Local thrombolysis in peripheral arteries and bypass grafts

Thrombolysis in the Management of Lower Limb Peripheral Arterial Occlusion—A Consensus Document

The aim of this paper is to develop an intercontinental consensus on the use of thrombolytic therapy in occlusive peripheral arterial disease affecting lower limbs. A working party of self-designated angiologists, hematologists, interventional radiologists, and vascular surgeons of Europe and North America convened at 4 closed meetings. All published data known to any of the participants was entered into discussion. The working party discussed the topics outlined in this paper and a first draft was prepared in segments by members of the working party, discussed, and further revised into an interim report. It was then circulated to a number of Societies for their input. A final meeting of the Working Party together with delegates of the Societies collaborated on the definitive version of the text. The Party appreciates that in many areas the scientific evidence is not yet available. Nevertheless, it was felt that enough practical and scientific data were available to establish recommendations for clinical practice as well as for reporting results of thrombolytic therapy, which could be updated as later evidence became available. The guidelines apply only to drugs currently available for clinical use. The data are also considered to be sufficiently cogent that regulatory agencies should move to approve thrombolytic agents for intra-arterial therapy of acute lower extremity ischemia.

Factors predicting the outcome of intraarterial thrombolysis in peripheral arterial and graft occlusions

PURPOSE

To determine the association between successful intraarterial thrombolysis and the following factors: sex, age, symptoms, duration of symptoms, length of occlusion, conduit type, runoff, and catheter localization.

MATERIAL AND METHODS

Forty-six patients with acute or subacute occlusions of peripheral native arteries and grafts were treated with continuous intraarterial infusion of streptokinase or urokinase. A univariate chi-square test and logistic regression analysis were used.

RESULTS

Successful lysis was achieved in 27 of 46 patients (59%). The logistic regression analysis revealed a significant association between successful thrombolysis and good runoff (p < 0.01). A catheter position above the occlusion resulted in lysis in only one of 11 patients. The variables rest pain and claudication were slightly significant (p = 0.07). None of the other variables were significant, but a trend toward a separate effect of duration of occlusion was found.

CONCLUSION

Good runoff and intrathrombotic infusion are virtual necessities in obtaining a positive immediate outcome in peripheral arterial and graft occlusions. In our study, other factors were less important.

Accelerated thrombolysis with high dose bolus t-PA extends the role of peripheral thrombolysis but may increase the risks

Low dose intra-arterial thrombolysis is too slow for many patients with severe acute limb ischaemia. Accelerated thrombolysis with high dose bolus t-PA was used in a consecutive series of 43 patients. Complete or clinically useful lysis was achieved in 39 patients, with a median duration of 7 h. Lysis occurred in 46% in under 4 h. Fifty-six per cent of patients required further procedures after lysis. Eleven per cent suffered a major bleed. The limb salvage rate at 30 days was 56%. Amputation was required in 22% and 22% died. Most deaths were due to associated thrombotic conditions: myocardial infarction (5), pulmonary embolism (1) and malignant thrombosis (1). One patient died from pneumonia two weeks after lysis and two died from renal failure within a week of thrombolysis. The high mortality rate was not associated with bleeding but may reflect the high risks involved in treating this group of patients. High dose bolus t-PA infusion appears to predict immediate outcome of thrombolysis as well as reducing infusion times. It may expand the indications for the non-surgical treatment of acute limb ischaemia to include most patients with the condition. Careful case selection is still necessary for optimal results.

Thrombolysis in acute peripheral arterial occlusion: predictors of immediate success

Thrombolytic therapy is frequently used for the treatment of peripheral arterial occlusion, but clinical predictors of success have not yet been defined. We prospectively evaluated 80 consecutive patients receiving intra-arterial urokinase for acute (< 14 days) ischemia. Fifty-five patients (69%) were treated for bypass graft occlusion and 25 patients (31%) for native arterial occlusion. Two primary outcome measures were evaluated using multivariate techniques (stepwise logistic regression) to determine the independent predictors of immediate arteriographic success: successful (> 80%) thrombolysis and avoidance of adjuvant operative or endovascular procedures. Independent variables examined included age, sex, comorbid conditions, severity, duration, etiology and location of the ischemic process, and positioning of the infusion catheter and guidewire. Overall, successful lysis was achieved in 57 patients (71%) and adjuvant procedures were avoided in 22 patients (28%). Successful outcome was more frequent in prosthetic graft (78%) and native arterial (72%) occlusions than in vein graft occlusions (53%, p = 0.017) and in nondiabetics than in diabetics (80% vs. 52%, p = 0.031). Lysis was dependent on placement of the catheter into the substance of the thrombus (85% vs. 0% success, p = 0.004) and passage of a guidewire through the occlusive process (92% vs. 10% success, p = 0.001). The only parameter independently predictive of successful outcome without the use of adjuvant procedures was the location of the occlusion; additional procedures were necessary in 88% of aortoiliac and 82% of infrainguinal occlusions vs. only 17% of upper extremity occlusions (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombolysis in acute lower limb ischaemia

For the past three decades balloon embolectomy has been the treatment of choice for acute lower limb occlusion. However, although usually successful in emboli, results are often disappointing in thrombotic atherosclerotic vessels. Attempted dissolution of the clot is accordingly attractive, and has theoretically been possible since the introduction of streptokinase in 1933. This was initially used intravenously, with variable success rates, although intraarterial administration is currently the method of choice. Later thrombolytic drugs such as tissue plasminogen activator, urokinase and anistreplase have been introduced. Lysis time has also been increased by using pharmaco-mechanical methods of administration such as pulsed spray catheters, which could increase the usefulness of thrombolysis in patients with rapidly progressive neurological signs where currently surgical embolectomy would be advocated. Several newer drugs with theoretical advantages over older drugs such as single-chain urokinase-type plasminogen activator or K1K2PU are currently undergoing trials. The role of thrombolysis as an adjunct to surgical embolectomy is also promising, though again requires further trials. There is still no consensus as to which patients are best suited to thrombolysis, nor an optimum drug or method of administration. However, there seems no doubt that thrombolysis will be increasingly used in the management of peripheral limb ischaemia, though requiring a team approach between surgeons, radiologists and haematologists.

Low-dose urokinase regimen for the treatment of lower extremity arterial and graft occlusions: experience in 132 cases

In a retrospective review, a low-dose urokinase (UK) infusion regimen (mean, 87,000 U of UK per hour and 100 U of heparin per hour) was evaluated for lower extremity arterial and graft occlusions. Results of 132 infusions in 111 patients were analyzed to determine efficacy, limb salvage, and complications. Angiographic success was achieved with 126 infusions (95%), and amelioration of presenting signs and symptoms was achieved after 116 infusions (88%). Patients who underwent additional percutaneous procedures were more likely to have a successful outcome. There was no significant difference in success rates for patients receiving low-dose heparin through the arterial sheath (n = 101) versus those receiving concomitant systemic heparinization (n = 29), (P = .08) [corrected]. Of 88 threatened extremities (with rest pain, cold, ulcers, or gangrene), nine were amputated (limb salvage = 90%), accounting for 82% (nine of 11) of amputations in the overall study. Patients with zero- or one-vessel runoff before infusion were more likely to require limb amputation compared with the group with two- or three-vessel runoff before infusion (P less than .01). Major periprocedural complications occurred in nine of 132 (7%) infusions, five of which necessitated specific surgery and/or transfusion for bleeding. Pericatheter thrombosis was not encountered in either subgroup. This standard local low-dose infusion represents a safe and effective treatment for lower extremity arterial and graft occlusions.

Thrombolytic therapy in the management of acute limb ischaemia

Acute limb ischaemia poses a threat to both the limb and life of a patient. Until recently, attempted revascularization by thromboembolectomy or vascular reconstruction held the best chance of limb salvage. Thrombolytic techniques afford an alternative method of management for this condition and are effective in selected patients. Low-dose intra-arterial streptokinase is the most established method of thrombolysis, although the recently developed tissue plasminogen activator offers a promising alternative. Intra-arterial thrombolysis is not an easy option, being labour intensive and requiring close co-operation between surgeon and radiologist. Thrombolytic and surgical techniques are not mutually exclusive but are best used to complement each other. Ideally patients with acute limb ischaemia should be managed by surgeons with knowledge of, and access to, optimal current surgical and non-surgical techniques.

Intra-arterial thrombolytic therapy in the management of acute and chronic limb ischaemia

A group of 54 patients with acute or chronic limb ischaemia were initially treated with low dose intra-arterial thrombolytic therapy using streptokinase (10,000 units h-1) or plasminogen activator (0.5 mg h-1). Complete thrombolysis was obtained in 90 per cent of patients with symptoms of less than 1 week duration, and in 50 per cent with symptoms of greater than 1 week (P less than 0.05). Successful lysis in 36 patients was followed by successful bypass surgery in seven, percutaneous angioplasty in 13, no further treatment in 13, repeat thrombolysis in two and amputation in one. Failed therapy was associated with major amputation in 40 per cent. One patient died of haemorrhage and another of stroke as a direct result of thrombolytic treatment. The most common complication was haematoma at the site of cannulation of the vessel. Intra-arterial thrombolytic therapy can be very useful for the management of acute and chronic limb ischaemia, but complications do occur and patients should be carefully selected.

Popliteal aneurysms identified by intra-arterial streptokinase: a changing pattern of presentation

Five patients presenting with chronic or subacute leg ischaemia due to thrombosed popliteal artery aneurysm are described. Only one of these aneurysms was diagnosed before intra-arterial streptokinase infusion, which successfully lysed the thrombus in all cases. One aneurysm had been symptomatic for 5 years and another for 2 years. Popliteal aneurysm may well be underdiagnosed as a cause of chronic leg ischaemia.

Current therapy of peripheral obstructive arterial disease. The non-surgical approach

In recent years double-blind trials have proved the effectiveness of nonsurgical therapy in the treatment of peripheral obstructive arterial disease (POAD). Among the non-pharmacologic measures taken, walking distance was increased by 40% in subjects who stopped smoking and by more than 100% in those who undertook physical exercise. Drug treatment reduces the atherosclerotic process and brings about an improvement in the symptoms of the disease. In subjects given hypolipidemic treatment the progression of the disease was reduced by two thirds. Two separate studies suggest that antiplatelet drugs, taken over a period of two to four years, significantly slow the progression of atherosclerosis in lower extremity arteries. In the treatment of claudication, two vasodilating drugs, naftidrofuryl and buflomedil, have shown a significant improvement in painfree walking distance and/or total walking distance, compared with treatment with placebo. Another effective approach is in the treatment of blood rheology through drugs such as pentoxifylline or by hemodilution. Double-blind trials with pentoxifylline demonstrated an average increase of 66% in maximum walking distance as compared with 22% with placebo. The effectiveness of hemodilution was demonstrated by two controlled trials, during which the reduction of the hematocrit to values of 40-42 for periods of four to six weeks increased both walking distance and resting blood flow. When introduced intraarterially in low doses in the vicinity of the occluding thrombus, thrombolytic agents have been found to be helpful in the treatment of acute and chronic POAD. This therapy should, however, be regarded as a substitute for surgical treatment only in high-risk patients. Further, after having produced the lysis of thrombi, the treatment permits the underlying parietal lesions to be accurately identified; at this point the appropriate therapy can be decided upon, either an operative procedure or a balloon dilation. In conclusion the many controlled clinical trials carried out over the past few years have clearly demonstrated that conservative treatment can alleviate clinical signs and symptoms in patients with claudication and pain at rest.

A protocol for the safe treatment of acute lower limb ischaemia with intra-arterial streptokinase and surgery

Over a 5-year period 70 patients, presenting with subacute ischaemia of the lower limb (more than 12 h), were treated with low-dose intra-arterial streptokinase. There were 72 infusions and effective lysis was achieved in 52 (72 per cent), with an average infusion time of 25 h. A total of 23 (32 per cent) also underwent percutaneous transluminal angioplasty when lysis showed an underlying stenosis, and a further 19 (26 per cent) required surgery to remove persistent stenosis, organized thrombus or atheromatous debris. Significant bleeding occurred in 4 patients (6 per cent) and 13 (18 per cent) underwent amputation. There were five deaths (7 per cent), one of which was directly related to the infusion, while three were due to myocardial infarction. All of the major complications occurred in the early part of the study and both the selection of patients and the technique of infusion were modified to improve safety. Complementary treatment by percutaneous transluminal angioplasty and surgery was used more frequently in the later part of the study. The technique is not recommended for the white leg of acute ischaemia (less than 12 h), or for lysis of clot in a retroperitoneal Dacron graft, but may be uniquely valuable to demonstrate the cause of subacute ischaemia.

Analysis of urokinase immobilization on the polytetrafluoroethylene vascular prosthesis

The polytetrafluoroethylene (PTFE) vascular prosthesis is thrombogenic and therefore not an ideal artificial blood vessel. The immobilization of urokinase on the surface of this substance has the potential to render the PTFE thrombolytic. Urokinase was immobilized to PTFE using tridodecylmethyl-ammonium chloride as a surfactant. In this preliminary study, a success rate of 45 percent was observed for the immobilization of active urokinase to PTFE. A model is proposed wherein application of the graft to an in vivo system is discussed. The urokinase graft is expected to be most effective under conditions of reduced blood flow which otherwise might promote thrombogenesis. The systemic side effects of the immobilized urokinase are expected to be significantly less when compared with the side effects of urokinase infused for clot lysis. The model presented of the urokinase-bound graft suggests that development and further study of the graft will result in an improved PTFE vascular prosthesis.