Thrombolytic therapy of pulmonary embolism: a comprehensive review of current evidence

Fluorescently conjugated annular fibrin clot for multiplexed real-time digestion analysis

Impaired fibrinolysis has long been considered as a risk factor for venous thromboembolism. Fibrin clots formed at physiological concentrations are promising substrates for monitoring fibrinolytic performance as they offer clot microstructures resembling in vivo. Here we introduce a fluorescently labeled fibrin clot lysis assay which leverages a unique annular clot geometry assayed using a microplate reader. A physiologically relevant fibrin clotting formulation was explored to achieve high assay sensitivity while minimizing labeling impact as fluorescence isothiocyanate (FITC)-fibrin(ogen) conjugations significantly affect both fibrin polymerization and fibrinolysis. Clot characteristics were examined using thromboelastography (TEG), turbidity, scanning electron microscopy, and confocal microscopy. Sample fibrinolytic activities at varying plasmin, plasminogen, and tissue plasminogen activator (tPA) concentrations were assessed in the present study and results were compared to an S2251 chromogenic assay. The optimized physiologically relevant clot substrate showed minimal reporter-conjugation impact with nearly physiological clot properties. The assay demonstrated good reproducibility, wide working range, kinetic read ability, low limit of detection, and the capability to distinguish fibrin binding-related lytic performance. In combination with its ease for multiplexing, it also has applications as a convenient platform for assessing patient fibrinolytic potential and screening thrombolytic drug activities in personalized medical applications.

American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism

BACKGROUND

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), occurs in ∼1 to 2 individuals per 1000 each year, corresponding to ∼300 000 to 600 000 events in the United States annually.

OBJECTIVE

These evidence-based guidelines from the American Society of Hematology (ASH) intend to support patients, clinicians, and others in decisions about treatment of VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and adult patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 28 recommendations for the initial management of VTE, primary treatment, secondary prevention, and treatment of recurrent VTE events.

CONCLUSIONS

Strong recommendations include the use of thrombolytic therapy for patients with PE and hemodynamic compromise, use of an international normalized ratio (INR) range of 2.0 to 3.0 over a lower INR range for patients with VTE who use a vitamin K antagonist (VKA) for secondary prevention, and use of indefinite anticoagulation for patients with recurrent unprovoked VTE. Conditional recommendations include the preference for home treatment over hospital-based treatment for uncomplicated DVT and PE at low risk for complications and a preference for direct oral anticoagulants over VKA for primary treatment of VTE.

Pulmonary Arteriovenous Malformation Masquerading as Massive Pulmonary Thromboembolus

We present a case of a 78-year-old male with hereditary haemorrhagic telangiectasia and severe hypoxia incorrectly diagnosed as pulmonary embolism following a false positive ventilation/perfusion scan. Anti-coagulation and thrombolysis was complicated by an upper gastro-intestinal haemorrhage. Pulmonary arteriovenous malformations resulted in a clinically significant right-left shunt and created an apparent perfusion defect evident upon radionuclide imaging, leading to diagnostic uncertainty and a potentially dangerous treatment modality.

Double Bolus Alteplase Therapy during Cardiopulmonary Resuscitation for Cardiac Arrest due to Massive Pulmonary Embolism Guided by Focused Bedside Echocardiography

Massive pulmonary embolism (PE) frequently leads to cardiac arrest (CA) which carries an extremely high mortality rate. Although available, randomized trials have not shown survival benefits from thrombolytic use. Thrombolytics however have been used successfully during resuscitation in clinical practice in multiple case reports and in retrospective studies. Recent resuscitation guidelines recommend using alteplase for PE related CA; however they do not offer a standardized treatment regimen. The most consistently applied approach is an intravenous bolus of 50 mg tissue plasminogen activator (t-PA) early during cardiopulmonary resuscitation (CPR). There is no consensus on the subsequent dosing. We present a case in which two 50 mg boluses of t-PA were administered 20 minutes apart during CPR due to persistent hemodynamic compromise guided by bedside echocardiogram. The patient had an excellent outcome with normalization of cardiac function and no neurologic sequela. This case demonstrates the benefit of utilizing bedside echocardiography to guide administration of a second bolus of alteplase when there is persistent hemodynamic compromise despite achieving return of spontaneous circulation after the initial bolus, and there is evidence of persistent right ventricle dysfunction. Future trials are warranted to help establish guidelines for thrombolytic use in cardiac arrest to maximize safety and efficacy.

Tenecteplase compared with streptokinase and heparin in the treatment of pulmonary embolism: an observational study

Background: Thrombolytics are recommended in high risk patients with massive pulmonary embolism (PE). However, clinical practice seems to be far different and questions related to its utility in less severely affected patients remain the subject of investigation. The objective of this observational study was to compare the efficacy and safety of tenecteplase with streptokinase and heparin. Method: A total of 103 patients (tenecteplase: 62, streptokinase: 17, heparin: 24) diagnosed with PE (massive: 33 [32.04%], submassive: 50 [48.54%], and minor: 20 [19.42%]) were included. Results: Mean age was 50.04 years and major risk factors were immobilization due to hospitalization, history of deep vein thrombosis, and diabetes. Common clinical symptoms of dyspnoea, right ventricular dysfunction, and cough were found in 94.17%, 81.55%, and 77.67% patients, respectively. Between treatment and day 7, death occurred in 4.84%, 5.88%, and 8.33% patients in the tenecteplase, streptokinase, and heparin groups, respectively. The differences among treatment groups were non-significant (p > .05). All treatments have demonstrated significant alleviation of dyspnoea and heart rate (p < .05). Significant (p < .05) increase in oxygen saturation was seen and it was markedly higher in the tenecteplase-treated patients compared with the streptokinase- and heparin-treated patients. By day 7, there was 100% resolution of right bundle branch block only in the tenecteplase group. No intracranial bleeding or fatal bleeding episodes were found in any group. Conclusion: Tenecteplase was found to be effective in patients with PE irrespective of their clinical status and no major adverse events were noted.

Retrospective evaluation of the incidence and prognostic significance of spontaneous echocardiographic contrast in relation to cardiac disease and congestive heart failure in cats: 725 cases (2006-2011)

OBJECTIVE

To determine whether the presence of spontaneous echocardiographic contrast (SEC) in cats with cardiomyopathy is associated with increased mortality. To establish whether specific types of cardiomyopathy are more often associated with SEC in an attempt to provide a risk-stratification scheme for cats with increased risk of thromboembolic events.

DESIGN

Retrospective study 2006-2011.

SETTING

Tertiary referral and teaching hospital.

ANIMALS

Seven hundred twenty-five client-owned cats undergoing echocardiographic evaluation.

MEASUREMENTS AND MAIN RESULTS

Patient characteristics, including age, breed, clinical signs, type of cardiovascular disease, presence of SEC, and survival time were recorded. Thyroxine, HCT, and blood pressure were recorded when available. Among cats diagnosed with cardiac abnormalities based on echocardiographic findings, those with SEC were at significantly increased risk of death as compared to those without SEC. Cats with dilated cardiomyopathy, unclassified cardiomyopathy, and hypertrophic cardiomyopathy were significantly more likely to have SEC compared to cats with other types of cardiac disease.

CONCLUSIONS

Cats with cardiomyopathy and SEC have an increased risk of death compared to cats without SEC, although other previously identified factors such as the presence of congestive heart failure and increased left atrium to aorta ratio remain important determinants of mortality. Cats with hypertrophic cardiomyopathy, unclassified cardiomyopathy, and dilated cardiomyopathy may benefit from anticoagulant therapy due to the increased risk of SEC in these subpopulations.

Thrombolytic Therapy for Massive Pulmonary Embolism in a Patient With a Known Intracranial Tumor

The objective was to describe and review the use of thrombolytic therapy in a patient with an intracranial tumor and massive pulmonary embolism. This is the first reported case of a patient with a known glioblastoma multiforme and massive pulmonary embolism who was successfully treated with alteplase. Pulmonary embolism was demonstrated by a ventilation-perfusion scan and transthoracic echocardiogram with repeat studies demonstrating resolution of the thromboembolism and reperfusion of pulmonary vasculature. A review of the literature revealed that the incidence of intracranial hemorrhage with thrombolysis is <3% and compares favorably with the much higher mortality rate of 25% to ≥50% in patients with hemodynamically unstable pulmonary emboli. The benefit of thrombolysis may outweigh the risks of intracranial hemorrhage in these patients, and careful consideration for its use in these patients is warranted.

Post-Pleuropneumonectomy Herniation of Liver Mimicking Major Pulmonary Embolism

Following right-sided pneumonectomy and hemidiaphragm resection in a 58-year-old man with epithelioid mesothelioma, acute respiratory insufficiency and life-threatening circulatory collapse developed after a forced Valsalva maneuver. Major pulmonary embolism was diagnosed on clinical grounds, however computed tomography revealed herniation of the liver into the right hemithorax.

Unsuccessful percutaneous mechanical thrombectomy in fibrin-rich high-risk pulmonary thromboembolism

Background

We report a case of unsuccessful percutaneous mechanical thrombectomy in treatment of a high-risk pulmonary embolism (PE). Pulmonary thromboemboli are commonly expected as a homogenous mass, rich with red blood cell content, which respond well to percutaneous mechanical thrombectomy (PMT). Catheter-based approach or surgical embolectomy are two treatment options that are usually considered for treatment of high-risk PE when the thrombolytic therapy fails or it is contraindicated due to a patient’s persisting hemodynamic compromise. Currently, selection criteria for PE treatment options are based mostly on the assessment of patient’s history. The aim of this report is to highlight a possible treatment complication in PMT of structurally heterogeneous thrombotic mass due to PMT inadequacy.

Case presentation

A 32 year-old male with polytrauma was admitted to an intensive care unit after a right-sided nephrectomy and evacuation of retroperitoneal hematoma. The patient initial haemostatic disorder was improved by administration of blood preparations, an anti-fibrinolytic agent and concentrates of fibrinogen. On the third day he presented sudden onset of hemodynamic instability and was incapable of standard CTA diagnostic procedure. Urgent and relevant investigations including transthoracic and transesophageal echocardiogram confirmed a high-risk PE. PMT was performed due to contraindications for systemic thrombolysis. Long-term PMT was attempted using aspiration with several devices. No major improvement was achieved in any of the treatments and the patient died. Autopsy confirmed a large heterogeneous thrombotic mass in the pulmonary trunk folding to the right main artery. Additional histological analysis revealed a high fibrin-rich content in the peripheral surroundings of the thrombus.

Conclusion

In the case, it was confirmed that the outcome of PMT was directly influenced by mechanical and histological features of the thromboembolus in high-risk PE. Formation of a rather complex thromboembolus in high-risk PE favors surgical embolectomy as the only life-saving treatment option. Current diagnostic imaging techniques do not enable precise assessment of thrombi structure and are therefore unable to identify patients who might benefit from PMT or open surgical embolectomy. Surgical backup treatment should be considered if there are no contraindications in the event of a failed catheter intervention.

Cost-effectiveness of quantitative pretest probability intended to reduce unnecessary medical radiation exposure in emergency department patients with chest pain and dyspnea

OBJECTIVES

Quantitative pretest probability (qPTP) incorporated into a decision support tool with advice can reduce unnecessary diagnostic testing among patients with symptoms suggestive of acute coronary syndrome (ACS) and pulmonary embolism (PE), reducing 30-day costs without an increase in 90-day adverse outcomes. This study estimates long-term (beyond 90-day) costs and outcomes associated with qPTP. The authors hypothesized that qPTP reduces lifetime costs and improves outcomes in low-risk patients with symptoms suggestive of ACS and PE.

METHODS

This was a cost-effectiveness analysis of a multicenter, randomized controlled trial of adult emergency patients with dyspnea and chest pain, in which a clinician encountering a low-risk patient with symptoms suggestive of ACS or PE conducted either the intervention (qPTP for ACS and PE with advice) or the sham (no qPTP and no advice). Effect of the intervention over a patient's lifetime was assessed using a Markov microsimulation model. Short-term costs and outcomes were from the trial; long-term outcomes and costs were from the literature. Outcomes included lifetime transition to PE, ACS, and intracranial hemorrhage (ICH); mortality from cancer, ICH, PE, ACS, renal failure, and ischemic stroke; quality-adjusted life-years (QALYs); and total medical costs compared between simulated intervention and sham groups.

RESULTS

Markov microsimulation for a 40-year-old patient receiving qPTP found lifetime cost savings of $497 for women and $528 for men, associated with small gains in QALYs (2 and 6 days, respectively) and lower rates of cancer mortality in both sexes, but a reduction in ICH only in males. Sensitivity analysis for patients aged 60 years predicted that qPTP would continue to save costs and also reduce mortality from both ICH and cancer. Use of qPTP significantly reduced the lifetime probability of PE diagnosis, with lower probability of death from PE in both sexes aged 40 to 60 years. However, use of qPTP reduced the rate of ACS diagnosis and death from ACS at age 40, but increased the death rate from ACS at age 60 for both sexes.

CONCLUSIONS

Widespread use of a combined qPTP for both ACS and PE has the potential to decrease costs by reducing diagnostic testing, while improving most long-term outcomes in emergency patients with chest pain and dyspnea.

[Basic lung ultrasound. Part 2. Parenchymal diseases]

In this second part, an analysis is made of the pathology of lung parenchyma. This text is structured into different sections, including the study of atelectasias, pneumonia and abscess, interstitial/alveolar or Blines patterns, and finally an analysis is made of pulmonary embolism. With this second part, the basic knowledge to develop lung ultrasound in the anesthesia department has been presented.

Acute pulmonary embolism masquerading as acute myocardial infarction

Pulmonary embolism can be extremely difficult to diagnose based on clinical presentation. Many studies have demonstrated certain electrocardiographic patterns commonly seen in pulmonary embolism, but few have described changes consistent with ST segment elevation myocardial infarction. In this report, we describe a patient who presented to the emergency department with electrocardiographic findings consistent with an anteroseptal myocardial infarction and his subsequent clinical course.

Endovascular Treatment of Deep Vein Thrombosis

Venous thromboembolism (VTE) is associated with substantial morbidity and mortality. Conventional treatment with anticoagulation therapy may undertreat the condition. Patients with VTE are at risk for recurrence with increasing time passage. Endovascular approaches exist for treating VTE, including deep vein thrombosis, but it is unclear which patients are appropriate candidates for endovascular versus medical approaches. Many new endovascular technologies are in development, and new oral anticoagulants are also on the market. Clinicians must be mindful of these new products and use them appropriately to better manage VTE.

Efficacy and safety of tenecteplase in pulmonary embolism

Pulmonary embolism (PE) is a relatively common life-threatening cardiovascular condition associated with significant morbidity and mortality. We present the efficacy and safety data of weight-adjusted tenecteplase in 30 consecutive patients of acute PE. 30 patients (22 male, 8 female) with acute PE were included in the study and divided into three groups: (1) Acute PE complicated by shock stage and/or persistent hypotension (12 patients). (2) RV dilatation and/or dysfunction without hypotension (14 patients). (3) Severe hypoxemia without hypotension and RV dysfunction (4 patients). Predominant symptoms were dyspnoea, cough, chest pain, syncope and haemoptysis, noted in 100% (30), 40% (12), 54% (16), 32% (9) and 10% (3) of patients respectively. RV dilatation and dyskinesia were present in 86%, septal paradoxical movement in 73% and inferior venacava collapse absent in 53% of patients respectively. 12 patients presented with acute PE and cardiogenic shock, 14 patients showed RV dilatation and dysfunction with systolic BP >90 mmHg and four patients were having RV dilation without dysfunction but severe hypoxemia. There was significant reduction in right ventricular systolic pressure and improvement in right ventricular dysfunction. Our study shows that tenecteplase is very effective and safe in the treatment of PE with minimal risk of bleeding in high risk group and intermediate risk and even in selective low risk category group of patients. However, in view of small number of patients in study group, a large multicentre randomized study would be required to draw a firm conclusion regarding the thrombolysis in low risk category patient.

Thrombolytic treatment (alteplase; rt-Pa) in acute massive pulmonary embolism and cardiopulmonary arrest

Patients with pulmonary thromboembolism (PE) often decompensate suddenly, and once hemodynamic compromise has developed, mortality is extremely high. Currently, thrombolytic therapy for PE is still controversial. We retrospectively evaluated 34 patients with PE between January 2010 and December 2013 in the Department of Pulmonary Medicine, Medical Park Samsun Hospital, Samsun, Turkey. The demographic and disease characteristics of patients who received thrombolytic treatment were retrospectively analyzed. The female to male ratio was 19/15 and the mean age was 63.1±13.2 years. PE diagnosis was made using echocardiography (64.7%) or contrast-enhanced thorax computed tomography with echocardiography (32.4%). Twenty-two (64.7%) patients went into the cardiopulmonary arrest due to massive PE and 17 (50%) patients recovered without sequelae. Eleven (32.4%) patients were diagnosed with massive PE during cardiopulmonary arrest with clinical and echocardiographic findings. Alteplase (recombinant tissue plasminogen activator [rt-PA]) was administered during cardiopulmonary resuscitation (CPR) and four (36.3%) patients responded and survived without sequelae. The complications of rt-PA treatment were hemorrhage in five (14.7%) patients and allergic reactions in two (5.9%) patients. There was no mortality due to rt-PA treatment complications. In conclusion, mortality due to massive PE is much more than estimated and alteplase can be used safely in patients with massive PE. This thrombolytic treatment was not associated with any fatal hemorrhage complication. If there is any sign of acute PE, echocardiography should be used during cardiopulmonary arrest/instability. Alteplase should be given to patients with suspected massive PE.

The impact of saddle embolism on the major adverse event rate of patients with non-high-risk pulmonary embolism

OBJECTIVE

Wider application of CT angiography (CTA) improves the diagnosis of acute pulmonary embolism (PE). It also permits the visualisation of saddle embolism (SE), namely thrombi, which are located at the bifurcation of the main pulmonary artery. The aim of this study was to assess the prevalence of SE and whether SE predicts a complicated clinical course in patients with non-high-risk PE.

METHODS

In total, 297 consecutive patients with non-high-risk PE confirmed using CTA in the emergency department were studied. The presence of SE and its ability to predict the occurrence of major adverse events (MAEs) within 1 month were determined.

RESULTS

Of the 297 patients, 27 (9.1%) had an SE. The overall mortality at 1 month was 12.5%; no significant difference was observed between the SE and non-SE groups (18.5% vs 11.9%, p=0.32). However, patients with SE were more likely to receive thrombolytic therapy (29.6% vs 8.1%, p<0.01) and had significantly more MAEs (59.3% vs 25.6%, p<0.01).

CONCLUSION

At the time of diagnosis, SE, as determined using CTA, is associated with the development of MAE within 1 month. It may be a simple method for risk stratification of patients with non-high-risk PE.

ADVANCES IN KNOWLEDGE

The prognosis of patients with SE, especially those who are haemodynamically stable, is unclear. This study shows that patients with SE, determined with CTA, is associated with the development of MAE.

High dose urokinase against massive pulmonary embolism in nephrotic syndrome

Patients with nephrotic syndrome carry a high risk of pulmonary embolism due to the abnormalities in coagulation and fibrinolysis. Thrombolytic therapy for critical pulmonary embolism in nephrotic syndrome patients was rarely reported and remains controversial in the regimen selection so far. We reported a case of fatal pulmonary embolism, complicating in hepatitis B virus-associated nephrotic syndrome. The patient presented with chest pain, hemoptysis and shortness of breath on admission and his initial vital signs showed a high risk of developing hypotension. Urgent radiological examinations confirmed massive embolisms in bilateral pulmonary arteries. Prompt thrombolytic therapy was performed right after the diagnosis of pulmonary embolism with an intravenous infusion of urokinase (20 000 U/kg) in 2 h. Complete resolution of pulmonary embolism was achieved after urokinase administration and the patient was discharged in good conditions. This report highlighted the efficacy and safety of prompt thrombolytic therapy with urokinase for nephrotic syndrome patients presented with massive pulmonary embolism. In this study, we also briefly discuss the recent findings on the current state of urokinase in the clinical practice of thrombolysis.

Value of cardiac troponin I for predicting in-hospital occurrence of hypotension in stable patients with acute pulmonary embolism

Although cardiac troponin I (cTnI) elevations during acute pulmonary embolism (PE) are predictive of in-hospital death, it is not clear whether cTnI measurements at emergency department (ED) admission are predictive of the occurrence of hypotension. The study subjects included all consecutive patients with acute PE (diagnosed by chest computed tomography angiography) in the ED between January 2006 and December 2011. All underwent cTnI tests at ED admission and were divided into two groups based on the occurrence of hypotension within 24 h. Of 457 stable patients with acute PE who were admitted to the ED during the study period, 301 patients were included. Within 24 h of hospitalization, 27 (9.0%) developed hypotension. The patients who developed hypotension had a significantly higher mean cTnI concentration than did the remaining patients (1.01 vs. 0.14 ng/mL, P < 0.00). They were also more likely to be treated with thrombolytic therapy and had higher 28-day and 6-month mortality rates. Cardiac TnI elevation (>0.05 ng/mL) at ED admission was a strong predictor of the development of hypotension within 24 h (odds ratio, 8.2; 95% confidence interval, 2.6-26.1; P = 0.00). The sensitivity, specificity, positive predictive value, and negative predictive value of elevated cTnI were 85%, 66%, 20%, and 98%, respectively. This study suggests that a normal cTnI nearly rules out subsequent development of hypotension within 24 h. This may help to select those patients who would benefit most from intensive clinical surveillance and escalated treatment.

Shear wave elastography quantification of blood elasticity during clotting

Deep venous thrombosis (DVT) affects millions of people worldwide. A fatal complication occurs when the thrombi detach and create a pulmonary embolism. The diagnosis and treatment of DVT depends on clot's age. The elasticity of thrombi is closely related to its age. Blood was collected from pigs and anticoagulated using ethylenediaminetetraacetic acid (EDTA). Coagulation was initiated using calcium ions. Supersonic shear wave imaging was used to generate shear waves using 100 μs tone bursts of 8 MHz. Tracking of the shear waves was done by ultrafast imaging. Postprocessing of the data was done using Matlab(®). Two-dimensional (2-D) maps of elasticity were obtained by calculating the speed of shear wave propagation. Elasticity varied with time from around 50 Pa at coagulation to 1600 Pa at 120 min after which the elasticity showed a natural decreased (17%) because of thrombolytic action of plasmin. Ejection of the serum from the clot showed a significant decrease in the elasticity of the clot next to the liquid pool (65% decrease), corresponding to the detachment of the clot from the beaker wall. The use of a thrombolytic agent (Urokinase) on the coagulated blood decreased the shear elasticity close to the point of injection, which varied with time and distance. Supersonic imaging proved to be useful mapping the 2-D clot's elasticity. It allowed the visualization of the heterogeneity of mechanical properties of thrombi and has potential use in predicting thrombi breakage as well as in monitoring thrombolytic therapy.

Successful thrombolysis in postoperative patients with acute massive pulmonary embolism

PURPOSE

The standard medical management for patients with acute massive pulmonary embolism (MPE) is systemic thrombolysis. However, it is generally thought that recent surgeries are a contraindication to thrombolytic therapy. In this study, we evaluated the efficacy and safety of systemic thrombolysis for postoperative patients with acute MPE and assessed the risk of bleeding.

METHODS

A retrospective review was performed on 21 postoperative patients with MPE in a timeframe of five years (from 2005 to 2010). The criteria for study inclusion were postoperative patients who received systemic thrombolysis for confirmed acute MPE within three weeks after surgery.

RESULTS

Seventeen postoperative patients, including men (12) and women (five) aged 53±16 (range 23-71) years, were treated with systemic thrombolysis. Significant haemodynamic improvement (shock index<0.9) was observed in 16 of 17 cases (94%). The remaining patient (6%) died of cardiac arrest within 24h. No major bleeding complication was observed. Sixteen patients survived and remained stable for 34±16 (range 11-52) days until hospital discharge.

CONCLUSION

Recent surgery is not an absolute contraindication to systemic thrombolysis. Further, to obtain a successful outcome, it is crucial to exclude patients who have received neurosurgical operations or those with other contraindications to thrombolytic therapy.

Pulmonary embolism

Pulmonary embolism (PE) remains one of the most challenging medical diseases in the emergency department. PE is a potentially life threatening diagnosis that is seen in patients with chest pain and/or dyspnea but can span the clinical spectrum of medical presentations. In addition, it does not have any particular clinical feature, laboratory test, or diagnostic modality that can independently and confidently exclude its possibility. This article offers a review of PE in the emergency department. It emphasizes the appropriate determination of pretest probability, the approach to diagnosis and management, and special considerations related to pregnancy and radiation exposure.

Silver nano particles prevent platelet adhesion on immobilized fibrinogen

Vascular thrombotic disorders have emerged as a serious threat to our society. Platelet adhesion to fibrinogen, collagen and other platelet activators exposed over the atherosclerotic plaques can trigger platelet signaling events, activate platelets and lead to thrombotic events. Since anticoagulant and thrombolytic treatment strategies are usually associated with serious bleeding complications, preventing platelets adhesion may help to maintain platelets in an inactive state. In this study we tried to find out the effect of Silver nanoparticles, through their interaction with various platelet surface integrins on platelet adhesion on immobilized fibrinogen. Platelets, isolated from anti-coagulated human whole blood sample from healthy donors, were suspended in physiological buffer and each sample was divided into four tubes. In three of them 0.05, 0.5, and 5 μM concentrations of Silver nanoparticles were added, fourth tube served as control. Platelet adhesion on immobilized fibrinogen matrices and integrin mediated cell signaling events were studied in all the four samples. In the present study we show that nanosilver prevent platelet adhesion without conferring any lytic effect on them and effectively prevents integrin-mediated platelet responses in a concentration-dependent manner.

Acute right ventricular failure in the setting of acute pulmonary embolism or chronic pulmonary hypertension: a detailed review of the pathophysiology, diagnosis, and management

The right ventricle (RV) is integral to normal cardiac function, but receives little attention in the medical literature. The etiologic causes of acute RV failure often differ from those encountered in left ventricular dysfunction. Thus, RV failure frequently requires diagnostic procedures and management strategies that differ from those routinely used in the management of intrinsic left ventricular dysfunction. In this summary, the structure and function of the RV will be reviewed, concentrating on the pathophysiologic mechanisms behind the development of RV dysfunction. We will then focus on two distinct populations of patients who are at risk for acute RV failure: those with chronic pulmonary arterial hypertension (PAH) and those with acute pulmonary embolism. In chronic PAH, we will examine clinical circumstances common to hospitalized patients that may provoke acute RV decompensation, as well as pharmacologic therapies that are unique to RV failure management in PAH. Individuals with acute RV failure in the setting of pulmonary embolism represent a group with particularly high mortality, and the specific diagnostic and management strategies that are important for improved survival will be discussed.

Fibrinolysis for acute pulmonary embolism

Acute pulmonary embolism (PE) presents as a constellation of clinical syndromes with a variety of prognostic implications. Patients with acute PE who have normal systemic arterial blood pressure and no evidence of right ventricular (RV) dysfunction have an excellent prognosis with therapeutic anticoagulation alone. Normotensive acute PE patients with evidence of RV dysfunction are categorized as having submassive PE and comprise a population at intermediate risk for adverse events and early mortality. Patients with massive PE present with syncope, systemic arterial hypotension, cardiogenic shock, or cardiac arrest and have the highest risk for short-term mortality and adverse events. The majority of deaths from acute PE are due to RV pressure overload and subsequent RV failure. The goal of fibrinolysis in acute PE is to rapidly reduce RV afterload and avert impending hemodynamic collapse and death. Although generally considered to be a life-saving intervention in massive PE, fibrinolysis remains controversial for submassive PE. Successful administration of fibrinolytic therapy requires weighing benefit versus risk. Major bleeding, in particular intracranial hemorrhage, is the most feared complication of fibrinolysis. Alternatives to fibrinolysis for acute PE, including surgical embolectomy, catheter-assisted embolectomy, and inferior vena cava (IVC) filter insertion, should be considered when contraindications exist or when patients have failed to respond to an initial trial of fibrinolytic therapy. Patients with massive and submassive PE may be best served by rapid triage to specialized centers with experience in the administration of fibrinolytic therapy and the capacity to offer alternative advanced therapies such as surgical and catheter-assisted embolectomy.

Increases in circulating matrix metalloproteinase-9 levels following fibrinolysis for acute pulmonary embolism

INTRODUCTION

Fibrinolyis is one of the first line therapies in high risk pulmonary embolism (PE) according to current guidelines. Previous studies showed that fibrinolytic therapy with tPA (tissue plasminogen activator, or alteplase) upregulates the concentrations of matrix metalloproteinases (MMPs) and contributes to hemorrhagic transformation after cardioembolic stroke. However, no previous study has described the circulating MMPs levels following fibrinolysis for acute PE.

MATERIALS AND METHODS

We serially measured the circulating levels of MMPs (MMP-9 and MMP-2) and their endogenous inhibitors, the tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in alteplase and in streptokinase-treated patients with acute PE by gelatin zymography and by enzyme-linked immunosorbent assays, respectively.

RESULTS

We found that therapy of PE streptokinase or with alteplase is associated increased pro-MMP-9, but not MMP-2, concentrations for up to 24hours, whereas no significant changes were found in TIMP-1 or TIMP-2 concentrations. This alteration returned to normal 3 to 5days after thrombolysis. This is the first study reporting on MMPs alterations following fibrinolysis for acute PE.

CONCLUSIONS

We found transient increases in circulating pro-MMP-9 levels following fibrinolysis for acute PE. Our findings support the hypothesis that increased MMP-9 levels may underlie the risk of intracerebral hemorrhage or other bleeding complication of thrombolysis for acute PE, and the use of MMP inhibitors may decrease such risk.

Low-dose urokinase in massive pulmonary embolism when standard thrombolysis is contraindicated

When acute massive pulmonary embolism is life threatening, thrombolysis could be a therapeutic option. However, lysis may be contraindicated once the risk of bleeding is high. We report on two patients who have massive pulmonary emboli complicated by severe hypotension, justifying thrombolytic treatment. Nevertheless, recent surgery in the first patient and a fresh hemorrhagic duodenal ulcer in the second patient precluded thrombolytic treatment at the usual dosage. Therefore, prolonged lysis with low-dose urokinase (1,000 units/kg/h) was initiated. After a few hours, the patients became hemodynamically stable and inotrope/vasopressor doses could be reduced and stopped. No major bleeding was observed. Consequently, prolonged thrombolysis with low-dose urokinase could be an alternative approach to therapy in patients with massive pulmonary emboli when recommended thrombolytic dosages are contraindicated.

Efficacy and safety of low dose recombinant tissue-type plasminogen activator for the treatment of acute pulmonary thromboembolism: a randomized, multicenter, controlled trial

Background

Optimal dosing of the recombinant tissue-type plasminogen activator (rt-PA) is important in treating pulmonary thromboembolism (PTE). The aim of this study was to compare the efficacy and safety of a 50 mg/2 h rt-PA regimen with a 100 mg/2 h rt-PA regimen in patients with acute PTE.

Methods

A prospective, randomized, multicenter trial was conducted in which 118 patients with acute PTE and either hemodynamic instability or massive pulmonary artery obstruction were randomly assigned to receive a treatment regiment of either rt-PA at 50 mg/2 h (n = 65) or 100 mg/2 h (n = 53). The efficacy was determined by observing the improvements of right ventricular dysfunctions (RVDs) on echocardiograms, lung perfusion defects on ventilation perfusion lung scans, and pulmonary artery obstructions on CT angiograms. The adverse events, including death, bleeding, and PTE recurrence, were also evaluated.

Results

Progressive improvements in RVDs, lung perfusion defects, and pulmonary artery obstructions were found to be similarly significant in both treatment groups. This is true for patients with either hemodynamic instability or massive pulmonary artery obstruction. Three (6%) patients in the rt-PA 100 mg/2 h group and one (2%) in the rt-PA 50 mg/2 h group died as the result of either PTE or bleeding. Importantly, the 50 mg/2 h rt-PA regimen resulted in less bleeding tendency than the 100 mg/2 h regimen (3% vs 10%), especially in patients with a body weight < 65 kg (14.8% vs 41.2%, P = .049). No fatal recurrent PTE was found in either group.

Conclusions

Compared with the 100 mg/2 h regimen, the 50 mg/2 h rt-PA regimen exhibits similar efficacy and perhaps better safety in patients with acute PTE. These findings support the notion that optimizing rt-PA dosing is worthwhile when treating patients with PTE.

Trial registration

clinicaltrials.gov; Identifier: NCT00781378

Venous thrombotic emergencies

Thrombosis is a common complication of cancer, occurring in up to 15% of patients. This article reviews the diagnosis and management of the most common cancer-related thrombotic problem; deep venous thrombosis, pulmonary embolism, and catheterrelated thrombosis. Rarer entities, such as cerebral vein thrombosis and Budd-Chiari syndrome, are also reviewed.

Characterization of antiplatelet properties of silver nanoparticles

Thrombotic disorders have emerged as serious threat to society. As anticoagulant and thrombolytic therapies are usually associated with serious bleeding complications, the focus has now shifted to regulating and maintaining platelets in an inactive state. In the present study we show that nanosilver has an innate antiplatelet property and effectively prevents integrin-mediated platelet responses, both in vivo and in vitro, in a concentration-dependent manner. Ultrastructural studies show that nanosilver accumulates within platelet granules and reduces interplatelet proximity. Our findings further suggest that these nanoparticles do not confer any lytic effect on platelets and thus hold potential to be promoted as antiplatelet/antithrombotic agents after careful evaluation of toxic effects.

Acute submassive pulmonary embolism following varicose vein surgery in a patient receiving hormonal replacement therapy

Acute pulmonary embolism following varicose vein surgery is reported in a patient receiving hormonal replacement therapy. A 45-year-old woman underwent partial stripping of the greater saphenous vein of her bilateral legs and division of the lesser saphenous vein of her left legs under spinal anesthesia. On the first postoperative day, she complained of severe chest discomfort and collapsed suddenly while walking to the toilet. Emergency spiral computed tomography and perfusion scintigraphy demonstrated multiple defects in the bilateral lower lobes. She recovered after aggressive anticoagulant therapy. Although acute pulmonary embolism occurs only rarely after varicose vein surgery, it is important to remember its possibility especially when a patient has known risk factors predisposing venous thromboembolism, such as hormone replacement therapy.

Unexpected complication of massive intraoperative pulmonary embolism following elective sigmoidectomy in the supine position

We describe a case of massive intraoperative pulmonary thromboembolism during elective sigmoidectomy in the supine position. During recovery from anesthesia, the patient developed hemodynamic compromise and severe hypoxemia. Intravenous inotropes and mechanical ventilation were instituted. The abrupt onset of symptoms and the pulmonary artery catheter, chest radiograph, and transesophageal echocardiography findings suggested massive pulmonary thromboembolism as a possible cause of the hemodynamic compromise and hypoxemia. Emergent angiography could not be carried out due to the patient's poor clinical status. Lack of experience in performing embolectomy, along with contraindication for thrombolysis, imposed the use of intravenous heparin and hemodynamic support as the only appropriate therapeutic modality. After 2 days' aggressive hemodynamic and ventilatory support, the patient had an uneventful course, and was discharged from the intensive care unit (ICU) 14 days later.