Coronary heart disease is short for coronary heart disease. Due to atherosclerosis of coronary artery wall, obstruction or stenosis of vascular lumen, coronary circulation blood flow is blocked, myocardial blood supply is insufficient, and severe obstruction can lead to myocardial infarction. In recent 40 years, the incidence of coronary atherosclerotic heart disease in China has gradually increased. According to the statistics of Shanghai Medical University, coronary heart disease accounts for only 6% of hospitalized heart disease patients from 1948 to 1958. 1959 ~ 197 1 year18%; From 1972 to 1979, rising to 29%, ranking first among all kinds of heart diseases at present. etiology

The pathogenesis of coronary atherosclerosis is complex and has not been fully understood so far. According to a large number of epidemiological and experimental research data, the main pathogenic factors are: high calorie, high fat, high sugar diet, smoking, hyperlipidemia, hypertension, diabetes, obesity, too little physical activity, nervous mental work, emotional irritability, mental stress, middle-aged and elderly men, low high density lipoprotein, abnormal coagulation function and so on. A few cases may have family genetic factors. [Back to the top]

pathological change

Anatomy of coronary artery: Coronary artery is a blood vessel that supplies blood and oxygen to myocardium, and its anatomical shape changes greatly. Under normal circumstances, the coronary artery has left and right branches, which open in the left and right coronary sinus of ascending aorta, and sometimes another smaller accessory coronary artery originates from aorta.

The left coronary artery trunk is about 4 ~ 5 mm in diameter and 0.5 ~ 2 cm in length. It originates from the ascending aorta, goes to the lower left behind the pulmonary artery trunk, and divides into anterior descending branch and spiral branch between the pulmonary artery trunk and the left atrial appendage along the left atrioventricular groove.

The anterior descending branch is the continuation of the left coronary artery trunk, descending along the anterior interventricular groove, bypassing the apical notch and reaching the posterior wall of the heart, and anastomosing with the posterior descending branch of the right coronary artery at 1/3 below the posterior interventricular groove. The anterior descending branch sends out the left conus branch, oblique branch, anterior branch of left ventricle, anterior branch of right ventricle and anterior branch of interventricular septum. The blood supply area includes the common trunk root of aorta and pulmonary artery, part of left atrial wall, anterior wall of left ventricle, part of right ventricular wall, most interventricular septum (upper and anterior), apical area and anterior papillary muscle.

After the spiral branch originates from the main coronary artery, it clings to the bottom of the left atrial appendage along the front of the left atrioventricular groove, walks backward to the left, and then descends through the left edge of the heart to reach the diaphragm. There are many variations in the branches of spiral branches. The main branches are several left marginal branches, left ventricular posterior branches and atrioventricular branches along the left atrioventricular groove. The atrioventricular branch is sometimes long (about 10%), and the posterior descending branch and the atrioventricular nodal artery originate from its end. 30% people still send sinus node artery from the circumflex branch. The blood supply areas of the circumflex branch are the lateral wall and posterior wall of the left ventricle and the left atrium, and sometimes the blood is supplied to the diaphragm, anterior papillary muscle, posterior papillary muscle, part of ventricular septum, atrioventricular node, atrioventricular bundle and sinus node.

After the right coronary artery originates from the right coronary sinus, it clings to the bottom of the right atrial appendage and descends outward along the right atrioventricular groove. The junction of ventricle, atrium, atrial septum and ventricular septum reaches the atrioventricular groove, which is divided into two branches, the right posterior descending branch is in the posterior interventricular groove towards the apical area, and the other smaller atrioventricular nodal artery turns upward. The main branches of the right coronary artery include right conus branch, right atrial branch, sinus node branch, right anterior ventricular branch, right posterior ventricular septal branch, posterior descending branch and atrioventricular nodal artery. The blood supply area of right coronary artery includes right atrium, sinus node, right ventricular outflow tract, pulmonary artery cone, right ventricular anterior wall, right ventricular posterior wall, interventricular septum 1/3 and atrioventricular node. Patients with dominant right coronary artery still supply blood to part of left ventricle and apex. There are many variations in the distribution area of left and right coronary arteries on the myocardial diaphragm. When the coronary artery with large blood supply range is narrowed, the area of myocardial ischemia injury is wider and the condition is more serious. [Back to the top]

type

According to the source of blood supply in the heart intersection area, that is, the junction of ventricle, atrium and atrioventricular septum on both sides of the posterior wall of the heart, the distribution of left and right coronary arteries can be divided into three main types:

1) the dominant type of right coronary artery is the most common, accounting for about 80%. The right coronary artery is thick and long, supplying blood to the posterior wall of the right ventricle, passing through the intersection area of the heart from the posterior descending branch of the heart, and reaching a part of the posterior wall of the left ventricle and the posterior part of the interventricular septum.

2) The advantage of the left coronary artery is that the right coronary artery is smaller, and the left coronary artery sends out the posterior descending branch, which supplies blood to the left right ventricular posterior wall and interventricular septum.

3) The left and right coronary arteries are balanced, and each coronary artery sends out a posterior descending branch to supply blood to the posterior wall of the left right ventricle (1). The right coronary artery is dominant. 2. The left coronary artery is dominant. 3. Balance of left and right coronary arteries. Distribution types of left and right coronary arteries.

Pathological anatomy: coronary atherosclerotic lesions mostly occur in the proximal segment of the main coronary artery, about 5cm away from the aortic opening, often located in the atrioventricular groove, surrounded by the main coronary artery with fatty tissue, and the lesion site provides favorable conditions for surgical treatment. Patients with hypertension or diabetes have a wide range of lesions, which may involve small branches of coronary artery. Atherosclerosis mainly involves the intima of coronary artery. At the early stage of the disease, lipids and lipid-containing macrophages infiltrated the intima and mesothelial cells, and the intima thickened and macula appeared. With the damage of intimal cells and the increase of intimal permeability caused by various reasons, lipid infiltration increases, and spots gradually increase and expand, forming plaques or stripes. Focal dense lamellar collagen also appeared in the intima, and the lesion involved the whole intima, resulting in stenosis or obstruction of vascular lumen. The blood flow of diseased coronary artery decreases, and the local myocardial blood supply and oxygen supply are insufficient during exercise or even at rest, which can lead to myocardial infarction in severe cases. Coronary atherosclerosis can be complicated with bleeding, thrombosis and aneurysm. Lipids enter the vascular cavity when atherosclerotic lesions rupture and bleed, which is easy to cause distal vascular embolism and thrombosis. Hematoma on the vascular wall can gradually form granulation tissue and fibrosis. The acute stage of intimal hemorrhage can promote the spasm of coronary artery and collateral circulation and aggravate the degree of myocardial ischemia. Thrombosis often coexists with bleeding, and can also cause distal vascular embolism and vascular wall fibrosis. It is very rare that the vascular wall necrosis under coronary atherosclerotic plaque complicated with aneurysm. In most cases, only one blood vessel has an aneurysm with a diameter of 2.5cm, and there may be blood clots in the lumen, but the lumen of the blood vessel remains unobstructed. If the coronary artery stenosis caused by atherosclerotic lesions is limited to one branch of the coronary artery, and the development process is slow, the communicating branch between the diseased blood vessel and the adjacent coronary artery will be significantly expanded, and effective collateral circulation can be established, and the myocardium in the diseased area can still obtain sufficient blood supply. If the lesion involves multiple blood vessels, or the stenosis progresses rapidly, collateral circulation is not fully established or complicated with bleeding, hematoma, thrombosis and vasospasm, it can lead to severe myocardial ischemia and even myocardial infarction. The myocardial tissue in the diseased area contracts, even dies, even ruptures or forms fibrous scar in the future, and the myocardial contraction function is seriously damaged, so arrhythmia or heart pumping failure may occur. The larger the range of myocardial ischemia, the more serious the damage. The left coronary artery supplies the most coronary blood flow, so the heart disease caused by the obstruction of the left coronary artery and its branches is more serious than that caused by the right coronary artery.

Pathophysiology: The blood flow per minute per 100g myocardium is 60 ~ 80 ml, which is about 0/0 times more than that per 100g whole body tissue. Another feature of coronary circulation is that the arterial blood flow is the largest in diastolic phase, and the systolic phase is reduced due to the compression of myocardial blood vessels, while other organs of the body are in systolic phase, and the blood flow is the largest when the arterial perfusion pressure is the highest. Myocardial oxygen uptake ability is strong, which can absorb about 65 ~ 75% oxygen from capillaries. Under normal circumstances, 8 ~ 10 ml oxygen is ingested per minute per 100g myocardium, while all organs and tissues can only ingest 25% oxygen from blood, and only about 0.3 ml oxygen per minute per 100g tissue. During exercise, cardiac output increases obviously, cardiac workload increases, and myocardial oxygen demand increases. Because there is not much room for further improving blood oxygen uptake, it is necessary to increase coronary lumen and coronary circulation blood flow to meet the requirement of increasing oxygen demand. Coronary circulation has sensitive regulating ability, and the factors regulating coronary circulation blood flow are: arterial perfusion pressure, coronary vascular resistance, heart rate, cardiac contraction and relaxation time limit, blood co2 tension, o2 tension, pH and neurohumoral factors.

The basic substances of myocardial metabolic energy are glucose, fatty acids, lactic acid and so on. When coronary circulation is insufficient and myocardium is in anoxic metabolism, fatty acid oxidation decreases, mainly carbohydrate oxidation. However, under anoxic conditions, the energy provided by glucose and glycogen decomposition is only a small part of aerobic metabolism. Sustained myocardial ischemia and hypoxia for more than 20 minutes can cause irreversible deterioration of mitochondria, myocardial cell necrosis and loss of myocardial enzyme activity, and clinical symptoms such as angina pectoris, arrhythmia and heart failure. [Back to the top]

clinical picture

Symptoms: Typical symptoms include angina pectoris caused by stress, angina pectoris caused by transient ischemia caused by imbalance of myocardial oxygen supply and demand, and sudden squeezing pain in precordial area during activity, emotional excitement, fullness or cold. The nature of pain can be severe colic, squeezing pain, compression pain, tight bundle pain, or the pain is very light, only feeling bloated and uncomfortable. Occasionally, a severe pain attack is accompanied by sweating and fear of death. Some patients were irradiated to the left shoulder, left upper arm, neck, throat and mandible for 1 ~ 10 minutes, which can be relieved by rest or taking nitroglycerin and other drugs. Some of them are accompanied by chest tightness or mainly chest tightness. In severe cases, the pain is heavier, the duration is prolonged, and it can also occur during rest or sleep. When inquiring about the medical history, we should pay attention to the inducement, the location and duration of pain, whether there is radiation, accompanying symptoms and ways to relieve it.

The etiology, frequency and duration of angina pectoris are relatively stable, which is called stable angina pectoris. In some cases, myocardial ischemia is serious, which can change from typical stable angina pectoris to unstable angina pectoris. The main manifestations are frequent angina pectoris attacks, prolonged pain duration, aggravated degree, and even pain at rest, which increases the risk of acute myocardial infarction. In the early stage of acute myocardial infarction, there may be nausea, vomiting, hiccups or epigastric pain. Angina pectoris is severe and lasts for several hours. Rest or taking nitroglycerin tablets can not be relieved, often accompanied by shock, arrhythmia and heart failure.

Signs: Patients with coronary atherosclerotic heart disease usually have no special signs. When angina pectoris attacks, blood pressure can be slightly increased or decreased, and heart rate can be normal, increased or decreased. People with severe pain are anxious, irritable, pale and sweaty, and occasionally have atrial or ventricular rhythm. In patients with papillary muscle dysfunction, systolic murmurs can be heard in the apical area. During myocardial infarction, the heart rate can be increased or decreased, the blood pressure can be decreased, the voiced boundary of the heart can be slightly increased, the apical area 1 heart sound can be weakened, and sometimes the third and fourth heart sounds or diastolic galloping rhythm can appear, and various signs of arrhythmia, shock or heart failure can appear. [Back to the top]

accessory examination

X-ray examination: chest X-ray examination generally has no abnormal findings. Hypertensive cases can be manifested as enlargement of left ventricle, widening, enlargement and tortuous lengthening of aorta. In patients with heart failure, the heart is obviously enlarged and the lungs are congested.

Electrocardiogram: Electrocardiogram is one of the important methods to reflect myocardial ischemia. When angina pectoris attacks, ST segment often decreases, T wave is low or inverted. It gradually recovers within a few minutes after the attack, sometimes accompanied by arrhythmia. Patients with no obvious abnormal ECG changes at ordinary times can do stress test to increase cardiac load, increase myocardial oxygen consumption and temporarily induce electrophysiological changes of myocardial hypoxia. ECG stress test can adopt double-step exercise test, treadmill exercise test, pedal exercise test and glucose stress test. Holter ECG monitor can also be used to continuously record dynamic electrocardiogram. The ECG characteristics of acute myocardial infarction cases are deep Q wave or QS wave, ST segment is obviously elevated, arch back is upward, and T wave is inverted. According to the leads showing the above characteristic changes, the location diagnosis of myocardial infarction can be made.

Serum enzyme examination: at the early stage of acute myocardial infarction, serum aspartate aminotransferase, creatine phosphokinase and lactate dehydrogenase all increased, and their dynamic changes are helpful to judge the evolution of the disease.

Other diagnostic methods, such as cross-sectional echocardiography and radionuclide cardiac imaging, are valuable for diagnosing coronary heart disease and myocardial infarction and understanding left ventricular motion function.

Selective coronary angiography and left ventricular angiography: Selective coronary angiography can clearly show the left and right coronary arteries and their branches, which can not only provide a basis for the diagnosis of coronary artery stenosis caused by atherosclerotic lesions, but also observe the exact location and scope of lesions, the degree of stenosis of diseased vessels and collateral circulation. The inner diameter of diseased coronary artery branches decreased by 65438 0/3, and the lumen area of blood vessels decreased by 50%. The inner diameter decreased by 1/2, and the lumen area decreased by 75%. The inner diameter is reduced by 2/3, and the lumen area is reduced by 90%. Left ventriculography can observe whether the systolic function of the left ventricular wall is normal, decreased or disappeared, and determine the left ventricular ejection fraction. Left ventriculography can also be used to diagnose mitral insufficiency caused by ventricular aneurysm, ventricular septal defect and myocardial infarction. For patients with coronary heart disease who are considering surgical treatment, it is necessary to perform selective coronary angiography and left ventricular angiography before operation in order to make clear the surgical indications and formulate the surgical plan. [Back to the top]

Prevention and treatment of coronary heart disease

It can be classified into two categories: internal medicine and surgery. Medical treatment has a history of many years. Treatment measures include adjusting diet and living habits, paying attention to mental health, using drugs to reduce blood lipid content, inhibiting platelet aggregation and controlling angina pectoris. The surgical treatment of coronary heart disease has a history of more than 70 years, and its concepts and methods have been developing continuously. 19 16 Jonnesco resection of cervical thoracic sympathetic nerve for angina pectoris. 1926 Boas underwent total thyroidectomy, trying to reduce the load of ischemic myocardium by reducing metabolism. Beck and Tichy performed a fixed suture between pectoralis major and myocardium in 1935, hoping that the adhesion formed could supply blood to myocardium. Since then, pericardium, omentum, lung, jejunum, stomach, spleen and other tissues and organs have been used for fixed suture with myocardium. Some surgeons also smear talcum powder and asbestos powder in pericardial cavity to promote the formation of pericardial adhesion. Zola and cesa-Bianchi ligated bilateral internal thoracic arteries at 1939, and thought that the pericardial diaphragm artery near the ligation site could deliver more blood flow to the myocardium. 1946 veneberg implanted the internal thoracic artery into the myocardium. 1955, Beck advocated partial ligation of coronary sinus, systemic coronary vein shunt, partial ligation of coronary sinus and perfusion of coronary circulation from the opposite direction. All the above surgical treatments were unsatisfactory and were abandoned one after another. From 65438 to 0955, direct coronary surgery was studied to improve myocardial blood supply. In 1958, Longmire et al. performed endarterectomy on the diseased coronary artery to relieve lumen stenosis. Senning used graft to repair enlarged coronary artery stenosis under cardiopulmonary bypass in 196 1 year. Gatrett underwent left anterior descending branch shunt of great saphenous vein on 1967, and it remained unobstructed after 7 years of follow-up. Selective coronary angiography has rapidly promoted the development of surgical treatment of coronary heart disease after its clinical application. Favaloro and Effler popularized the application of great saphenous vein in ascending aorta-coronary artery bypass grafting in 1967, and introduced the surgical technique in 1969. Up to 197 1, 74 1 operations have been performed. 1968 qingbao internal thoracic artery-anterior descending coronary artery anastomosis. 197 1 year, Flemma et al reported the surgical method of sequential transplantation, that is, a great saphenous vein was used to anastomose with multiple branches of coronary artery for many times. Since then, the surgical treatment of coronary heart disease has entered a new stage. At present, there are more than 400 thousand cases of coronary heart disease in the world, which is the main method of surgical treatment of coronary heart disease. Grüntzig et al. reported in 1979 that percutaneous transluminal coronary angioplasty is simple, does not require thoracotomy and has low medical expenses, but the incidence of restenosis can reach 30-40% 6-9 months after operation. In recent years, there have been new devices and technologies to treat myocardial infarction caused by early coronary embolism by percutaneous coronary thrombolysis and to eliminate atherosclerotic plaque and stenosis by intracoronary cold laser.

Due to the complex pathogenic factors of coronary atherosclerotic heart disease, it has not been fully understood so far; There are many changes in the number, range, development speed of coronary arteries involved in the disease and the damage to ventricular function. Therefore, according to the natural course of various types of coronary heart disease, it is necessary to compare the effects of internal medicine and surgical treatment in depth and in detail, which needs to be gradually enriched through long-term investigation and research. According to the existing clinical experience, although the surgical treatment of coronary heart disease can not change or reverse the process of coronary atherosclerosis, it can increase coronary blood flow and improve coronary circulation. After the great saphenous vein ascending aorta-coronary artery bypass grafting, the clinical follow-up observation data of a large number of cases showed that the curative effect on angina pectoris was good, and 60 ~ 95% cases disappeared after 1 ~ 5 years. Electrocardiogram returned to normal. After 10 years, due to the patency of transplanted blood vessels or the progress of coronary heart disease, 46% of cases of angina pectoris disappeared, while only 3% of cases without surgical treatment disappeared. After 3 ~ 10 years, the endurance of physical activity was significantly improved compared with that of non-surgical cases. Two years after operation, 60% of the patients were competent for normal work, while only 26% of the patients treated by internal medicine returned to work. [Back to the top]

Coronary artery bypass grafting

Indications for surgical treatment of coronary atherosclerotic stenosis: ascending aorta-coronary artery bypass with great saphenous vein

Surgery, commonly known as bypass surgery, is the most commonly used surgical method for coronary heart disease. Surgical indications are:

1. The factors that affect the course development and prognosis of stable angina pectoris are: the number of coronary artery branch lesions, especially whether the left main coronary artery or the anterior descending branch is involved, the functional state of left ventricle, the severity of myocardial ischemia, the sex and age of patients and whether there are other diseases. The long-term effect of medical treatment is close to that of patients with occlusive lesions of one or two coronary arteries without involving the main left coronary artery. Medical treatment should be carried out first and regular review should be carried out. However, if anti-angina drugs such as nitrates, β -blockers and calcium antagonists are not effective in treating chronic stable angina pectoris, which seriously affects patients' work and life, selective coronary angiography should be performed, and it is found that the vascular cavity area is reduced to more than 50%, especially when the lesion involves the left main coronary artery, the left anterior descending coronary artery or the three coronary arteries, surgical treatment should be considered.

2. Most cases of unstable angina pectoris have severe coronary artery obstruction, and some cases have small or scattered myocardial infarction under endocardium, which can develop into acute myocardial infarction in a short time, leading to severe arrhythmia or sudden death. Gazes et al. reported that 1, 2-year mortality and 10 mortality were 18%, 25% and 50% respectively. If the angina pectoris is still not controlled after active medical treatment 1 week, selective coronary angiography should be performed and surgery should be performed as soon as possible according to the results.

3. The opinions of patients with acute myocardial infarction undergoing coronary artery bypass grafting are still inconsistent. Supporters of surgical treatment believe that the area of myocardial infarction can be reduced within 8 hours after myocardial infarction, and less myocardial scar tissue will be formed later. The incidence of complications such as left ventricular aneurysm, arrhythmia, heart failure and sudden death caused by infarction is low, and the left ventricular function is obviously improved. However, patients with acute myocardial infarction have a high mortality rate and a high incidence of postoperative complications. The follow-up data of long-term curative effect need to be enriched. However, for the cases with obvious depression of ST segment in treadmill exercise test 2 weeks after myocardial infarction, the follow-up period was 65,438 0 years, and the mortality rate was 65,438 0.3 times higher than that of those with negative test. Such cases should be considered for surgical treatment.

In recent years, thrombolysis and percutaneous transluminal coronary angioplasty have been used to treat patients with early myocardial embolism. At present, there is not enough data to draw a conclusion on the long-term efficacy of these therapies and their comparison with bypass grafting.

4. According to statistics, during the follow-up period of 2 ~ 3 years, about 1/3 ~ 1/2 cases suffered from severe ventricular arrhythmia during the recovery or later period after myocardial infarction and died suddenly. Therefore, myocardial ischemic ventricular arrhythmia should be regarded as an indication of coronary artery bypass grafting.

Surgical techniques for coronary heart disease: great saphenous vein or internal thoracic artery can be used for the operation of reconstructing coronary circulation blood flow. The great saphenous vein has large caliber, convenient material collection, the most cases and satisfactory curative effect. In recent years, there are more and more cases of end-to-end anastomosis between pedicled internal thoracic artery and coronary artery, especially the left anterior descending branch of coronary artery. Atherosclerosis of internal thoracic artery is rare, and vascular stenosis caused by postoperative intimal hyperplasia is also rare. Postoperative vascular patency rate is higher than that of great saphenous vein, but the internal thoracic artery is difficult to dissect and dissociate, and the incidence of postoperative bleeding complications is high. Free bilateral internal thoracic arteries may have adverse effects on sternal healing. Selective coronary angiography showed that the coronary artery branch was larger than 1.5mm, and the lumen diameter was reduced by more than 50%, so shunt should be performed to fully rebuild myocardial blood flow. Cases with multiple coronary artery lesions sometimes need to be shunted to five or more branches. In order to simplify the operation and shorten the operation time, sequential anastomosis can be used, that is, a section of great saphenous vein is applied at the proximal end of end-to-side anastomosis, and then 1 ~ 2 side-to-side anastomosis is performed, so that two or more coronary arteries can be shunted by only one section of vein, and the anastomosis between aorta and great saphenous vein can be reduced. After sequential anastomosis, the patency rate of blood vessels is high and the blood flow velocity is fast, but the operation needs to be meticulous and accurate, and attention should be paid to avoiding the distortion of great saphenous vein. Sometimes, the thicker branch of the great saphenous vein can be used for Y-shaped anastomosis with another coronary artery branch.

Preoperative preparation: lung, liver and kidney function were examined before operation, digitalis and diuretics were stopped 2 days before operation, but nitroglycerin drugs, beta blockers and calcium antagonists should not be stopped.

Surgical techniques of great saphenous vein shunt transplantation: general anesthesia with tracheal intubation, cardiopulmonary bypass combined with hypothermia operation, and blood pressure, central venous pressure, electrocardiogram, body temperature and urine volume were monitored during operation. Skin preparation should include chest, abdomen, groin and lower limbs. Surgeons were divided into two groups and performed thoracotomy and great saphenous vein stripping at the same time. When the great saphenous vein is free, the operation must be gentle, and it is forbidden to pull the vein to cause injury. When the great saphenous vein is free, it is better to take a long incision in the lower limbs to free the vein in sections than several small incisions to protect the blood vessels from traction injury. In the process of free great saphenous vein, it is forbidden to clamp the vein with vascular forceps, and only the adventitia of vein wall can be clamped with tissue forceps to avoid damaging and rupturing the intima of vein. When dealing with venous branches, we should also pay attention to cutting off the ligation branches at a certain distance from the venous trunk to avoid shrinking the venous wall and narrowing the vascular lumen. The lower segment of the great saphenous vein near the ankle is more suitable for transplantation and shunt than the upper segment of the great saphenous vein, because it has no venous valve and the vascular lumen has good compression resistance. After a section of great saphenous vein is taken out, a syringe with a smooth needle is inserted into the distal end of the vein and ligated to identify the proximal and distal ends of the vein. It can be used to inject a small amount of cold heparin solution (containing heparin 1000 U 1000ml solution) to enlarge the vascular cavity and check whether the vein wall leaks. The vein taken out was injected with solution in the cavity and stored in 65438 00℃ solution under moderate expansion. Local use of diluted papaverine (60mg per 500ml normal saline) can prevent venous spasm. At the same time of free incision of great saphenous vein, another group of surgeons made a median sternotomy, longitudinally split the sternum, cut the pericardium to expose the heart, respectively inserted blood drawing and blood supply catheters in the vena cava and the distal end of ascending aorta, and placed decompression and drainage catheters in the left heart cavity to connect with artificial heart-lung machine to establish cardiopulmonary bypass. Attention should be paid to myocardial protection during operation, and measures such as blood cooling, local myocardial cooling and perfusion of cold cardioplegia should be taken to shorten the blocking time of ascending aorta as much as possible. Generally, the distal great saphenous vein is anastomosed with the coronary artery branches first, but there are also cases where the ascending aorta is anastomosed with the great saphenous vein first, and then the distal anastomosis is performed. The coronary artery branches were exposed at the selected anastomosis site, and the middle part of the anterior wall of the artery was cut longitudinally with a sharp knife, and then the coronary artery incision was enlarged to about 6 ~ 8 mm with fine scissors. Sometimes it is necessary to remove a small triangular anterior wall of coronary artery branch to facilitate vascular anastomosis. After repairing the adventitia, the severed end of the great saphenous vein for anastomosis was obliquely cut into a 45 incision, so that the blood vessel would not be twisted after anastomosis. If necessary, a small section of vein wall can be cut longitudinally to enlarge the anastomotic end. The length of great saphenous vein incision should be longer than that of coronary artery branch incision 10 ~ 20%. The anastomosis should be sutured continuously or intermittently with 6-0 or 7-0 polypropylene thread. The needle distance is generally around 1mm, and the side of great saphenous vein is slightly wider. The intima of blood vessels should be properly anastomosed. When anastomosing, a small amount of heparin solution should be dripped through the other end of the great saphenous vein. For those who need sequential anastomosis, after the distal end-to-side anastomosis is completed, according to the walking direction of the transplanted great saphenous vein and its anatomical relationship with another coronary artery branch, longitudinal incision or transverse incision is made on the wall of the great saphenous vein for anastomosis. It should be noted that the distance between several incisions of great saphenous vein is appropriate, the anastomosis is not distorted and the blood flow is smooth. After the distal anastomosis is completed, the aortic occlusion forceps can be loosened and the cardiopulmonary bypass can be rewarming. Under the condition of keeping the great saphenous vein filled, the ascending aorta was anastomosed and the aortic wall was partially clamped with noninvasive vascular forceps. During each anastomosis, a small hole with a diameter of about 5mm was cut with an aortic wall perforator, and the great saphenous vein was used for oblique cutting of the incision end of anastomosis. The venous anastomosis should be larger than the aortic wall incision 10 ~ 20%, and the anastomosis should be sutured continuously with 5-0 polypropylene thread.

(1) Enlarge the venous cavity with heparin solution.

(2) Cut the great saphenous vein at 45, and then cut it longitudinally.

(3) great saphenous vein-coronary artery end-to-side anastomosis

(4) Sequential anastomosis: the incision of great saphenous vein can be longitudinal or transverse.

End-to-side anastomosis of internal thoracic artery and coronary artery: the diameter of internal thoracic artery is similar to that of coronary artery, and the patency rate of blood vessel after shunt with internal thoracic artery is higher than that of great saphenous vein, so there is no need for proximal aortic anastomosis. However, due to the limitation of length and anatomical position, it is generally only suitable for anastomosis with the left internal thoracic artery and the anterior descending branch or diagonal branch of the left coronary artery. The diameter of the right internal thoracic artery is smaller than that of the right coronary artery, and the length is insufficient. It is seldom used to anastomose the right internal thoracic artery with the right coronary artery branch.

After the sternum was split open, before heparin was injected into the pericardium, the intrathoracic fascia was cut along both sides of the internal thoracic artery about 65438±0cm away from the blood vessels, starting from the sixth intercostal space to the upper part of the sternum, and the internal thoracic artery, vein, surrounding adipose tissue, muscle and pleura were separated. The branches of intercostal artery need to be ligated and cut off. The free internal thoracic artery and its surrounding tissues should be carefully protected from trauma and wrapped with gauze soaked in dilute papaverine solution. After systemic heparinization before cardiopulmonary bypass, the internal thoracic artery was ligated and cut off at the sixth intercostal level, and the bleeding per minute at the cut-off end of the proximal artery could reach 120 ~ 240ml. If the blood loss per minute is less than 100ml, the blood vessel quality is poor and it is not suitable for application. The left anterior descending branch was cut off, and the tissue around the distal segment of the internal thoracic artery with appropriate length was peeled off, exposing the artery with a length of about 65438±0cm. The lumen was slightly expanded with a dilator with a diameter of 65438 0.0 ~ 65438 0.5 mm, and then it was cut obliquely. The incision of the anterior descending branch was sutured continuously or intermittently with 7 ~ 0 polypropylene thread, and then the soft tissue around the internal thoracic artery was sutured and fixed with the myocardium by multiple intermittent sutures, so as to achieve the following goals.

During coronary artery bypass grafting, if pathological conditions require, coronary endarterectomy can be performed at the same time.

Postoperative treatment: Blood pressure, central venous pressure, left atrial pressure, heart rate, heart rhythm, body temperature, thoracic drainage, urine volume, blood gas analysis, blood PH value and electrolyte content should be closely monitored after coronary artery bypass grafting to prevent hypovolemia, hypoxia, acidosis and electrolyte disorder. Oral beta blockers can prevent arrhythmia. Aspirin and dipyridamole can prevent deep venous thrombosis of lower limbs in patients undergoing great saphenous vein shunt. A few patients with postoperative low cardiac output syndrome need intra-aortic balloon counterpulsation if the drug treatment effect is not satisfactory.

Efficacy of shunt transplantation: In recent years, the operative mortality rate has dropped below 5%. The most common cause of death is acute heart failure. The factors that affect the operative mortality are: the range of coronary artery branch lesions, the severity of angina pectoris, the preoperative left ventricular function, the patient's age, gender, whether it is complicated with myocardial infarction, the number of transplanted blood vessels, the time of aortic occlusion and whether the surgical technique is appropriate. Perioperative myocardial infarction is a common factor affecting the curative effect, and its incidence rate is 2 ~ 10%. Mild symptoms are only abnormal serum enzymology examination, and severe symptoms are ECG changes. Improving anesthesia technology and paying attention to myocardial protection measures during operation can reduce the incidence of myocardial infarction.

Long-term results after shunt transplantation: angina pectoris was obviously relieved or disappeared, left ventricular function was improved, cardiac output was increased and cardiac function was obviously improved. About 2/3 patients can return to work after operation, and nearly 70% patients can survive for more than 10 years after operation. The 10-year survival rate was 78% after single coronary artery disease, 69% after two-vessel disease, 48% after three-vessel disease and 67% after left coronary artery disease. After shunt transplantation, the intima of great saphenous vein may proliferate, resulting in stenosis of vascular lumen and poor blood flow. Five years after operation, the incidence of intimal hyperplasia of great saphenous vein can reach 10 ~ 45%. [Back to the top]

Prevention of acute myocardial infarction

Various physical or mental factors that can increase myocardial oxygen consumption or induce coronary artery spasm may cause acute myocardial infarction in patients with coronary heart disease. Common reasons are as follows: 1. Overwork: engaging in incompetent manual labor, especially climbing stairs with heavy load, excessive physical activity, persistent intense fatigue, etc. , can significantly increase the burden on the heart, myocardial oxygen demand suddenly increased, and the coronary artery of patients with coronary heart disease has hardened and narrowed, and can not be fully expanded. Ischemia and hypoxia can cause arterial spasm, which in turn aggravates myocardial hypoxia and even leads to acute myocardial infarction. 2. Excitement: Some patients with acute myocardial infarction are induced by strong emotional changes such as excitement, tension and anger. It is reported that there is a state in the United States. On average, every 10 game, there are 8 spectators with acute myocardial infarction. 3. Overeating: Many cases of myocardial infarction occur after overeating. Data at home and abroad show that the incidence of acute myocardial infarction is high on weekends and holidays. After eating a large number of foods containing high fat and calories, the blood lipid concentration suddenly rises, leading to an increase in blood viscosity and platelet aggregation. Thrombosis is formed on the basis of coronary artery stenosis, causing acute myocardial infarction. 4. Cold stimulation: Sudden cold stimulation may induce acute myocardial infarction. This is why doctors always tell patients with coronary heart disease to pay great attention to cold and warmth, and it is also one of the reasons for the high incidence of acute myocardial infarction in winter and spring. 5. Constipation: Constipation is very common in the elderly, but it