Very long-term outcome of 68 vena cava filters percutaneously implanted

Between January 1987 and December 1991, 68 consecutive patients aged 71.5 +/- 12.0 years underwent percutaneous implantation of a vena caval filter, mainly the LGM (N = 64). Fifty seven patients had pulmonary embolism, 61 had deep vein thrombosis of the lower limbs. The average follow-up interval was 4.9 +/- 3.3 years (7.0 +/- 2.7 years for the patients still alive). The follow-up included a telephonic enquiry to determine the date and cause of death, recurrent deep vein thrombosis and/or pulmonary embolism; surviving patients underwent clinical examination, plain abdominal X-ray with a lateral decubitus view and duplex ultrasonography of the lower limb veins to assess the patency of the filter. Fifty three per cent of the patients died. Four predictive factors for mortality were identified: a contra-indication to anticoagulant therapy, chronic post-embolic cor pulmonale, an indication of prophylactic implantation in the elderly and the presence of underlying malignant disease. There were 5.8% recurrences of pulmonary embolism, 26.1% of lower limb deep vein thrombosis and 25% of filter thrombosis. The only predictive factor of thrombosis was a proximal venous thrombus and was associated in 50% of filter thrombosis. Seventy per cent of the plain abdominal X-rays were abnormal with 9 displacements. 9 migrations and 10 closures of the filters. There was a significant correlation between closure on plain abdominal X-ray and caval thrombosis and between recurrent deep vein thrombosis and caval thrombosis. The frequency of long-term complications after implantation of a caval filter in this study suggests that interruption of the vena cava should be reserved for the only validated indications in the presence of a formal contra-indication to or failure of anticoagulant therapy. Other indications require evaluation with prospective randomised trials.     

Initial clinical experience with an endoluminal spiral prosthesis for treating complicated venous thrombosis and preventing pulmonary embolism

Fourteen patients with complicated venous thrombosis or recurrent pulmonary embolism were treated by implantation of an endoluminal spiral prosthesis subsequent to balloon angioplasty, surgical thrombectomy or embolectomy, a combination of these, or, in 2 cases, no other treatment. The patients were divided into 2 groups, based on their primary diagnosis and the purpose of the prosthesis. Group I included 8 patients with extensive iliofemoral or caval thrombosis, caused by congenital caval stenosis (1 case) or extravascular compression or retraction (7 cases); 7 of these patients had had previous operations, and the remaining patient had undergone thrombolysis, which failed. The current treatment consisted of balloon angioplasty and surgical thrombectomy or embolectomy, and implantation of an endoluminal spiral stent to prevent elastic recoil of the vessel. In 4 cases, an arteriovenous fistula was constructed and was taken down 3 months later; in 1 additional patient, a bilateral arteriovenous fistula was created. Group II comprised 6 patients with recurrent pulmonary embolism (4 cases), massive pulmonary embolism (1 case), or paradoxical bilateral carotid artery embolism (1 case). Four of these patients underwent surgical thrombectomy or embolectomy, while 2 had no treatment other than filter implantation. All 6 underwent transluminal implantation of a helix caval filter (a modification of the endoluminal spiral stent). All but 1 implantation was accomplished by means of either a transfemoral or a transjugular cutdown; the remaining implantation was performed transatrially after a pulmonary embolectomy. The only device-related complication was a retroperitoneal hematoma in Group I, resulting from perforation of the inferior vena cava by the guidewire during device implantation. This complication necessitated an emergency laparotomy and takedown of the arteriovenous fistula, which resulted in rethrombosis of the left iliofemoral vein. The other 7 stented veins were patent at early phlebographic follow-up, as were all 5 of those studied later. One Group-I patient died 4 months after surgery, due to tumor progression and without signs of caval restenosis. Twelve months postoperatively, 1 Group-II patient died of urosepsis without a recurrence of pulmonary embolism. Four of the 6 Group-II patients were studied late postoperatively, and all of their stented vessels were patent. There was no operative mortality or postoperative embolism. On the basis of these results, we conclude that endoluminal stenting with an expandable spiral prosthesis is a promising method for remote venous reconstruction. Moreover, it appears that the modified stent, or helix caval filter, compares favorably with commercially available filters.     

Partial interruption of the inferior vena cava using a percutaneous endovenous filter

Partial interruption of the inferior vena cava (IVCI) by a percutaneous endovenous filter (Günther filter n = 65, LEM filter n = 36) was undertaken in 100 patients with an average of 72 +/- 11 years for recent deep vein thrombosis. The indications were: contraindications to anticoagulant therapy (36.5%); recurrent pulmonary embolism (12%); threatening venous thrombosis with a previous embolic episode (12%); caval thrombosis (15.7%); prophylactic, with no previous pulmonary embolism (23.8%). The filters were evaluated at short and mid term. There were no technical problems. The mortality rate was 17.5%, one death being probably due to recurrent pulmonary embolism. No other recurrences of pulmonary embolism were observed, indicating an efficacy of 99 per cent. The early patency rate was 96.5%, there being no difference between the two filters used, independent of the initial site of venous thrombosis, of distal migration of the filter and associated medical treatment (anticoagulation). Distal migration was observed in 76% of IVCI by the Günther filter and 48.5% by the LEM filter (p less than 0.001); tilting was observed in 7.4% of Günther and 3% of LEM filters. Five LEM filters were incompletely opened. The IVC was transfixed by 3 Günther filters. One Günther filter had fractured spokes. There were 12 recurrences of lower limb deep vein thrombosis and 16 post-deep vein thrombosis complications were recorded. These percutaneous endovenous filters are similar to the Kimray Greenfield filter with respect to efficacy and permeability although the follow-up was relatively short. The advantages of these percutaneous filters are the facility, innocuity and rapidity of their insertion with, however, a higher incidence of distal migration.     

Experience with the helix cava filter

A new caval filter of helico-spiral geometry (Helix-Filter) was implanted in 13 patients for the prevention of pulmonary embolism (PE). The indications for implantation were: recurrent PE despite adequate anticoagulation (5 cases) or contraindication to anticoagulation (3 cases), incomplete local therapeutic fibrinolysis after severe paracentral PE (2 cases), and prophylaxis in high risk patients (3 cases). Implantation was effected by the saphenous/femoral vein approach in 12 patients, and via the right atrial appendage during open heart surgery in one instance. There were no intraoperative technical problems and in no case was the filter misplaced. During the follow-up period (mean 14.8 months, maximum 28 months) no filter-related complications were encountered. One patient with an exceptionally enlarged vena cava, due to abnormal renal vein inflow, had a fatal recurrent PE despite high dosage heparinization. One patient with an event-free follow-up died 12 months after filter placement from unrelated diseases. The remaining 11 patients are free of symptoms with no recurrent PE, no deterioration of venous circulation or presence of caval thrombosis. Emboli trapped at the filter were documented in 2 patients; spontaneous resolution occurred in one case. Experimental and early clinical results indicate that the hemodynamically optimal design of the Helix-Filter permits controlled and uniform luminal filtering with high patency. As such, it represents an alternative and highly promising solution to the problem of "mechanical" prevention of pulmonary embolism in selected patients.     

In-Hospital Risks and Management of Deep Venous Thrombosis According to Location of the Thrombus

BackgroundWhether deep venous thrombosis involving the pelvic veins or inferior vena cava is associated with higher in-hospital mortality or higher prevalence of in-hospital pulmonary embolism than proximal or distal lower extremity deep venous thrombosis is not known.MethodsThis was a retrospective cohort study based on administrative data from the Nationwide Inpatient Sample, 2016, 2017. Patients hospitalized with a primary diagnosis of deep venous thrombosis at known locations were identified by International Classification of Diseases-10-Clinical Modification codes.ResultsIn-hospital all-cause mortality with deep venous thrombosis involving the inferior vena cava in patients treated only with anticoagulants was 2.2% versus 0.8% with pelvic vein deep venous thrombosis (p<0.0001), 0.7% with proximal deep venous thrombosis (p<0.0001) and 0.2% with distal deep venous thrombosis (p<0.0001). Mortality with anticoagulants was similar with pelvic vein deep venous thrombosis compared with proximal lower extremity deep venous thrombosis, 0.8% versus 0.7% (p=0.39). Lower mortality was shown with pelvic vein deep venous thrombosis treated with thrombolytics than with anticoagulants, 0% versus 0.8% (p<0.0001). In-hospital pulmonary embolism occurred in 11% to 23%, irrespective of the site of deep venous thrombosis.ConclusionPatients with deep venous thrombosis involving the inferior vena cava had higher in-hospital mortality than patients with deep venous thrombosis at other locations. Pelvic vein deep venous thrombosis did not result in higher mortality or more in-hospital pulmonary embolism than proximal lower extremity deep venous thrombosis. The incidence of in-hospital pulmonary embolism was considerable with deep venous thrombosis at all sites.     

Prevention of venous thromboembolism

The aim of prophylaxis in venous thromboembolism is firstly to prevent fatal pulmonary embolism and secondly to reduce the morbidity associated with deep vein thrombosis and the post-phlebitic limb. Particularly high-risk groups are identifiable and include those over 60 years of age undergoing major surgery, patients with malignancy and those undergoing hip operations. Low-dose subcutaneous heparin (5000 U s.c. commenced two hours preoperatively and continued eight to twelve hourly until the patient is fully mobile) is unequivocally effective in preventing deep vein thrombosis in medical and surgical patients and, most importantly, significantly reduces the incidence of fatal postoperative pulmonary embolism and total mortality. Furthermore, in established deep vein thrombosis, low-dose heparin limits proximal clot propagation, which is the prelude to pulmonary embolism. Despite this, surveys have demonstrated an alarming deficiency amongst clinicians in the application of measures to prevent venous thromboembolism. Heparin prophylaxis carries a small risk of increased bleeding complications, mostly evidenced by the frequency of wound haematoma rather than major haemorrhage. Low molecular heparin fragments (e.g. Fragmin, Choay, Enoxaprin) are now emerging as useful alternative agents, having the advantage of once daily administration and yet providing similar efficacy in the prevention of deep vein thrombosis. However, protection against fatal pulmonary embolism has yet to be demonstrated. Mechanical methods of prophylaxis designed to counteract venous stasis, such as graduated elastic compression stockings, are also beneficial in protection against deep vein thrombosis but by themselves do not achieve such consistently good prophylaxis as low-dose heparin. However, clinical trials with combinations of mechanical methods and low-dose heparin indicate that this may be the optimum approach to very high-risk patients. In the presence of established acute deep vein thrombosis, anticoagulant therapy is the mainstay in preventing pulmonary embolism. Vena caval interruption procedures should be reserved for patients in whom anticoagulation is contraindicated or for those who develop recurrent pulmonary embolism despite adequate anticoagulation.     

Multidetector-row computed tomography management of acute pulmonary embolism.

BACKGROUND: The purpose of this study was to evaluate the usefulness and safety of multidetector-row computed tomography (MDCT) pulmonary angiography and indirect venography management of acute pulmonary embolism (PE), including indication for inferior vena cava (IVC) filter. METHODS AND RESULTS: Seventy-one consecutive patients who were clinically suspected of PE and underwent 16-slice MDCT pulmonary angiography and indirect venography were enrolled. Management included indication of IVC filter for patients with extensive deep venous thrombosis (DVT) in submassive or massive PE. A right ventricular to left ventricular short-axis diameter by MDCT>1.0 was judged as submassive PE. All patients were followed for 1 year. MDCT identified 50 patients with venous thromboembolism and 47 patients had acute PE: 4 were judged as massive, 14 as submassive, and 29 as non-massive by MDCT; 3 patients had DVT alone and 7 patients had caval or iliac DVT. Only 1 patient with massive PE and DVT near the right atrium died of recurrence. No other patients died of PE. CONCLUSION: Management based on MDCT pulmonary angiography combined with indirect venography is considered to be safe and reliable in patients with suspected acute PE.     

Percutaneous closure of patent foramen ovale guided by intracardiac echocardiography and performed through the transfemoral approach in the presence of previously placed inferior vena cava filters: a case series.

We present three patients with cryptogenic stroke who underwent transcatheter closure of a patent foramen ovale. All patients have had history of deep venous thrombosis and pulmonary embolism with placement of inferior vena caval filters. The patients were not initially considered suitable candidates for the procedure because of risk of dislodgment of previously implanted inferior vena cava filter.     

Interruption of the inferior vena cava for prevention of pulmonary embolism: transvenous filter devices

The availability of a safe, effective, and easily introducible percutaneous vena cava filter is crucial in the management of certain patients with pulmonary embolism. If thrombolytic or anticoagulant therapy for pulmonary embolism is contraindicated or fails, interruption of the inferior vena cava (IVC) blood flow is the logical alternative. Indications for filter insertion include a contraindication to anticoagulation, or recurrent pulmonary embolism despite adequate anticoagulation therapy. Common routes of filter insertion are from the right internal jugular vein, or the right or left femoral veins. The Mobin-Uddin umbrella filter (no longer available in the USA) and the Kimray-Greenfield filters have been the most widely used. Complications of vena cava filters include malpositioning, migration, venous thrombosis proximal or distal to the filter, hemorrhage at the percutaneous site of insertion, or sepsis. Despite these problems, IVC filters have been extremely useful in the management of pulmonary embolism among certain subsets of patients. Percutaneously inserted filters have now superseded surgical vena caval interruption in most US centers. Newer filters are currently under development in the US and Europe, and feature improved filtering function, anti-tilt abilities, retrievability, memory wire properties, and improved ease of insertion.     

Deep venous thrombosis. Implications after open heart surgery

We reviewed the cases of 10,638 cardiac surgical patients to determine the incidence of deep vein thrombosis (DVT) after open heart surgery (OHS). Seventy-seven patients (0.7 percent) had DVT. Group 1 included 36 patients who had DVT without pulmonary embolism (PE). Occurrence was equal in either leg. Anticoagulation with heparin and warfarin sodium (Coumadin) was employed as treatment. Extension of hospital stay was 10.8 days. Group 2 consisted of 41 patients who experienced PE 9.9 days after OHS. Sixteen patients had known DVT and were receiving heparin. In 25 patients, PE was the first event. Risk factors for PE included perioperative myocardial infarction (16 percent), atrial fibrillation (41 percent); blood type A (70 percent) (p less than 0.05), and coronary artery bypass graft (CABG) (98 percent). Twenty-four patients were treated with anti-coagulation alone. Six died of recurrent PE; mortality was 25 percent. Seventeen patients received anticoagulation plus inferior vena cava (IVC) interruption using a Hunter balloon. There were no recurrent PEs and there was one death from myocardial infarction (6 percent). Deep vein thrombosis and PE are rare complications of OHS. Routine prophylaxis with either heparin or warfarin is unnecessary. Patients with DVT, atrial fibrillation (AF), and perioperative myocardial infarction are at high risk of PE. Aggressive diagnosis to identify major venous thrombi along with anticoagulation and early consideration of IVC interruption are recommended for these patients. Patients who have undergone OHS and who have PE are at an unusually high risk for recurrent PE with death and are more safely treated with IVC interruption and anticoagulation than anticoagulation alone.     

Present-day role of vena cava filters

BACKGROUND: The purpose of the present is to assess the effectiveness of pulmonary embolism prevention using temporary or permanent vena cava filters in deep venous thromboses of the lower extremities with a discussion of indications and complications. METHODS: In the period between 1989 and 1998 we observed 46 patients (33 m, 13 f) suffering from deep venous thrombosis of the lower extremities. RESULTS: The cases treated with cava filter showed an improvement in clinical conditions in 15-19 cases with 4/19 cases of complications: filter ascent, lipothymia, one case of pneumothorax and one case of filter ascent with thrombosis of the contralateral venous axis. All complications were solved without further sequelae. After catheterisation of the femoral vein, the thrombosis of the contralateral venous axis in patients with caval filter was a frequently observed event (in 75% of cases). In the cases without filter, an evident improvement was observed in 22/27 cases, a slight improvement in 2/27 cases, with 3/27 cases of complications: two cases of cardiocirculatory arrest and one case of severe dyspnea with suspected pulmonary embolism which survived the event. CONCLUSIONS: From our experience, the use of caval filters is unquestionably useful for the prevention of pulmonary embolism, but is not wholly free from complications.     

Arterial and venous thrombosis in rare congenital bleeding disorders: a critical review

A thorough review of the literature and of personal files has allowed the gathering of 81 patients with rare congenital bleeding disorders and thrombotic phenomena. Sixteen of these patients had congenital afibrinogenemia, eight involved factor V deficiency, 20 factor VII defects, 33 factor XI deficiencies and only one, a factor XIII defect. Altogether 42 patients showed arterial thrombosis (myocardial infarction [MI] in 28 cases; ischemic stroke in 4; arterial occlusion in 8; 2 patients with disseminated intravascular coagulation (DIC)). Ages varied between 13 and 74. Twenty-two patients were males and 16 females. In four cases, sex was not reported. There were three fatalities: two after a MI and one because of heart failure. With regard to venous thrombosis: 9 patients had pulmonary embolism, 15 patients had deep vein thrombosis, 9 patients had both pulmonary embolism and deep vein thrombosis; 1 patient had superficial vein thrombosis, whereas, 5 cases had an unusual site venous thrombosis (two portal systems, two cerebral sinuses, one inferior vena cava) for a total of 39 cases. Age varied between 3 and 86. In this case, 20 patients were males and 17 were females. In two cases, sex was not reported. There were three fatalities: two because of pulmonary embolism and one because of inferior vena cava thrombosis. The fact that thrombosis has never been described in patients with factor II or factor X seems to underscore the central antithrombotic role that these two factors have in the coagulation system.     

Streptokinase Therapy in the Routine Management of Deep Venous Thrombosis in the Lower Extremities

ABSTRACT. One hundred and eight patients with phlebographically verified deep venous thrombosis were treated with streptokinase. Total or partial thrombolysis was phlebographically demonstrated in 60 patients (55.6%). Three patients died during treatment, all from pulmonary embolism. Six patients developed clinical signs suggestive of pulmonary embolism. In 16 patients (14.8%), major bleeding complicated the treatment. One patient had anaphylactic shock, while various allergic reactions were recorded in 22. Streptokinase therapy in the routine management of deep venous thrombosis carries an acceptable efficacy and safety similar to what has been achieved under research conditions.     

A population-based study of the effectiveness of inferior vena cava filter use among patients with venous thromboembolism

BACKGROUND: There are few population-based data regarding the effectiveness of inferior vena cava filter use in the prevention of symptomatic pulmonary embolism. OBJECTIVE: To determine the 1-year cumulative incidence of rehospitalization for venous thrombosis or pulmonary embolism among patients with thromboembolism treated with a vena cava filter compared with the incidence in a control population with thromboembolism. PATIENTS AND METHODS: Population-based retrospective analysis of linked hospital discharge abstracts in California. From January 1, 1991, through December 30, 1995, 3632 patients were treated with a filter and 64,333 controls were admitted with a principal diagnosis of venous thromboembolism. RESULTS: Filter-treated patients had significantly greater comorbidity, with a higher frequency of previous pulmonary embolism, recent major bleeding, malignant neoplasm, and stroke. Patients who initially manifested pulmonary embolism were significantly more likely to be rehospitalized for pulmonary embolism than patients with an initial diagnosis of venous thrombosis alone, among filter-treated patients (relative risk, 6.72; 95% confidence interval, 3.61-12.49) and controls (relative risk, 5.30; 95% confidence interval, 4.61-6.10). Risk-adjusted proportional hazards modeling showed no significant difference between filter-treated patients and controls in the relative hazard of rehospitalization for pulmonary embolism. However, filter placement was associated with a significantly higher relative hazard of rehospitalization for venous thrombosis among patients who initially manifested pulmonary embolism (relative hazard, 2.62; 95% confidence interval, 2.09-3.29), but not among those who presented with venous thrombosis (relative hazard, 1.14; 95% confidence interval, 0.92-1.43). CONCLUSIONS: Insertion of a vena cava filter was not associated with a significant reduction in the 1-year incidence of rehospitalization for pulmonary embolism. Use of a filter was associated with a higher incidence of rehospitalization for venous thrombosis, but only among patients who initially manifested pulmonary embolism. A prospective clinical study is needed to determine the efficacy of filter use among patients with pulmonary embolism who do not meet strict guidelines for insertion of a vena cava filter.     

Bilateral inferior venae cava combined with the persistent left superior vena cava and hemiazygos continuation of left inferior vena cava with drainage into right atrium: A case report

The persistent left superior vena cava (PLSVC) is a common venous abnormality. However, malformation of the bilateral inferior venae cava (IVC) is extremely rare, with an incidence rate of .3%. IVC malformation is associated most frequently with heart defects and isomerism and often has a poor prognosis. We presented a case of vascular malformations in the fetus of bilateral caval veins with the interruption of the left-sided venous return with hemiazygos continuation in presence of a right-sided inferior caval vein. Also noted were the PLSVC and a dilated right heart with a widened pulmonary trunk. In this case, there were no heart defects or chromosomal abnormalities, and the newborn postpartum was in a good condition.     

Venous thromboembolism in patients hospitalized with nephrotic syndrome

Purpose

Whether pulmonary embolism in patients with the nephrotic syndrome is caused by deep venous thrombosis or renal vein thrombosis is controversial. To determine which is the likely cause of pulmonary embolism in patients with the nephrotic syndrome, we investigated data from the National Hospital Discharge Survey.

Methods

The number of patients discharged from nonfederal short-stay hospitals in the United States with a diagnostic code of nephrotic syndrome, deep venous thrombosis, renal vein thrombosis, and pulmonary embolism was obtained using ICD-9-M (International Classification of Diseases, Ninth Revision, Clinical Modification) codes.

Results

From 1979 to 2005, 925,000 patients were discharged from hospitals with the nephrotic syndrome and 898,253,000 patients did not have the nephrotic syndrome. With the nephrotic syndrome, 5000 (0.5%) had pulmonary embolism, 14,000 (1.5%) had deep venous thrombosis, and fewer than 5000 had renal vein thrombosis. The relative risk of pulmonary embolism comparing patients with the nephrotic syndrome to those who did not have it was 1.39, and the relative risk of deep venous thrombosis was 1.72. Among patients aged 18-39 years, the relative risk of deep venous thrombosis was 6.81. From 1991-2005, after venous ultrasound was generally available, the relative risk of deep venous thrombosis (all ages) was 1.77.

Conclusion

The nephrotic syndrome is a risk factor for venous thromboembolism. This is strikingly apparent in young adults. Renal vein thrombosis was uncommon. Therefore, pulmonary embolism, if it occurs, is likely to be due to deep venous thrombosis and not renal vein thrombosis.     

Unexpected high prevalence of silent pulmonary embolism in patients with deep venous thrombosis

In patients presenting with clinically suspected deep vein thrombosis, symptomatic pulmonary embolism is rarely apparent. To assess the prevalence of silent pulmonary embolism in outpatients with proven deep vein thrombosis but without symptoms of pulmonary embolism, perfusion ventilation lung scans were performed in 101 consecutive patients at presentation. Fifty-one percent of these patients had a high probability lung scan at the initiation of treatment. In comparison, in patients referred with suspected venous thrombosis, but who on subsequent objective testing did not have venous thrombosis (n = 44), the prevalence of a high probability-scan for pulmonary embolus was only 5 percent. At repeat lung scanning, performed after one week of anticoagulant treatment, complete to partial improvement was observed in 68 percent of the patients with initially abnormal scans. Lung-scan detected asymptomatic pulmonary embolism occurs frequently in patients presenting with symptomatic deep venous thrombosis, and the majority of these emboli showed significant to complete resolution within one week of anticoagulant treatment.     

Portal venous occlusion

Summary Morbidly obese patients are significantly more susceptible to clotting phenomena, including recurrent deep venous thrombosis, pulmonary emboli, inferior vena caval thrombosis, and renal vein thrombosis. The patient described in this report developed the sudden onset of massive ascites two years following jejunoileal bypass for morbid obesity. Occlusion of the portal vein and its tributaries was demonstrated. Our experience and one previous report suggest that portal vein thrombosis may be a rare complication of this surgical procedure.     

Vena caval filters: a comprehensive review

Hematologists are often asked to treat patients with venous thromboembolic disease. Although anticoagulation remains the primary therapy for venous thromboembolism, vena caval filters are an important alternative when anticoagulants are contraindicated. To assess the evidence supporting the utility of these devices, a comprehensive review of the English language literature was performed. Except for one randomized trial, the vena caval filter literature consists of case series or consecutive case series. The mean duration of follow-up for each of the 5 filter types varies from 6 to 18 months. All are about equally effective in the prevention of pulmonary embolism (2.6%-3.8%). Deep venous thrombosis (6%-32%) and inferior vena cava thrombosis (3.6%-11.2%) after filter placement vary widely among different filter types primarily because of differences in outcome assessment. Thrombosis at the insertion site is a common complication of filter placement (23%-36%). In view of the absence of randomized comparisons, no filter can be designated as superior in safety or efficacy. Vena caval filters represent a potentially important but poorly evaluated therapeutic modality in the prevention of pulmonary emboli. Randomized trials are necessary to establish the appropriate place for vena caval filters in the treatment of venous thromboembolic disease. (Blood. 2000;95:3669-3677)     

A comparison of 3 and 6 weeks' anticoagulation in the treatment of venous thromboembolism

One hundred hospital in-patients treated for pulmonary embolism (PE) and/or deep vein thrombosis (DVT) were randomly allocated to receive 3 or 6 weeks' anticoagulation with heparin and warfarin. At one year recurrence rates were 12% in the 6 week group and 10% in those treated for 3 weeks. No patient died as a result of recurrence. Our study suggests that 3 weeks' anticoagulation therapy, using intravenous heparin for the first 5 days and warfarin from the third day, is adequate for patients without persisting risk factors.