Survey of the use of thrombolysis for acute limb ischaemia in the UK and Ireland

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.

A systematic review of intra-arterial thrombolytic therapy for lower-limb ischaemia

METHODS

a search of the major databases was carried out to identify randomised controlled trials of intra-arterial thrombolytic therapy in the treatment of limb ischaemia. The search was limited to English language articles, or those that provided a sufficiently detailed English summary, and to articles published after 1980. In addition, key journals were hand-searched and citations were also reviewed. Two reviewers independently performed data extraction and aggregate outcomes were obtained using a random effects meta-analysis.

RESULTS

a total of 34 articles were found, but only 10 were reports of randomised controlled trials. Meta-analysis showed no significant differences between thrombolysis and surgery in terms of major amputation (relative risk (RR) 0.893 95% confidence interval (CI) 0.576, 1.383) and mortality (RR 1.24 95% CI 0.795, 1.9). However, there was an increased risk of haemorrhage with thrombolysis (RR 2.94 95% CI 1.1, 7.9). Sub-group analysis suggests that short-duration occlusions (relative risk reduction (RRR) 72%, numbers needed to benefit (NNB)=3) and occluded grafts (RRR 58%, NNB=4) may benefit from thrombolysis. However, thrombolysis should be avoided in occlusions of greater than 14 days - particularly native vessel occlusions.

CONCLUSION

despite the theoretical advantages of thrombolysis, there is still insufficient evidence to justify its widespread use except in graft occlusions and short-duration ischaemia.

Immediate and early follow-up results of purse spray thrombolysis in patients with peripheral ischaemia

Pulse spray thrombolysis is a technique of accelerated peripheral thrombolysis which has been evaluated in 38 patients, 29 with threatened limb viability and nine with a viable but critically ischaemic limb. The median length of occlusion was 26.5 (range 3-65) cm. The lytic agent used was recombinant tissue plasminogen activator (rtPA), injected manually via a pulse spray catheter at a concentration of 0.33 mg/ml and a bolus size of 0.2 ml. The median total dose of rtPA was 18 (range 5-35)mg. Patency and flow were completely restored in 34 of 38 patients and clinical success at 30 days was maintained in 27 of 38. The median lysis time was 120 (range 35-1125) min, compared with a median duration of 1545 (range 42-5760) min in 120 consecutive patients previously treated with conventional low-dose infusion thrombolysis using rtPA. This represents a 12-fold reduction in lysis time (P < 0.001). The overall estimated cumulative limb salvage rate for the 38 patients who entered the study was 84 per cent and the cumulative patency rate for the 34 patients in whom patency was restored was 74 per cent at 18 months follow-up. Pulse spray thrombolysis rapidly restores patency with good limb salvage at 30 days; the benefit is sustained even in patients with limbs at immediate risk of irreversible ischaemic injury who are not considered suitable for conventional thrombolysis.

The treatment of upper limb vascular occlusions using intraarterial thrombolysis

Acute ischaemia of the lower limb is increasingly treated by intraarterial thrombolysis. Four cases are reported in which this technique has been used successfully for treatment of upper limb emboli. The possible indications and potential drawbacks of such treatment are discussed.

Long-term results of a single protocol for thrombolysis in acute lower-limb ischaemia

In a prospective study, 78 of 157 patients with acute lower-limb ischaemia were considered suitable for thrombolysis. The immediate and 4-year results of 52 patients managed by a single protocol are reported. Of 34 patients alive at 4 years, 23 had limb salvage. Initial treatment produced effective lysis in 38 patients (73 per cent) with significant benefit in 35 (67 per cent); that benefit was sustained for a minimum of 4 years in 30 patients (58 per cent). Seven of the 18 deaths by 4 years occurred within 30 days. Amputation was carried out in six patients within 30 days and in five during the next 4 years. Delayed amputation followed persistent distal occlusion or progression of distal disease. No death or amputation was caused by complication of treatment. In selected patients the risks of thrombolysis can be reduced to an acceptable level by personal supervision and a strict protocol. In survivors, limb salvage is generally sustained for at least 4 years.

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.

Management of asymptomatic popliteal aneurysms: the use of a Markov decision tree to determine the criteria for a conservative approach

With recent improvements in the results of treatment of popliteal aneurysms, it has been suggested that it may be preferable to treat asymptomatic aneurysms conservatively and to operate only if symptoms develop. This hypothesis has been tested using decision analysis, with sensitivity and threshold analysis to establish the conditions under which such a policy would be appropriate. A Markov decision tree has been used to model the problem and the relevant probabilities have been obtained from a review of the current literature. A computer spreadsheet was used to calculate the results of policies of immediate operation or operation only if symptoms occur. Sensitivity and threshold analysis have been carried out to assess the effect of inaccuracy or alteration in the key variables and to determine the optimum policy under different conditions. The results suggest that early elective operation produces better results than conservative management at 1-2 years after presentation. Sensitivity analysis reveals that the most crucial data are the rate of development of symptoms in patients with asymptomatic aneurysms and the expected limb loss and mortality of treatment for symptomatic aneurysms. Threshold analysis has been used to define the values of these parameters that would be necessary for conservative management to be preferred. It is concluded that, based upon the currently available data, the optimum policy is elective treatment of asymptomatic aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Recombinant tissue-type plasminogen activator is superior to streptokinase for local intra-arterial thrombolysis

The results of local intra-arterial thrombolysis in 98 patients treated with streptokinase and 69 patients treated with recombinant tissue plasminogen activator (rtPA) have been compared. The two groups of patients were well matched and their treatment protocols were identical except with regard to the thrombolytic agent used. Strict criteria for defining successful thrombolysis were used. Successful lysis was achieved in 40 of 98 patients (41 per cent) receiving streptokinase and 40 of 69 patients (58 per cent) receiving rtPA (P less than 0.05). The time to lysis was significantly shorter with rtPA, median time 22 h, than with streptokinase, median time 40 h (P less than 0.002). There was no difference in the incidence of haemorrhagic complications. These results suggest that rtPA is superior to streptokinase for local intra-arterial thrombolysis.

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.

Thromboembolic events in a severely burned patient

A patient with severe burns suffered spontaneous bilateral peripheral arterial thromboses which were successfully treated with recombinant human tissue plasminogen activator (rt PA) (Actilyse). The patient later died from complications of burns.

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

Despite encouraging results, intra-arterial thrombolysis (IAT) has not been readily accepted by British surgeons. In an attempt to clarify the reasons for this we sent a postal questionnaire to surgeons with a vascular interest, asking them to define their present attitude towards IAT. Subsequently, we re-analysed our own clinical data in the light of the answers received. In all 134 surgeons (58%) replied to the questionnaire; 48 (38%) never used IAT and 56 (45%) used it only occasionally. When stated, the main reasons for this limited use were the doubts about efficacy (45%) and lack of radiological support (47%). From November 1988 to August 1990 we used IAT for 82 occlusions (streptokinase 74, rt-PA8). Lysis was achieved in 82% of cases when treatment was started within 1 week of symptoms starting, and 62% with symptoms of longer duration. Following successful IAT no further treatment was required in 44% of cases, reconstruction was needed in 26% and angioplasty in 23%, one major amputation was performed. Unsuccessful lysis resulted in reconstruction in 40% of cases. Overall, the limb salvage rate was 89%. Major complications occurred in six cases. One patient sustained a fatal CVA and five bled from the catheter insertion site. Two of these patients required an emergency operation and one other, who had an angioplasty immediately following lysis, died. Minor complications included local haematoma formation (16), catheter problems (6), and allergic reactions (2). After insertion of the perfusing catheter, angiograms (median 4, maximum 10) were performed at intervals, with repositioning of the catheter if necessary, until lysis was complete.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Acute limb ischaemia: the place of intravenous streptokinase

Intravenous streptokinase infusions (100,000 units/h) have been used to treat 48 patients, with 50 episodes of acute limb ischaemia who were unlikely to benefit from a surgical approach. These included 17 acute thromboses, 14 late or distal emboli and 19 bypass graft occlusions. Overall, 17 (34 per cent) instances had complete lysis with reappearance of distal pulses and a further 28 per cent had clinical improvement without change in pulse status. Final outcome after 30 days was limb salvage in 60 per cent, amputation in 24 per cent and death in 16 per cent, but this was achieved after eight patients without lysis had vascular reconstructive surgery. Serious complications were infrequent, but included a fatal stroke, a haematemesis and two episodes of distal embolization. The outcome was not related to the duration of ischaemia or the site of occlusion. Lysis was more frequent with emboli (50 per cent) and graft occlusions (47 per cent) than arterial thromboses (6 per cent). Limb salvage was more likely in patients with no neurological deficit in the limb (70 per cent) than if a deficit was present (37 per cent). In conclusion, intravenous streptokinase produced a moderate benefit with low morbidity and has a role in acute limb ischaemia if surgery is inappropriate and intra-arterial lysis unavailable. In particular, selected patients with emboli or graft occlusions without a neurological deficit may be most suitable.