OBJECTIVE: To evaluate the safety and efficacy of opening long-segment iliofemoral artery occlusive lesions using the Reekross balloon catheter. METHODS: The Reekross balloon catheter was applied to 68 patients (75 limbs) with long-segment chronic total occlusions (CTO) of the iliofemoral artery treated endovascularly from January 2011 to May 2013, all of whom were TASC (Trans-Atlantic Inter- Society Consensus) II Class C and D. Fifty-three of the patients were male and 15 were female. There were 53 males and 15 females; age 47-89 years, mean age 69±12 years. The limbs were staged according to Rutherford lower limb ischemia as 41 in stage 3, 13 in stage 4, 19 in stage 5, and 2 in stage 6. The technical success rate, postoperative clinical symptoms, ankle brachial index (ABI) changes, complication rate and patency rate of the affected limbs were summarized and analyzed. RESULTS: The technical success rate was 92.0% (69/78), and the postoperative ABI was 0.77±0.20, which was significantly higher than the preoperative 0.41±0.12. 56 patients (61 limbs) were followed up for 12-40 months, with a mean follow-up time of 26.3±7.1 months. The cumulative first-stage patency rates were 98.4%±1.6%, 86.7%±4.4%, 80.0%±5.2%, and 69.4±6.3% at 3, 6, 12, and 24 months postoperatively, respectively. CONCLUSION: The Reekross balloon catheter has good value in the treatment of CTO lesions of the iliofemoral artery with a safe and effective method. Endoluminal therapy has become an important treatment modality for lower extremity atherosclerotic occlusive disease, but it has been difficult for long-segment chronic total occlusion (CTO) lesions, which may lead to interventional failure. In this paper, we review and analyze the clinical data of patients with CTO lesions of the iliac and femoral arteries opened with the Reekross balloon to investigate the effectiveness and safety of this balloon catheter. DATA AND METHODS 1. Treatment methods (1) Procedure: All treatments were performed in a hybridized operating room. Brachial artery access was chosen for iliac artery lesions, and contralateral femoral artery access was chosen for superficial femoral artery lesions. A long sheath was placed proximal to the lesion, and a superslip guidewire (0.035″, Terumo, Japan) combined with a single-curved catheter (MPA or VER, Cordis, USA) was used to reach the occluded segment and replaced with a 0.018″ guidewire (V-18, Boston Scientific, USA) with a Reekross-18 balloon catheter (ClearStream Technologies, Ireland), the guidewire is passed through the occluded segment with the aid of path diagram fluoroscopy. If the tip of the guidewire is free to move, it suggests entry into the true lumen, which is confirmed by hand-pushing a small amount of contrast medium. If the guidewire and balloon enter the subendocardium and cannot enter the true lumen, follow up the balloon to the junction of the true and false lumen, use a high-pressure syringe to create a multi-angle image and magnify the image, and after finding the endocardial fissure at the junction, break the membrane via the fissure under the guidance of the path diagram. After entering the true lumen, the balloon was pre-expanded and exchanged into an ultra-hard guide wire for stent placement. (2) Postoperative medication: Enteric aspirin 100mg and Polivyte 75mg antiplatelet therapy was routinely given, and changed to aspirin to continue antiplatelet therapy after 6 months. (3) Technical success determination: Arteriography results after endoluminal treatment showed patency and residual stenosis rate <30%. (4) Evaluation of clinical efficacy: ABI was retested on the third day after surgery. divided into clinical symptoms improvement: patients' ischemic symptoms reduced or disappeared compared with preoperative symptoms, ABI increased >0.10; no change: no improvement in clinical symptoms, ABI decreased <0.10; deterioration: amputation was required, ABI decreased >0.10. 2. Discussion The traditional view is that long-segment stenosis and occlusion of TASC II C and D lower limb arteries lesions are preferred to vascular bypass surgery. In recent years, with the maturation of endoluminal techniques and the rapid development of interventional devices, more and more long-segment CTO lesions of the lower extremity are treated endoluminally. However, these cases are often characterized by distorted arterial alignment and severe calcification of the lesion. The severely distorted arterial alignment causes the catheter, balloon and guidewire to fail to transfer the force well to the end when passing through the occluded segment, which, together with severe intimal and mesenteric calcification, results in the catheter or balloon not being able to follow through the occluded segment well and ultimately leads to treatment failure. Also severely calcified lesions may cut through the balloon leading to balloon rupture. Some data show that the technical failure rate reaches 20% when using the conventional guidewire balloon technique for lower extremity CTO lesions. Therefore, for these complex cases, it is extremely important to choose the appropriate endoluminal treatment tool. The Reekross balloon is a balloon catheter specifically designed for the treatment of complex multi-segmental calcified lesions of the lower extremity. Its push rod uses a metal delivery sheath system with a certain degree of stiffness that allows for good transfer of proximal pushing force to the distal end of the catheter, making this balloon catheter have good penetration force, while the outer diameter of the balloon is only 3.9F, which can effectively reduce pushing resistance, thus allowing the entire system to pass through distorted paths Spaargaren et al. used the Reekross balloon catheter to open severely calcified occlusive lesions in lower extremity arteries, achieving a 97% technical success rate. The balloon catheter is available in 0.035″, 0.018″, and 0.014″ systems with appropriate guidewire sizes. In all cases, the Reekross-18 was used with the V-18 guidewire to pass the occluded segment, with a technical success rate of 92%. Considering that the selected cases were all CTO lesions of TASC II grade C or above, we achieved a high success rate without adding additional operating steps and auxiliary devices. In the specific operation, we first used an ultra-slip guidewire with a single-curved catheter to selectively enter the lesion segment and explored the tiny accesses in the true lumen of the diseased artery using the soft tip of the guidewire. After the catheter enters the lesion segment about 3-100 px, the V-18 guidewire and the Reekross-18 balloon are used. The balloon is always positioned 1-50 px behind the guidewire to provide adequate support. When the advancement of the guidewire is obstructed, the balloon is followed approximately 2-3 mm from the tip of the guidewire, and the balloon and guidewire are pushed together to pass the occluded segment using the Reekross balloon in concert with the guidewire. In a few patients with severe calcified occlusion of the artery who have difficulty returning to the true lumen, the ReeKross balloon can be used to pre-dilate the high resistance area and tear the gap between the subintima and the true lumen of the artery before manipulating the guidewire under path guidance to superselect into the true lumen of the distal artery. Care should be taken not to use blind violence resulting in extension of the subendothelial false lumen into the long segment of the distal patent artery, enlarging the lesion area and destroying important collateral branches, or even losing the opportunity for subsequent conversion to vascular bypass as a result. In recent years, new devices and techniques have emerged, such as subintimal techniques to assist back to the true lumen devices (e.g., Outback, Pioneer catheters), bidirectional subintimal arterial flossing with antegrade-retrograde intervention (SAFARI) Setacci et al. selected cases in which traditional interventional techniques failed and completed the luminal treatment with 0utback catheters, and their technical success rate reached 79%. Ye Meng et al. used the SAFARI technique to treat CTO lesions in the lower extremities, and their technical success rate reached 93.3%. However, these methods inevitably have the disadvantages of complex technical operation and high economic cost, and some of the equipment is not yet available in China, which is not conducive to popularization. In contrast, the Reekross balloon catheter was used in this group of cases to achieve good therapeutic results through traditional interventional techniques, which has high promotion value. In conclusion, the Reekross balloon catheter can improve the success rate of intraluminal treatment of CTO lesions in lower extremity arteries with few complications and high limb preservation rate. However, this study lacks control with conventional balloon catheter and requires follow-up studies for validation.