Alteplase treatment of acute pulmonary embolism in the intensive care unit

Comparison of therapeutic effect of catheter direct thrombolysis and peripheral venous thrombolysis on acute pulmonary embolism

We compared the therapeutic effect of catheter direct thrombolysis (CDT) and peripheral venous thrombolysis (PVT) for patients with acute pulmonary embolism (APE). Totally, 74 patients with APE were enrolled, including 37 in the CDT group and 37 in the PVT group. The changes in clinical indicators pre and posttreatment were observed. Clinical efficacy was evaluated. Kaplan-Meier method was used to analyze the survival of patients during follow-up. In both the PVT group and CDT group, partial pressure of oxygen after treatment increased significantly than that before treatment (P < .05). However, in both groups, the levels of partial pressure of carbon dioxide, D-dimer, B-type brain natriuretic peptide, pulmonary arterial pressure, and thrombus volume after treatment were significantly decreased than those before treatment (P < .05). After treatment, patients from the CDT group had significantly lower D-dimers, partial pressure of carbon dioxide, brain natriuretic peptide, and pulmonary arterial pressure, and significantly higher partial pressure of oxygen compared to patients from the PVT group (P < .05). The total effective rate was 97.2% in the CDT group and 81.0% in the PVT group. The bleeding incidence in the CDT group was significantly lower than that in the PVT group (P < .05). The median survival time in the CDT group was significantly longer than that in the PVT group (P < .05). CDT can more effectively improve symptoms, cardiac function, and survival rate of APE patients while reducing bleeding incidence than PVT, and thus is safe and effective in treating APE.

Effect of alteplase on platelet function and receptor expression

Objective

To investigate the role of alteplase, a widely-used thrombolytic drug, in platelet function.

Methods

Human platelets were incubated with different concentrations of alteplase followed by analysis of platelet aggregation in response to adenosine diphosphate (ADP), collagen, ristocetin, arachidonic acid or epinephrine using light transmittance aggregometry. Platelet activation and surface levels of platelet receptors GPIbα, GPVI and αIIbβ3 were analysed using flow cytometry. The effect of alteplase on clot retraction was also examined.

Results

This study demonstrated that alteplase significantly inhibited platelet aggregation in response to ADP, collagen and epinephrine in a dose-dependent manner, but it did not affect ristocetin- or arachidonic acid-induced platelet aggregation. Alteplase did not affect platelet activation as demonstrated by no differences in P-selectin levels and PAC-1 binding being observed in collagen-stimulated platelets after alteplase treatment compared with vehicle. There were no changes in the surface levels of the platelet receptors GPIbα, GPVI and αIIbβ3 in alteplase-treated platelets. Alteplase treatment reduced thrombin-mediated clot retraction.

Conclusions

Alteplase inhibits platelet aggregation and clot retraction without affecting platelet activation and surface receptor levels.

Safety of Thrombolysis in a Patient with an Intracranial Dural Arteriovenous Fistula

Intracranial dural arteriovenous fistula is an abnormal connection between an artery and a vein that has an increased risk of bleeding. This case report presents a 53-year-old man diagnosed with a dural arteriovenous malformation fistula in occipital topography, lacking therapeutic indication because of an extension. He was admitted to an intensive care unit due to a high-risk pulmonary thromboembolism with indication for thrombolysis. Taking into account the hemorrhagic risk associated with arteriovenous malformation, the authors discuss the therapeutic options and the inherent risks.

LEARNING POINTS

Intracranial dural arteriovenous fistulas are pathologic shunts between dural arteries and veins that have an inherent risk of intracranial hemorrhage.Systemic thrombolytic agents are a therapeutic option for high-risk pulmonary thromboembolism. Their potential benefits outweigh the risk of life-threatening bleeding; however, careful patient risk stratification should be performed and other options, such as surgical embolectomy or percutaneous catheter-directed treatment, should be considered if available.Multidisciplinarity is the key to better therapeutic decisions and the patient's opinion should always be taken into account.

Efficacy evaluation of reteplase in a novel canine acute pulmonary thromboembolism model developed by minimally invasive surgery and digital subtraction angiography

Purpose

In order to evaluate the thrombolytic effects of reteplase in pulmonary thromboembolism (PTE), we developed a novel canine PTE model. The efficacy of reteplase against PTE in comparison to alteplase was clarified for the first time, and this PTE model could be further applied to studies of novel thrombolytic therapies.

Patients and methods

Twenty-four dogs were divided into four groups: sham operation, vehicle, alteplase, and reteplase. Autologous thrombi/saline were injected into the pulmonary artery, and thrombolytic agents were administrated. Thrombus formation and dissolution were monitored by real-time digital subtraction angiography (DSA), and pulmonary pressures were measured simultaneously. Blood coagulation, blood gas, hematology, and histopathologic examinations were used as subsidiary methods.

Results

The canine PTE model was established with a significant decrease of blood flow and ~75% blocking area. Administration of reteplase (0.6 mg/kg) resulted in effective thrombus dissolution with a recovery of over 80% blood flow, as effective as alteplase (1.6 mg/kg). Correspondingly, the elevated pulmonary systolic, diastolic, and mean arterial pressures declined to the normal level. Blood coagulation was changed by reteplase, with a dramatic elongation of prothrombin time, activated partial thromboplastin time, and thrombin time, even longer than alteplase. In contrast to the vehicle group, no obvious pathological changes were found in the two thrombolytic groups. Hematological, blood biochemical, and blood gas results also indicated that reteplase had no adverse reactions in this PTE model.

Conclusion

Reteplase proved to be an effective and safe therapy for PTE for the first time, and a small dosage of reteplase exerted an efficacy comparable to the routine dosage of alteplase. Our findings indicated the potential of reteplase as clinical treatment against PTE. This technically innovative, stability- and validity-proved canine PTE model developed by minimally invasive surgery and DSA resembled major clinical features. This may further facilitate our understanding of thrombotic disorders and development of prophylactic and therapeutic approaches.