Aortoiliac artery occlusion is the most common arterial occlusive disease. The cause is mostly atherosclerosis. Its prevalence increases with age: about 10% of men over 65 years of age have lower extremity atherosclerotic occlusive disease, while the prevalence in people over 75 years of age is 20%. Treatment methods mainly include basic treatment based on drug therapy, open surgical treatment represented by classical surgical bypass and the newly developed endovascular treatment. With the maturity of surgical techniques and the continuous improvement of vascular graft materials, surgical bypass has a relatively superior long-term patency rate, thus maintaining its traditional status of revascularization. Endovascular techniques are gradually accepted by clinicians and patients for their minimally invasive, safe, and effective advantages, and have tended to surpass bypass surgery in terms of the number of applications. Aortoiliac artery occlusion is far more difficult to manage than simple iliac artery occlusion, so this article describes the endoluminal treatment of this disease compared to iliac artery occlusion. The anatomic staging of aortoiliac occlusion is the most common type of arterial occlusion. According to the extent of the lesion involving the artery, it can be divided into 3 types. Type I: main-iliac artery type, accounting for about 10%. The lesion involves the bifurcated segment of the abdominal aorta and the common iliac artery. The typical clinical presentation is Lerich’s sign: intermittent claudication and sexual dysfunction. The relatively normal iliac artery and its distal arterial bed provide a good outflow tract for the performance of bypass diversion. Type II: main-iliac-femoral artery type, accounting for approximately 25% of cases. The lesion involves the bifurcated segment of the aorta, the common iliac artery, the external iliac artery, and the proximal segment of the femoral artery. The N artery and its distal artery usually remain patent, with intermittent claudication of the lower extremities as the main clinical manifestation. Type III: Multi-segmental obstruction type, accounting for about 65% of cases. The lesion may occur in a wide area from the aortic bifurcation to the tibio-fibular artery, showing multiplanar stenosis or obstruction, and may involve one or more branches including the deep femoral artery and three main arteries of the lower leg. As a result, the clinical manifestations are severe, with severe intermittent claudication or resting pain, ischemic necrosis or ulceration of the distal limb, and the risk of amputation. For iliac artery stenosis lesions, the ipsilateral femoral artery approach is mostly chosen, while for those who need precise positioning of the distal end of the stent, the contralateral femoral artery approach is mostly chosen and a vascular sheath of corresponding length is applied. For occluded iliac artery lesions, preoperative ultrasound-guided puncture of the ipsilateral femoral artery is required to provide access to the procedure and to ensure that the distal end of the lesion is within the true lumen of the vessel. A unilateral iliac artery occlusion is often chosen from the contralateral femoral artery, or from the brachial artery via the upper extremity. After the guidewire passes through the occluded segment, a catcher is fed from the distal puncture site of the diseased vessel, and the guidewire is pulled out of the true lumen of the ipsilateral femoral artery vessel for endoluminal treatment via the distal side of the lesion. In the case of bilateral iliac artery occlusion, a brachial artery approach is often chosen, and the guidewire is managed to pass through the occluded segment and then pulled out of the body through the true lumen of the femoral artery on both sides using the catcher as the working guidewire for the subsequent “kissing method” (i.e., simultaneous balloon dilation and simultaneous release of the stent on both sides). (2) Opening of the occluded segment Through the above access, one or more of the following techniques are used to open the occluded iliac artery according to the location and extent of the lesion: the bi-directional fluoroscopic technique of the guidewire catheter and the patient opening using the “path mapping technique”. If the lesion is severely calcified and the guidewire catheter is difficult to open, ultrasound ablation and “alternating step technique” are first applied to open a narrow “tunnel”, and the guidewire is guided through the occluded segment and then a small diameter balloon is used for experimental dilation, followed by a predetermined diameter balloon for dilation. (3) Revascularization For stenotic lesions, PTA is used, and the balloon diameter is about 1 mm larger than the normal diameter, and its length covers the lesion as much as possible. If the length of the lesion is longer than the balloon, the balloon should be placed at one end of the stenosis first and then gradually shifted, but there should be partial overlap before and after each shifting and expansion. After PTA, if the residual stenosis is greater than 30% or the pressure difference across the stenosis is greater than 10 mmg, an internal stent is placed. If the lesion is severely calcified or if plaque dislodgement is predicted to cause distal vessel embolism, an internal stent is placed directly, and then post-dilated if stent deployment is unsatisfactory. For bilateral iliac artery occlusion involving the terminal opening of the abdominal aorta, PTA and placement of the internal stent are performed by the “Kissing” method, i.e., simultaneous balloon dilation on both sides and simultaneous release of the stent, with both stents requiring 2-3 cm beyond the bifurcation of the iliac artery and consistent stent opening. 3. Techniques to improve technical success and efficacy (1) Reasonable access, application of long sheath and catcher: correct access is the basis and guarantee of successful surgery, and as much as possible, choose the access with short operation diameter for easy operation and control. For iliac artery stenosis lesions, the ipsilateral femoral artery approach is mostly chosen, while for those who need precise positioning of the distal end of the stent, the contralateral femoral artery approach is mostly chosen, and a long metal vascular sheath is applied to reach the opening of the contralateral common iliac artery to facilitate the delivery of the stent, and the stent can be readily imaged via the vascular sheath to facilitate the positioning of the stent. Bilateral iliac artery occlusion should be selected for transcranial access, whereas ipsilateral femoral access is generally not chosen in cases of complete occlusion to avoid causing aortic coarctation. For occluded iliac artery lesions, the key to the success of the procedure is to ensure the return of the guidewire to the true lumen after passing through the occluded segment. The use of a catcher to pull the guidewire out of the true lumen of the vessel to establish subsequent working access is often effective. (2) Thrombolysis before recanalization: arterial catheter directed thrombolysis as the basic treatment for endoprosthesis can dissolve the thrombus secondary to arterial stenosis or occlusion and facilitate the opening of the diseased artery; even if there is no significant improvement in imaging after thrombolysis, the opening of the lumen of the occluded artery can be experienced more easily intraoperatively. (3) Subendothelial angioplasty technique: The basic principle of subendothelial angioplasty is to use a guidewire catheter to sharply cut the endothelium in the proximal segment of the lesion wall to reach between the endothelium and the mesothelium, and to extend this potential lumen to the distal part of the lesion, until the endothelium is broken again to re-enter the distal true lumen. The key points of the technique include monitoring the head end of the guidewire throughout the procedure, rotating the guidewire under the support of the catheter to enter the subendothelium of the occluded proximal endothelium with the J-shaped end of the guidewire in the form of a collaterals, when the resistance will suddenly decrease, if the resistance increases instead, it means that the entry level is wrong and should be withdrawn and repeatedly tried until the resistance decreases. When advancing subintima, operate gently, keep the guidewire in J-shape and advance slowly to avoid wide collaterals, do not be impatient or use violence to prevent penetration of the arterial wall or breakage of the guidewire. The direction of the tip of the guidewire is controlled by the catheter to advance along the artery until it enters the true lumen again. Subintimal angioplasty re-establishes a smooth new lumen free of atherosclerotic plaque and intimal tissue, reducing the chance of luminal stenosis due to distant intimal hyperplasia. (4) Intravascular ultrasound ablation technique: Intravascular ultrasound ablation for peripheral vascular disease started to be used clinically in China in the late 1990s, and has demonstrated better efficacy and safety. The principle is the “acoustic cavitation” effect of low frequency (20-45 KHz) high energy ultrasound on the liquid phase material. The cavitation effect can trigger the “internal explosion” of thrombus and plaque, generating temperature, energy and high local pressure up to 1-3 atmospheres, which can break the thrombus and plaque into tiny particles, 95% of which are no more than 10-20 µm and can be digested by enzymes in the blood and engulfed by the reticuloendothelial system, without causing distal vascular It can be digested by enzymes in blood and engulfed by reticuloendothelial system. At the same time, ultrasound ablation also has a certain mechanical fragmentation effect and activation of the fibrinolytic system. Because of its specific wavelength, ultrasound ablation can re-establish blood flow in completely occluded arteries without serious pathological damage to the intima, and the ablated atherosclerotic plaque and thrombus fragments have no effect on the distal vessels. For lesions with severe calcification, ultrasonic ablation can be performed by “alternating step technique” to open a narrow “tunnel” in the occluded arterial lumen first, and then supplemented by balloon dilation, stent placement and other angioplasty techniques to obtain better treatment results. In summary, with the advancement of technology and the accumulation of clinical experience, endoluminal treatment has been increasingly used as the treatment of choice for aortoiliac artery occlusions because of its safety, effectiveness, and minimally invasive advantages. The improvement of its technical success rate and long-term efficacy is largely dependent on the clinician’s in-depth understanding of medical imaging, careful study and mastery of each interventional device, individualized treatment plan design and patient surgical operation for each patient.