Abstract:
Deep venous thrombosis (DVT) is a venous reflux disorder caused by abnormal blood coagulation in the deep veins, which often occurs in the legs. Thrombus shedding can cause pulmonary embolism (PE). DVT and PE are collectively referred to as venous thromboembolism (VTE), and it is the manifestation of the same disease in different stages. The High incidence of DVT and the risk of sudden death caused by PE have been widely concerned by clinicians. When anticoagulation is contraindicated or anticoagulation treatment fails in VTE patients, an inferior vena cava filter (IVCF) can be inserted to capture blood clots through its mesh filter structure to prevent fatal PE. IVCF has been widely used in the world. According to the usage, it can be divided into permanent type, temporary type and retrievable type. Permanent IVCF cannot be removed unless the vena cava is surgically incised after implantation, The long-term occurrence rate of filter fracture, displacement, embolism and symptomatic perforation is high, which has been eliminated in clinical practice. Temporary IVCF is easy to be recovered by connecting with external catheter and fixed equipment, but it is easy to be infected, so it is rarely used in clinical practice. The retrievable IVCF has a hook-like structure for retrieving. When the patient's VTE risk period has passed, it can be removed by interventional surgery, which is the main type of clinical application. However, due to a series of complications caused by the treatment time of some patients exceeding the filter indwelling time window and the loss of follow-up, the actual recovery rate is low, and the related disputes are increasing. At the same time, the research and development of new IVCF is being carried out closely. Drug-eluting IVCF is coated with inhibition of smooth muscle proliferation and anti-inflammatory drugs, which can prevent the excessive proliferation of vascular intima, prolong the indwelling time of IVCF and facilitate the retrieval; In order to reduce the long-term complications, convertible IVCF allows the filter structure to be transformed in vivo from filter screen to open stent, but the converted metal stent can’t be removed, and the long-term effect on vena cava still needs long-term follow-up observation; Biodegradable IVCF can be completely absorbed by the body and avoid secondary surgery, which is a hot research topic of scholars at home and abroad. However, there is no clear research data to confirm how to design materials to ensure that IVCF maintains its strength before the thrombus intercepted by the filter is absorbed, so as to prevent the hemostatic clot or degraded fragment from thromboembolism again. The new type of IVCF with controllable degradation characteristics is a clear research and development goal. On the other hand, some scholars have used computer simulation to analyze the influence of different structures of filter units and the number of support rods on the performance of the filter, which provided a more scientific reference and theoretical basis for the study of new type of IVCF with optimal structure and minimal hemodynamic impact. In summary, on the basis of advocating the application of more meticulous patient management and clinical follow-up to improve the IVCF removal rate, it is imminent and significant to further develop an ideal IVCF. The new type of IVCF should have the following functions: it can effectively intercept blood clots to prevent new or recurring PE; after the high-risk period of VTE, it can be remotely controlled for conversion or overall simultaneous degradation; the filter is well fixed, maintaining good radial support performance at the same time does not damage the vena cava wall; has good biocompatibility; has little impact on hemodynamics; can be clearly visualized in imaging examinations for follow-up. It is believed that with the in-depth research and development in the fields of materials science and tissue engineering, a new type of IVCF with excellent clinical efficacy and few complications can be developed as soon as possible.
