What Is Coronary Artery Surgery?

Coronary artery bypass surgery

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Chinese name: Coronary artery bypass grafting
Foreign name: Coronary Artery Bypass Grafting

Short name: Coronary bypass surgery
Abbreviation: CABG

Coronary artery bypass grafting is called coronary artery bypass grafting, referred to as coronary artery bypass grafting, or CABG for English Coronary Artery Bypass Grafting, which is recognized internationally as the most effective method for treating coronary heart disease. Coronary artery bypass surgery, which began in 1964, is a procedure used to replace obstructed coronary arteries to improve myocardial blood supply, relieve angina, improve quality of life, and reduce the risk of coronary heart disease death. The method is to use transplanted blood vessels, that is, bridge vessels (usually large saphenous veins and pedicled internal mammary arteries, but also radial arteries, pedicled gastric omentum arteries and other limb arteries and veins) at the ascending aortic root and diseased coronary arteries. Establish a vascular path beyond the obstruction, so that the blood that the heart beats passes from the aorta through the vascular bridge, bypasses the coronary artery lesion, flows to the distal end of the coronary artery stenosis or obstruction, and reaches the ischemic myocardium, thereby improving Coronary perfusion increases myocardial oxygen supply, and the pedicled artery need not be connected to the root of the ascending aorta. Surgery can be performed under cardiac arrest, which requires extracorporeal circulation, that is, traditional coronary artery bypass graft (CABG); it can also be performed on a beating heart, that is, "off-pump" coronary artery bypass surgery (off- pump CABG, OPCAB or OPCABG). At present, the number of cases of bypass surgery under cardiopulmonary bypass exceeds the number of cases of bypass bypass under extracorporeal circulation ^[1]

The coronary arteries are divided into the left coronary arteries (that is, the left main trunk) and the right coronary arteries, and most of them open in the left coronary sinus and right coronary sinus, respectively. The left coronary artery, the left main branch, is divided into two large branches, namely the anterior descending branch and the circumflex branch. Clinically, the left anterior descending branch, the circumflex branch, and the right coronary artery are regarded as the "three blood vessels" that supply the blood supply to the heart. Generally speaking, several lesions of coronary heart disease refer to the three vessels of the anterior descending branch, the circumflex branch, and the right coronary artery. In terms of.
The coronary arteries mostly walk in the myocardium, the right coronary artery and the circumflex branch walk in the atrioventricular sulcus, and the anterior descending branch and posterior descending branch walk in the interventricular sulcus. But a part of the coronary arteries walk on the surface of the heart, and these parts are the parts of the anastomosis when the coronary artery is bypassed.
The anterior descending branch, walking in the interventricular sulcus, is the most important artery in most people. It supplies the anterior wall of the left ventricle, the anterior ventricular septum, the apex, and part of the anterior wall of the right ventricle. The anterior descending branch has several diagonal branches and spacer branches, of which the diagonal branch is also commonly used for bypass coronary arteries.
The circumflex branch may have 1 to several branches, namely the blunt limb. The blood supply range of the circumflex branch is part of the anterior wall, lateral wall, posterior wall, and left atrium of the left ventricle. The blunt limb is a coronary artery commonly used for bypass.
The blood supply range of the right coronary artery is the right ventricle, the right atrium and the posterior ventricular septum, and its branches are the sinoatrial node artery, the sharp limb, the posterior descending branch of the posterior left ventricle and the right coronary artery. A few posterior descending branches originate from the circumflex branch (left-dominant type). When bypassing, the site of the anastomosis can be at the sharp limb, posterior left ventricle, posterior descending limb, and right coronary artery.
There may be collateral circulation between the above coronary arteries. When one blood vessel is blocked, another blood vessel may pass through the collateral circulation to supply coronary blood flow beyond the blocked blood vessel ^[2]

Because patients with coronary heart disease are generally older and have problems with the function of various organs in the body, the effects of coronary artery bypass grafting are related to the patient's heart, but also closely related to lung, brain, liver, kidney function and peripheral vascular conditions. Cardiac-related conditions are mainly left and right heart functions, and the quality of bridge vessels is related to the conditions of target vessels (ie, diseased coronary arteries or criminal vessels). The heart is small and the left ventricular systolic function, such as left ventricular ejection fraction (LVEF)> 40%, has a good prognosis. The internal mammary artery is the best bridge material. The most commonly used large saphenous vein is too thick or too thin to match the coronary target blood vessels, or thicken the vein wall due to multiple infusions, which are not effective. If the target vessel has obvious calcification, the wall is thickened, and the effect is not good. If the inner diameter is less than 1mm, it is not recommended to make anastomosis in this vessel. Other influencing factors, such as: poor lung function, difficulty in detaching from the ventilator after surgery, and a high chance of lung infection; lesions in the brain and central nervous system before surgery, liver and kidney dysfunction, may be further worsened after surgery, may Serious complications have occurred; if the carotid artery is severely narrowed or completely occluded, the incidence of postoperative cerebral infarction is extremely high. Carotid endarterectomy can be performed at the same time, and coronary bypass surgery is recommended under off-pump. It affects the curative effect of surgery a lot. Foreign countries use multiple organ failure scoring system (MODS), APACHE scoring system, and sequential failure scoring system (SOFA) to evaluate the effect of coronary artery bypass surgery. The MODS and SOFA systems all observe the six major systems of breathing, circulation, kidney, liver, coagulation, and nerves. Each system has a score of 0-4 and a total score of 24. In addition, age, gender, and weight are also influencing factors ^[3]

Coronary heart disease treatment is divided into drug therapy, medical interventional therapy (coronary balloon dilation, that is, PTCA and coronary stent implantation PCI) and surgical treatment. Surgery, or coronary artery bypass grafting (coronary artery bypass graft), is the last resort for coronary heart disease. Its indications are not static. With the evolution of internal and surgical techniques, the indications will also change. The American College of Cardiology (ACC) / American Heart Association (AHA) publishes guidelines for the treatment of coronary heart disease, which are frequently updated, starting from the principles of evidence-based medicine, and specifically discussing the indications for surgical treatment of coronary heart disease. In general, patients with coronary heart disease who are ineffective, unsuitable for treatment, significantly poorly treated, or have a high risk of treatment may be suitable for surgery.
1. Stable angina pectoris: Angina pectoris affects daily life and work. Conservative medical treatment is not effective. Coronary angiography found that the coronary artery or the proximal descending anterior descending branch / rotation is significantly narrower than 70%. Those with three coronary lesions, especially the heart Functional low ventricular ejection fraction.
2. Unstable angina pectoris: Typical angina pectoris affects daily life and work. Conservative medical treatment is not effective. Coronary angiography found that the coronary artery or the proximal descending anterior descending branch / circulation was significantly narrower than 70%.
3, after myocardial infarction: failure of medical interventional treatment, patients with persistent symptoms, hemodynamic instability, and combined with ventricular aneurysm, mitral regurgitation and ventricular septal defect.
4. Severe coronary stenosis: The three major branches of the coronary artery (anterior descending branch, circumflex branch, right coronary artery) have severe stenosis (stenosis more than 75%), regardless of the severity of the symptoms, surgery can be considered.
5. Fatal ventricular arrhythmias caused by coronary heart disease, such as caused by left main or three coronary lesions.
6. Cases of failed medical intervention.
7. Patients who have undergone coronary artery bypass grafting in the past with symptoms and non-surgical treatment failure.
The 2005 ACC (American College of Cardiology) / AHA (American Heart Association) guidelines state that coronary bypass is the preferred treatment in the following cases: left main coronary artery disease; all three coronary artery disease (left anterior descending branch, right Coronary arteries and left circumflex branch); diffuse disease not suitable for interventional treatment.
The 2011 ACCF (American College of Cardiology Foundation) / AHA (American Heart Association) CABG guidelines further state that in patients with other high-risk diseases such as severe cardiac insufficiency (such as low ejection fraction) or diabetes, the coronary artery Bypass is the treatment of choice ^[4]

Traditional extracorporeal bypass surgery

Cardiopulmonary function is temporarily replaced by an extracorporeal circulation machine. During the operation, the heart stopped beating, and bloodless surgery facilitated the operation. This surgery has relatively low technical requirements, but the use of extracorporeal circulation may cause damage to the human body, and there are many postoperative complications.
Non-stop and off-pump bypass surgery. In the case of a beating heart, a special heart surface fixture is used to fix part of the heart for surgery. Because the operation does not use extracorporeal circulation assistance, completing bypass surgery on a beating heart requires a higher level of surgical skills, but excluding complications caused by extracorporeal circulation, and the postoperative recovery is relatively fast.
Minimally invasive bypass surgery / robot bypass surgery is a further improvement of off-pump coronary artery bypass surgery, which is minimally invasive coronary artery bypass surgery. The operation is performed through a 5 to 10 cm incision between the ribs or through several small holes in the chest wall. Special surgical instruments are placed in the pericardial cavity without splitting the sternum, which reduces the chance of injury and postoperative infection. Under direct vision, or with the help of a real-time big picture from a thoracoscope, surgical operations are performed using special surgical instruments. This type of minimally invasive bypass surgery is currently only suitable for a small number of specific lesions. For patients with a large number of vascular lesions, it is not easy to achieve complete revascularization. With the improvement of technology, the future is a development direction.
Robotic bypass surgery uses 3D simulation technology, using special machines and medical equipment, to place the camera probe into the heart surface of the patient's pericardial cavity in real time, and a large screen is transmitted. A tiny manipulator that simulates a human hand is placed into the heart surface through the chest wall. On the operating table, under the table, a finger-closing control device is used to remotely control the manipulator, and the remote-control manipulator performs coronary artery bypass surgery in the patient's body through the image of the display screen. This operation must be completed with the assistance of special equipment, which is expensive (equipment valued at tens of millions of yuan), high in technical requirements, and difficult to achieve complete revascularization of ischemic myocardium. At present, China is still in the stage of exploration and development.

Hybrid surgery

That is, while performing coronary artery bypass surgery, it is supplemented with medical intervention surgery in the operating room.

Bridge vessel material:
Arteries: Left internal mammary artery, right internal mammary artery, left / right radial artery, gastric omentum artery, superior abdominal wall artery, splenic artery, etc.
The left / right internal mammary artery works best, the radial artery is easily spasm after operation (usually treated with heparin and calcium channel blocker), and the gastric omentum artery is traumatized.
Veins: Great saphenous vein, expensive main vein of the upper limbs, etc. The great saphenous vein is the most commonly used artificial material for bridging blood vessels: allogeneic veins, tissue engineering artificial blood vessels, the former has a low patency rate, and the latter has not yet been used clinically.

Brief procedure of anesthesia for coronary artery bypass surgery: combined intravenous anesthesia. The anesthesiologist places various intravenous catheters and injects anesthetics and analgesics. After tracheal intubation, the ventilator assists in breathing, and vital signs are monitored by the anesthesiologist. Anesthesia is slowly and continuously injected intravenously throughout the entire procedure, supplemented by intermittent inhalation of anesthetic gas to maintain general anesthesia.
Surgery: take the blood vessels used for bypassing-generally the left internal mammary artery and the great saphenous vein are selected. At the same time, heparin is applied throughout the patient to prevent blood clotting. Explore the coronary arteries to find the diseased coronary arteries and their lesions (obstruction or stenosis). Use the coronary knife to open the anterior wall of the artery at the appropriate part of the coronary artery far away from the lesion. The internal diameter of the artery and the diameter of the bridge vessel are determined, and then an incision of the corresponding size is made at the corresponding site of the bridge vessel that has been measured in advance. -0 thin polypropylene sutures, very few use 9-0 sutures for anastomosis of bridge vessels and diseased coronary arteries. There are two types of end-to-side anastomosis and side-to-side anastomosis (commonly used for sequential bypass). Because most of the coronary arteries are cut with an anterior wall for anastomosis during anastomosis, it is called "side". End-to-side anastomosis means that one end of the bridge vessel is anastomosed with the coronary arteries; Lateral anastomosis with the coronary arteries. Except for the anastomosis of the pedicled internal mammary artery (or other pedicled artery) with the diseased coronary artery, other bridge vessels should be anastomosed with the root of the aorta after the anastomosis with the coronary artery, so that the aortic blood can be introduced into the coronary through the bridge vessel. Arterial lesions farther away.
If the coronary artery disease is serious, the thickened wall of the blood vessel is calcified, the inner diameter of the lesion becomes smaller, and the blood vessels are very important. Such as the anterior descending branch disease, endometrial ablation is feasible, that is, the thickened calcified coronary intima with the help of the device. Completely exfoliate, and then bypass the diseased coronary artery.
If the patient is young or has poor venous conditions and can't cooperate with the bridge vessels, then the whole artery bypass can be used. The scheme is: left internal mammary artery / right internal mammary artery (right internal mammary artery with pedicle or right internal mammary free end connected to the left internal mammary artery / Ascending aorta, the other end is anastomosed with the diseased coronary artery); Internal mammary artery / radial artery (the radial artery is connected to the ascending aorta at one end, and the other end is anastomosed with the diseased coronary artery); Gastric omentum artery is currently used in clinical practice less.
In the case of bypass bypass surgery (ONCABG), the surgeon first intubates the aortic root, right atrium, and left atrium (if necessary) to establish extracorporeal circulation. Block the ascending aorta, fill the aortic root with myocardial protection solution, and place ice on the surface of the heart. After cardiac arrest, use the aforementioned method to perform coronary artery bypass surgery, pay attention to myocardial protection during operation, and make the heart beat again after operation.
In the case of off-pump bypass surgery (OPCAB), the surgeon uses a special epicardial fixator to relatively fix the part of the heart that is intended to be an anastomosis, to make the heart at this particular part relatively stationary, and to block the proximal end of the intended anastomosis. And / or the distal coronary blood flow, then cut the coronary arteries, and clean the opening of the coronary arteries with water or carbon dioxide, so that in a relatively bloodless state, the above method is used for coronary artery bypass grafting.
Similarly, minimally invasive surgery and robotic surgery methods are similar to OPCAB, the difference is the size of the incision and whether to use special instruments.
If the patient has a left ventricular wall tumor, surgery should be performed at the same time. The principle of surgical treatment of ventricular aneurysm is to eliminate abnormal movement of the ventricular wall and reshape the left ventricle as much as possible. Main 1, there is a "sandwich" method: suitable for cases with abnormal wall motion, using two sticky pads, sandwich the wall motion abnormal area inside, tightly with polypropylene suture, can be extracorporeal circulation In addition, surgery can also be performed without extracorporeal circulation; 2. "Dor" and modified "Dor" method: Under extracorporeal circulation, ring or patch at the junction of normal and necrotic in the left ventricle, and then use the "sandwich" method to close Ventricular incision.
If moderate and above mitral insufficiency is combined, depending on the condition, it can be left untreated, an annuloplasty (with or without an annulus) can be performed, and mitral valve replacement can be performed if necessary.
If ventricular septal defects are combined, ventricular septal repair can be performed under cardiopulmonary bypass.
If the patient has severe cardiac insufficiency, hemodynamic instability, or inability to disengage the extracorporeal circulation machine during the operation, cardiac assistive devices such as intra-aortic balloon counterpulsation (IABP), left-heart assist or extracorporeal membrane lung therapy (ECMO ).

Surgeons will evaluate before surgery

Same as routine treatment after cardiac surgery, such as replenishing volume, keeping water and electrolyte stable, anti-inflammatory and sedative. In the field of coronary heart surgery, postoperative anticoagulation is very important. Intravenous heparin or small molecule heparin can be injected subcutaneously, and enteric-coated antiplatelet drugs can be taken orally for life. Two antiplatelet drugs can be used in a short period of time. Nitrate drugs are used. Calcium channel blockers act on the coronary arteries, and beta blockers regulate heart rate. If necessary, drugs such as blood pressure control, blood lipids, and blood glucose are added to keep them at low levels.

Patients undergoing coronary artery bypass grafting have the same complications as other surgeries, and some of the more common or specific risks of coronary artery bypass grafting.
1. General complications:
Bleeding, infection or sepsis of the incision, deep vein thrombosis, complications of anesthesia, malignant fever, scar, acute / chronic pain incision, psychiatric symptoms, pneumothorax, hemothorax.
2. Associated with cardiac surgery 1) Central nervous system complications, cases with extracorporeal circulation surgery, the incidence rate is between 5% and 6%, and cases without extracorporeal circulation surgery, neurological complications have decreased significantly.
2) Mediastinal infection and non-union of sternum: the incidence is 1% -4%. Obesity is an important risk factor. Others include diabetes, previous coronary artery bypass graft surgery, and use of unilateral / bilateral internal mammary arteries.
3) Myocardial infarction during perioperative period: Myocardial infarction due to embolism, hypoperfusion or unobstructed bridge.
4) Acute renal insufficiency.

Preoperative assessment methods provide an overview of surgical risks. Early complications are related to older age, women, whether emergency surgery, decreased cardiac function, left main disease, diffuse coronary disease and previous coronary bypass surgery.
Coronary artery bypass surgery in an experienced heart center has a 30-day surgical mortality rate of less than 1%. The long-term prognosis of coronary artery bypass surgery depends on various factors, such as the quality of the bridge vessel, the target vessel, the surgeon's microsurgical anastomosis technique, and the patient's satisfaction with blood glucose, blood pressure, and lipid control. Coronary artery bypass graft occlusion is a serious complication. Successful surgery usually maintains the patency rate of the venous bridge for 10 years (more than 60%) and the internal mammary artery bridge for 15 years (more than 90%).

Months to years after coronary artery bypass grafting, the vascular bridge can become diseased and possibly blocked. The patency of the vascular bridge depends on some factors, including the type of vascular bridge, whether the intima of the blood vessel is damaged when the bridge vessel is intercepted, the degree of coronary artery disease such as thickening and calcification of the arterial wall, the diameter of the distal coronary artery and the surgeon's vascular suture skill. Arterial bridges are much more sensitive to rough treatment than the great saphenous vein. The bridge vessels removed by gentle technique, the intimal protection is good, and the long-term patency rate is bound to increase. In the case of the great saphenous vein, the great saphenous vein and the ascending aorta anastomosis, 20% of cases will be narrowed within a year, but only 25% of them will be obstructed within 5 years. The long-term patency of the left internal mammary artery is much higher than that of the great saphenous vein. Its 10- to 20-year patency rate is 90% -95%, so it is usually anastomosed to the left anterior descending coronary artery (the most important coronary artery).

Postoperative activities

If the physical strength allows in the early stage, you can carry out a small amount of activities in an appropriate amount, from bed activities to bedside activities to activities on the ground, all with the help of family members. Proper activities are conducive to recovery and reduce the chance of infection.

Considerations for the sternum

Cardiac surgery is mostly performed through the thoracotomy method. After the operation, the sternum is fixed with a wire. Therefore, patients should avoid doing some exercise on their upper limbs within 8 to 12 weeks after coronary bypass surgery to facilitate early healing of the sternum and reduce complications. . First, patients need to avoid using their arms excessively, such as pushing themselves away from the seat or dragging the seat before sitting down. Second, patients should avoid lifting any heavy objects. Finally, patients should avoid raising their hands too far. After 12 weeks (March), you can basically resume normal life.

Notes on surgical incisions

After the operation, slight redness, pain, swelling, and local numbness are common in the incision. As the body recovers and nutrition gradually strengthens, the discomfort will be reduced until it disappears. Experienced hospitals use analgesic pumps (a slow-release compound analgesic device) early in the postoperative period, allowing patients to spend the early postoperative period smoothly. Because the saphenous vein is intercepted, pain will occur in the lower limbs, and the lower limbs will swell due to poor reflux. Solutions include raising the affected limb, using elastic socks or elastic bandages.

Postoperative diet

Some patients have symptoms such as bloating, nausea, and vomiting after surgery. The initial diet consists of light, digestible foods, supplemented with appropriate activities to stimulate the digestive system. Families can use hot towels or hot water bags to apply hot compresses to the lower abdomen to promote voluntary urination; use Kailulu to help defecate.
Limiting fat in food after surgery, especially limiting saturated fatty acids from animal foods is the first principle. Should also pay attention to adequate protein supplements, high-protein and low-fat foods include skimmed dairy products, soy products, some birds and fish. Semi-liquid foods made from grains (congee, soup, rice flour, etc.) are suitable as the main source of energy. Nutritional deficiency caused by preventive drugs. Some diuretics have a great impact on the electrolyte balance of potassium, sodium, magnesium, and calcium in the body. Anticoagulant drugs can cause gastrointestinal tract mucosal damage, reduce the absorption of iron, calcium, and vitamins and increase the loss. Therefore, after coronary surgery Proper supplementation of vitamin C, vitamin K, vitamin E, folic acid, and iron is necessary. If pre-diabetes is using insulin, you may need to add B vitamins and potassium that promote energy metabolism. Water-soluble dietary fiber is also suitable for patients after coronary surgery, which can prevent gastrointestinal dysfunction caused by surgical stress and prevent constipation. Reasonable application of health foods can regulate blood lipids, lower blood pressure, control blood sugar, and ensure long-term effects of surgery ^[5] .

Postoperative follow-up

Before leaving the hospital, the contact information of the doctor in the surgical group must be obtained so that the doctor can be contacted if necessary after surgery. When you are discharged, you must understand the precautions for postoperative medication to the surgeon. You can return to the hospital for review after 6 months. Mainly review blood biochemistry, electrocardiogram, echocardiogram, chest radiograph, coronary CTA if necessary, and adjust postoperative medication.

What Is Coronary Artery Surgery?

Coronary artery bypass surgery

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