Severe ischemia of the lower limbs with pain around the clock, sitting on the knees and unable to walk, is currently the cause of the highest rate of amputation in lower limb vascular lesions. It seriously affects the quality of life of patients and brings a serious burden to the whole family. Although there are many surgical methods, the efficacy is not very satisfactory. This type of disease is also a major problem in the current vascular surgery community. In our department, based on the past in situ saphenous vein bypass diversion, we recently performed interposition of artificial vessel (under local anesthesia) plus in situ saphenous vein arterialization in two patients who were on the verge of amputation with severe ischemia in the lower limbs, and the patients recovered well after the surgery. The patient was diagnosed with thrombo-occlusive vasculitis, acute arterial thrombosis of both lower extremities, old heart infarction, and atrial appendage thrombosis in the local hospital, and the right lower extremity pain cyanosis was relieved after giving urokinase thrombolytic therapy. In April 2009, the patient came to a major hospital in Beijing and underwent embolization of the left femoral artery first, and then had a high amputation of the left thigh. In November 2010, the patient again developed coldness and numbness in the right toe, and the pain worsened, and was again seen at the original operating hospital, where the artificial vessel was completely occluded. He was admitted to our department in January 2012 for further treatment, and his right foot became cold and numb, and his resting pain worsened, requiring intramuscular injection of dulcolax 5-6 times a day for relief. He was admitted to our department in January 2012 for further treatment. Examination: changes after high amputation of the left lower limb. Doppler auscultation: no pulsating sounds were heard in the right dorsalis pedis artery, anterior tibial, N and femoral arteries. Auxiliary examinations: ECG: sinus rhythm, not excluding inferior wall myocardial infarction, II, III, avF abnormal Q waves; echocardiography: EF: 37%, aortic sclerosis, left atrial left ventricular enlargement, mitral valve closure insufficiency, left ventricular wall motion is reduced, left atrial abnormal mixed echogenic mass, size about 2.4*1.5 cm (old attached wall thrombus), cardiac function; lower limb artery ultrasound: right lower limb posterior tibial and No blood flow signal was seen in the segmental arteries of the N artery, and the artificial vessels were occluded. CTA of both lower extremities: abdominal aortic stenosis, partial occlusion of the left iliac artery, complete occlusion of the artificial vessels of the right lower extremity, occlusion of the right external iliac, common femoral, and superficial femoral arteries, and the establishment of collateral circulation was seen, and the right infrapopliteal artery was not visualized. Diagnosis: 1. thrombo-occlusive vasculitis occlusion of the left iliac-N artery after artificial vessel diversion 2. bilateral lower extremity arterial thrombosis (old) 3. peripheral neuropathy 4. old infarction 5. cardiac insufficiency 6. mitral valve closure insufficiency ventricular appendage thrombosis 7. arrhythmia 8. hyperuricemia 9. fatty liver 10. gallbladder stones 11. mild chronic damage to the left kidney 12. left thigh after high amputation . Preoperative lower extremity CTA showed: CTA of both lower extremities: abdominal aortic stenosis, partial occlusion of the left iliac artery, complete occlusion of the right lower extremity artificial vessel, occlusion of the right external iliac, common femoral and superficial femoral arteries, visible establishment of collateral circulation, and no visualization of the right infrapopliteal artery. Case 2: The patient was a female, 83 years old, from Beijing. The patient had been diagnosed with occlusive atherosclerosis and interventional treatment of the left lower extremity at several tertiary hospitals in the city, which was unsuccessful. The pain of gangrene in the left foot increased, and the patient and his family refused to amputate the leg. On examination: both lower limbs could not be straightened, the knee joint was flexed and deformed in an arched shape (heavy on the left side), the skin color was pale yellow, the skin was dry and flaky, the sweat hair was sparse, the skin color below the left knee joint was pale, the skin temperature was lower than the opposite side, the left foot had dry gangrene of the thumb, and the dorsum of the foot was cyanotic. The dorsalis pedis artery and posterior tibial artery were not pulsating bilaterally. Auxiliary examination: electrocardiogram showed sinus tachycardia with a heart rate of 109 beats per minute. Cardiac ultrasound showed: aortic sclerosis and aortic valve fibrosis; large left atrium and thickened septum; hypocardial function, EF: 45%. Ultrasound of lower extremity arteries showed: occlusive atherosclerosis in both lower extremities, and no blood flow signal was seen in the left N artery. CTA of the lower extremities showed: occlusion of the lower segment of the left superficial femoral artery, bilateral segmental stenosis occlusion of the anterior tibial, posterior tibial and peroneal arteries. Diagnosis: 1. occlusive atherosclerosis 2. diabetic foot disease 3. type 2 diabetes 4. peripheral neuropathy 5. hypertensive disease grade 3 very high risk group 6. old cerebral infarction 7. sinus tachycardia 8. chronic cystitis urinary tract infection. Preoperative CTA of the lower extremity showed that the left lower extremity was curved in an arched sub-knee vascular occlusion Surgical procedure: The patient was placed in the supine position, the routine skin disinfection sheet was laid in the groin of the left lower extremity, local infiltration anesthesia was applied, the skin and subcutaneous tissue were incised longitudinally, the root of the great saphenous vein was exposed, and 0.5 cm from the root, the ligature was cut. The saphenous vein is then punctured with a trocar needle from 5-15 cm above the ankle (distal to the saphenous vein) and an ultra-smooth mudskipper guidewire is implanted. A contrast catheter is placed along the guidewire to the beginning of the saphenous vein, a microguide is placed, the catheter is withdrawn, and a valve knife is introduced to destroy the saphenous vein valve and set aside. Example 1: Procedure: remove the original embolized external iliac artery-N artery artificial vessel, separate and reveal the external iliac and common femoral arteries, heparinize, remove the thrombus and plaque at the residual artificial vessel after blood patency and set aside, use an 8 mm diameter PTFE artificial vessel about 12 cm long, anastomose one end with the residual artificial vessel and the other end with the root of the saphenous vein, check for arterial blood flow above the ankle joint (the beginning of the saphenous artery) There was arterial blood flow ejected from the top of the ankle joint (the beginning of the saphenous artery), so the puncture point was sutured and the subcutaneous tissue and skin were sutured, and the operation was completed. Postoperative vascular ultrasound of the lower extremity showed that the right saphenous vein was 0.5 cm in diameter, with arterial-like flow and a maximum flow velocity of 90 cm/s, and good filling of blood flow; a high-speed arterial-like flow signal was seen at the anastomosis, with a maximum flow velocity of about 262 cm/s; the deep veins of the right lower extremity were filling well, and no thrombus was seen in them. The superficial femoral artery and N artery of the right lower extremity did not show any flow signal. Doppler auscultation was clear that the flow sound at the beginning of the saphenous vein was of arterial type. After heparinization, an 8 mm diameter PTFE artificial vessel about 10 cm long was anastomosed with the external iliac artery at one end and the saphenous vein at the other end, and the arterial blood flow was ejected above the ankle joint (the beginning of the saphenous artery). The temperature of the calf gradually became ambiguous within 6 hours after the operation, and the resting pain disappeared that night. The temperature of the calf gradually became warm within 8 hours after the operation, and the resting pain disappeared that night. Postoperative vascular ultrasound of the lower extremity showed that the left saphenous vein was 0.6 cm in diameter, with arterial-like flow, maximum flow velocity of 100 cm/s, and good filling of blood flow; high speed arterial-like flow signal was seen at the anastomosis, with maximum flow velocity of about 242 cm/s; the deep vein of the left lower extremity was filling well, and no thrombus was seen inside. A small amount of blood flow signal was seen in the superficial femoral artery and N artery of the left lower extremity. Doppler auscultation was clear, and the flow sound at the beginning of the saphenous vein was arterial. Discussion: 1. Choice of anesthesia and procedure: In the face of the patient’s many underlying diseases, severe ischemia and necrosis of the limb, and inability to tolerate general anesthesia and lumbar anesthesia, the decision was made to perform interposition of artificial vessel under local anesthesia plus in situ saphenous vein stage I arterialization surgery in a comprehensive condition. The skin temperature and color of the affected limb gradually recovered after surgery, and the pain level was significantly reduced on the night of surgery. Traditional surgical treatment including partial adrenalectomy, lumbar sympathectomy, thromboendarterectomy, autologous vascular bypass diversion, greater omental graft, thromboendarterectomy, vascular graft, and artificial vascular bypass diversion all require an outflow tract distal to the occluded artery to be open. Due to severe lower extremity ischemia, lower extremity arteries are occluded throughout, making direct arterial reconstruction difficult to perform. Therefore, in recent years, veno-arterialization has gradually become the main treatment for severe lower extremity ischemic lesions, but the authors still experience poor results through clinical experience and do not have a more reliable surgical method. In this study, we performed a one-stage arterialization of the saphenous vein with an in situ prosthesis, which greatly increased the intravascular hemodynamic pressure and effectively increased the perfusion pressure in all branches of the saphenous vein throughout the procedure. Arterialization of the vein is the introduction of arterial flow into the vein and the use of the venous pathway to perfuse the distal tissues in a reverse direction, allowing the vein to act as an artery. Clinical data show that after arteriovenous diversion, blood flow to the affected limb increases, tissue nutrition improves significantly, and nutrition of ischemic tissues can be reestablished. Applying the branch vein of saphenous vein as the perfusion channel of arterial blood flow, the postoperative swelling is lighter and the blood perfusion of distal tissues of the limb can be restored rapidly. 2. Clinical application value: Integrating the advantages and disadvantages of various surgeries, we adopted the interposition of artificial vessel plus in situ saphenous vein arterialization in one phase, and improved on this basis by placing 8mm diameter artificial vessel between external iliac artery and saphenous vein to complete the arterialization of saphenous vein in one phase, so that the blood flow pressure in saphenous vein is greatly enhanced and the effect is very satisfactory. We believe that this method has the following advantages: ① the surgery uses a one-stage valve knife to get rid of the valve: the blood flow is opened intraoperatively, when even the arterial blood flow perfuses the distal vein in one direction, while the valves of the venous branches open slowly with the high pressure of arterialization, so that no excessive perfusion is formed; ② the indications are wide: this method is not only applicable to extensive occlusion of the calf artery, but also to extensive occlusion below the common iliac, external iliac or femoral arteries, as long as the deep veins ③Small impact on venous return, rapid elimination of edema, the superficial femoral vein has enough small venous branches to return, the operation only uses one saphenous vein, there are still multiple venous return of the superficial femoral vein and deep femoral vein system, the impact on venous return is very small, there is only a slight swelling in the calf and foot and ankle in the short term after the operation; ④Prevent the formation of thrombosis of the arterialized vessels of the veins: arterial blood needs to overcome the venous valves and When these two confrontations are similar, the blood flow is slow and thrombosis is easily formed. Therefore, to prevent the formation of thrombosis, we should try to increase the perfusion pressure and reduce the resistance, which can effectively prevent the possibility of thrombosis in the saphenous vein and superficial femoral vein. We use interposition artificial vessel: firstly, the anastomosis is established at the height of external iliac artery, mainly because we want to increase the anastomosis and increase the hemodynamic gradient pressure, which can greatly improve the flow and flow rate of arterialized vessels; secondly, the saphenous vein valve is destroyed at the same time, which completely eliminates the hemodynamic resistance and can immediately relieve the ischemic symptoms. We used interposition of artificial vessel plus in situ saphenous vein one-stage arterialization procedure without destroying the integrity of saphenous vein and saphenous vein branches. Therefore, relying on the collateral circulation of the saphenous vein can rapidly improve the ischemic symptoms of the patient’s lower extremity. Therefore, after the surgery, rapid improvement in skin color and skin temperature of the distal limb, relief of ischemic symptoms, and disappearance of resting pain at night on the same day were seen.