Double-Blind, Randomized Comparison of Systemic Continuous Infusion of 0.25 Versus 0.50 mg/kg/24 h of Alteplase over 3 to 7 Days for Treatment of Deep Venous Thrombosis in Heparinized Patients: Results of the European Thrombolysis with rt-PA in Venous Thrombosis (ETTT) Trial

Venous Haemodynamics and Morphology in Relation to Recanalisation and Thrombus Resolution in Patients with Proximal Deep Venous Thrombosis

Objective:

Follow-up studies of deep venous thrombosis (DVT) are needed to gain increased knowledge of the process of recanalisation over time. In this study modern diagnostic techniques were used to analyse changes in venous circulation during the process of recanalisation and thrombus resolution.

Design and setting:

Prospective follow-up study of patients with symptomatic DVT referred to a vascular diagnostic laboratory. The patients were evaluated by repeated examinations with colour duplex ultrasound and computerised strain-gauge plethysmography.

Patients:

Eighteen consecutive patients with acute DVT occluding the calf veins and femoropopliteal vein segments.

Main outcome measures:

Ultrasonographic assessment of thrombus resolution and flow patterns in deep and superficial veins. Plethysmographic determination of venous volume and venous outflow capacity.

Results:

At 3 months' and 6 months' follow-up, 33% and 56%, respectively, were recanalised but almost all limbs still had some degree of functional outflow obstruction. Duplex evaluation further demonstrated a complex pattern of recanalisation with thrombus resolution from above, from below or both. Computerised strain-gauge plethysmography showed a progressive time-related increase in venous outflow capacity and venous volume over 6 months, but volumetric variables could not be used to distinguish between limbs with patent veins and those with still-occluded veins. None of the limbs had completely compressible femoropopliteal venous segments at the end of the follow-up.

Conclusion:

The combination of these two modern diagnostic techniques, suitable for repeated studies, can provide detailed information on morphological and haemodynamic changes occurring during the process of recanalisation and thrombus resolution.

Temporary vena caval interruption and thrombolysis in the management of deep vein thrombosis

Temporary interruption of the inferior vena cava (IVC) with a retrievable filter should be considered in patients with objectively verified proximal deep vein thrombosis (DVT) of the legs who have a temporary contraindication to therapeutic anticoagulation, or in patients who experience severe complications from anticoagulation. The risk of the temporary filter being left in place permanently must be considered. Use of a retrievable filter in conjunction with therapeutic anticoagulation during the early phase of therapy for acute DVT in patients whose cardiopulmonary reserve is limited (ie, those with pre-existing pulmonary hypertension) may be a future indication for this intervention. Interruption of the superior vena cava with a retrievable filter has been performed in a small number of cases, but there are insufficient data to guide risk:benefit analysis for this procedure. Thrombolysis, either systemic or local, results in a higher rate of thrombus resolution than anticoagulation alone. However, the long-term benefit of thrombolysis in preventing or improving the post-thrombotic syndrome remains unproven. Due to the substantial risk and cost of thrombolytic therapy, it should not be performed in the routine treatment of DVT. Thrombolytic therapy, in the absence of contraindication, should be considered in highly symptomatic, massive iliofemoral DVT. Catheter-directed thrombolytic therapy has shown promise in case series, but its role remains to be elucidated in randomized trials.

Invasive approaches to treatment of venous thromboembolism

Deep vein thrombosis (DVT) occurs in one-quarter of a million individuals annually in the United States and results in significant disability from pulmonary embolism and chronic venous insufficiency, especially when the proximal iliofemoral is involved. Treatment has centered on early institution of adequate anticoagulation to prevent thrombus propagation and embolism, but anticoagulation alone does not always restore venous patency and many patients are left with venous outflow obstruction and valvular incompetence-the anatomic underpinnings of the postthrombotic syndrome. Various strategies have been used to restore patency of thrombosed veins, including open surgical thrombectomy, pharmacological thrombolysis, and percutaneous mechanical thrombectomy. Each modality has benefits and shortcomings. Surgical thrombectomy had previously been abandoned secondary to poor long-term results. More recently, with improved techniques and better patient selection, surgical thrombectomy has regained a therapeutic role in treating acute DVT in young patients with short segment occlusions. The advent of percutaneous techniques has allowed thrombolysis, percutaneous mechanical thrombectomy, and stenting to be used in conjunction with each other-allowing for better resolution of venous clot burden than when an individual modality is used alone. Practitioners who treat patients with DVT should be familiar with all the options available to restore venous patency, preserve valvular function, and thereby minimize the risk of late postthrombotic complications.

Local and systemic thrombolytic therapy for acute venous thromboembolism

Thrombolytic therapy unquestionably leads to more rapid and complete clot lysis with a significantly higher risk of bleeding when compared with anticoagulation. The most definite indication for thrombolytic therapy in patients with VTE is massive PE associated with hemodynamic instability. Other potential indications, although not widely accepted or proven, include PE-related respiratory failure with severe hypoxemia and massive iliofemoral thrombosis with the risk of phlegmasia cerulea dolens. Routine use of thrombolytic therapy in all other cases of PE and DVT cannot be justified. Future research using randomized controlled studies should focus on the following key questions: Do hemodynamically stable patients with PE and right ventricular dysfunction benefit from thrombolysis, and, if so, is there a subset of patients within this group who are most likely to benefit? Does thrombolytic therapy improve long-term outcomes of DVT with a favorable risk-to-benefit ratio, and, if so, which patients are most likely to benefit long-term? What is the precise role of catheter-directed thrombolysis in the treatment of VTE, particularly the use of a low-dose thrombolytic agent in conjunction with mechanical clot disruption to minimize bleeding in patients at high risk? Until these questions are answered, clinicians must approach decision-making regarding the use of thrombolytic therapy in PE and DVT with careful consideration of the potential risks and benefits for the patient within the framework of currently available data.

The rationale and evidence for the treatment of lower-extremity deep venous thrombosis with thrombolytic agents

This article presents the rationale and evidence for the treatment of lower-extremity deep venous thrombosis (DVT) with thrombolytic agents. DVT is a common condition that has both acute and chronic complications. Standard treatment including anticoagulation therapy and compression stockings may not be entirely adequate, because a significant proportion of patients eventually develop severe post-thrombotic syndrome (PTS). Thrombolytic agents offer a potential advantage because they may reduce residual vein stenosis and valve damage. The authors performed a systematic review of published randomized trials evaluating thrombolytic agents for DVT. The authors determined that thrombolysis therapy results in greater lysis and complication rates than does anticoagulation alone. The authors also found that PTS incidence is lower in patients treated with thrombolytics. However, several methodological flaws limit the conclusions with respect to reduction in PTS. Therefore, the authors conclude that although the lysis rate is greater for thrombolytic agents, they cannot be recommended routinely for DVT treatment.

Tissue plasminogen activator for the treatment of deep venous thrombosis of the lower extremity: a systematic review

OBJECTIVE

To assess, by systematic review, the efficacy and safety of recombinant tissue plasminogen activator (rt-PA) in the treatment of lower extremity deep venous thrombosis (DVT). A secondary objective is to assess the optimal dose and route of administration of rt-PA.

METHODS

Included studies were randomized, controlled trials comparing rt-PA plus unfractionated heparin (UFH) to UFH alone, rt-PA at different doses, or rt-PA by different routes of administration in the treatment of DVT. Outcomes had to be described in terms of percent change in venographic patency for efficacy (>50% lysis) and in sufficient detail for complications (major and minor hemorrhages and other). The search strategy included searching electronic databases and contacting pharmaceutical agencies and content experts. Study quality was assessed using the Jadad scale. A threshold quality score was used to exclude trials.

RESULTS

Five studies met the following inclusion criteria: three comparing rt-PA plus UFH vs UFH alone (180 patients); one comparing high-dose vs low-dose rt-PA (32 patients); and one comparing systemic vs local administration of rt-PA (151 patients). In studies comparing rt-PA vs placebo, patients assigned to rt-PA were more likely to have > 50% lysis and complications (summary odds ratios [OR], 11.7; 95% confidence interval [CI], 2.61 to 52.5; and OR, 9.95; 95% CI, 2.21 to 44.7, respectively). Major and intracerebral hemorrhages were not significantly increased. One study comparing different doses demonstrated that high-dose and low-dose rt-PA were equally efficacious (OR, 0.88; 95% CI, 0.05 to 14.78). Local rt-PA was neither more efficacious nor riskier than systemic rt-PA.

CONCLUSION

This systematic review does not support routine use of rt-PA for DVT.

Loco-regional thrombolysis for deep vein thrombosis: fact or fiction? A study of hemostatic parameters

Loco-regional thrombolysis for deep-vein thrombosis (DVT) has been claimed to be equally effective and safe compared with systemic thrombolysis. It is not known whether a loco-regional thrombolytic effect exists and of what it might consist. To investigate this issue, we studied eight patients with DVT undergoing loco-regional thrombolysis with 20 mg alteplase infused over 4 h in a dorsal foot-vein of the affected leg, while the leg was kept tightly bandaged; alteplase infusions were repeated every 24 h, the number of therapy cycles (TC) was seven, and full-dose heparin was given. For coagulation analyses, 'loco-regional' blood samples were taken from a vein of the affected leg and 'systemic' samples were taken from an antecubital vein. After a median number of six TC, good partial reperfusion was achieved in 4/8 patients, moderate partial reperfusion in 2/8, major bleedings occurred in 2/8, and minor bleedings in 1/8 patients. During the first TC, recombinant tissue-type plasminogen activator (rtPA) activity and antigen, as well as FgDPs and d-dimers, were elevated significantly loco-regionally over systemic values, and a complete breakdown of plasmin-inhibitor activity occurred with only a slight systemic reduction; no other differences were found. During successive TC, differences in rtPA-activity and -antigen levels decreased, and no significant differences were found for all other parameters. Thus, a local fibrinolytic effect was demonstrable during loco-regional thrombolysis for DVT; the magnitude of this effect diminished during successive TC, giving rise to the hypothesis that the fibrinolytic efficacy may be decreased due to growing, antifibrinolytic activity. The preserved, loco-regional plasmin-inhibitor activities during the later TC, in contrast to the complete breakdown during the first TC, suggest that part of the enhanced antifibrinolytic activity is due to loco-regionally increased plasmin-inhibitor activity. The ultimate goal of loco-regional thrombolysis, the induction of local fibrinolysis without systemic effects, has not, however, been achieved.

Sequestrated thrombolysis: comparative evaluation in vivo

PURPOSE

Lysis of a thrombus is a function of the local concentration of thrombolytic enzymes. This study was designed to determine in a porcine model of acute deep vein thrombosis (DVT) whether perithrombic sequestration of small volumes of a concentrated enzyme solution can accelerate the process of thrombolysis.

METHODS

DVT was induced in both hind limbs using a previously described technique (n = 32). Thirty minutes later the animal was heparinized and unilateral thrombolysis was attempted using 8 mg recombinant tissue plasminogen activator (rt-PA); saline was administered in the opposite leg. For conventional high-volume infusion (CI) (n = 5) rt-PA (0.067 mg/ml) was infused at 1 ml/min. For sequestrated thrombolysis the external iliac vein was endoluminally occluded, and rt-PA (0.25 mg/ml) administered either for proximal injection (ST-P) (n = 5), as a bolus every 3 min through a microcatheter placed via the balloon catheter, or for transthrombic injection (ST-T) (n = 5), as a bolus every 3 min through a Katzen wire in the balloon catheter. At autopsy, the thrombus mass in the iliofemoral veins was measured, and the extent of residual thrombosis in the venous tributaries graded at four sites. From these data a thrombolysis score was calculated.

RESULTS

One pig died before thrombolysis could be performed. Only with ST-T was residual thrombus mass in the test limb normalized to control, residual thrombus index (RTI), consistently less than unity. The median RTI of this group was 0.50 (range 0.39-0.97) compared with 1.22 (0.64-1.38) for ST-P and 0.88 (0.37-1.13) for CI. Compared with contralateral controls, a lower grade of residual thrombosis in tributaries was observed in test limbs at more venous sites with ST-T (8/20; 95% confidence interval 5-13) and ST-P (9/20; confidence interval 5-13) than with CI (2/20; confidence interval 0-5) (p = 0.04). A trend toward lower thrombolysis scores was observed with ST-T (p = 0.08). Systemic fibrinogenolysis was not observed in any of the groups. Changes in coagulation parameters during thrombolysis were similar irrespective of treatment protocol.

CONCLUSIONS

"Transthrombic" sequestrated thrombolysis may offer some advantages over conventional selective infusion for the treatment of acute DVT. However further refinements will be necessary before it can be considered an alternative to the latter.

Selective thrombolysis in acute deep vein thrombosis: evaluation of adjuvant therapy in vivo

PURPOSE

To evaluate in a porcine model of acute deep vein thrombosis (DVT) the efficacy of dalteparin and antithrombin with respect to heparin for local adjuvant therapy during selective thrombolysis, and the utility of nitroglycerin and iloprost as heparin supplements.

METHODS

DVT was induced in both hind limbs using a previously described technique (n = 20). Thirty minutes later, the animal was heparinized (2500 IU IV), and bilateral sequestrated thrombolysis was performed using 8 mg alteplase: both external iliac veins were endoluminally occluded with Swan-Ganz catheters, and a multi-sideport infusion wire coaxially introduced through each catheter and advanced into the ipsilateral popliteal vein. In the control limbs, tissue plasminogen activator (tPA) 8 mg was injected as 0.8-ml boluses at 3-min intervals for 2 hr as a 0. 25-mg/ml solution containing heparin 50 IU/ml (n = 20). On the contralateral side, heparin was substituted with either dalteparin 50 IU/ml (n = 5) or antithrombin 12.5 IU/ml (n = 5), or supplemented with either nitroglycerin 0.075 mg/ml (n = 5) or iloprost (150 ng/ml) (n = 5). Blood samples were taken at predetermined intervals to measure the activated partial thromboplastin time (aPTT), prothrombin time (PT), and fibrinogen concentration. At autopsy, the thrombus mass in the iliofemoral veins was measured, and the extent of residual thrombosis in the venous tributaries graded at four sites.

RESULTS

Bilateral thrombolysis was successfully completed in all animals. The median thrombus mass in the iliofemoral veins after thrombolysis was 0.48 g (range 0.06-1.58 g), 0.95 g (0.59-1.29 g), 0. 74 g (0.52-0.96 g), and 0.29 g (0.0-0.77 g) for dalteparin, antithrombin, iloprost, and nitroglycerin respectively, as compared with 0.53 g (0.18-0.88 g) (p = 0.69), 0.97 g (0.46-1.15 g) (p = 0. 69), 0.53 g (0.48-1.10 g) (p = 0.69), and 0.18 g (0.13-1.04 g) (p = 0.5) for the respective controls. Likewise, the severity of residual thrombosis in the venous tributaries was not affected by the constituents of adjuvant therapy. Nitroglycerin induced a small drop in blood pressure, which was transient. The temporal change in aPTT was similar in all four groups. Invariably PT progressively shortened during thrombolysis (p = 0.0001); this effect was somewhat blunted with antithrombin. Fibrinogen levels demonstrated a time-dependent increase (p = 0.004) that was not influenced by the adjuvant therapy used.

CONCLUSIONS

Dalteparin or antithrombin demonstrated no appreciable advantage over heparin as local adjuvant therapy for selective venous thrombolysis. Supplementation of heparin with iloprost or nitroglycerin also had virtually no effect on thrombolytic efficacy.

Thrombolytic therapy for venous thrombosis and pulmonary embolism

Streptokinase, urokinase, tissue plasminogen activator and similar drugs can all cause lysis of venous thrombi and pulmonary emboli, but there is small evidence that accelerated lysis achieves a significantly better clinical outcome, on average, in the shorter or longer term, than heparin alone. Thrombolytic therapy for deep leg vein thrombosis aims to restore flow and to preserve venous valves, and so to prevent chronic post-phlebitic disability, but no trial has convincingly demonstrated that the last can be achieved in more than a few patients. Only a small minority of people with extensive proximal thrombosis develop disabling post-phlebitic venous insufficiency, and there are no good clinical predictors of this outcome. As a result, any widespread use of thrombolytics would bring an immediate risk of major bleeding to many people who will never be destined to develop a clinically important problem. Thrombolytic therapy after venous thrombosis should be avoided except, perhaps, in a few carefully selected patients with severe obstruction. The case for using thrombolytics after recent pulmonary embolism is strongest in the limited number of patients with ongoing hypoxia, respiratory distress, pulmonary hypertension and right heart failure, because thrombolytic therapy often achieves an impressive and almost immediate clinical benefit in this clinical setting. Whether early relief from pulmonary artery obstruction translates into longer-term advantage over heparin remains uncertain, however, because no comparative trial has ever shown these drugs to reduce mortality after pulmonary embolism. In all cases, both the physician and the patient must balance the certainty of an immediate bleeding risk against the uncertainty of a better than marginal real benefit.

Thrombolysis in Central Splanchnic Thrombosis

We present 4 patients treated with streptokinase for different forms of abdominal venous thrombosis. Two patients suffered from central splanchnic venous thrombosis (superior mesenteric vein and bilateral iliac veins in Patient A, portal and superior mesenteric veins in Patient B). Both patients' presenting complaint was abdominal pain. In both, a temporary infection-associated circulating lupus anticoagulant presumably caused this condition. Two other patients presented with isolated portal vein thrombosis without lupus anticoagulant. Thrombolysis with high dose streptokinase (9 MU over 6 hours) successfully reopened the veins involved in all 4 patients. A literature survey showed that thrombolysis is a therapeutic option for mesenteric vein thrombosis, but there was no consensus on which thrombolytic drug should be given or on method of administration.

Thrombolytic therapy of non-cardiac disorders

Patients with a recent (less than 10 days) proximal deep vein thrombosis of the leg or pelvis are candidates for thrombolysis as the major benefit over heparin seems to be the prevention of the postphlebitic limb, an aim which is still not proven in a satisfactory manner. Nonocclusive thrombi appear to lyse more readily than occlusive thrombi. For this indication the optimal dose regimens for the three thrombolytic drugs (streptokinase, urokinase, alteplase) are not established. Acute massive pulmonary embolism with hypotension or shock should be treated with thrombolytic drugs and, pending the outcome in the first hour, be considered for pulmonary embolectomy. Major acute pulmonary embolism with haemodynamic instability responds well to thrombolysis. Whether thrombolysis is superior to heparin in subacute intermediate pulmonary embolism has not been proven unequivocally in terms of mortality or clinically important endpoints. Systemic administration of thrombolytic drugs for peripheral arterial occlusion has been abandoned for catheter-directed and intraoperative intra-arterial repeated bolus or short-term infusions. The efficacy and safety of intravenous thrombolytic treatment following a major ischaemic stroke is presently being tested in large scale trials; its use must be restricted to experimental protocols.

Catheter-directed thrombolysis following vena cava filtration for severe deep venous thrombosis

Massive deep venous thrombosis with marked venous outflow obstruction can result in limb loss or end-organ injury. Systemically administered drugs may not reach thrombi in therapeutic concentrations and surgical and thrombolytic strategies carry a small but real risk of pulmonary embolus--similar to the risks with anticoagulation alone. We therefore developed a strategy in which catheter-directed thrombolysis was used to deliver high concentrations of a plasminogen activator directly to the thrombus combined with placement of a downstream Greenfield filter to protect patients from pulmonary embolus. From 1984 to 1993 six patients were treated with this regimen. All had severe symptoms of less than 4 days' duration. On radiologic evaluation four patients had large iliofemoral and/or inferior vena cava thrombosis, one had subclavian/innominate vein thrombosis, and one had transplant renal vein/iliofemoral/inferior vena cava thrombosis. A Greenfield filter was first placed downstream prior to imbedding an infusion catheter in the greatest mass of thrombus for subsequent infusion of urokinase (n = 4) or streptokinase (n = 2). In four patients the catheter traversed the Greenfield filter. All patients were given bolus lytic therapy followed by maintenance infusions ranging in duration from 24 hours to 12 days. Five patients remained on heparin simultaneously. Clot lysis was achieved in all patients with hemodynamic, symptomatic, and arteriographic improvement. There were no deaths, pulmonary emboli, or complications of filter placement. One patient had minor bleeding at the puncture site and another had catheter-related infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy and safety of repeated boluses of urokinase in the treatment of deep venous thrombosis

The only Food and Drug Administration-approved thrombolytic regimen for treatment of deep venous thrombosis (DVT) is a 24- to 72-hour continuous infusion of intravenous streptokinase. This approach to DVT thrombolysis is not entirely satisfactory because of the bleeding complications that may accompany this therapy. In the current study, we treated 27 patients with DVT with a novel dosing regimen of urokinase: 1,000,000 U administered as a 10-minute bolus, with a total of 3 boluses given over approximately 24 hours. Patients were given heparin overnight between bolus urokinase doses. Efficacy was assessed by comparing baseline and prehospital discharge vascular imaging studies, which constituted either venous ultrasound or contrast venography. A vascular-imaging panel of physicians, unaware of the sequence of paired studies, found that 14 patients (52%) had clot lysis (6 slight, 6 moderate and 2 marked), 9 (33%) had no change, and 4 (15%) had more extensive thrombosis after treatment (1 slight, 2 moderate and 1 marked). There were no bleeding complications. At 48 hours after starting urokinase, mean plasma fibrinogen levels had decreased 61% from baseline, and the mean bleeding time had increased 28% from baseline (but remained within the normal range). Because of the promising efficacy and safety that were found in this case series, it is concluded that further testing of bolus urokinase is warranted against anticoagulation alone.

Tissue plasminogen activator (alteplase) treatment for femoral artery thrombosis after cardiac catheterisation in infants and children

OBJECTIVE

To determine the efficacy of fibrinolytic therapy with tissue plasminogen activator (alteplase) in infants and children with arterial thrombosis after cardiac catheterisation.

DESIGN

Use of alteplase (Actilyse) in a protocol with prospective data collection. Alteplase was administered to infants and children with arterial thrombosis after cardiac catheterisation. A dose of 0.5 mg/kg/h was given continuously via a peripheral vein for the first hour followed by 0.25 mg/kg/h till clot lysis occurred or treatment had to be stopped because of bleeding complications.

SETTING

University hospital, intensive care unit.

PATIENTS

17 consecutive infants and children with femoral artery thrombosis after cardiac catheterisation between 1 April 1988 and 31 October 1991.

MAIN OUTCOME MEASURE

Reopening of the vessel.

RESULTS

Complete clot lysis was achieved in 16 of 17 patients within 4-11 hours after the start of treatment. In one patient only partial lysis occurred. After complete lysis rethrombosis developed in one patient 15 hours after the end of treatment. Bleeding complications were seen in nine patients. These were restricted to the arterial puncture site, except for one who showed mild epistaxis. Three patients had to be treated with packed erythrocytes.

CONCLUSIONS

Alteplase was an effective treatment of arterial thrombosis after cardiac catheterisation in infants and children. Further studies are needed to determine whether lower doses will reduce the frequently observed bleeding complications.