descending aorta replacement

Lower aortic replacement is applicable to: 1. Thoracic descending aortic aneurysm is more common in arteriosclerosis, often with fusiform lesions. Because its blood vessel wall is relatively fragile, it is prone to rupture. If the diameter of the tumor is above 6.0cm, surgical treatment is needed. 2. Type III arterial dissection, in the chronic phase, whose outer diameter is above 6.0 cm; in the acute phase, continuous exfoliation to the ascending aorta or outer diameter > 5.5 cm, or when a cystic aortic aneurysm has formed and will rupture, Or blood pressure and pain are not easy to control, should be treated surgically. 3. Pseudoaneurysm or traumatic aneurysm, regardless of its outer diameter, should be operated as soon as possible. 4. After the ascending aorta and arch replacement in the type I arterial dissection, the diameter of the descending aortic aneurysm was >6.0 cm or more. 5. Type I, II, and III of thoracic and abdominal aortic aneurysms. Treatment of diseases: abdominal aortic aneurysm Indication Lower aortic replacement is applicable to: 1. Thoracic descending aortic aneurysm is more common in arteriosclerosis, often with fusiform lesions. Because its blood vessel wall is relatively fragile, it is prone to rupture. If the diameter of the tumor is above 6.0cm, surgical treatment is needed. 2. Type III arterial dissection, in the chronic phase, whose outer diameter is above 6.0 cm; in the acute phase, continuous exfoliation to the ascending aorta or outer diameter > 5.5 cm, or when a cystic aortic aneurysm has formed and will rupture, Or blood pressure and pain are not easy to control, should be treated surgically. 3. Pseudoaneurysm or traumatic aneurysm, regardless of its outer diameter, should be operated as soon as possible. 4. After the ascending aorta and arch replacement in the type I arterial dissection, the diameter of the descending aortic aneurysm was >6.0 cm or more. 5. Type I, II, and III of thoracic and abdominal aortic aneurysms. Contraindications 1. Obvious or severe pulmonary ventilatory insufficiency. 2. Renal failure, or severe liver dysfunction. 3. The general condition is poor, or there is obvious cerebrovascular disease. Preoperative preparation 1. Identify the extent and extent of the lesion. Spiral CT or MRI angiography reconstruction or digital subtraction angiography (DSA) must be routinely performed. Because most patients with descending aortic aneurysm are older, have hypertension and arteriosclerosis, or have hyperlipidemia and diabetes, special attention should be paid to the presence or absence of coronary heart disease, carotid stenosis, etc. in preoperative examination. If there is severe carotid stenosis, Surgical treatment should be performed before aneurysm surgery. 2. Carefully check kidney function, lung ventilation and ventilation function, with or without diabetes or hypothyroidism. For smokers, stop smoking for at least 2 weeks before surgery. 3. For the arterial dissection, the blood pressure should be controlled at 100-120mmHg before operation, and the drug should be used to prevent the blood pressure from rising and the interlayer to be ruptured. 4. If you need to apply deep cryo-circulatory surgery, you should prepare 10 to 20 U of platelets or 1000 ml of fresh blood before surgery. Surgical procedure Simple blocking method That is, the descending aorta is blocked at the upper and lower ends of the aneurysm at normal temperature, the aneurysm is excised or cut, and the artificial blood vessel is transplanted. Because the aorta is blocked, the burden on the left heart is increased, and at the same time, the aorta blocks the vital organs at the distal end, such as spinal cord, liver, kidney and other ischemia, especially the spinal cord tissue is most vulnerable to ischemia and hypoxia. . The safe time to tolerate ischemia after blocking the thoracic aorta at room temperature is 45 minutes for the kidney, 30 minutes for the liver, and 20 minutes for the spinal cord. Spinal cord tissue is ischemia for 20 minutes at room temperature, which may lead to serious complications of permanent paraplegia. Therefore, the simple blockade method is only suitable for true or pseudoaneurysms with a small range of proximal aorta. The length of the aneurysm is generally less than 10 cm, and the aortic occlusion forceps are easier to place on the upper and lower ends of the aneurysm. (1) Left chest posterolateral incision: the chest is inserted through the 6th or 6th intercostal space, and the rear end of the upper rib or the next rib is cut to enlarge the incision. (2) free aneurysm: acute or blunt separation of aneurysm and adhesion of lung tissue, free upper and lower end of aneurysm until the placement of blocking forceps, free ligation of the intercostal artery connected with the aneurysm, right rib The inter-arterial artery can be temporarily free from ligation. If the aneurysm is located below the 8th intercostal artery, it must be preserved. Do not free ligation. (3) Blocking the thoracic aorta: Before blocking the thoracic aorta, intravenous heparin 1.5 mg/kg, and the arterial pressure was reduced to 90-100 mmHg with sodium nitroprusside, and a blocking forceps was placed on the upper and lower end of the aneurysm. (4) Transplantation of artificial blood vessels: After cutting the thoracic aorta, the tumor is quickly cut, the blood is exhausted, the right intercostal artery opening is sutured, and an artificial blood vessel of appropriate size is taken, with 3-0 or 4-0 polypropylene. The line was firstly anastomosed, and the posterior wall was sutured first, and then the anterior wall was sutured. The distal anastomosis was completed in the same way. Pay attention to the stitch length and margin as much as possible when sewing. When the descending aortic aneurysm does not exceed the eighth intercostal artery, there is no need for intercostal artery grafting. (5) Open blocking forceps: first open the proximal blocking forceps, and then gradually open the distal blocking forceps according to the arterial pressure to prevent severe hypotension caused by sudden release of the blocking forceps. At the same time, rapid infusion, blood transfusion, and maintain arterial pressure above 80mmHg. According to the patient's weight and blocking time, an appropriate amount of sodium bicarbonate was intravenously administered to correct metabolic acidosis caused by distal ischemia. Use a dry gauze to compress around the anastomosis. (6) Hemostasis: When the blood pressure is basically stable, the protamine is injected with heparin, and the anastomosis is checked at the same time. If there is no active bleeding, the residual tumor wall is wrapped around the artificial blood vessel to achieve the purpose of stopping bleeding. (7) Close the chest: bilateral lung ventilation, to ensure that there is no bleeding after the anastomosis, place the left chest drainage tube and close the chest. Arterial blood gas must be reviewed before closing the chest to completely correct acidosis. complication Paraplegia The most serious complications after descending aortic aneurysm. The main reason for this is that intraoperative spinal cord ischemia exceeds its safe time limit or intraoperative intercostal artery is not properly transplanted. The general incidence is 2% to 8%. The incidence of thoracic and abdominal aortic replacement is generally higher than that of simple thoracic descending aortic replacement. 2. hoarse voice Intraoperative injury vagus or recurrent laryngeal nerve, the incidence rate is 5% to 10%, some patients can fully recover after surgery, but intraoperative electrocoagulation injury or disconnection, you need to perform vocal cord surgery to restore the vocal cords Normal function. 3. chylothorax Intraoperative injury to the thoracic duct, mostly in the lower thoracic aneurysm or distal subclavian artery aneurysm, damage the thoracic duct, the incidence rate is 1% to 5%. If the drainage fluid is not much (<500ml/d) after surgery, conservative treatment can be performed, otherwise the chest tube should be opened or sutured in time. 4. Pulmonary bleeding Mainly due to systemic heparin, repeated compression of lung tissue in the left chest operation, and poor left heart drainage. Generally, after protamine and heparin, intrapulmonary hemorrhage stops. However, blood or blood clots in the trachea and bronchi should be fully aspirated after surgery to avoid lung infection or atelectasis.