Endovascular isolation of abdominal aortic aneurysm

Endovascular exclusion of abdominal aortic aneurysm is used for the treatment of abdominal aortic aneurysm. Classical abdominal aortic aneurysm resection (accurate name is abdominal aortic aneurysm incision vascular replacement) with large trauma, multiple complications, and high mortality. Many elderly patients or those with underlying diseases such as heart, lung, liver and kidney have lost the opportunity to treat because of the inability to tolerate such surgery. In 1990, Parodi first carried out endovascular isolation, which was subsequently promoted and improved globally, opening up new therapeutic approaches for patients with abdominal aortic aneurysms. Endovascular grafting is to introduce the stent-artificial vascular complex (the outer layer is a polyester artificial blood vessel, and the inner layer is a refillable metal stent) into the abdominal aorta. After inflation, the abdominal aortic aneurysm is isolated from the vascular lumen, prompting it to gradually Machine and shrink, thus eliminating the hidden danger of tumor rupture and bleeding, and achieving the goal of cure. A variety of introduction (tool) systems and graft systems have been developed for the implementation of endovascular graft exclusion. Here, the TALENT system currently widely used in China is briefly introduced. The introduction system consists of a silicone plastic sheath (16-17F), a multi-lumen catheter (with a central balloon under the tip for dilating the graft, and some with a balloon at the tip for blocking proximal blood) Flow) and push rod (with a stainless steel cap on the front). The graft is fully elastic and self-expanding, and has three types: straight tube type, bifurcation type and aortic-iliac artery type. The components are: 1 self-expanding stent, which is made of a single titanium-plated nickel alloy wire which is Z-folded into a ring; 2 polyester woven unthreaded artificial blood vessel. Before use, several stents were sequentially inserted into the artificial blood vessel, the stent was kept at a pitch of 5 mm, the polyester thread was continuously sutured, and all the stents were connected by a straight wire. This full-grade internal stent graft has a certain bendability and sufficient strength. A slightly larger diameter Z-shaped stent is placed on the proximal and distal ends of the graft, one end is sutured to the graft, and the other end is exposed to the artificial blood vessel in a flared shape to provide sufficient circumferential tension to maintain the graft. The seamless combination of objects. Appropriate grafts should be selected based on various parameters measured by preoperative CT angiography. Treatment of diseases: abdominal aortic aneurysm Indication Abdominal aortic aneurysm is suitable for: 1. In principle, all abdominal aortic aneurysms below the renal artery opening and proximal tumor neck 1.5 cm are indications for endovascular exclusion. However, at present, endovascular exclusion is mostly used in patients with older age, with more serious disease or multiple morbidity, and can not tolerate traditional abdominal aortic aneurysm replacement. 2. If the distal neck is 1cm, a straight tube or a bifurcated graft can be used. 3. If the tumor invades the aorta bifurcation and the distal neck disappears, a bifurcated graft must be used. 4. If the tumor invades the common iliac artery, it is necessary to extend the single branch on the basis of the bifurcated graft, and sometimes even extend to the external iliac artery (blocking the internal iliac artery). Contraindications 1. The location or shape of the abdominal aortic aneurysm is not suitable for patients with endovascular exclusion, such as a wide range of thoracic and abdominal aortic aneurysms or proximal cervical neck <1.5 cm and thus unable to fix the graft. However, in recent years, grafts with a bare stent at the proximal end have been developed. The proximal renal aortic aneurysm is not an absolute contraindication. 2. Introduce the pathological lesions to make the operation difficult to complete, such as bilateral iliac artery severe stenosis twisted and the guide wire, catheter can not pass. 3. There are serious associated diseases, such as severe myocardial insufficiency, arrhythmia, difficult to correct heart failure, severe renal dysfunction, severe coagulopathy. 4. Coexisting with malignant tumors or other serious diseases, the life expectancy is not more than 1 year. Preoperative preparation 1. Comprehensive examination, focusing on the investigation and careful evaluation of the patient's heart, lung, liver, kidney and coagulation system function. 2. If there is a combination of hypertension and diabetes, the treatment should be strengthened and controlled as much as possible. 3. Carefully prepare the skin for puncture and placement. 4. Enteral enteric-coated aspirin (50 mg, 4 times / d) and dipyridamole (25 mg, 3 times / d) 3 days before surgery. 5. Indwelling catheterization before surgery. 6. Prophylactic antibiotics. Surgical procedure 1. Select the side of the radial artery that is smooth, and walk along the femoral artery under the inguinal ligament to make a longitudinal incision about 5cm long. Dissect a section of the common femoral artery 3cm long. The distal and distal ends are respectively passed through the hemostatic sling. 2. The femoral artery was punctured by Seldinger method under direct vision and introduced into a 5F catheter sheath. 3. The guide wire is fed into the abdominal aorta through the guide sheath, and the pig tail catheter is sent along the guide wire to the level of the 12th thoracic vertebra, the guide wire is withdrawn, and the aorta is performed. 4. After the corresponding marking on the monitor screen, accurately measure the length and diameter of the neck and the tumor, the diameter of the common iliac artery, the distance from the renal artery opening to the opening of the internal iliac artery, and preoperative spiral CT and magnetic resonance angiography. Results Control, according to which the appropriate caliber and length of the graft were selected. The following is a description of the most common bifurcation implant placement methods. 5. After inserting the super-strong guide wire, the catheter was withdrawn and the heparin was intravenously injected with 125 U/kg to make the whole body heparinized. A transverse incision of the femoral artery was made about 1/2 of the circumference with the puncture point as the center, and the TALENT catheter was introduced along the guide wire to the abdominal aorta. When the upper edge of the graft reaches the opening of the renal artery, the front end of the graft is released, and the graft is pulled distally so that the preset upper edge marker of the graft coincides with the lower edge of the renal artery opening, and then the attached catheter is attached. The balloon expands the proximal end of the graft and secures it to the wall of the abdominal aorta. 6. Keep the balloon filled to fix the graft, and withdraw the outer sheath tube, so that the released memory alloy stent is automatically opened, the short arm of the lower end of the graft is located in the tumor body, and the long arm enters the radial artery. The balloon is slowly withdrawn, during which the graft is expanded segment by section and fixed to the vessel wall. 7. Expose the contralateral common femoral artery, insert the superhard guide wire into the graft body through the short arm opening of the graft after puncture. The femoral artery is incised, and the artificial blood vessel of appropriate length is fed into the short arm of the graft along the guide wire. After accurate positioning, the single branch is released, and the single branch is automatically opened, and the short arm of the graft is properly connected, and the connecting portion at least overlaps. The length of one of the stents is fixed to the wall of the radial artery. 8. Perform abdominal aorta angiography again to observe whether the graft and renal artery and iliac artery are unobstructed, whether the graft is distorted or ectopic, and whether there is endoleosis at the proximal and distal ends. 9. After confirming that the tumor has been completely isolated, exit the TALENT catheter and suture the femoral artery incision laterally with a 5-0 Prolene line. The incision was sutured layer by layer. 10. The straight tube type graft only needs to fix its distal end above the abdominal aortic bifurcation, which is easier to operate, but it has been less used because of the tendency of the abdominal aortic aneurysm to spread to the distal end. complication Internal leakage The incidence rate is about 7% to 20%. Persistent internal hemorrhoids can lead to failure of endovascular grafting, and the tumor continues to expand or even rupture. The main causes of endoleak leakage include: 1 improper selection of indications (calcification of plaque in the neck wall of the tumor, severe distortion of the neck, a large number of plaques on the aneurysm wall, etc.); 2 improper selection of grafts; 3 grafts The caliber and length are not appropriate; 4 the lumbar artery and the inferior mesenteric artery that remain unobstructed have not been treated. Secondary endoleak can be found by anterior abdominal aortic angiography; the diagnosis of delayed endoleak depends on regular follow-up. The proximal endoleak has the most serious consequences and should be resolved immediately during surgery. The balloon can be properly expanded in the neck of the tumor, or a sleeve can be added, which generally works. If there is still a large amount of internal leakage, traditional surgery should be performed decisively to avoid rupture. Most of the endolecular leakage at the distal attachment point is caused by a mismatch between the graft and the artery. Prolonging a segment of the graft is usually effective, but avoiding simultaneous isolation of the bilateral internal iliac artery. 2. Renal artery occlusion Renal artery occlusion occurs mostly immediately after the release of the graft. The reason is that the positioning is inaccurate or the operation is incorrect, causing the stent to cover the renal artery opening. Delayed renal artery occlusion after surgery in a small number of patients may be related to the interference of renal artery hemodynamics with the naked stent of the graft. Renal artery occlusion can lead to renal dysfunction and hypertension, but if the area of renal infarction is not large, renal function may be reversed, and hypertension can also be controlled by drugs. If the renal artery is completely occluded, abdominal aorta-renal artery bypass surgery is required. 3. Abdominal aortic aneurysm endovascular exclusion syndrome Some patients have unexplained fever after surgery, generally no more than 38.5 ° C, red blood cells, white blood cells and platelet count decreased, transient C-reactive protein increased, but no evidence of infection, so generally referred to as "postoperative syndrome" . The mechanism of occurrence is still unclear, and may be related to the absorption after thrombosis in the tumor cavity, the foreign body reaction of the graft, and the mechanical damage of the graft to the blood cells. Symptomatic treatment can be done with non-steroidal analgesics (such as indomethacin) and adrenal glucocorticoids. 4. Ischemic colitis Occurred in the sigmoid colon, the main reason is the sigmoid collateral circulation after the inferior mesenteric artery occlusion. Therefore, the internal iliac arteries on both sides should not be isolated or embolized at the same time, at least one side remains unobstructed. The immediate incidence of sigmoid ischemia is very high (>50%), but it is rare. After endovascular grafting, most of the ischemia is caused by the occlusion of the internal iliac artery, and the condition is progressive. There is a process from symptom onset to intestinal necrosis. Early detection and early treatment are very important. The main symptom is abdominal pain. Colonoscopy reveals that the intestinal mucosa is pale, edematous or scattered at the bleeding point. The use of vasodilators and drugs that reduce blood viscosity, dredge microcirculation, and promote the establishment of collateral circulation as soon as possible are the main treatment measures, and the effect is still good. If intestinal necrosis occurs, it can only be surgically removed.