Thrombolysis in arterial graft thrombosis

The role of thrombolysis in acute infrainguinal bypass occlusion: a prospective nonrandomized controlled study

Current treatment of acute infrainguinal bypass occlusion consists of either surgical revascularization or catheter-guided intra-arterial thrombolysis with adjunctive correction of the underlying flow-limiting lesion. In maintaining long-term patency, improving the number of outflow vessels could be of utmost importance. To compare the efficiency of both thrombolysis and primary surgical revascularization and to study the effect of thrombolysis on the number of patent outflow vessels, a prospective nonrandomized study was performed. Between February 2002 and August 2003, 54 patients with 56 occluded bypasses were included. Thirty bypasses were treated with thrombolysis, 26 primarily with surgery. Thrombolysis was successful in 80% of cases, with restoration of patency of the bypass but also with doubling of the amount of patent outflow vessels; surgery was successful in 85.71% of cases. However, in only 60% of the successfully lysed bypasses no adjunctive major surgery was needed. Amputation-free survival was 87.5% 1 year after surgery and 82.6% 1 year after thrombolysis. One year after thrombolysis without adjunctive major surgery, the amputation-free survival was only 39.7%. Therefore, a strategy could be to start with thrombolysis to improve outflow followed by a new bypass, whatever the underlying causative lesions are.

Lysis/balloon angioplasty versus thrombectomy/ open patch angioplasty of failed femoropopliteal polytetrafluoroethylene bypass grafts

PURPOSE

Several studies have reported on the outcome of lysis/percutaneous transluminal balloon angioplasty (PTA) of failed or failing femoropopliteal bypass grafts (FPGs) with mixed results. None of these studies have compared the results of lysis/PTA versus thrombectomy/open patch repair for failed above-knee polytetrafluoroethylene (PTFE) FPGs.

METHODS

Patients with failed (thrombosed) above-knee FPGs (PTFE, Goretex) during a 10-year period were given the option to choose between thrombectomy/open patch repair for localized anastomotic short stenosis (less-than-or-equal2 cm; group A, 31 patients) and lysis/PTA or thrombectomy/balloon angioplasty when lysis failed or was contraindicated (group B, 26 patients). The cumulative patency rates were compared by using a Kaplan-Meier life table analysis. All patients underwent routine color duplex ultrasound scanning/ankle brachial index measurements at 30 days, 6 months, and every 6 months thereafter.

RESULTS

Demographic and clinical characteristics and indications for intervention were comparable in both groups. The mean follow-up period was 54.1 and 46.2 months in group A and group B, respectively. There were four perioperative complications in group A (13%) and seven perioperative complications in group B (27%). Initial technical success and 30-day secondary graft patency rates were 100% in both groups. Overall, 17 of 31 patients (55%) had open grafts, with no further revisions in group A and six of 26 patients (23%) in group B requiring further revisions (P =.012). Nine of 31 grafts (29%) failed in group A versus 15 of 26 grafts (58%) in group B (P =.027). The rate of limb loss was comparable in both groups (6% vs 12%). The overall cumulative secondary patency rates at 6 months and 1, 2, 3, 4, and 5 years were 100%, 93%, 85%, 72%, 67%, and 62% for group A and 100%, 96%, 88%, 76%, 63%, and 45% for group B (P =.035). Thirty-five further interventions were needed to maintain graft patency in group B (mean, 1.35; range, 0-3) versus five further interventions in group A (mean, 0.16; range, 0-1; P <.05).

CONCLUSION

Thrombectomy/open surgical repair is superior to lysis/PTA (or thrombectomy/balloon angioplasty) for the treatment of failed above-knee PTFE FPGs with anastomotic stenoses. Therefore, balloon angioplasty should be reserved for patients who are at high risk for surgery.

Indications for directed thrombolysis or new bypass in treatment of occlusion of lower extremity arterial bypass reconstruction

The long-term results after directed thrombolytic therapy for thrombosis of infrainguinal arterial bypass reconstructions are disappointing if broad indications are applied. This work presents criteria for determining the indications for thrombolysis or the insertion of a new bypass. In a retrospective study we compared the secondary cumulative patency after bypass thrombolysis (n = 82) and after replacement bypass (n = 143). Using multivariate analysis, the influence of prognostic factors on secondary long-term patency was investigated. Our results showed that brief occlusions (< or = 3 days) in older bypasses (> or = 11 months) should be treated by thrombolysis. In all other cases, efforts should be made to replace the bypass with autologous vein. In the absence of autologous vein, we found umbilical vein to be a suitable material for vessel replacement.

Patency following successful thrombolysis of occluded vascular grafts

AIM

to determine patency after successful lysis of occluded bypass grafts.

METHODS

data were collected from four centres with a wide experience of thrombolysis. Outcome following successful lysis was determined from prospectively collected data or case notes. Data from 75 patients, 53 men, were analysed.

RESULTS

median age at time of lysis was 68 years (range 33-88). Median age of graft was 12 months (range 1-120). Patency at 12 months was 33% (95% conf. interval: 21-44%). There were no differences in patency depending on whether the graft was above or below the inguinal ligament or whether an additional procedure eg. percutaneous or vein patch angioplasty was carried out. However in those 48 cases when lysis was deemed complete, i.e. there was restoration of graft patency and at least one vessel run off patency at 12 months was 39% compared with 17% if lysis was incomplete (p=0.04).

CONCLUSIONS

at the present time it is difficult to justify routine thrombolysis of occluded grafts when patency, based on intention to treat, is approximately 20% at one year. Following successful graft lysis the role of anticoagulation and careful graft surveillance require further investigation.

Intraarterial catheter-directed thrombolysis: urokinase versus tissue plasminogen activator

The purpose of this study was to evaluate the differences between tissue plasminogen activator (TPA) and urokinase (UK) in the management of ischemic limbs. A total of 58 limbs (24 in the TPA group and 34 in the UK group) in 53 patients were studied prospectively. The two groups were based on the surgeon's preference for lytic agent. The dose regimen for UK was 150,000 IU/hr over 1/2 to 2 hr followed by a continuous infusion of 50,000 IU/hr. TPA was given as a 5-mg bolus followed by 1 mg/hr. Both groups received heparin at a rate of 400 IU/hr through the side arm of the arterial sheath. There was no significant difference in efficacy between UK and TPA, but TPA acted faster and had a higher incidence of bleeding complications.

Clinical applications of thrombolytic therapy for arterial and graft occlusion

Catheter-directed thrombolysis and intraoperative intra-arterial thrombolysis are important adjuncts to how we care for patients with acute arterial and bypass graft occlusions. Of importance is that intra-arterial thrombolysis not to be thought of as a competitor to operative revascularization, but rather as an adjunct to what can be accomplished, which enables the responsible physician to offer the best care for these patients.

Myointimal hyperplasia in vein collars for ePTFE grafts

OBJECTIVE

To understand the cause of intermediate ePTFE graft failure when a venous boot is used. This might give insight into the improvement in patency that results from the use of a venous boot.

DESIGN

A histological and radiological study of failed and failing grafts.

METHODS

A review of patients operated upon in St Mary's Hospital under the care of a single consultant.

RESULTS

Four anastomoses were retrieved following irretrievable occlusion and found to have myointimal hyperplasia at the function between the ePTFE graft and collar. The artery was relatively spared. In a further six patients these results have been corroborated by angiography.

CONCLUSIONS

Myointimal hyperplasia occurs at the interface between ePTFE and vein collar and the recipient artery is relatively spared. This manipulation of the site of myointimal hyperplasia may result in improved patency rates.