Limitations to the widespread usage of low-dose intra-arterial thrombolysis

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.

The current role of intra-arterial thrombolysis

BACKGROUND

the role of intra arterial thrombolysis (IAT) in the management of peripheral vascular disease has come under scrutiny. This study aims to assess current usage and indications for IAT in the U.K.

METHOD

the use of IAT was assessed at our own centre and a questionnaire was sent to all centres that provide data for the U.K. "Thrombolysis Study Group".

RESULTS

there has been a steady decline in the use of IAT at our centre from a peak of 40 cases per annum to zero. Response was received from 22 of 24 centres (92%). Nineteen (86%) reported a decline in IAT use. Main reasons were concerns over lack of efficacy (74%) and complication rate (63%). Most centres would use IAT for acute limb ischaemia (86%). However, for acute thrombosis in specific indications the results varied; synthetic graft (82%), vein graft (54%), supra-inguinal graft (54%) and thrombosed popliteal artery aneurysm (54%). When asked what their commonest usage for IAT was, the results again varied; acute limb ischaemia (40%), graft thrombosis (40%), embolism post radiological intervention (12%), other (8%).

CONCLUSION

there has been a significant decrease in IAT use. Concerns exist as to efficacy and complication rate. There is no clear consensus on indications.

Prospective randomised comparative study of pulse spray and conventional local thrombolysis

OBJECTIVES

To compare the time required to achieve lysis with the pulse spray technique and the conventional slow continuous infusion technique.

DESIGN

Prospective randomised open Study.

METHODS

Eighteen patients suitable for intra-arterial thrombolytic therapy with conventional and pulse spray technique were randomised 1:1 to receive either pulse spray thrombolysis with 0.33 mg/ml rt-PA injected as a bolus of 0.2 ml or conventional thrombolysis with 0.05 mg/ml rt-PA infused at a rate of 10 ml/h.

RESULTS

The age, duration of symptoms, length of occlusion and prethrombolysis ankle brachial pressure index were comparable in the two groups. The median duration of thrombolytic therapy in the pulse spray group was 195 min (range 90-1260) compared to 1390 min (range 300-2400) in the Conventional group. The difference between the two groups was significant, p < 0.002 (Mann-Whitney test).

CONCLUSIONS

Significantly shorter time is required to achieve local thrombolysis with pulse spray compared to the conventional infusion method.

Lower limb intra-arterial thrombolysis

In the UK, approximately 5000 patients present annually with acute lower limb ischaemia. The aetiology is usually thromboembolic disease, other causes include aortic dissection and arterial trauma. Over the past two decades thrombosis has replaced embolism as the principal cause of acute ischaemia, and now accounts for approximately 59% of cases. As a consequence, intra-arterial thrombolysis is being increasingly used as first-line treatment for this condition.

Popliteal aneurysm: morphology and management

Since January 1988, 32 patients have presented with 44 popliteal aneurysms (22 thrombosed, 22 non-thrombosed). Patients with thrombosed aneurysms were older (median age 72 versus 66 years), and more likely to have bilateral lesions (P < 0.02) and serious associated cardiovascular disease (P < 0.02). Nineteen aneurysms thrombosed acutely; 12 were treated with intra-arterial thrombolysis, which was at least partially successful in seven. All 12 were subsequently bypassed, as were the other seven which were associated with such severe ischaemia that they required urgent operation. One patient died and two others required major amputation. Other complications included foot-drop (two patients), renal failure (one) and wound infection (two). Two grafts thrombosed and required re-exploration. Elective bypass was carried out in 11 patients without acutely thrombosed aneurysms; there were no significant postoperative problems. Distortion within the aneurysm (P < 0.01), large size (P < 0.01) and distortion of the popliteal artery above or below the lesion (P < 0.02) were all associated with thrombosis. Stenosis within the aneurysm was more likely in patients with multiple lesions (P < 0.01) and distortion with larger aneurysms (P < 0.01). After correcting for distortion, none of the other variables was independently significant. The combination of distortion and diameter > 3 cm was present in 13 of 15 thrombosed aneurysms. Morbidity is high following acute thrombosis of popliteal aneurysm. Distortion of the aneurysm appears to be a more sensitive predictor of thrombosis than size alone. The combination of distortion with a diameter > 3 cm may help to define popliteal aneurysms that should be bypassed electively.

Acute limb deterioration during intra-arterial thrombolysis

Approximately 12 per cent of limbs undergoing intra-arterial thrombolysis (IAT) develop distal embolism or extension of thrombus during the procedure. These are usually of little clinical consequence and can be treated by increasing the rate of administration of the lytic agent. However, in some patients the clinical condition of the limb deteriorates rapidly. In an attempt to define the incidence of acute limb deterioration during IAT, information was collected from five centres in the UK with experience of the technique. A total of 866 treatments were recorded, with 20 limbs (2.3 per cent) undergoing acute deterioration. This complication was more common during the treatment of thrombosed popliteal aneurysm than during that of emboli or thrombosed atheromatous arteries or grafts (P < 0.001). The amputation rate associated with the complication was high, and operative intervention provided better results than continuation of lysis.

Surgical treatment versus thrombolysis in acute arterial occlusion: a randomised controlled study

Thrombolytic treatment has been tried in various forms for acute limb ischaemia with varying degrees of success but is also often accompanied by bleeding problems. The present investigation compares the effect of surgical thrombectomy (TE) and thrombolysis (TL) using recombinant tissue plasminogen activator (rt-PA). Twenty patients with a need for intervention owing to ischaemia lasting more than 24 h but less than 14 days were included. Patients randomised to TE were operated under epidural anaesthesia and patients in the TL group received 30 mg rt-PA during a 3 h period through a catheter placed into the thrombus and advanced as lysis was achieved. Thrombectomy resulted in an immediate restitution of blood flow in six out of nine cases, in three cases a bypass procedure was performed, and one of these failed with a resultant amputation. Thrombolysis gave a good primary result in six cases which lasted in four of them. Three had a subsequent percutaneous transluminal angioplasty. Partial lysis was seen in two cases and a further two failed. Five went to surgery with three bypass and two fogarty procedures being necessary. There was no hospital mortality and there were no bleeding complications due to the rt-PA treatment in this series. In 19 out of 20 patients the circulation was re-established. Appropriate handling of acute ischaemic conditions implies the use of both thrombolysis and appropriate surgical procedures, including distal bypass grafts.

Low-dose intra-arterial thrombolysis in the treatment of occluded vascular grafts

As the use of intra-arterial thrombolysis increases, its application to specific areas requires definition. The results of treatment of occluded vascular grafts are presented. Thrombolysis using streptokinase or tissue plasminogen activator was planned in the treatment of 18 occluded vascular grafts (five aortofemoral bifurcation grafts and 13 infrainguinal grafts). Two patients, both with infrainguinal occlusions, did not receive thrombolytic therapy and were considered failures of treatment. Successful lysis occurred in three of five aortofemoral grafts, in both infrainguinal vein grafts and in five of nine infrainguinal synthetic grafts. The overall success rate was approximately 60 per cent. Two-thirds of the patients required no intervention following successful lysis. Percutaneous transluminal angioplasty was not found to be a useful additional procedure. A review of the literature revealed that intra-arterial thrombolysis is significantly more successful in the treatment of suprainguinal graft occlusion than in infrainguinal occlusions, there being no difference between infrainguinal vein and synthetic grafts. Provided that the limb is viable and there are no contraindications, intra-arterial thrombolysis is a useful means of clearing occluded grafts.