Internal mammary artery-coronary artery bypass grafting

The inner diameter of the inner mammary artery is about 2 to 3 mm, which is similar to the inner diameter of the coronary artery. The distal end is anastomosed to the distal end of the coronary artery lesion, which can form a good bypass channel and improve the blood supply of the myocardium. Compared with the saphenous vein bridge, the advantages of the internal mammary artery as a vascular bridge are as follows: (1) The inner iliac artery with pedicle can regulate blood flow according to physiological needs; 2 the inner mammary artery can produce more prostaglandins, and the latter has dilated blood vessels. And anti-platelet accumulation; 3 less chance of atherosclerosis in the internal mammary artery, so the long-term patency rate is high. Due to the limited length of the internal mammary artery and the small lumen, it is often used in combination with the saphenous vein bridge. The internal mammary artery is mainly used as the left anterior descending vascular bridge to ensure a satisfactory patency rate. The right internal mammary artery has a smaller caliber and is less used. Treatment of diseases: unstable angina pectoris, unstable angina pectoris, angina pectoris Indication Internal mammary artery-coronary artery bypass surgery is applicable to: 1. There are angina pectoris, especially unstable angina pectoris, drug treatment is invalid. 2. Coronary angiography confirmed the local coronary stenosis, the diameter of the stenosis was more than 50%, the distal end of the stenosis was smooth, and the caliber was >1.5mm. 3. Percutaneous transluminal coronary angioplasty failure or restenosis; acute myocardial infarction after thrombolysis still has obvious stenosis. In the above-mentioned interventional treatment cases, if the plaque exfoliation blocks the distal lumen, and the electrocardiogram has a persistent ischemic wave or angina pectoris, emergency surgery should be performed. 4. Ischemic cardiomyopathy has a large number of viable myocardium. These patients have very poor heart function and should be treated with caution. 5. The indication for secondary surgery refers to the obstruction of more than one vascular bridge, or the expansion of atherosclerotic lesions to other blood vessels, and meet the above two indications. Contraindications 1. Diffuse coronary artery lesions, the distal vascular lumen of the lesion is <1mm or has been occluded. 2. Chronic heart failure, severe pulmonary insufficiency. 3. Left ventricular function is low, left ventricular ejection fraction <25%, or left ventricular end-diastolic pressure > 20mmHg. 4. Systemic atherosclerosis with hypertension or diabetes and renal insufficiency, etc., drugs can not be controlled, for relative contraindications. Preoperative preparation Satisfactory coronary angiography and left ventricular angiography are prerequisites for determining the surgical plan. In addition to the routine preparation of general cardiopulmonary bypass surgery before surgery, it is necessary to pay attention to the following points: 1. Carefully read coronary angiography, identify the location, extent and extent of the obstruction, estimate the number of grafts and determine the surgical plan. 2. Correct assessment of cardiopulmonary function, if left ventricular ejection fraction <30%, left ventricular end-diastolic pressure > 20mmHg or left ventricular end-diastolic volume > 103ml / m2, suggesting that left heart function is significantly impaired, for such patients before surgery Drug therapy should be done first to improve myocardial blood supply and increase cardiac function reserve. In addition, positron emission tomography should be performed before ischemic cardiomyopathy to understand the survival of myocardium in the ischemic area, which has guiding significance for the diagnosis of surgery, postoperative treatment and prognosis. 3. Pay attention to check the carotid artery for stenosis. For patients with carotid stenosis, simultaneous or staging surgery should be considered to prevent cerebrovascular complications. 4. For patients with hyperlipidemia, should be given a low-fat diet and anti-hyperlipidemic drugs. People with high blood pressure need to apply drugs to lower blood pressure to the normal range. People with diabetes can be operated with drugs before surgery. 5. Before surgery, adequate analgesia and sedation should be taken to prevent angina pectoris caused by emotional stress, and coronary artery spasm can be prevented by expanding the crown. Beta blockers can reduce myocardial oxygen consumption and reduce angina pectoris, and can be applied to patients with unstable angina pectoris. Surgical procedure 1. The internal mammary artery vascular bridge prepares the midline incision of the chest, and the left sternum is retracted upwards to the left to reveal the left internal mammary artery under the chest wall. The parietal pleura was bluntly excised from the intrathoracic fascia to the lateral side about 6 cm away from the sternal border. The small vascular communication branch between the chest wall and the mediastinum was cut with an electric knife. At this time, the inner breast vasculature under the pleural fascia appeared. . In order to better protect the blood vessel, the accompanying vein, the intrathoracic fascia and its adjacent tissue are generally formed into a pedicled vascular bridge. The intrathoracic fascia was incised 1 cm inside the inner mammary artery with an electric knife. The incision should be the full length of the vessel. The vascular pedicle was separated from the chest wall in the third and fourth costal cartilage planes, carefully treated and ligated. Its intercostal branches, small branches can be burned by electric burning, and the larger branches are clamped with silver clips. The upper edge of the inner vascular pedicle is separated from the origin of the left subclavian artery, and the lower edge is up to the sixth intercostal space. When separating the lower chest wall, in order to better reveal, sometimes the transverse muscles of the chest are freed. When the entire length of the vascular pedicle is free, the outer thoracic fascia is cut by electrocautery. Do not cut the distal end before systemic heparinization. Cover with saline gauze to keep it moist. After extracorporeal circulation intubation, the vascular pedicle of the distal wall of the chest wall was first ligated, and the distal vascular of the internal mammary artery was separated between the two ligature lines, and the intrathoracic fascia surrounding the end of the internal mammary artery was dissected. Fat pedicle tissue, ligation of all branches, measurement of the full length of the vascular pedicle to ensure no tension or tear after anastomosis. Insert the 22nd olive needle into the vascular cavity, inject the diluted papaverine solution (60mg diluted in 40ml normal saline) and gently dilate the lumen, pay attention to the presence or absence of leaks and repair. Remove the needle and measure the flow rate of the internal mammary artery, which should be above 100ml/min (normally 120-180ml/min). The prepared distal part of the vascular pedicle is clamped with a small vascular clamp and wrapped in saline gauze for later use. 2. Internal mammary artery-left anterior descending anastomosis technique: The left apex is slightly elevated with a gauze pad to expose the left anterior descending artery. The incision on the coronary artery should be smaller than that of the saphenous vein, generally 5 to 6 mm. The pedicled inner mammary artery vascular bridge was moved into the surgical field, and the broken end was cut into a 45° slant. The 7-0 polypropylene suture was applied, and the needle was firstly inserted from the heel of the internal mammary artery to the coronary artery. The proximal end of the incision is needled from the inside to the outside. After suturing 3 to 4 needles continuously, the suture was tightened so that the distal end of the inner mammary artery was aligned with the incision of the anterior descending branch. Continuous suturing is continued on both sides, and the excess internal mammary artery wall is cut off to the "toe" section, and the remaining part can be sutured continuously or 5-6 needle sutures are used to complete the anastomosis. Before ligation of the last needle suture, exhaust the vascular bridge and the gas in the coronary system, first compress the proximal end of the anterior descending artery, so that the distal return blood is reversely filled, loosen the proximal compression and the upper end of the internal mammary artery. After the gas is exhausted, it is ligated. Check for no blood leaks. Use a 2-needle suture to secure the thoracic fascia near the vascular bridge to the epicardium to reduce anastomotic tension and prevent tearing of the anastomosis.