Deep venous thrombosis (DVT) is one of the most common peripheral vascular diseases in clinical practice. Thrombotic Syndrome (PTS), which seriously affects people’s health. PTS is the most common complication of DVT and can reduce the quality of life and increase the economic burden on patients and society. The direct cost of this disease in the United States is $200 million annually, while the indirect cost results in the loss of 2,000,000 labor days per year. Yunbiao Guan, Department of Vascular and Thyroid Surgery, Union Hospital of Fujian Medical University
The treatment of DVT mainly includes 3 methods: surgical embolization, anticoagulation and thrombolysis.
①Anticoagulation is the basic treatment of DVT, which can inhibit the spread of thrombus, facilitate thrombus autolysis and lumen recanalization, thus alleviating symptoms and reducing the incidence of PE and morbidity and mortality. However, the effect of anticoagulation alone on reducing the scope of thrombus and shortening the course of disease is small. Since anticoagulant drugs cannot dissolve thrombus, they cannot effectively eliminate thrombus and reduce the incidence of PTS.
②Embolysis was first popular, but because of the incomplete removal of the clot. However, because of incomplete embolization and the possibility of varying degrees of deep venous valve insufficiency. Therefore, surgical embolization is only indicated for patients with femoral cyanosis and contraindications to thrombolysis.
③ In 1980, the National Institutes of Health proposed that thrombolytic drug therapy could be the basic treatment for acute DVT. The methods of thrombolysis include catheter-contact thrombolysis and systemic thrombolysis. Catheter-contact thrombolysis involves the placement of a thrombolytic catheter into a venous thrombus, and the thrombolytic drug acts directly on the thrombus. Systemic thrombolysis is the systemic application of thrombolytic drugs via peripheral veins. Catheter directed thrombolysis (CDT) can concentrate the thrombolytic drug into the thrombus, which can be more effective in local thrombolysis and restore the patency of the vein, and can reduce the risk associated with systemic thrombolysis, so it is a commonly used treatment method nowadays.
1.Treatment indications of CDT
CDT is widely used in the treatment of DVT because of its advantages such as less trauma and faster effect. For acute central or mixed DVT with onset not more than 14 days, CDT can achieve better results in good systemic condition and no contraindication to thrombolysis, which is recommended by ACCP (American College of Chest Physicians) guidelines and the 2012 guidelines for diagnosis and treatment of deep vein thrombosis of the Vascular Surgery Group of the Chinese Society of Medical Surgery. The use of thrombolytic therapy for patients with non-acute DVT has been controversial, and Grossman and Semba have treated non-acute thrombosis with CDT for less than 60 days with an efficiency of 60% and 7%; in June 2009, the author’s department started to treat non-acute DVT patients (15-35 d) with significant swelling of the lower extremity and willingness to treat. CDT treatment, with similar results. Numerous studies have confirmed that CDT for DVT of the lower extremities is effective for the acute onset and moderately effective for patients in the non-acute phase, but the results vary from center to center and are largely ineffective for patients with a disease duration of more than 60 d. Some scholars believe that the formation and development of thrombosis in lower limb veins is a continuous and progressive process, and the application of thrombolytic drugs in non-acute stage patients can not completely dissolve the old thrombus, but it still has a certain therapeutic effect on the continuous formation of fresh thrombus and inhibit and prevent the expansion and spread of thrombus.
2.The choice of CDT access
The exploration of the access route has been one of the directions of CDT research, and the currently reported access veins for CDT include: reverse deep vein placement via internal jugular vein or contralateral femoral vein “over the hill”, and cascade placement via ipsilateral femoral vein, N vein or superficial vein puncture. Since most patients with iliofemoral vein thrombosis have left iliac vein occlusion and are obstructed by the venous valves of the affected limb, the failure rate of retrograde cannulation is high; ipsilateral femoral vein or saphenous vein cannulation is easy to succeed, but it has no significant effect on LDVT far from the femoral vein and may affect the patient’s activity during treatment, so it is less used clinically. The internal jugular vein placement not only has the disadvantage of high failure rate of retrograde placement, but also has the possibility of fatal risk (such as jugular hematoma, hemopneumothorax, etc.) during operation and treatment, so it is rarely used in clinical practice. However, it has its disadvantages, such as high technical requirements for performing N vein CDT, and complications such as damage to the N artery, tibial nerve and N fossa thrombosis. The small saphenous vein is a superficial subcutaneous vein in the lower leg, with fixed position, straight shape, trunk diameter of about 2~5 mm and thick wall, etc. Its trunk mostly crosses the deep fascia at or below the midpoint of the N fossa and joins the N vein. Thrombolysis via the small saphenous vein has the same efficacy as thrombolysis via the N vein, and avoids the risk of N vein puncture. Huang Xiaozhong et al. used trans-saphenous vein initiation section to perform CDT in patients with acute mixed lower extremity DVT with good results. In the author’s department, the use of perfusion thrombolysis through the small saphenous vein for acute lower limb deep vein thrombosis also achieved satisfactory results. The author summarizes the following benefits of saphenous vein puncture placement thrombolysis.
①The small saphenous vein is superficial and superficial, and its shape is straight and easy to locate under B-ultrasound, so its placement has the advantages of easy operation, no damage to arteries and nerves, and relatively unrestricted movement of lower limbs compared with direct puncture of N vein;
(ii) Thrombolysis through the small saphenous vein has the advantage of lower location compared to N vein placement, which is more advantageous in the treatment of mixed thrombosis.
③Compared with the method used, the small saphenous vein is punctured in the upper mid calf under ultrasound guidance, which has no incision and reduces the chance of infection and is relatively less branched, making it easier to access the deep veins.
Of course, there are some anatomical variations in the small saphenous vein, and not all small saphenous veins converge into the N vein. Therefore, not all patients should be treated with small saphenous vein cannulation and thrombolysis, and preoperative ultrasound should be performed to understand the traffic of small saphenous vein and deep vein. The treatment of CDT should be optimized.
3.Optimization of the treatment of CDT
Mechanical thrombus ablation is a thrombosis treatment device which is initially applied in the clinic in recent years. A special catheter is inserted into the blood vessel to soften, cut, disintegrate and dissolve the thrombus and aspirate it out to eliminate the thrombus directly. At present, the following are commonly used in clinical practice.
Ultrasonic thrombolysis Through the biological effects of mechanical vibration and cavitation of low-frequency and high-intensity ultrasound, plaque and thrombus are directly ablated, and the narrowed or occluded blood vessel is reopened. The current ultrasonic ablation is difficult to completely remove the thrombus in the lumen of iliofemoral vein with vessel diameter >10 mm, and the inner surface of the channel is often rough and uneven, which cannot completely remove the residual wall thrombus in the lumen of the vein and may lead to recurrence of thrombus after the procedure.
ATD is a rotating thrombus ablation catheter that is placed percutaneously into the venous lumen, and uses a helium motor to drive a rotating device that softens, cuts, and dissolves the thrombus into fragments of approximately 100 μm in diameter without withdrawal, When the head end of the ATD is against the vessel wall, it is difficult to push, and the thrombus ablation effect is poor, and the vessel wall is easily damaged.
③Negative pressure aspiration of thrombus. Heparin solution is injected by high-pressure syringe, and the solution flows out through the side hole of the catheter head, thus creating a negative pressure in the blood vessel, causing the thrombus to break up and flow out along with the catheter and heparin solution. However, negative pressure aspiration of thrombus can cause more blood loss, and the removal of thrombus is often incomplete, so it is rarely used in clinical practice.
Because the above methods have different degrees of limitations, and the cost of using equipment is high, the efficacy is not exact, so it has not been widely promoted in China. Based on the combination of CDT and mechanical thrombus ablation, CDT combined with pig tail catheter for thrombus fragmentation has also achieved more reasonable results in recent years. The use of pig tail catheters for thrombus fragmentation was first investigated in the treatment of acute pulmonary embolism. In recent years, a large number of studies have found that pig tail catheter fragmentation has the advantages of easy access, no significant complications, and accelerated thrombolysis as a minimally invasive alternative to surgical embolization in the treatment of acute pulmonary embolism. The retrospective analysis of the author’s department compared 137 cases of left iliac vein occlusion combined with acute lower extremity deep vein central thrombosis treated by interventional methods between January 2007 and October 2012, of which 81 cases were treated by simple perfusion thrombolysis and 56 cases were treated by pigtail catheter fragmentation combined with perfusion thrombolysis, and the results confirmed that pigtail catheter fragmentation combined with perfusion thrombolysis in the treatment of lower extremity deep vein thrombosis The results confirmed that the combination of thrombolysis with infusion of pig tail catheter had the advantages of improving the efficiency of thrombolysis, shortening the time of thrombolysis and reducing the dosage of urokinase.
The theoretical basis for the application of pig tail catheter fragmentation in the treatment of DVT in the lower extremities in terms of safety is that
1, in combination with Cockett syndrome, because the lumen of the common iliac vein is obviously compressed and the lumen is narrowly occluded, the fragmented thrombus starts from the distal side of the compressed segment from near to far, so that the fragmented thrombus is not easy to pass through the compression of the common iliac vein, which reduces the risk of pulmonary artery embolism caused by the thrombus;
At the same time, attention should be paid to avoid violent stirring and exchange into the guidewire when encountering the valve, so as to reduce the damage of the valve and the occurrence of postoperative deep venous valve insufficiency. The above points show that pigtail catheter fragmentation combined with perfusion thrombolysis is a safe operation in the treatment of Cockett syndrome combined with acute lower extremity deep vein thrombosis.
3.Filter placement
The use of inferior vena cava filter can reduce the risk of PE in patients with DVT, but increase the possibility of recurrence of DVT, and the principle of inferior vena cava filter placement during CDT treatment is basically to reduce the occurrence of PE associated with CDT. The indications for inferior vena cava filter placement are: for most patients with DVT, the routine application of inferior vena cava filters is not recommended; for patients with anticoagulation. The placement of an inferior vena cava filter is recommended for those with contraindications to treatment or complications, or for those who develop PE despite adequate anticoagulation therapy. Placement of an inferior vena cava filter may be considered in the following cases.
(1) floating thrombus in the iliac or femoral vein or in the inferior vena cava;
(2) Acute DVT with thrombectomy such as catheter thrombolysis or surgical thrombectomy;
(3) abdominal, pelvic or lower extremity surgery in patients with high risk factors for PE.
In the author’s opinion, for patients with DVT, the use of inferior vena cava filters should follow the principle of “therapeutic use, prophylactic caution”, and try to use retrievable filters, and when the treatment of DVT is finished and the risk of PE is greatly reduced, remove the filters as much as possible to avoid the risk of long-term retention.
4.Iliac vein stent placement
Under normal physiological anatomy, there is a special anatomical relationship between the right common iliac artery and the left common iliac vein at their respective starting sites. The bilateral common iliac veins converge on the right side of the fifth lumbar vertebral body in the lower middle plane to form the inferior vena cava and travel up the spine. The right common iliac vein is almost straight and continuous with the inferior vena cava, whereas the left common iliac vein runs transversely from the left side of the pelvis to the right and meets the inferior vena cava at an almost right angle before passing through the lumbosacral vertebrae. The right common iliac artery crosses the front of the left common iliac vein, and the iliac vein is compressed by the iliac artery that crosses from its front, resulting in changes such as intravenous adhesions and luminal narrowing, which in turn cause obstruction of iliac vein blood flow and lower limb reflux. The syndrome that results in a series of clinical symptoms is called iliac vein compression syndrome or Cockett’s syndrome. Recent studies have confirmed that Cockett’s syndrome causes slow blood flow in the left common iliac vein and is prone to complications of DVT.
After thrombolytic treatment, severe stenosis and occlusion of the iliac vein still exist in a significant proportion of patients. Balloon dilatation and stenting of the left common iliac vein lesion can be corrected anatomically to reduce the recurrence of DVT. Several studies have confirmed that simultaneous correction of iliac vein occlusion after CDT or surgical embolization is can significantly improve mid- and long-term patency of the iliofemoral vein and reduce the incidence of PTS segments.
In conclusion, the treatment of DVT is a comprehensive and individualized treatment process. CDT should be used as much as possible for those with thrombolytic indications and conditions, and the principles of filter use should be strictly grasped, while the vessels can be opened at the same time to reduce the occurrence of PTS and improve the quality of life of patients. It also reduces the burden on patients and society.