Deep vein thrombosis of the lower extremities is a vascular disease frequently encountered in the clinic. Due to the lack of knowledge about this disease in the past, most cases in the clinic were misdiagnosed or missed. In recent years, with the improvement of clinicians’ knowledge and the maturity of ultrasound and angiography, the detection rate of lower extremity deep vein thrombosis has been greatly improved.
As the deep vein thrombosis, once dislodged, can follow the course of the blood vessel to reach the pulmonary artery, leading to pulmonary embolism. Some patients can die within minutes, so vena cava filters are widely used in clinical practice as an effective means of preventing pulmonary embolism. However, not all patients with deep vein thrombosis require a vena cava filter. The choice of vena cava filters and the circumstances under which they should be implanted varies from one medical institution to another in China and is a matter of confusion.
There is a basic international consensus on the indications for vena cava filter implantation, which is based on a large number of clinical cases and evidence-based research methods.
It is generally accepted that the following conditions are indications for vena cava filter implantation.
(1) The patient has had a pulmonary embolic event;
(2) Thrombus has spread to the inferior vena cava;
(3) The patient has had an embolic event despite standard anticoagulation;
(4) The patient is bleeding and cannot use anticoagulants;
(5) Patients in cerebrovascular accident or major surgical perioperative period where anticoagulation may lead to fatal bleeding;
(6) The presence of a floating thrombus in the iliac vein;
The indications for temporary filter implantation are, in addition to the above, the following
(1) Severe multiple trauma;
(2) Major surgical procedures that may lead to venous embolism events, such as hip replacement.
Of course there are some relative indications for vena cava filter implantation, such as.
(1) Use in conjunction with deep vein thrombosis or thrombolysis;
(2) Patients with malignant tumors who are expected to survive for more than 2 years;
In China, some medical institutions inform patients and their families of the need for vena cava filters whenever they admit patients with DVT. Objectively speaking, the probability of fatal pulmonary embolism in patients with DVT is less than 0.6%, which means that the majority of patients are not threatened by fatal pulmonary embolism, and the disease can be controlled clinically with standard anticoagulation methods.
In addition, although the vena cava filter implantation procedure is not complicated, there are still certain complications. These complications include.
(1) Complications associated with puncture of the femoral vein on the healthy side, such as hematoma and thrombosis;
(2) accidental injury to arteries, nerves, etc.;
(3) Complications from contrast agents, such as allergy, phlebitis, etc;
(4) Complications when releasing the filter incorrectly, such as filter inversion, filter displacement, filter misalignment, etc;
(5) Other rare complications include vena cava perforation, filter blockage of pulmonary artery, etc.
Most of these complications can be avoided by an experienced vascular surgeon. However, most medical institutions in China do not have a vascular surgery specialty, and most doctors are still relatively inexperienced. In addition, skilled interventionalists tend to focus on technical operations and ignore the patient’s condition. As a result, clinical complications due to vena cava filter implantation continue to be reported.
In addition to the inherent complications of vena cava filter implantation, the cost of the procedure remains high. For patients who do not have an indication for the procedure, it adds an unwarranted financial burden to them in addition to the possible risks of the procedure.
The indication of vena cava filter implantation is one of the ways to test the level of knowledge and medical ethics of our vascular surgeons. Whether to strictly grasp the surgical indications and whether to consider the interests of the patient is a question that every vascular surgeon must think about.
Of course, the research on vena cava filters is also in progress. In recent years we have started to use the technique of implanting a vena cava filter through the saphenous vein, which has led to a significant reduction in the complications of the traditional procedure. This procedure is characterized by the fact that it does not damage the femoral vein, does not use contrast, can be performed in a small operating room under a C-arm X-ray machine, and does not require postoperative compression. As for the positioning of the filter and the evaluation of the vena cava system are done preoperatively using 64-row spiral CT or MRI. Nearly 200 patients who have undergone this technique have had no complications so far.
It is believed that in the near future, a comprehensive review of the current status of vena cava filter use will be made by the vascular surgery community, and scientific guidelines and surgical indications for vena cava filter implantation will be proposed.