Lys-plasminogen as an adjunct to local intra-arterial fibrinolysis for carotid territory stroke: laboratory and clinical findings

Novel Ex-Vivo Thrombolytic Reconditioning of Kidneys Retrieved 4 to 5 Hours After Circulatory Death

BACKGROUND

Due to organ shortage, many patients do not receive donor organs. The present novel thrombolytic technique utilizes organs from donors with uncontrolled donation after circulatory deaths (uDCD), with up to 4-5 h warm ischemia, without advanced cardiopulmonary resuscitation (aCPR) or extracorporeal circulation (EC) after death.

METHODS

The study group of pigs (n = 21) underwent simulated circulatory death. After 2 h, an ice slush was inserted into the abdomen. Kidneys were retrieved 4.5 h after death. Lys-plasminogen, antithrombin-III (ATIII), and alteplase (tPA) were injected through the renal arteries on the back table. Subsequent ex vivo perfusion at 15 °C was continued for 3 h, followed by 3 h with red blood cells (RBCs) at 32 °C. Perfusion outcome and histology were compared between uDCD kidneys, receiving no thrombolytic treatment (n = 8), and live donor kidneys (n = 7). The study kidneys were then transplanted into pigs as autologous grafts with a single functioning autologous kidney as the only renal support. uDCD control pigs (n = 8), receiving no ex vivo perfusion, served as controls.

RESULTS

Vascular resistance decreased to <200 mmHg/mL/min ( P < 0.0023) and arterial flow increased to >100 mL/100 g/min ( P < 0.00019) compared to controls. In total 13/21 study pigs survived for >10 days, while all uDCD control pigs died. Histology was preserved after reconditioning, and the creatinine level after 10 days was next to normal.

CONCLUSIONS

Kidneys from extended uDCD, not receiving aCPR/EC, can be salvaged using thrombolytic treatment to remove fibrin thrombi while preserving histology and enabling transplantation with a clinically acceptable early function.

Acute vertebrobasilar occlusion: current treatment strategies

Acute vertebrobasilar occlusion (VBO) remains a disease with a high mortality. Local intraarterial fibrinolysis (LIF) can reduce the mortality rate from about 90 to 60%. The combined therapy of i.v. Abciximab and i.a. rt-PA with additional PTA/stenting may improve neurological outcome and significantly reduce mortality, despite an increase of overall bleeding complications. Additional PTA/stenting is an important treatment factor in cases of atherothrombotic occlusion. In embolic occlusions, mechanical catheter devices, such as basket or snare devices or rheolytic systems, are promising therapies for the near future. This article describes diagnostic criteria and treatment factors in acute VBO. Different treatment strategies, such as i.v. and i.a. fibrinolysis, adjunctive application of GP IIb/IIIa inhibitors, PTA/stenting and mechanical embolectomy are addressed in detail.

Direct fibrinolytic agents: biochemical attributes, preclinical foundation and clinical potential

Direct fibrinolytics are proteolytic enzymes that degrade fibrin without requiring an intermediate step of plasminogen activation. This review summarizes the current information available for five such agents, namely, plasmin (the prototypical form), three derivatives of plasmin (mini-plasmin, micro-plasmin, and delta-plasmin), and alfimeprase, a recombinant variant of a snake venom alpha-fibrinogenase, fibrolase. Biochemical attributes of molecular size, fibrin binding and inhibitor neutralization are compared. Preclinical investigations that assess the potential for thrombolytic efficacy in vitro and in animal models of vascular occlusion and for hemostatic safety in animal models of bleeding are detailed. Clinical potential has been assessed in patients with peripheral arterial and graft occlusion, acute ischemic stroke, and access catheter and hemodialysis shunt occlusions. The direct fibrinolytic agents have impressive biochemical and preclinical foundations for ultimate clinical application. However, clinical trial results for micro-plasmin and alfimeprase have not measured up to their anticipated benefit. Plasmin has thus far shown encouraging hemostatic safety, but efficacy data await completion of clinical trials. Whether direct fibrinolytics will provide clinical superiority in major thrombotic disorders over currently utilized indirect fibrinolytics such as tissue plasminogen activator remains to be determined.

Anterior cerebral artery emboli in combined intravenous and intra-arterial rtPA treatment of acute ischemic stroke in the IMS I and II trials

BACKGROUND AND PURPOSE

Anterior cerebral artery (ACA) emboli may occur before or during fibrinolytic revascularization of middle cerebral artery (MCA) and internal carotid artery (ICA) T occlusions. We sought to determine the incidence and effect of baseline and new embolic ACA occlusions in the Interventional Management of Stroke (IMS) studies.

MATERIALS AND METHODS

Case report forms, pretreatment and posttreatment arteriograms, and CTs from 142 subjects entered into IMS I & II were reviewed to identify subjects with baseline ACA occlusion, new ACA emboli occurring during fibrinolysis, subsequent CT-demonstrated infarction in the ACA distribution, and to evaluate global and lower extremity motor clinical outcome.

RESULTS

During M1/M2 thrombolysis procedures, new ACA embolus occurred in 1 of 60 (1.7%) subjects. Baseline distal emboli were identified in 3 of 20 (15%) T occlusions before intra-arterial (IA) treatment, and new posttreatment distal ACA emboli were identified in 3 subjects. At 24 hours, 8 (32%) T occlusions demonstrated CT-ACA infarct, typically of small volume. Infarcts were less common following sonography microcatheter-assisted thrombolysis compared with standard microcatheter thrombolysis (P = .05). Lower extremity weakness was present in 9 of 10 subjects with ACA embolus/infarct at 24 hours. The modified Rankin 0 to 2 outcomes were achieved in 4 of 25 (16%) subjects with T occlusion overall, but in 0 of 10 subjects with distal ACA emboli or ACA CT infarcts (P = .07).

CONCLUSIONS

With IV/IA recombinant tissue plasminogen activator treatment for MCA emboli, new ACA emboli are uncommon events. Distal ACA emboli during T-occlusion thrombolysis are not uncommon, typically lead to small ACA-distribution infarcts, and may limit neurologic recovery.

Review of the Current Status of Intra-Arterial Thrombolysis for Treating Acute Cerebral Infarction: a Retrospective Analysis of the Data from Multiple Centers in Korea

Objective

The purpose of the study was to review the current status of intra-arterial (IA) thrombolysis in Korea by conducting a retrospective analysis of the data from multiple domestic centers.

Materials and Methods

The radiologists at each participating institution were asked to fill out case report forms on all patients who had undergone IA recanalization due to acute anterior circulation ischemia. These forms included clinical, imaging and procedure-related information. A central reader analyzed the CT/MR and angiographic results. The rates of successful recanalization, hemorrhagic transformation and functional outcome were obtained. The univariate analyses were performed together with the multivariate analysis.

Results

We analyzed the data from 163 patients, and they had been treated at seven institutes. The initial imaging modalities were CT for 46 patients (28%), MR for 63 (39%), and both for 54 (33%). Various mechanical treatment methods were applied together in 50% of the patients. Radiologically significant hemorrhage was noted in 20/155 patients (13%). We found various factors that influenced the recanalization rate and the occurrence of significant hemorrhagic transformations. The favorable outcome rate, reported as modified Rankin Scale ≤ 2, was 40%, and the mortality rate was 11%. The factors that predicted a poor functional outcome were old age (p = 0.01), initially severe neurological symptoms (p < 0.0001), MR findings of a wide distribution of lesions (p = 0.001), involvement of the basal ganglia (p = 0.01), performance of procedures after working hours (p = 0.01), failure of recanalization (p = 0.003), contrast extravasation after the procedure (p = 0.007) and significant hemorrhagic transformation (p = 0.002). The subsequent multivariate analysis failed to show any statistically significant variable.

Conclusion

There was a trend toward increased dependency on MR imaging during the initial evaluation and increased usage of combined pharmacologic/mechanical thrombolysis. The imaging and clinical outcome results of this study were comparable to those of the previous major thrombolytic trials.

Can the time window for administration of thrombolytics in stroke be increased?

Level 1 evidence now shows that thrombolysis in cases of acute ischaemic stroke is effective if administered within 3 hours of stroke onset. This benefit has been shown to be time dependent and potentially extends beyond 3 hours, with evidence that potentially viable penumbral tissue may be present in a significant proportion of cases well beyond 3-6 hours and, in isolated cases, perhaps up to 48 hours. This exposes a "stroke recovery gap", the difference observed between the clinical response to thrombolytic therapy in a given population of patients presenting with ischaemic stroke and the potential clinical recovery if all of the penumbra were salvaged under ideal circumstances. The means of bridging this "stroke recovery gap" using thrombolysis must involve extending the therapeutic time window (i.e. the time between stroke onset and administration of thrombolytics). Approaches to do this include the use of: (i) improved patient selection with modern neuroimaging techniques, particularly magnetic resonance imaging using perfusion-weighted image/diffusion-weighted image mismatch; (ii) newer thrombolytic agents; (iii) lower doses of these agents; (iv) varied methods of administration of thrombolytic therapy including combined intravenous and intra-arterial approaches; and (v) adjunctive therapies such as neuroprotectants. Should these means of extending the time window for thrombolysis prove successful, a more widespread use of this form of acute stroke therapy will be possible.

Local intraarterial urokinase thrombolysis of acute ischemic stroke with or without intravenous abciximab: a pilot study

PURPOSE

One of the most important prognostic factors in the thrombolytic treatment of acute ischemic stroke is the time to recanalization. To shorten the recanalization time, an antiplatelet agent, abciximab (platelet glycoprotein receptor IIb/IIIa antagonist), was administered intravenously before the initiation of local intraarterial urokinase thrombolysis. The purpose of this study was to evaluate the effectiveness and safety of this combined therapy.

MATERIALS AND METHODS

A total of 26 patients with acute ischemic stroke (National Institutes of Health Stroke Scale score >10) were enrolled in this study. In the earlier phase of this study, conventional local intraarterial urokinase thrombolysis was performed in 16 patients (urokinase group). In the later phase, combined use of intravenous abciximab and local intraarterial urokinase thrombolysis was performed in 10 patients (urokinase + abciximab group). Recanalization rate (Thrombolysis in Myocardial Infarction grade >or=2), total amount of urokinase used, incidence of symptomatic hemorrhage, and better functional outcome rate (modified Rankin scale <or=2) were compared between the two groups with use of the Fisher exact test or Mann-Whitney U test.

RESULTS

The recanalization rate in the urokinase + abciximab group (90%, nine of 10) was significantly higher than that in the urokinase group (43.8%, seven of 16) (P =.037). The mean amount of urokinase required for recanalization was significantly lower in the urokinase + abciximab group (828,000 IU vs 418,000 IU; P <.005). As for the incidence of symptomatic hemorrhage, no significant difference was noted between the two groups (four of 16 vs three of 10) (P = 1.0). The urokinase + abciximab group showed a trend of better functional outcome (50% vs 80%; P =.2).

CONCLUSIONS

Combined therapy employing intravenous abciximab and local intraarterial urokinase thrombolysis showed a marked improvement in recanalization rate and showed a trend of better functional outcome. The safety of this regimen still remains to be justified with modification of the indication and regimen dosage.

Acute basilar artery occlusion treated with combined intravenous Abciximab and intra-arterial tissue plasminogen activator: report of 3 cases

BACKGROUND

Acute vertebrobasilar occlusion remains a disease with a high mortality even after treatment by local intra-arterial fibrinolysis. Adjunctive treatment with platelet glycoprotein IIb/IIIa receptor inhibitors such as abciximab may facilitate recanalization and improve the neurological outcome. Results after treatment of 3 patients by combined intravenous abciximab and local intra-arterial tissue plasminogen activator (tPA) are reported.

CASE DESCRIPTIONS

Treatment was performed within 6 hours of stroke onset. Angiography revealed embolic occlusion of the basilar artery in 2 patients and atherothrombotic occlusion at the vertebrobasilar junction in 1 patient. Therapy consisted of intravenous abciximab bolus administration (0.25 mg/kg) followed by 12-hour infusion therapy (0.125 microg/kg per minute) and local intra-arterial thrombolysis with tPA (10 mg/h). Heparin was only applied for catheter flushing (500 IU/h). The patient with the atherothrombotic occlusion was treated with additional percutaneous transluminal angioplasty and stenting. Complete recanalization of the basilar artery occurred in 2 patients, whose conditions improved clinically to functional independence. In the third patient only partial recanalization was seen, with only slight clinical improvement. This patient died of cardiac failure 2 months later. Besides a subtle subarachnoid hemorrhage (n=1), no intracranial or extracranial bleeding complication was observed.

CONCLUSIONS

The combination of glycoprotein IIb/IIIa receptor inhibitor with local intra-arterial tPA might be a promising therapy for patients with acute vertebrobasilar occlusion. Further studies are necessary to define the clinical benefit and the bleeding rate of this new pharmacological approach.

Thrombolytic properties of leukocytes from peripheral blood in healthy subjects and in patients with acute cerebral ischemia

Polymorphonuclear leukocytes are activated in acute ischemic stroke. Activated polymorphonuclear leukocytes may contribute to thrombolysis by proteolytic degradation of fibrin and by modification of the plasminogen system. We used an in vitro thrombolysis model to investigate (1) thrombolytic properties of leukocytes in young and healthy subjects, (2) to test the hypothesis of increased polymorphonuclear leukocyte-associated thrombolysis in patients with acute cerebral ischemia, and (3) to assess plasminogen-dependent and -independent thrombolytic properties of polymorphonuclear leukocyte elastase. Coincubation of polymorphonuclear leukocytes with fibrin clots led to increased thrombolysis, a process reaching statistical significance after 8 hours [1x10(7) polymorphonuclear leukocytes/mL; 12.8+/-1.9% (mean+/-SEM), spontaneous clot lysis: 7.3+/-0.7%]. Polymorphonuclear leukocytes inside clots caused more efficient thrombolysis than polymorphonuclear leukocytes in the incubation medium. Spontaneous and polymorphonuclear leukocyte-associated lysis tended to be lower in patients with acute cerebral ischemia (n=9, 24 hours, 9.5+/-1.8% and 12.9+/-2.2%) than in age- and sex-matched control subjects (n=8; 12.2+/-2.0% and 17.4+/-1.9%). In the presence of alpha(2)-antiplasmin, thrombolysis tended to be faster with elastase-digested plasminogen (miniplasminogen) than with native plasminogen. Purified polymorphonuclear leukocyte elastase itself had no thrombolytic effect. We conclude that the thrombolytic capacity of polymorphonuclear leukocytes from peripheral blood is small and slow and may have been overestimated in previous reports. Polymorphonuclear leukocyte thrombolytic activity may not be increased in acute cerebral ischemia. Miniplasminogen may be an interesting adjunct to plasminogen activators in acute stroke models.

Human homozygous type I plasminogen deficiency and ligneous conjunctivitis

On the basis of a questionnaire sent to the ophthalmology departments of hospitals throughout Germany, 10 patients with ligneous conjunctivitis or pseudomembranous disease, ranging in age from 1 to 71 years were identified. All 10 patients had severely reduced plasminogen levels. Genetic analysis revealed homozygous type I plasminogen deficiency (which had not previously been described in humans) in 7 patients and compound heterozygous plasminogen deficiency in 1 patient. Clear differentiation was not possible in 2 patients. Most of the parents had heterozygous plasminogen deficiency. None of the patients had experienced any episodes of thrombosis. Additionally, the following observations were made: 1) Levels of polymorphonuclear (PMN)-elastase protein were markedly elevated in 6 of 6 patients and 10 of 11 parents tested, and levels were higher in homozygotes than in heterozygotes. 2) Hereditary factor XII deficiency was found in 3 of 6 patients tested. 3) C1-inhibitor was elevated in 2 of 4 patients, prekallikrein was elevated in 1 of 4 patients, and plasminogen activator inhibitor type 1 was elevated in 1 of 4 patients. Infusions of lys-plasminogen concentrate induced pronounced fibrinolytic activity as indicated by high levels of D-dimer, increases in plasmin-antiplasmin complex and decreases in polymorphonuclear elastase. C1-inhibitor, prekallikrein and PAI-1 normalized after repeated infusions of lys-plasminogen. In contrast to dysplasminogenemia, severe type I plasminogen deficiency might be seen as a problem of extravascular space, in particular of the mucous membranes, possibly triggered by mechanically induced or inflammatory lesions of the vessels supplying the tissue.