reduced ejection fraction Left ventricular angiography showed a dilated left ventricular cavity and a weakened left ventricular wall motion; however, coronary angiography was normal.
(two) alcoholic cardiomyopathy
Alcoholic cardiomyopathy refers to myocardial lesions caused by long-term heavy drinking, mainly manifested as cardiac enlargement, heart failure and arrhythmia. There are many similarities between clinical and expanded ICM, and identification is more difficult. Compared with ICM, the following characteristics of alcoholic cardiomyopathy contribute to the identification of the two:
(1) There is a long history of heavy drinking.
(2) Most of the men are 30 to 50 years old, and most of them are accompanied by alcoholic cirrhosis.
(3) After stopping drinking for 3 to 6 months, the condition may gradually reverse or stop worsening, and the enlarged heart may be reduced.
(4) Electrocardiogram examination: visible non-specific ST-T changes (no diagnostic value); those who stopped drinking early in the course of the disease, ST-T changes can return to normal after a few months; if the disease is advanced, even if drinking is stopped, its ST- It is also difficult for T to change back to normal.
(5) Chest X-ray examination: the heart shadow is large, and the ratio of heart to chest is more than 0.6. Above, the heart beat is weakened, and there is no sign of augmentation of the ascending aorta and calcification of the aorta.
(6) Cardiac ultrasonography: the chambers of the heart are enlarged, but the left atrium and left ventricle are enlarged; the wall motion is diffusely weakened, and the left ventricular ejection fraction is significantly reduced; often combined with mitral valve, three The cusp is incomplete. However, there were no segmental wall motion abnormalities and aortic valve thickening and calcification signs. In addition, the dynamic observation of the patient after stopping drinking showed that the left atrium and left ventricular diameter were significantly reduced.
(c) Keshan disease
Keshan disease is an endemic cardiomyopathy with unknown causes. It is clinically classified into acute, sub-acute, slow and late-type according to its rapid onset and cardiac function. Patients with chronic Keshan disease mainly present with heart enlargement and congestive heart failure. The electrocardiogram, echocardiography and chest X-ray findings have many similarities with dilated ICM, but the following clinical features of Keshan disease Helps differential diagnosis of both:
(1) It has obvious regional characteristics. The ward is distributed in 15 provinces and autonomous regions including Hei, Ji, Liao, Inner Mongolia, Jin, Yi, Lu, Henan, Shaanxi, Gansu, Sichuan, Yunnan, Tibet, Guizhou and Hubei. Selenium on the strip.
(2) It has the characteristics of frequent populations. The vast majority of patients are women in the agricultural population and pre-weaning preschool children. ICM is more common in the elderly.
(3) Electrocardiogram examination showed that most patients with Keshan disease had ECG changes, among which ventricular premature beats were the most common, followed by ST-T changes and atrioventricular block. However, ST-T changed to non-specific and had no diagnostic value for localization.
(4) Chest X-ray examination showed that the majority of patients had a large heart shadow, a small number of mitral valve or aortic type; the pulsation was significantly weakened under fluoroscopy; no ascending aortic widening and aortic calcification.
(5) Cardiac ultrasonography: The heart of patients with Keshan disease is generally enlarged, the diffuse movement of the wall is weakened, the myocardial contraction is weak, the systolic function of the heart is significantly reduced, and the valvular regurgitation is accompanied by multiple valves; and the ICM patient room The wall is a segmental dyskinesia, and often combined with aortic valve thickening and calcification.
