Management of massive and submassive pulmonary embolism: focus on recent randomized trials

Open Surgical Treatment of Acute and Chronic Pulmonary Embolism

Acute pulmonary embolism (PE) is a common cause of death and morbidity in the United States and the prevalence of chronic thromboembolic pulmonary hypertension (CTEPH), a possible sequela of PE, has increased during the past decade. The mainstay treatment of CTEPH is open pulmonary endarterectomy, a procedure performed under hypothermic circulatory arrest, which entails endarterectomy of the branch, segmental and subsegmental pulmonary arteries. Acute PE may be similarly be treated with an open embolectomy in certain select circumstances.

Potential role of sympathetic activity on the pathogenesis of massive pulmonary embolism with circulatory shock in rabbits

Background

We recently showed that intravenous sodium nitroprusside treatment (SNP) could relieve the pulmonary vasospasm of pulmonary embolism (PE) and non-pulmonary embolism (non-PE) regions in a rabbit massive pulmonary embolism (MPE) model associated with shock. The present study explored the potential role of cardiopulmonary sympathetic activity on the pathogenesis and the impact of vasodilators on cardiopulmonary sympathetic activity in this model.

Methods

Rabbits were randomly divided into sham operation group (S group, n = 8), model group (M, equal volume of saline intravenously, n = 11), SNP group (3.5 μg/kg/min intravenously, n = 10) and diltiazem group (DLZ, 6.0 μg/kg/min intravenously, n = 10).

Results

MPE resulted in reduced mean arterial pressure and increased mean pulmonary arterial pressure as well as reduced PaO₂ in the M, SNP and DLZ groups. Tyrosine hydroxylase (TH), neuropeptide Y (NPY) and endothelin-1 (ET-1) expression levels were significantly increased, while nitric oxide (NO) levels were reduced in both PE and non-PE regions in the M group. Both SNP and DLZ decreased mean pulmonary arterial pressure, reversed shock status, downregulated the expression of TH, NPY and ET-1, and increased NO levels in PE and non-PE regions.

Conclusion

Present results indicate that upregulation of the sympathetic medium transmitters TH and NPY in whole lung tissues serves one of the pathological features of MPE. The vasodilators SNP and DLZ could relieve pulmonary vasospasm in both embolization and non-embolization regions and reverse circulatory shock, thereby indirectly downregulating the sympathetic activation of the whole lung tissues and breaking a vicious cycle related to sympathetic activation in this model.

Catheter-directed Thrombolysis for Intermediate-Risk Pulmonary Embolism

Intermediate-risk pulmonary embolism is common and carries a risk of progression to hemodynamic collapse and death. Catheter-directed thrombolysis is an increasingly used treatment option, based largely on the assumptions that it is more efficacious than anticoagulation alone and safer than systemic thrombolysis. In this review, we critically analyze the published data regarding catheter-directed thrombolysis for the treatment of intermediate-risk pulmonary embolism. Catheter-directed thrombolysis reduces right heart strain and lowers pulmonary artery pressures more quickly than anticoagulation alone. The mortality for patients with intermediate-risk pulmonary embolism treated with catheter-directed thrombolysis is low, between 0% and 4%. However, similarly low mortality is seen with anticoagulation alone. Catheter-directed thrombolysis appears to be safer than systemic thrombolysis, and procedural complications are uncommon. Bleeding risk appears to be slightly higher than with anticoagulation alone. Randomized, controlled trials are needed to compare the efficacy and safety of catheter-directed thrombolysis versus anticoagulation for intermediate-risk pulmonary embolism. There is no evidence that catheter-directed thrombolysis decreases the incidence of chronic thromboembolic pulmonary hypertension. There is no evidence from clinical studies that ultrasound-assisted thrombolysis is more effective or safer than standard catheter-directed thrombolysis.

Management of Pulmonary Thromboembolism Based on Severity and Vulnerability to Thrombolysis

Background: The incidence of pulmonary thromboembolism has been considered rare in Japan. However, its occurrence has been increasing because of westernized lifestyle and diet, increased diagnostic technique, and recognition of this disease. Method: Between January 2003 and September 2014, 179 patients were treated for pulmonary thromboembolism. We classified these patients into 3 groups; Massive (n=35), Sub-massive (n=29) and Nonmassive (n=115) and retrospectively reviewed the treatment options and the outcome. Results: Percutaneous cardiopulmonary support (PCPS) was applied for patients with hemodynamic instability and IVC filter was inserted if there was proximal DVT. In non-massive group (n=115), 95.7% of the patient underwent anticoagulant therapy and 47.0% of the patients received IVC filter. In submassive group (n=29), 48.3% of the patient received thrombolytic therapy and 93.1% of the patient underwent IVC filter insertion. Surgical pulmonary embolectomy was performed in 3 patients who had high risk of thrombolytic therapy in submassive group. There was no death in this group. In massive group, 4 patients who had cardiogenic shock died in acute phase. PCPS was applied in 5 patients, pulmonary embolectomy was performed in 13 patients, thrombolytic therapy was performed in 4 patients and 13 patients underwent anticoagulant therapy alone. There were 7 deaths (20.0%) in this group. Conclusions: In submassive group, treatment should be decided depending on the bleeding risk. In massive group, pulmonary embolectomy was effective. (This is a translation of Jpn J Phlebol 2016; 27: 53-59.).

Initial anticoagulation in patients with pulmonary embolism: thrombolysis, unfractionated heparin, LMWH, fondaparinux, or DOACs?

The initial treatment of haemodynamically stable patients with pulmonary embolism (PE) has dramatically changed since the introduction of low molecular weight heparins (LMWHs). With the recent discovery of the direct oral anticoagulant drugs (DOACs), initial treatment of PE will be simplified even further. In several large clinical trials it has been demonstrated that DOACs are not inferior to standard therapy for the initial treatment of PE, and because of their practicability they are becoming the agents of first choice. However, many relative contraindications to DOACs were exclusion criteria in the clinical trials. Therefore, LMWHs will continue to play an important role in initial PE treatment and in some cases there still is a role for unfractionated heparin (UFH). In this review we will give an overview of the biophysical, pharmacokinetic and pharmacodynamic properties of anticoagulants currently available for the initial management of PE. In addition, we will provide a comprehensive overview of the indications for the use of UFH, LMWHs and DOACs in the initial management of PE from a pharmacokinetic/-dynamic point of view.