1.Surgical indications
① Coronary artery bypass grafting is preferred for three-branch coronary artery lesions; ② bypass grafting is preferred for left main artery lesions; ③ single or double-branch coronary artery lesions, but the lesions are complex or diffuse and not suitable for medical intervention; ④ restenosis after stenting; ⑤ if there is a combined left ventricular ventricular wall tumor requiring surgical resection, the coronary artery lesion should be treated by bypass grafting at the same time and medical intervention should not be considered; ⑥ if there is an intracardiac operation such as valvuloplasty or replacement, or (6) If there is intracardiac surgery, such as valve angioplasty or replacement, or other intracardiac operations, coronary artery lesions should be bypassed at the same time, and medical intervention should not be considered.
2.Surgical counter indications
(1) The coronary artery lesion is diffuse or slender, and there is no alternative bypass vessel. To make this conclusion requires extensive experience in coronary surgery, especially for those with distal slenderness, the effect of insufficient coronary artery perfusion should be taken into account, and the combination of positive and negative perfusion should be considered.
(ii) No selective bypass material vessels are available. In general, we have bilateral internal mammary arteries, bilateral radial arteries, bilateral saphenous veins to choose from, the above vessels are not available and there are also gastric omental arteries, bilateral small saphenous veins to choose from, and the chance of not being available at the same time is very rare. If none of the above vessels are available, or if the total number of bridges is not enough, more sequential anastomoses and Y-shaped anastomoses can be chosen. In addition, the application of the superior abdominal wall artery and the veins of the upper extremity can be considered. Theoretically, any artery of the forearm can be taken. If the Allen test is positive, an artificial vessel can be applied instead.
(3) The general condition of the patient is poor. Some patients with coronary artery disease have long disease duration, heavy vascular lesions, patients have been bedridden for a long time, and their general condition is poor, and they are unable to sit up and move to the floor. Such patients need good drug adjustment and appropriate physical exercise, after a period of restorative exercise before giving the patient a conclusion.
④Severe functional impairment of other organs and organs. Post-stroke hemiplegia is not a contraindication to surgery, but in case of fresh stroke, it is advisable to wait for the stabilization of neurological symptoms, which should generally be more than one month, preferably more than three months, before coronary artery bypass surgery. Transient ischemic attack (TIA) generally has little effect and surgery can be scheduled after a few days. Coma is a contraindication to surgery.
Patients with renal failure and uremia should be discussed with nephrology. If the patient is stable on dialysis, bypass surgery can be done with one dialysis before surgery. If the patient has had a kidney transplant and the kidney function is stable, it is not a contraindication to surgery.
Respiratory function bypass
At present, we mainly look at Po2 and Pco2 and whether the patient has respiratory symptoms. The presence of respiratory failure is an absolute contraindication to surgery. If the patient does not have respiratory symptoms, we generally require Po2 to be above 60 mmHg and Pco2 to be less than 45 mmHg. The limit of Po2 is set at 55 mmHg for my personal experience, and there is no uniform standard. If there is no history of occupational disease, Pco2 should not be greater than 45mmHg, which is a more sensitive indicator. Individual coal miners we have also done Pco2 to 55mmHg, but in short if Pco2 is increased need to be carefully considered, 50mmHg or more we generally do not consider surgery, if necessary, can be combined with pulmonary function test comprehensive consideration.
There is no standard for the degree of liver impairment that contraindicates surgery, and it is usually necessary to consult with a hepatologist to discuss it together.
⑤ Patients with other more serious diseases, such as advanced malignancy, advanced AIDS, or various other diseases that have endangered the patient’s life.
⑥Patients and family members who do not agree to the surgery.
3. Surgery method
Conventional extracorporeal circulation CABG is still routinely used in the median sternal incision. Although the second subcostal incision in the lower sternum can be used in some patients, it greatly increases the difficulty of surgery. The incision is made from about 1 cm below the superior sternal fossa to about 2-4 cm below the saber process, and the skin is incised, and the skin tissue and chest wall fascia are cut with an electrocoagulation knife. The sternotomy is rarely deflected to both sides if the line connecting the saber and the sternum is used as the lower marker point and the upper marker point is used as the upper marker point. The sternotomy is carefully hemostatic, and the bone marrow is hemostatic with bone wax or hemostatic gauze.
At this point, it is advisable to place a small sternal retractor, dissect the thymic tissue, fully expose the pre-cardiac pericardium of the ascending aorta, and separate upward to the innominate vein. If the thymus tissue is too much and affects the surgical exposure, partial resection can be done. We routinely dissect the pericardium for coronary artery exploration before taking the internal mammary artery, especially the anterior descending branch. If a vessel is not well visualized on preoperative imaging, it is difficult to determine whether the vessel can be bypassed before surgery, so appropriate exploration should be done to determine how many bridges are needed and how long the vessels should be. The principle of exploration is not to obviously affect the patient’s blood pressure, not to cause the patient ischemia and other acute events, and basically determine the number of bypass branches.
It is advisable to start the procedure with simultaneous acquisition of the radial artery and saphenous vein. After dissection of the pericardium, the coronary vessels are explored and the internal mammary artery is obtained.
If the perfusionist is on the same side as the surgeon, the extracorporeal circulation tube is routinely placed on the table before opening the chest. If the perfusionist is on the opposite side of the surgeon, the extracorporeal circulation tube is placed on the table after taking the radial artery if the left radial artery is taken, and before opening the chest if the radial artery is not taken. As a routine preparation, it is also advisable to attach the intracardiac defibrillator before the opening of the chest and fix the right sterile surgical sheet of the first assistant.
Heparin 3mg/kg is injected intravenously when the proximal freeing of the left internal mammary artery is basically completed, and ACT is measured for 5 minutes, so that the ACT value reaches more than 480 seconds before the extracorporeal circulation is diverted (the ACT value required for diverting should be adjusted according to the different instruments and methods used in patients who have applied peptidase intravenously before blood sampling).
After the internal mammary artery is removed, the large sternal retractor is replaced and the superior and right pericardium are suspended in order to reveal the aortic root and right atrium, while the left pericardium does not need to be suspended. The aortic root is made double-loaded as far as possible against the upper part and single-loaded near the root. A larger load is made on the right atrial surface lateral to the right auricle, and the aortic duct, aortic root arrest fluid perfusion duct, and venous return to the cavernous atrium duct are inserted.
The length and quality of the taken radial artery were checked for bleeding points before transfer, and the branches were ligated, and the lacerations were made with 7/0 Prolene for purse-string sutures. Check the adequacy of blood flow in the left internal mammary artery. The ideal internal mammary artery blood flow should reach a straight line ejection, if the blood flow rate is not satisfactory enough, there are three ways to deal with it: First, observe its blood flow after transferring in extracorporeal circulation. Second, the blood flow is not satisfactory to determine the distal vessels of which there is no problem, do free internal mammary artery. Third, if the vessel itself is not determined to have problems or if problems are determined, the vessel is discarded. If the internal mammary artery is of good quality, the pericardium should be slotted close to the LAD and separated upward along the left pleura to the superior end of the left internal mammary artery, thus enabling the left internal mammary artery to pass flat and straight outside the left pleura to the LAD.
Extracorporeal circulation is started, the temperature is maintained at 32-34°C, and after full flow the ventilator is stopped, the heart is evacuated, and a surface exploration of the heart is done.
The general order of exploration is RCA system, LCX system and LAD, combined with the preoperative coronary angiography to explore the thickness of the bypass vessel, local plate, calcification, and the appearance of the distal vessels, select the appropriate anastomosis position, and compare with the preoperative coronary angiography, and use a 15-gauge circular knife to cut the epicardium on the surface of the local vessels as a marker; after the exploration, the number of bypass branches should be determined, and the length of the bypass vessel should be estimated. The number of bypass branches should be determined and the length of the vessels taken should be estimated. Vascular exploration should generally be completed before cardiac arrest. After cardiac arrest, the coronary artery deflates and becomes pale, which is not conducive to exploration, and the coronary vein can easily be mistaken for an artery if inexperienced, resulting in serious consequences.
Before ascending aortic block I personally routinely separate the main-pulmonary artery gap and place a blocking forceps. No ice chips or ice water is placed on the body surface of the heart, and the aortic root is perfused with cardiac arrest fluid, and the first bridge vessel anastomosis is started after perfusion is completed.
The routine bypass sequence is usually done first for the RCA system, and the most commonly selected part is the PDA. 2-3 pieces of wet gauze are placed at the bottom of the heart, so that the cardiac diaphragm is reversed upward, parallel to the upper part of the PDA, and a piece of wet gauze is placed near the pre-anastomosis site, and the first assistant presses the gauze with the four fingers of the right hand, and the finger end is close to the lower edge of the gauze to get a good exposure.
Before the operation, the first assistant and the first assistant each clamp the epicardium on both sides of the vessel, and use a 15# circular knife to cut the epicardium until the surface of the vessel, revealing the vessel only needs to reveal the anterior wall, do not free out the lateral wall, which is easy to cause injury, and too much freeing is also easy to cause distortion of the anastomosis, as shown in the figure.
After freeing, a small incision is made in the anterior wall with a coronary tip knife (be careful not to pierce the posterior wall of the coronary artery, especially for small coronary arteries), and the incision is cut upward and downward with Portts forceps to 4-6 mm, and the graft is fixed to the wet gauze at the lower edge of the thoracic incision with small strips of forceps to start the anastomosis.
The anastomosis is performed by applying a counterstitch to the end of the graft vessel (tentatively designated RA). The second stitch is placed at the heel of the RA end from the outside to the inside and at the tip of the corresponding proximal coronary incision from the inside to the outside; the third stitch is placed at the left side of the heel of the RA and at the right side of the coronary incision, and the sutures are placed simultaneously. After the first three stitches are closed, the suture is tightened and the RA is placed under the coronary vessel.
The right side of the original anastomosis line is still used, and the RA is sutured from the outside to the inside, and the coronary end is sutured from the inside to the outside continuously, and the last few remaining stitches can be used to reverse the suture at the other end.
The key to the anastomosis of the gyral branch is good exposure. Adequate wet gauze should be placed at the base of the heart so that the apical part of the heart is elevated upward, and the obtuse marginal branch, even at the left atrioventricular sulcus, can be better revealed by pressing the heart laterally with wet gauze. The anastomosis and dissection of the coronary artery are performed in the same way as the PDA branch, and the sequence of the anastomosis needle is also the same as that of the PDA branch, but because of the relatively poor exposure, errors such as suturing to the posterior wall and tearing of the vessel wall are likely to occur and should be avoided.
The anastomosis of the intermediate branch, diagonal branch and anterior descending branch has many similarities, which are described here together.
The first three stitches of the bridge vessel and coronary artery are inserted in the same way as PDA and OM, but the next anastomosis is performed by changing the other end of the anastomosis line, first from the coronary side from the outside to the inside, and from the bridge vessel side from the inside to the outside, and then the remaining anastomosis is completed by another suture after turning over the toe.
My method for LAD anastomosis using internal mammary artery is to dissect the longer vessel at the LIMA anastomosis, dissect the vessel facially at the excess end and analyze it by stacking it on the distal end of the anastomosis, and make 3 fixed sutures at the distal and proximal sides of the anastomosis respectively after the anastomosis is completed. This is the more special part of my anastomosis method. There are many advantages of this anastomosis method, which can be experienced slowly in application.
It is usually possible to rewarm the heart at the beginning of the anastomosis from LIMA to LAD, and the ascending aorta can be opened after the completion of the LIMA to LAD anastomosis to allow the heart to resume beating.
After the heart resumes beating, the lateral wall clamp on the aortic root is used to do the proximal anastomosis. After the proximal anastomosis is completed, respiration can be resumed, extracorporeal circulation can be gradually stopped and heparin can be neutralized.
4. Hemostasis off the chest
After checking the anastomosis and the mouth of the bridge vessel, the pericardium can be partially closed. The closure of the pericardium starts from the upper end and gradually closes down to the middle of the right ventricle. Generally, the first stitch at the upper end should be sutured at the edge of the pericardium, and downward according to the situation whether to close the pericardium or to close the loose tissue outside the pericardium, so that the pericardium can be partially closed to protect the bridge vessels and not affect the filling of the heart as appropriate.
After hemostasis is complete, two mediastinal drainage tubes are placed in front of the heart (if the pleura is broken on one side, one can be placed in the mediastinum and one in the chest). Epicardial pacing leads may be placed.
To close the adult sternum I follow a policy of applying at least six wires and then 1 wire/10kg depending on the patient’s weight; two are placed above the sternal angle and the rest below, good fixation reduces incisional complications.
Two layers (2/0) of absorbable sutures are applied to the anterior sternal muscles and fascia as well as to the subcutaneous tissue, and one layer (4/0) of intracutaneous absorbable sutures.