Coronary atherosclerotic heart disease is a heart disease caused by atherosclerotic lesions in the coronary vessels that narrow or block the lumen of the vessels, resulting in ischemia, hypoxia or necrosis of the myocardium, often referred to as “coronary heart disease”. However, the scope of coronary artery disease may be broader, including inflammation, embolism, etc., resulting in narrowing or occlusion of the lumen. The World Health Organization classifies coronary artery disease into five major categories: asymptomatic myocardial ischemia (occult coronary artery disease), angina pectoris, myocardial infarction, ischemic heart failure (ischemic heart disease), and sudden death. In the clinic, they are often divided into stable coronary artery disease and acute coronary syndrome.
A multi-provincial survey of people aged 35-64 years in China (China MONICA) from 1987 to 1993 found that the highest incidence was 108,7/100,000 (Qingdao, Shandong) and the lowest was 3,3/100,000 (Chuzhou, Anhui), with more significant regional differences, with northern provinces and cities generally higher than southern provinces and cities. The prevalence of coronary heart disease is 1, 59% in urban areas and 0, 48% in rural areas, with a total of 0, 77%, an increasing trend. Coronary heart disease ranks as the first cause of death in the United States and many developed countries. However, the United States has seen a declining trend in coronary heart disease mortality since the 1960s. Thanks to the efforts to reduce the risk factors of coronary heart disease carried out in the United States in the 1960s and 1980s, mainly controlling the risk factors and improving the treatment of myocardial infarction, the crude rate of coronary heart disease deaths in 2009 was 94,96/100,000 in urban China and 71,27/100,000 in rural areas, with higher rates in urban than in rural areas and higher rates in men than in women.
I. Risk factors and causative factors
Risk factors of coronary heart disease include modifiable risk factors and non-modifiable risk factors. Understanding and intervening risk factors can help the prevention and treatment of coronary heart disease.
Modifiable risk factors include: hypertension, dyslipidemia (high total cholesterol or high LDL cholesterol, high triglycerides, low HDL cholesterol), overweight/obesity, hyperglycemia/diabetes, poor lifestyle including smoking, unreasonable diet (high fat, high cholesterol, high calories, etc.), lack of physical activity, excessive alcohol consumption, and psychosocial factors. Non-modifiable risk factors are: gender, age, and family history. In addition, they are related to infections, such as cytomegalovirus, Chlamydia pneumoniae, and Helicobacter pylori.
Episodes of coronary heart disease are often associated with seasonal changes, emotional excitement, increased physical activity, satiety, heavy smoking and alcohol consumption.
II. Clinical manifestations
1.Symptoms
(1) Typical chest pain Suddenly felt pain in the precordial region, mostly episodic colic or crushing pain, can also be suffocating sensation, triggered by physical activity, emotional excitement, etc. The pain starts from the posterior sternum or precordial area and radiates upward to the left shoulder, arm, and even the little finger and ring finger, and can be relieved by rest or nitroglycerin. The site of chest pain dispersion may also involve the neck, jaw, teeth, abdomen, etc. Chest pain can also appear in the quiet state or at night and is caused by coronary spasm, also known as variant angina pectoris. If the nature of chest pain changes, such as the newly emerged progressive chest pain, the pain threshold gradually decreases to the point that it can also occur during slight physical activity or emotional excitement or even at rest or when sleeping. The pain gradually increases, frequency, and lengthens in duration, and cannot be relieved by removing the trigger or taking nitroglycerin, then unstable angina is often suspected.
Grading of angina pectoris: internationally, the CCSC Canadian Cardiovascular Society grading method is generally used.
Grade Ⅰ: daily activities, such as walking, climbing ladders, without angina attack.
Grade II: Daily activities are mildly limited by angina.
Class III: Daily activities are significantly limited by angina attacks.
Grade IV: Any physical activity can lead to an angina attack.
Myocardial infarction occurs with severe chest pain that lasts for a long time (often more than half an hour) and cannot be relieved by nitroglycerin, and may include nausea, vomiting, sweating, fever, and even cyanosis, blood pressure drop, shock, and heart failure.
(2) Need to pay attention A part of patients have atypical symptoms, only presenting with precordial discomfort, palpitations or weakness, or with gastrointestinal symptoms mainly. Certain patients may have no pain, such as the elderly and diabetic patients.
(3) Sudden death About 1/3 of patients with a first episode of coronary heart disease present with sudden death.
(4) Other systemic symptoms, such as fever, sweating, panic, nausea, vomiting, etc., may be present. Patients with combined heart failure may present
2.Signs
Patients with angina are not special when they do not have an attack. Patients may have diminished heart sounds and pericardial friction sounds. If there is septal perforation or papillary muscle insufficiency, murmurs can be heard in the corresponding area. In the case of arrhythmia, the heart rhythm is irregular on auscultation.
III. Examination
1.Electrocardiogram
ECG is the easiest and most commonly used method to diagnose coronary heart disease. It is the most important test especially when the patient has an attack, and it can also detect arrhythmia. Most of them are non-specific when there is no attack. The S-T segment is abnormally depressed during an angina attack, and patients with variant angina present with transient S-T segment elevation. Unstable angina mostly has significant S-T segment depression and T-wave inversion. Electrocardiographic manifestations in myocardial infarction.
① Abnormal Q waves and S-T segment elevation in the acute phase.
②Sub-acute phase with abnormal Q waves and T-wave inversion only (days to weeks after infarction).
③The chronic or old phase (3 to 6 months) has only abnormal Q waves. If S-T segment elevation persists for more than 6 months, there is a risk of complicating ventricular wall tumor. If the T wave is persistently inverted, it is called old myocardial infarction with coronary ischemia.
2.Electrocardiographic stress test
It includes exercise stress test and drug stress test (such as pansentine, isoproterenol test, etc.). For patients who are asymptomatic in the quiet state or whose symptoms are very short and difficult to capture, myocardial ischemia can be induced by increasing the load on the heart through exercise or drugs, and the presence of myocardial ischemia can be confirmed by the change of ST-T recorded on the ECG. Exercise stress tests are most commonly used, and a positive result is considered abnormal. However, it is contraindicated in patients with suspected myocardial infarction.
3.Electrocardiogram
It is a method that allows continuous recording and analysis of ECG changes in active and quiet states over a long period of time. This technique was first used by Holter in 1947 to monitor electrical activity, so it is also called Holter, and it can record the changes of ECG in patients’ daily life, such as ST-T changes due to transient myocardial ischemia. It is non-invasive, convenient, and easily accepted by patients.
4.Nuclear myocardial imaging
This test can be done when angina pectoris cannot be ruled out based on medical history and ECG examination, and when some patients cannot perform exercise stress test. Nuclear myocardial imaging can show the ischemic area and clarify the location and extent of ischemia. In combination with exercise stress test, the detection rate can be increased.
5.Echocardiography
Echocardiography is one of the most commonly used tests to examine the morphology, structure, wall motion, and function of the left ventricle. It has important diagnostic value for ventricular wall tumor, intra-cardiac thrombus, heart rupture, and papillary muscle function. However, its accuracy is closely related to the experience of the ultrasonographer.
6.Hematological examination
Blood collection is usually required to measure blood lipids, blood glucose and other indicators to assess the presence of risk factors for coronary heart disease. Myocardial damage markers are one of the important tools for the diagnosis and differential diagnosis of acute myocardial infarction. At present, cardiac troponin is mainly used in clinical practice.
7.CT of coronary arteries
Multilayer spiral CT cardiac and coronary imaging is a non-invasive, low-risk, rapid screening method that has gradually become an important means of early screening and follow-up of coronary heart disease. It is indicated for.
①Patients with atypical chest pain symptoms, where the diagnosis cannot be confirmed by ancillary tests such as ECG, exercise stress test or nuclear myocardial perfusion.
②Diagnosis of patients with low risk of coronary artery disease.
③Suspected coronary artery disease, but coronary angiography cannot be performed.
④Screening of asymptomatic patients with high-risk coronary artery disease.
⑤Follow-up after known coronary artery disease or interventional and surgical treatment.
8.Coronary angiography and intravascular imaging technology
It can clarify the presence or absence of coronary artery stenosis, the location, degree and extent of stenosis, and can guide further treatment accordingly. Intravascular ultrasound can clarify the wall morphology and degree of stenosis in the coronary arteries. Optical coherence tomography (OCT) is a high-resolution tomographic imaging technique that allows better observation of the lumen and vessel wall changes. Left ventriculography allows the evaluation of cardiac function. The main indications for coronary angiography are.
(i) For those with angina pectoris that remains severe under medical treatment, clarification of the arterial lesion in order to consider bypass graft surgery.
(2) Those with chest pain resembling angina pectoris but cannot be diagnosed.
IV. Diagnosis
The diagnosis of coronary artery disease mainly relies on typical clinical symptoms, combined with auxiliary examinations to find evidence of myocardial ischemia or coronary artery obstruction, as well as myocardial damage markers to determine whether there is myocardial necrosis. The most commonly used tests to detect myocardial ischemia include conventional electrocardiogram and electrocardiographic stress test, and nuclear myocardial imaging. Invasive tests include coronary angiography and intravascular ultrasound. However, a normal coronary angiogram does not completely negate coronary artery disease. Usually, non-invasive and convenient ancillary tests are performed first.
V. Treatment
Treatment of coronary heart disease includes.
①Living habit change: quit smoking and limit alcohol, low-fat and low-salt diet, appropriate physical exercise, weight control, etc.
②Pharmacological treatment: antithrombotic (antiplatelet, anticoagulation), reducing myocardial oxygen consumption (β-blockers), relieving angina pectoris (nitrates), lipid regulating and stabilizing plaque (statin lipid regulators).
(iii) Hemodynamic reconstructive therapy: this includes interventional therapy (endovascular balloon dilatation angioplasty and stenting) and surgical coronary artery bypass grafting. Drug therapy is the basis of all treatment. Interventional and surgical treatment is also followed by long-term adherence to standard drug therapy. For the same patient, medications are ideally controlled at one stage of the disease, while at another stage medications alone are often ineffective and need to be combined with interventional or surgical procedures.
1.Pharmacological treatment
The purpose is to relieve symptoms, reduce angina attacks and myocardial infarction; delay the development of coronary atherosclerotic lesions and reduce coronary heart disease deaths. Standardized drug treatment can effectively reduce the mortality rate and the occurrence of re-ischemic events in patients with coronary heart disease and improve the clinical symptoms of patients. And for some patients with severe vascular lesions or even complete obstruction, revascularization therapy can further reduce the mortality of patients based on pharmacological treatment.
(1) Nitrate drugs This class of drugs mainly includes: nitroglycerin, isosorbide nitrate (cardiac pain relief), isosorbide 5-mononitrate, long-acting nitroglycerin preparation (nitroglycerin ointment or rubber paste patch), etc. Nitrates are routinely used in patients with stable angina. Sublingual nitroglycerin or nitroglycerin aerosol can be used during angina attacks. For patients with acute myocardial infarction and unstable angina, the drugs should be given intravenously first, and then changed to oral or skin patches after the condition is stable and the symptoms improve, and the drugs can be stopped after the pain symptoms disappear completely. Nitrate drugs can be used continuously to develop drug resistance and decrease effectiveness, and can be taken at intervals of 8 to 12 hours to reduce drug resistance.
(2) Antithrombotic drugs include antiplatelet and anticoagulant drugs. Anti-platelet drugs mainly include aspirin, clopidogrel (Bolivar), tirofiban, etc., which can inhibit platelet aggregation and avoid thrombosis and blockage of blood vessels. Aspirin is the drug of choice, and the maintenance amount is 75-100 mg per day. All patients with coronary artery disease without contraindications should take it for a long time. The side effect of aspirin is irritation of the gastrointestinal tract, and it should be used with caution in patients with gastrointestinal ulcers. Daily oral clopidogrel should be maintained after coronary interventions, usually for six months-1 year.
Anticoagulants include regular heparin, low molecular heparin, Juanda heparin sodium, bivalirudin, etc. They are usually used in the acute phase of unstable angina pectoris and myocardial infarction, as well as during interventional procedures.
(3) Fibrinolytic drugs Thrombolytic drugs mainly include streptokinase, urokinase, tissue-type fibrinogen activator, etc., which can dissolve the formed thrombus at the coronary occlusion, open the blood vessel and restore blood flow, and are used in the acute myocardial infarction attack.
(4) β-blockers β-blockers have the effect of angina pectoris and can prevent arrhythmia. In the absence of obvious contraindications, β-blockers are the first-line drugs for coronary heart disease. Commonly used drugs are: metoprolol, atenolol, bisoprolol and both alpha-blocking effect of carvedilol, armolol (Almal), etc. The dose should be to reduce the heart rate to the target range. β-blockers are contraindicated and cautioned for conditions such as asthma, chronic bronchitis and peripheral vascular disease.
(5) Calcium channel blockers can be used in the treatment of stable angina pectoris and angina pectoris caused by coronary artery spasm. Commonly used drugs include: verapamil, nifedipine controlled release, amlodipine, diltiazem, etc. The use of short-acting calcium channel blockers, such as nifedipine generic tablets, is not advocated.
(6) Renin angiotensin system inhibitors include angiotensin converting enzyme inhibitors (ACEI), angiotensin 2 receptor antagonists (ARB), and aldosterone antagonists. These drugs should be used especially in patients with acute myocardial infarction or recent myocardial infarction combined with cardiac insufficiency. Commonly used ACEI drugs are: enalapril, benazepril, ramipril, fosinopril, etc. ARBs include: valsartan, telmisartan, irbesartan, coxsartan, etc. If there are obvious side effects of dry cough, angiotensin 2 receptor antagonists can be used instead. Care should be taken to prevent low blood pressure during drug administration.
(7) Lipid-regulating therapy Lipid-regulating therapy is applicable to all patients with coronary artery disease. Statins are given on the basis of lifestyle changes in coronary heart disease. statins mainly lower LDL cholesterol, and the therapeutic goal is to drop to 80 mg/dl. commonly used drugs include: lovastatin, pravastatin, simvastatin, fluvastatin, atorvastatin, etc. Recent studies have shown that statins can reduce mortality and morbidity.
2.Percutaneous coronary intervention (PCI)
Percutaneous transluminal coronary angioplasty (PTCA) applies a specially designed catheter with a balloon, which is delivered to the coronary stenosis via a peripheral artery (femoral or radial artery). Filling the balloon dilates the narrowed lumen, improves blood flow, and places a stent in the dilated stenosis to prevent restenosis. It can also be combined with thrombus aspiration and rotational grinding. It is indicated for patients with stable angina pectoris, unstable angina pectoris and myocardial infarction that are poorly controlled by medications. Emergency intervention is preferred in the acute phase of myocardial infarction, and the timing is very important, the earlier the better.
3.Coronary artery bypass grafting (abbreviated as coronary artery bypass grafting, CABG)
Coronary artery bypass grafting relieves chest pain and local ischemia, improves patients’ quality of life, and can prolong their lives by restoring myocardial blood perfusion. It is indicated for patients with severe coronary artery disease, patients who cannot receive interventional therapy or who have relapsed after treatment, and patients with angina pectoris after myocardial infarction, or with complications such as ventricular wall aneurysm, mitral valve insufficiency, or septal perforation, who should undergo coronary artery bypass grafting while treating the complications. The choice of surgery should be decided jointly by the cardiologist and cardiac surgeon and the patient.